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Sample records for symmetry breaking induced

  1. Gedanken Worlds without Higgs: QCD-Induced Electroweak Symmetry Breaking

    Energy Technology Data Exchange (ETDEWEB)

    Quigg, Chris; /Fermilab /Karlsruhe U., TTP; Shrock, Robert; /YITP, Stony Brook

    2009-01-01

    To illuminate how electroweak symmetry breaking shapes the physical world, we investigate toy models in which no Higgs fields or other constructs are introduced to induce spontaneous symmetry breaking. Two models incorporate the standard SU(3){sub c} {circle_times} SU(2){sub L} {circle_times} U(1){sub Y} gauge symmetry and fermion content similar to that of the standard model. The first class--like the standard electroweak theory--contains no bare mass terms, so the spontaneous breaking of chiral symmetry within quantum chromodynamics is the only source of electroweak symmetry breaking. The second class adds bare fermion masses sufficiently small that QCD remains the dominant source of electroweak symmetry breaking and the model can serve as a well-behaved low-energy effective field theory to energies somewhat above the hadronic scale. A third class of models is based on the left-right-symmetric SU(3){sub c} {circle_times} SU(2){sub L} {circle_times} SU(2){sub R} {circle_times} U(1)B?L gauge group. In a fourth class of models, built on SU(4){sub PS} {circle_times} SU(2){sub L} {circle_times} SU(2){sub R} gauge symmetry, lepton number is treated as a fourth color. Many interesting characteristics of the models stem from the fact that the effective strength of the weak interactions is much closer to that of the residual strong interactions than in the real world. The Higgs-free models not only provide informative contrasts to the real world, but also lead us to consider intriguing issues in the application of field theory to the real world.

  2. Lipid Aggregates Inducing Symmetry Breaking in Prebiotic Polymerisations

    Science.gov (United States)

    Piotto, Stefano

    2004-02-01

    It is a long-standing and still open problem to determine the origin of biomolecular homochirality, and many scenarios have been suggested. Amphiphilic molecules are renowned for their capability to reorganize themselves in a variety of different morphologies and topologies, and for their capability to partition chemicals in well defined domains. Here a possible role for amphiphilic molecules inducing symmetry breaking is suggested in the framework of the research on origin of life.

  3. Could dynamical Lorentz symmetry breaking induce the superluminal neutrinos?

    Energy Technology Data Exchange (ETDEWEB)

    Nojiri, Shin' ichi [Nagoya University, Department of Physics, Nagoya (Japan); Nagoya University, Kobayashi-Maskawa Institute for the Origin of Particles and the Universe, Nagoya (Japan); Odintsov, Sergei D. [Facultat de Ciencies, Institucio Catalana de Recerca i Estudis Avancats (ICREA) and Institut de Ciencies de l' Espai (IEEC-CSIC), Campus UAB, Bellaterra (Barcelona) (Spain); Tomsk State Pedagogical University, Tomsk (Russian Federation)

    2011-11-15

    A toy fermion model coupled to the Lagrange multiplier constraint field is proposed. The possibility of superluminal neutrino propagation as a result of dynamical Lorentz symmetry breaking is studied. (orig.)

  4. Curvature-induced symmetry breaking in nonlinear Schrodinger models

    DEFF Research Database (Denmark)

    Gaididei, Yuri Borisovich; Mingaleev, S. F.; Christiansen, Peter Leth

    2000-01-01

    We consider a curved chain of nonlinear oscillators and show that the interplay of curvature and nonlinearity leads to a symmetry breaking when an asymmetric stationary state becomes energetically more favorable than a symmetric stationary state. We show that the energy of localized states decrea...

  5. Effects of translational symmetry breaking induced by the boundaries in a driven diffusive system

    DEFF Research Database (Denmark)

    Andersen, Jørgen Vitting; Leung, Kwan-tai

    1991-01-01

    We study the effects of the boundary conditions in a driven diffusive lattice-gas model which is known to display kinetic phase transitions. We find, in the case of attractive interaction, that a boundary-condition-induced symmetry breaking of the translational invariance, along the direction of ...

  6. Bootstrap Dynamical Symmetry Breaking

    Directory of Open Access Journals (Sweden)

    Wei-Shu Hou

    2013-01-01

    Full Text Available Despite the emergence of a 125 GeV Higgs-like particle at the LHC, we explore the possibility of dynamical electroweak symmetry breaking by strong Yukawa coupling of very heavy new chiral quarks Q . Taking the 125 GeV object to be a dilaton with suppressed couplings, we note that the Goldstone bosons G exist as longitudinal modes V L of the weak bosons and would couple to Q with Yukawa coupling λ Q . With m Q ≳ 700  GeV from LHC, the strong λ Q ≳ 4 could lead to deeply bound Q Q ¯ states. We postulate that the leading “collapsed state,” the color-singlet (heavy isotriplet, pseudoscalar Q Q ¯ meson π 1 , is G itself, and a gap equation without Higgs is constructed. Dynamical symmetry breaking is affected via strong λ Q , generating m Q while self-consistently justifying treating G as massless in the loop, hence, “bootstrap,” Solving such a gap equation, we find that m Q should be several TeV, or λ Q ≳ 4 π , and would become much heavier if there is a light Higgs boson. For such heavy chiral quarks, we find analogy with the π − N system, by which we conjecture the possible annihilation phenomena of Q Q ¯ → n V L with high multiplicity, the search of which might be aided by Yukawa-bound Q Q ¯ resonances.

  7. Chiral symmetry and chiral-symmetry breaking

    Energy Technology Data Exchange (ETDEWEB)

    Peskin, M.E.

    1982-12-01

    These lectures concern the dynamics of fermions in strong interaction with gauge fields. Systems of fermions coupled by gauge forces have a very rich structure of global symmetries, which are called chiral symmetries. These lectures will focus on the realization of chiral symmetries and the causes and consequences of thier spontaneous breaking. A brief introduction to the basic formalism and concepts of chiral symmetry breaking is given, then some explicit calculations of chiral symmetry breaking in gauge theories are given, treating first parity-invariant and then chiral models. These calculations are meant to be illustrative rather than accurate; they make use of unjustified mathematical approximations which serve to make the physics more clear. Some formal constraints on chiral symmetry breaking are discussed which illuminate and extend the results of our more explicit analysis. Finally, a brief review of the phenomenological theory of chiral symmetry breaking is presented, and some applications of this theory to problems in weak-interaction physics are discussed. (WHK)

  8. Tadpole-induced electroweak symmetry breaking and pNGB Higgs models

    Energy Technology Data Exchange (ETDEWEB)

    Harnik, Roni; Howe, Kiel; Kearney, John [Theoretical Physics Department, Fermi National Accelerator Laboratory, Batavia, IL 60510 (United States)

    2017-03-22

    We investigate induced electroweak symmetry breaking (EWSB) in models in which the Higgs is a pseudo-Nambu-Goldstone boson (pNGB). In pNGB Higgs models, Higgs properties and precision electroweak measurements imply a hierarchy between the EWSB and global symmetry-breaking scales, v{sub H}≪f{sub H}. When the pNGB potential is generated radiatively, this hierarchy requires fine-tuning to a degree of at least ∼v{sub H}{sup 2}/f{sub H}{sup 2}. We show that if Higgs EWSB is induced by a tadpole arising from an auxiliary sector at scale f{sub Σ}≪v{sub H}, this tuning is significantly ameliorated or can even be removed. We present explicit examples both in Composite Higgs models based on SO(5)/SO(4) and in Twin Higgs models. For the Twin case, the result is a fully natural model with f{sub H}∼1 TeV and the lightest colored top partners at 2 TeV. These models also have an appealing mechanism to generate the scales of the auxiliary sector and Higgs EWSB directly from the scale f{sub H}, with a natural hierarchy f{sub Σ}≪v{sub H}≪f{sub H}∼TeV. The framework predicts modified Higgs coupling as well as new Higgs and vector states at LHC13.

  9. Heat-induced symmetry breaking in ant (Hymenoptera: Formicidae escape behavior.

    Directory of Open Access Journals (Sweden)

    Yuan-Kai Chung

    Full Text Available The collective egress of social insects is important in dangerous situations such as natural disasters or enemy attacks. Some studies have described the phenomenon of symmetry breaking in ants, with two exits induced by a repellent. However, whether symmetry breaking occurs under high temperature conditions, which are a common abiotic stress, remains unknown. In our study, we deposited a group of Polyrhachis dives ants on a heated platform and counted the number of escaping ants with two identical exits. We discovered that ants asymmetrically escaped through two exits when the temperature of the heated platform was >32.75°C. The degree of asymmetry increased linearly with the temperature of the platform. Furthermore, the higher the temperature of heated platform was, the more ants escaped from the heated platform. However, the number of escaping ants decreased for 3 min when the temperature was higher than the critical thermal limit (39.46°C, which is the threshold for ants to endure high temperature without a loss of performance. Moreover, the ants tended to form small groups to escape from the thermal stress. A preparatory formation of ant grouping was observed before they reached the exit, indicating that the ants actively clustered rather than accidentally gathered at the exits to escape. We suggest that a combination of individual and grouping ants may help to optimize the likelihood of survival during evacuation.

  10. Population structure induces a symmetry breaking favoring the emergence of cooperation.

    Directory of Open Access Journals (Sweden)

    Jorge M Pacheco

    2009-12-01

    Full Text Available The evolution of cooperation described in terms of simple two-person interactions has received considerable attention in recent years, where several key results were obtained. Among those, it is now well established that the web of social interaction networks promotes the emergence of cooperation when modeled in terms of symmetric two-person games. Up until now, however, the impacts of the heterogeneity of social interactions into the emergence of cooperation have not been fully explored, as other aspects remain to be investigated. Here we carry out a study employing the simplest example of a prisoner's dilemma game in which the benefits collected by the participants may be proportional to the costs expended. We show that the heterogeneous nature of the social network naturally induces a symmetry breaking of the game, as contributions made by cooperators may become contingent on the social context in which the individual is embedded. A new, numerical, mean-field analysis reveals that prisoner's dilemmas on networks no longer constitute a defector dominance dilemma--instead, individuals engage effectively in a general coordination game. We find that the symmetry breaking induced by population structure profoundly affects the evolutionary dynamics of cooperation, dramatically enhancing the feasibility of cooperators: cooperation blooms when each cooperator contributes the same cost, equally shared among the plethora of games in which she participates. This work provides clear evidence that, while individual rational reasoning may hinder cooperative actions, the intricate nature of social interactions may effectively transform a local dilemma of cooperation into a global coordination problem.

  11. Spontaneous mirror-symmetry breaking induces inverse energy cascade in 3D active fluids

    CERN Document Server

    Słomka, Jonasz

    2016-01-01

    Classical turbulence theory assumes that energy transport in a 3D turbulent flow proceeds through a Richardson cascade whereby larger vortices successively decay into smaller ones. By contrast, an additional inverse cascade characterized by vortex-mergers exists in 2D fluids and gases, with profound implications for meteorological flows and fluid mixing. The possibility of a helicity-driven inverse cascade in 3D fluids had been rejected in the 1970s based on equilibrium-thermodynamic arguments. Recently, however, it was proposed that certain symmetry breaking processes could potentially trigger a 3D inverse cascade, but no physical system exhibiting this phenomenon has been identified to date. Here, we present direct analytical and numerical evidence for the existence of a robust inverse energy cascade in an experimentally validated 3D active fluid model, describing microbial suspension flows that spontaneously break mirror-symmetry. We show analytically that self-organized scale selection, a generic feature ...

  12. Dynamical instability induced by the zero mode under symmetry breaking external perturbation

    Science.gov (United States)

    Takahashi, J.; Nakamura, Y.; Yamanaka, Y.

    2014-08-01

    A complex eigenvalue in the Bogoliubov-de Gennes equations for a stationary Bose-Einstein condensate in the ultracold atomic system indicates the dynamical instability of the system. We also have the modes with zero eigenvalues for the condensate, called the zero modes, which originate from the spontaneous breakdown of symmetries. Although the zero modes are suppressed in many theoretical analyses, we take account of them in this paper and argue that a zero mode can change into one with a pure imaginary eigenvalue by applying a symmetry breaking external perturbation potential. This emergence of a pure imaginary mode adds a new type of scenario of dynamical instability to that characterized by the complex eigenvalue of the usual excitation modes. For illustration, we deal with two one-dimensional homogeneous Bose-Einstein condensate systems with a single dark soliton under a respective perturbation potential, breaking the invariance under translation, to derive pure imaginary modes.

  13. Symmetry breaking of localized discrete matter waves induced by spin–orbit coupling

    Energy Technology Data Exchange (ETDEWEB)

    Salerno, M. [Dipartimento di Fisica “E.R. Caianiello”, CNISM and INFN–Gruppo Collegato di Salerno, Universitá di Salerno, Via Giovanni Paolo II, 84084 Fisciano (Italy); Abdullaev, F.Kh., E-mail: fatkhulla@yahoo.com [Department of Physics, Kulliyyah of Science, International Islamic University of Malaysia, 25200 Kuantan, Pahang (Malaysia)

    2015-10-02

    We study localized nonlinear excitations of a dilute Bose–Einstein condensate (BEC) with spin–orbit coupling in a deep optical lattice (OL). For this we introduce a tight-binding model that includes the spin–orbit coupling (SOC) at the discrete level in the form of a generalized discrete nonlinear Schrödinger equation. Existence and stability of discrete solitons of different symmetry types is demonstrated. Quite interestingly, we find three distinctive regions in which discrete solitons undergo spontaneously symmetry breaking, passing from on-site to inter-site and to asymmetric, simply by varying the interatomic interactions. Existence ranges of discrete solitons with inter-site symmetry depend on SOC and shrink to zero as the SOC parameter is increased. Asymmetric discrete solitons appear as novel excitations specific of the SOC. Possible experimental implementation of these results is briefly discussed.

  14. Dynamical instability induced by the zero mode under symmetry breaking external perturbation

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, J., E-mail: phyco-sevenface@asagi.waseda.jp; Nakamura, Y., E-mail: nakamura@aoni.waseda.jp; Yamanaka, Y., E-mail: yamanaka@waseda.jp

    2014-08-15

    A complex eigenvalue in the Bogoliubov–de Gennes equations for a stationary Bose-Einstein condensate in the ultracold atomic system indicates the dynamical instability of the system. We also have the modes with zero eigenvalues for the condensate, called the zero modes, which originate from the spontaneous breakdown of symmetries. Although the zero modes are suppressed in many theoretical analyses, we take account of them in this paper and argue that a zero mode can change into one with a pure imaginary eigenvalue by applying a symmetry breaking external perturbation potential. This emergence of a pure imaginary mode adds a new type of scenario of dynamical instability to that characterized by the complex eigenvalue of the usual excitation modes. For illustration, we deal with two one-dimensional homogeneous Bose–Einstein condensate systems with a single dark soliton under a respective perturbation potential, breaking the invariance under translation, to derive pure imaginary modes. - Highlights: • Zero modes are important but ignored in many theories for the cold atomic system. • We discuss the zero mode under symmetry breaking potential in this system. • We consider the zero mode of translational invariance for a single dark soliton. • We show that it turns into an anomalous or pure imaginary mode.

  15. Baryon and chiral symmetry breaking

    Energy Technology Data Exchange (ETDEWEB)

    Gorsky, A. [Institute for Theoretical and Experimental Physics (ITEP), Moscow, Russia and Moscow Institute of Physics and Technology (MIPT), Dolgoprudny (Russian Federation); Krikun, A. [NORDITA, KTH Royal Institute of Technology and Stockholm University Stockholm, Sweden and Institute for Theoretical and Experimental Physics (ITEP), Moscow (Russian Federation)

    2014-07-23

    We briefly review the generalized Skyrmion model for the baryon recently suggested by us. It takes into account the tower of vector and axial mesons as well as the chiral symmetry breaking. The generalized Skyrmion model provides the qualitative explanation of the Ioffe’s formula for the baryon mass.

  16. Strong coupling electroweak symmetry breaking

    Energy Technology Data Exchange (ETDEWEB)

    Barklow, T.L. [Stanford Linear Accelerator Center, Menlo Park, CA (United States); Burdman, G. [Univ. of Wisconsin, Madison, WI (United States). Dept. of Physics; Chivukula, R.S. [Boston Univ., MA (United States). Dept. of Physics

    1997-04-01

    The authors review models of electroweak symmetry breaking due to new strong interactions at the TeV energy scale and discuss the prospects for their experimental tests. They emphasize the direct observation of the new interactions through high-energy scattering of vector bosons. They also discuss indirect probes of the new interactions and exotic particles predicted by specific theoretical models.

  17. A model of intrinsic symmetry breaking

    Energy Technology Data Exchange (ETDEWEB)

    Ge, Li [Research Center for Quantum Manipulation, Department of Physics, Fudan University, Shanghai 200433 (China); Li, Sheng [Department of Physics, Zhejiang Normal University, Zhejiang 310004 (China); George, Thomas F., E-mail: tfgeorge@umsl.edu [Office of the Chancellor and Center for Nanoscience, Department of Chemistry and Biochemistry, University of Missouri-St. Louis, St. Louis, MO 63121 (United States); Department of Physics and Astronomy, University of Missouri-St. Louis, St. Louis, MO 63121 (United States); Sun, Xin, E-mail: xin_sun@fudan.edu.cn [Research Center for Quantum Manipulation, Department of Physics, Fudan University, Shanghai 200433 (China)

    2013-11-01

    Different from the symmetry breaking associated with a phase transition, which occurs when the controlling parameter is manipulated across a critical point, the symmetry breaking presented in this Letter does not need parameter manipulation. Instead, the system itself suddenly undergoes symmetry breaking at a certain time during its evolution, which is intrinsic symmetry breaking. Through a polymer model, it is revealed that the origin of the intrinsic symmetry breaking is nonlinearity, which produces instability at the instance when the evolution crosses an inflexion point, where this instability breaks the original symmetry.

  18. Models of electroweak symmetry breaking

    CERN Document Server

    Pomarol, Alex

    2015-01-01

    This chapter present models of electroweak symmetry breaking arising from strongly interacting sectors, including both Higgsless models and mechanisms involving a composite Higgs. These scenarios have also been investigated in the framework of five-dimensional warped models that, according to the AdS/CFT correspondence, have a four-dimensional holographic interpretation in terms of strongly coupled field theories. We explore the implications of these models at the LHC.

  19. Big break for charge symmetry

    CERN Document Server

    Miller, G A

    2003-01-01

    Two new experiments have detected charge-symmetry breaking, the mechanism responsible for protons and neutrons having different masses. Symmetry is a crucial concept in the theories that describe the subatomic world because it has an intimate connection with the laws of conservation. The theory of the strong interaction between quarks - quantum chromodynamics - is approximately invariant under what is called charge symmetry. In other words, if we swap an up quark for a down quark, then the strong interaction will look almost the same. This symmetry is related to the concept of sup i sospin sup , and is not the same as charge conjugation (in which a particle is replaced by its antiparticle). Charge symmetry is broken by the competition between two different effects. The first is the small difference in mass between up and down quarks, which is about 200 times less than the mass of the proton. The second is their different electric charges. The up quark has a charge of +2/3 in units of the proton charge, while ...

  20. History of electroweak symmetry breaking

    CERN Document Server

    Kibble, T W B

    2015-01-01

    In this talk, I recall the history of the development of the unified electroweak theory, incorporating the symmetry-breaking Higgs mechanism, as I saw it from my standpoint as a member of Abdus Salam's group at Imperial College. I start by describing the state of physics in the years after the Second World War, explain how the goal of a unified gauge theory of weak and electromagnetic interactions emerged, the obstacles encountered, in particular the Goldstone theorem, and how they were overcome, followed by a brief account of more recent history, culminating in the historic discovery of the Higgs boson in 2012.

  1. Marangoni-induced symmetry-breaking pattern selection on viscous fluids

    Science.gov (United States)

    Shen, Li; Denner, Fabian; Morgan, Neal; van Wachem, Berend; Dini, Daniele

    2016-11-01

    Symmetry breaking transitions on curved surfaces are found in a wide range of dissipative systems, ranging from asymmetric cell divisions to structure formation in thin films. Inherent within the nonlinearities are the associated curvilinear geometry, the elastic stretching, bending and the various fluid dynamical processes. We present a generalised Swift-Hohenberg pattern selection theory on a thin, curved and viscous films in the presence of non-trivial Marangoni effect. Testing the theory with experiments on soap bubbles, we observe the film pattern selection to mimic that of the elastic wrinkling morphology on a curved elastic bilayer in regions of slow viscous flow. By examining the local state of damping of surface capillary waves we attempt to establish an equivalence between the Marangoni fluid dynamics and the nonlinear elastic shell theory above the critical wavenumber of the instabilities and propose a possible explanation for the perceived elastic-fluidic duality. The authors acknowledge the financial support of the Shell University Technology Centre for fuels and lubricants.

  2. Dynamical time-reversal symmetry breaking and photo-induced chiral spin liquids in frustrated Mott insulators.

    Science.gov (United States)

    Claassen, Martin; Jiang, Hong-Chen; Moritz, Brian; Devereaux, Thomas P

    2017-10-30

    The search for quantum spin liquids in frustrated quantum magnets recently has enjoyed a surge of interest, with various candidate materials under intense scrutiny. However, an experimental confirmation of a gapped topological spin liquid remains an open question. Here, we show that circularly polarized light can provide a knob to drive frustrated Mott insulators into a chiral spin liquid, realizing an elusive quantum spin liquid with topological order. We find that the dynamics of a driven Kagome Mott insulator is well-captured by an effective Floquet spin model, with heating strongly suppressed, inducing a scalar spin chirality S i · (S j  × S k ) term which dynamically breaks time-reversal while preserving SU(2) spin symmetry. We fingerprint the transient phase diagram and find a stable photo-induced chiral spin liquid near the equilibrium state. The results presented suggest employing dynamical symmetry breaking to engineer quantum spin liquids and access elusive phase transitions that are not readily accessible in equilibrium.

  3. Light-induced symmetry breaking and related giant enhancement of nonlinear properties in CdZnTe:V crystals.

    Science.gov (United States)

    Shwartz, Sharon; Weil, Raoul; Segev, Mordechai; Lakin, Eugene; Zolotoyabko, Emil; Menon, Vinod M; Forrest, Stephen R; El-Hanany, Uri

    2006-10-02

    We report on enormous light-induced reversible strain effects in CdZnTe:V crystals, which lead to a remarkable enhancement of their nonlinear properties, such as electrostriction and electro-optic effects. Using both high resolution x-ray diffraction and optical interferometry we measure light-induced relative deformation of the initial crystalline lattice (changes in d-spacings) up to 0.15%. The experimental findings are attributed to light-induced breaking of the initial cubic crystalline symmetry. Our results point to a family of inorganic materials whose nonlinear properties can be remarkably enhanced by light, offering new possibilities for nonlinear frequency conversion, generation of Terahertz radiation, electro-optic modulation, and self-deflection of optical beams.

  4. Mathematical models of spontaneous symmetry breaking

    OpenAIRE

    Sardanashvily, G.

    2008-01-01

    The Higgs mechanism of mass generation is the main ingredient in the contemporary Standard Model and its various generalizations. However, there is no comprehensive theory of spontaneous symmetry breaking. We summarize the relevant mathematical results characterizing spontaneous symmetry breaking phenomena in algebraic quantum theory, axiomatic quantum field theory, group theory, and classical gauge theory.

  5. Symmetry breaking signaling mechanisms during cell polarization

    NARCIS (Netherlands)

    Bruurs, LJM|info:eu-repo/dai/nl/413640779

    2017-01-01

    Breaking of cellular symmetry in order to establish an apico-basal polarity axis initiates de novo formation of cell polarity. However, symmetry breaking provides a formidable challenge from a signaling perspective, because by definition no spatial cues are present to instruct axis establishment.

  6. Ras activation and symmetry breaking during Dictyostelium chemotaxis

    NARCIS (Netherlands)

    Kortholt, Arjan; Keizer-Gunnink, Ineke; Kataria, Rama; Van Haastert, Peter J. M.

    2013-01-01

    Central to chemotaxis is the molecular mechanism by which a shallow spatial gradient of chemoattractant induces symmetry breaking of activated signaling molecules. Previously, we have used Dictyostelium mutants to investigate the minimal requirements for chemotaxis, and identified a basal signaling

  7. Symmetry Breaking in Hofstadter's Butterfly in graphene

    Science.gov (United States)

    Forsythe, Carlos; Dean, Cory; Wang, Lei; Maher, Patrick; Ghahari, Fereshte; Moon, Pilkyung; Koshino, Mikito; Taniguchi, Takashi; Watanabe, Kenji; Shepard, Ken; Hone, Jim; Kim, Philip

    2013-03-01

    We will present magnetotransport measurements in hBN encapsulated bilayer graphene devices where one of hBN substrates provides a weak modulation of lattice potential. Under a strong magnetic field, interplay between periodic electric potential and quantizing magnetic field lead to a fractal energy spectrum known as Hofstadter's butterfly. In graphene, while spin and layer symmetry breakings are expected in dual gated devices under large magnetic fields, valley symmetry breaking in the Hofstadter regime is not so easily understood. We will present the observance of these measured gaps along with a discussion of symmetry breaking in our BLG-hBN devices. Further quantitative analysis of these breakings will be presented through the temperature dependence of quantized conductance at these gaps. Through careful modulation of temperature and electron density, we have extracted a range of activation energies associated with symmetry breakings. the speaker acknowledges support from the Columbia Optics and Quantum Electronics IGERT under NSF grant DGE-1069420

  8. Systems with Symmetry Breaking and Restoration

    Directory of Open Access Journals (Sweden)

    Vyacheslav I. Yukalov

    2010-01-01

    Full Text Available Statistical systems, in which spontaneous symmetry breaking can be accompanied by spontaneous local symmetry restoration, are considered. A general approach to describing such systems is formulated, based on the notion of weighted Hilbert spaces and configuration averaging. The approach is illustrated by the example of a ferroelectric with mesoscopic fluctuations of paraelectric phase. The influence of the local symmetry restoration on the system characteristics, such as sound velocity and Debye-Waller factor, is discussed.

  9. Model for chiral symmetry breaking in QCD

    Energy Technology Data Exchange (ETDEWEB)

    Govaerts, J.; Weyers, J.; Mandula, J.E.

    1984-04-30

    A recently proposed model for dynamical breaking of chiral symmetry in QCD is extended and developed for the calculation of pion and chiral symmetry breaking parameters. The pion is explicitly realized as a massless Goldstone boson and as a bound state of the constituent quarks. We compute, in the limit of exact chiral symmetry, Msub(Q), the constituent quark mass, fsub(..pi..), the pion decay coupling, , the constituent quark loop density, ..mu..sub(..pi..)/sup 2//msub(q), the ratio of the Goldstone boson mass squared to the bare quark mass, and sub(..pi..), the pion electromagnetic charge radius squared.

  10. Electromagnetic radiation under explicit symmetry breaking.

    Science.gov (United States)

    Sinha, Dhiraj; Amaratunga, Gehan A J

    2015-04-10

    We report our observation that radiation from a system of accelerating charges is possible only when there is explicit breaking of symmetry in the electric field in space within the spatial configuration of the radiating system. Under symmetry breaking, current within an enclosed area around the radiating structure is not conserved at a certain instant of time resulting in radiation in free space. Electromagnetic radiation from dielectric and piezoelectric material based resonators are discussed in this context. Finally, it is argued that symmetry of a resonator of any form can be explicitly broken to create a radiating antenna.

  11. Strain-induced chiral symmetry breaking leads to Dirac cone opening in graphene heterostructure

    Science.gov (United States)

    Munoz, Enrique; Das, Deya; Bhattacharyya, Swastibrata; Singh, Abhishek

    Using first-principles calculations, we report a large band-gap opening in the van der Waals heterostructure of graphene and graphane (hydrogenated graphene) under normal compressive (NC) strain. In the presence of graphane, interlayer charge transfer from graphene to graphane triggers the intralayer charge redistribution in graphene, breaking the equivalence of the two sublattices. The application of the NC strain enhances the inter- and intralayer charge transfer leading to a splitting of the Dirac cone, reflected as a redshift of the G peak in Raman spectra. We further present an analytical theory, based on the Dirac approximation, that provides a simple explanation of this effect within a general framework that suggests the same mechanism for band gap opening can be observed in other graphene based heterostructures. The authors acknowledge the Materials Research Centre and Super-computer Education and Research Centre, Indian Institute of Science for the computing facilities. E. Munoz Acknowledges Fondecyt No 1141146.

  12. Spontaneous Symmetry Breaking in Nonrelativistic Systems

    Science.gov (United States)

    Watanabe, Haruki

    The subject of condensed matter physics is very rich --- there are an infinite number of parameters producing a diversity of exciting phenomena. As a theorist, my goal is to distill general principles out of this complexity --- to construct theories that can coherently explain many known examples altogether. This thesis is composed of several attempts to develop such theories in topics related to spontaneously symmetry breaking. A remarkable feature of many-body interacting systems is that although they are described by equations respecting various symmetries, they may spontaneously organize into a state that explicitly breaks symmetries. Examples are numerous: various types of crystalline and magnetic orders, Bose-Einstein condensates of cold atoms, superfluids of liquid helium, chiral symmetry in QCD, neutron stars, and cosmic inflation. These systems with spontaneously broken continuous symmetries have gapless excitations, so called Nambu-Goldstone bosons (NGBs). Although the properties of NGBs are well understood in Lorentz-invariant systems, surprisingly, some basic properties of NGBs such as their number and dispersion in nonrelativistic systems have not been discussed from a general perspective. In the first part of this thesis, we solve this issue by developing and analyzing an effective Lagrangian that coherently captures the low-energy, long-distance physics of many different symmetry-breaking states all at once. Next, we examine whether these NGBs originating from spontaneous symmetry breaking remain to be well-defined excitations inside a metal, where low-energy electrons near Fermi surface can collide with them. Our result is a one equation criterion that specifies whether the interactions between electrons and NGBs can be ignored, or whether it completely changes their character. In the latter case, unusual phases of matter such as non-Fermi liquids may arise; in that case, NGBs are overdamped and cannot form particle-like excitations in spite of the

  13. Workshop on electroweak symmetry breaking: proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Hinchliffe, I. (ed.)

    1984-10-01

    A theoretical workshop on electroweak symmetry breaking at the Superconducting Supercollider was held at Lawrence Berkeley Laboratory, June 4-22, 1984. The purpose of the workshop was to focus theoretical attention on the ways in which experimentation at the SSC could reveal manifestations of the phenomenon responsible for electroweak symmetry breaking. This issue represents, at present, the most compelling scientific argument for the need to explore the energy region to be made accessible by the SSC, and a major aim of the workshop was to involve a broad cross section of particle theorists in the ongoing process of sharpening the requirements for both accelerator and detector design that will ensure detection and identification of meaningful signals, whatever form the electroweak symmetry breaking phenomenon should actually take. Separate entries were prepared for the data base for the papers presented.

  14. Noise-induced symmetry breaking far from equilibrium and the emergence of biological homochirality

    Science.gov (United States)

    Jafarpour, Farshid; Biancalani, Tommaso; Goldenfeld, Nigel

    2017-03-01

    The origin of homochirality, the observed single-handedness of biological amino acids and sugars, has long been attributed to autocatalysis, a frequently assumed precursor for early life self-replication. However, the stability of homochiral states in deterministic autocatalytic systems relies on cross-inhibition of the two chiral states, an unlikely scenario for early life self-replicators. Here we present a theory for a stochastic individual-level model of autocatalytic prebiotic self-replicators that are maintained out of thermal equilibrium. Without chiral inhibition, the racemic state is the global attractor of the deterministic dynamics, but intrinsic multiplicative noise stabilizes the homochiral states. Moreover, we show that this noise-induced bistability is robust with respect to diffusion of molecules of opposite chirality, and systems of diffusively coupled autocatalytic chemical reactions synchronize their final homochiral states when the self-replication is the dominant production mechanism for the chiral molecules. We conclude that nonequilibrium autocatalysis is a viable mechanism for homochirality, without imposing additional nonlinearities such as chiral inhibition.

  15. Spontaneous symmetry breaking in gauge theories.

    Science.gov (United States)

    Kibble, T W B

    2015-01-13

    The aim of this historical article is to describe the development of the idea of spontaneous symmetry breaking in gauge theories as seen from my perspective as a member of Abdus Salam's group at Imperial College London, UK. Beginning with an account of particle physics in the years after the Second World War, I describe early attempts at constructing a unified theory of weak and electromagnetic interactions, the obstacles encountered and how they were eventually overcome with the mass-generating mechanism incorporating the idea of spontaneous symmetry breaking, one of whose features is the now-famous Higgs boson.

  16. Dynamical Symmetry Breaking in RN Quantum Gravity

    Directory of Open Access Journals (Sweden)

    A. T. Kotvytskiy

    2011-01-01

    Full Text Available We show that in the RN gravitation model, there is no dynamical symmetry breaking effect in the formalism of the Schwinger-Dyson equation (in flat background space-time. A general formula for the second variation of the gravitational action is obtained from the quantum corrections hμν (in arbitrary background metrics.

  17. Effects Induced by the Initial Condition in the Quantum Kibble–Zurek Scaling for Changing the Symmetry-Breaking Field

    Directory of Open Access Journals (Sweden)

    Liang-Jun Zhai

    2016-12-01

    Full Text Available The Kibble–Zurek scaling describes the driven critical dynamics starting with an equilibrium state far away from the critical point. Recently, it has been shown that scaling behaviors also exist when the fluctuation term changes starting near the critical point. In this case, the relevant initial conditions should be included in the scaling theory as additional scaling variables. Here, we study the driven quantum critical dynamics in which a symmetry-breaking field is linearly changed starting from the vicinity of the critical point. We find that, similar to the case of changing the fluctuation term, scaling behaviors in the driven dynamics can be described by the Kibble–Zurek scaling with the initial symmetry-breaking field being included as its additional scaling variable. Both the cases of zero and finite temperatures are considered, and the scaling forms of the order parameter and the entanglement entropy are obtained. We numerically verify the scaling theory by taking the quantum Ising model as an example.

  18. Covalent bond symmetry breaking and protein secondary structure

    OpenAIRE

    Lundgren, Martin; Niemi, Antti J.

    2011-01-01

    Both symmetry and organized breaking of symmetry have a pivotal r\\^ole in our understanding of structure and pattern formation in physical systems, including the origin of mass in the Universe and the chiral structure of biological macromolecules. Here we report on a new symmetry breaking phenomenon that takes place in all biologically active proteins, thus this symmetry breaking relates to the inception of life. The unbroken symmetry determines the covalent bond geometry of a sp3 hybridized ...

  19. Symmetry and symmetry breaking; Symetrie et brisure de symetrie

    Energy Technology Data Exchange (ETDEWEB)

    Balian, R. [CEA/Saclay, Direction des Sciences de la Matiere (DSM), 91 - Gif-sur-Yvette (France); Lambert, D. [Facultes Universitaires Notre-Dame de la Paix, Namur (Belgium); Brack, A. [Centre National de la Recherche Scientifique (CNRS), 45 - Orleans-la-Source (France). Centre de Biophysique Moleculaire; Englert, F. [Universite Libre de Bruxelles (Belgium). Laboratoire de Physique Theorique; Chomaz, Ph. [Grand Accelerateur National d`Ions Lourds (GANIL), 14 - Caen (France); Lachieze-Rey, M. [CEA/Saclay, Dept. d`Astrophysique, de la Physique des Particules, de la Physique Nucleaire et de l`Instrumentation Associee (DAPNIA), 91 - Gif-sur-Yvette (France); Emery, E. [Ecole Polytechnique Federale, Lausanne (Switzerland); Cohen-Tannoudji, G.; Sacquin, Y

    1999-11-01

    The symmetry concept is a powerful tool for our understanding of the world. It allows a reduction of the volume of information needed to apprehend a subject thoroughly. Moreover this concept does not belong to a particular field, it is involved in the exact sciences but also in artistic matters. Living beings are characterized by a particular asymmetry: the chiral asymmetry. Although this asymmetry is visible in whole organisms, it seems it comes from some molecules that life always produce in one chirality. The weak interaction presents also the chiral asymmetry. The mass of particles comes from the breaking of a fundamental symmetry and the void could be defined as the medium showing as many symmetries as possible. The texts put together in this book show to a great extent how symmetry goes far beyond purely geometrical considerations. Different aspects of symmetry ideas are considered in the following fields: the states of matter, mathematics, biology, the laws of Nature, quantum physics, the universe, and the art of music. (A.C.) 103 refs.

  20. Symmetry and symmetry breaking. Symetrie et brisure de symetrie

    Energy Technology Data Exchange (ETDEWEB)

    Balian, R. (CEA/Saclay, Direction des Sciences de la Matiere (DSM), 91 - Gif-sur-Yvette (France)); Lambert, D. (Facultes Universitaires Notre-Dame de la Paix, Namur (Belgium)); Brack, A. (Centre National de la Recherche Scientifique (CNRS), 45 - Orleans-la-Source (France). Centre de Biophysique Moleculaire); Englert, F. (Universite Libre de Bruxelles (Belgium). Laboratoire de Physique Theorique)

    1999-01-01

    The symmetry concept is a powerful tool for our understanding of the world. It allows a reduction of the volume of information needed to apprehend a subject thoroughly. Moreover this concept does not belong to a particular field, it is involved in the exact sciences but also in artistic matters. Living beings are characterized by a particular asymmetry: the chiral asymmetry. Although this asymmetry is visible in whole organisms, it seems it comes from some molecules that life always produce in one chirality. The weak interaction presents also the chiral asymmetry. The mass of particles comes from the breaking of a fundamental symmetry and the void could be defined as the medium showing as many symmetries as possible. The texts put together in this book show to a great extent how symmetry goes far beyond purely geometrical considerations. Different aspects of symmetry ideas are considered in the following fields: the states of matter, mathematics, biology, the laws of Nature, quantum physics, the universe, and the art of music. (A.C.) 103 refs.

  1. Mechanochemical symmetry breaking in Hydra aggregates.

    Science.gov (United States)

    Mercker, Moritz; Köthe, Alexandra; Marciniak-Czochra, Anna

    2015-05-05

    Tissue morphogenesis comprises the self-organized creation of various patterns and shapes. Although detailed underlying mechanisms are still elusive in many cases, an increasing amount of experimental data suggests that chemical morphogen and mechanical processes are strongly coupled. Here, we develop and test a minimal model of the axis-defining step (i.e., symmetry breaking) in aggregates of the Hydra polyp. Based on previous findings, we combine osmotically driven shape oscillations with tissue mechanics and morphogen dynamics. We show that the model incorporating a simple feedback loop between morphogen patterning and tissue stretch reproduces a wide range of experimental data. Finally, we compare different hypothetical morphogen patterning mechanisms (Turing, tissue-curvature, and self-organized criticality). Our results suggest the experimental investigation of bigger (i.e., multiple head) aggregates as a key step for a deeper understanding of mechanochemical symmetry breaking in Hydra. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  2. Insulators and metals with topological order and discrete symmetry breaking

    Science.gov (United States)

    Chatterjee, Shubhayu; Sachdev, Subir

    2017-05-01

    Numerous experiments have reported discrete symmetry breaking in the high-temperature pseudogap phase of the hole-doped cuprates, including breaking of one or more of lattice rotation, inversion, and time-reversal symmetries. In the absence of translational symmetry breaking or topological order, these conventional order parameters cannot explain the gap in the charged fermion excitation spectrum in the antinodal region. Zhao et al. [L. Zhao, D. H. Torchinsky, H. Chu, V. Ivanov, R. Lifshitz, R. Flint, T. Qi, G. Cao, and D. Hsieh, Nat. Phys. 12, 32 (2016), 10.1038/nphys3517] and Jeong et al. [J. Jeong, Y. Sidis, A. Louat, V. Brouet, and P. Bourges, Nat. Commun. 8, 15119 (2017), 10.1038/ncomms15119] have also reported inversion and time-reversal symmetry breaking in insulating Sr2IrO4 similar to that in the metallic cuprates, but coexisting with Néel order. We extend an earlier theory of topological order in insulators and metals, in which the topological order combines naturally with the breaking of these conventional discrete symmetries. We find translationally invariant states with topological order coexisting with both Ising-nematic order and spontaneous charge currents. The link between the discrete broken symmetries and the topological-order-induced pseudogap explains why the broken symmetries do not survive in the confining phases without a pseudogap at large doping. Our theory also connects to the O(3) nonlinear sigma model and CP1 descriptions of quantum fluctuations of the Néel order. In this framework, the optimal doping criticality of the cuprates is primarily associated with the loss of topological order.

  3. Higgsless approach to electroweak symmetry breaking

    CERN Document Server

    Grojean, Christophe

    2007-01-01

    Higgsless models are an attempt to achieve a breaking of the electroweak symmetry via boundary conditions at the end-points of a fifth dimension compactified on an interval, as an alternative to the usual Higgs mechanism. There is no physical Higgs scalar in the spectrum and the perturbative unitarity violation scale is delayed via the exchange of massive spin-1 KK resonances. The correct mass spectrum is reproduced in a model in warped space, which inherits a custodial symmetry from a left–right gauge symmetry in the bulk. Phenomenological challenges as well as collider signatures are presented. From the AdS/CFT perspective, this model appears as a weakly coupled dual to walking technicolour models.

  4. Coleman-Weinberg symmetry breaking in SU(8) induced by a third rank antisymmetric tensor scalar field II: the fermion spectrum

    Science.gov (United States)

    Adler, Stephen L.

    2017-07-01

    We continue our study of Coleman-Weinberg symmetry breaking induced by a third rank antisymmetric tensor scalar, in the context of the SU(8) model (Adler 2014 Int. J. Mod. Phys. A 29 1450130) we proposed earlier. We focus in this paper on qualitative features that will determine whether the model can make contact with the observed particle spectrum. We discuss the mechanism for giving the spin \\frac{3}{2} field a mass by the BEH mechanism, and analyze the remaining massless spin \\frac{1}{2} fermions, the global chiral symmetries, and the running couplings after symmetry breaking. We note that the smallest gluon mass matrix eigenvalue has an eigenvector suggestive of U(1) B-L , and conjecture that the theory runs to an infrared fixed point at which there is a massless gluon with 3 to  -1 ratios in generator components. Assuming this, we discuss a mechanism for making contact with the standard model, based on a conjectured asymmetric breaking of Sp(4) to SU(2) subgroups, one of which is the electroweak SU(2), and the other of which is a ‘technicolor’ group that binds the original SU(8) model fermions, which play the role of ‘preons’, into composites. Quarks can emerge as 5 preon composites and leptons as 3 preon composites, with consequent stability of the proton against decay to a single lepton plus a meson. A composite Higgs boson can emerge as a two preon composite. Since anomaly matching for the relevant conserved global symmetry current is not obeyed by three fermion families, emergence of three composite families requires formation of a Goldstone boson with quantum numbers matching this current, which can be a light dark matter candidate.

  5. Symmetry Breaking in MILP Formulations for Unit Commitment Problems

    KAUST Repository

    Lima, Ricardo

    2015-12-11

    This paper addresses the study of symmetry in Unit Commitment (UC) problems solved by Mixed Integer Linear Programming (MILP) formulations, and using Linear Programming based Branch & Bound MILP solvers. We propose three sets of symmetry breaking constraints for UC MILP formulations exhibiting symmetry, and its impact on three UC MILP models are studied. The case studies involve the solution of 24 instances by three widely used models in the literature, with and without symmetry breaking constraints. The results show that problems that could not be solved to optimality within hours can be solved with a relatively small computational burden if the symmetry breaking constraints are assumed. The proposed symmetry breaking constraints are also compared with the symmetry breaking methods included in two MILP solvers, and the symmetry breaking constraints derived in this work have a distinct advantage over the methods in the MILP solvers.

  6. Quantum electroweak symmetry breaking through loop quadratic contributions

    Directory of Open Access Journals (Sweden)

    Dong Bai

    2015-06-01

    Full Text Available Based on two postulations that (i the Higgs boson has a large bare mass mH≫mh≃125 GeV at the characteristic energy scale Mc which defines the Standard Model (SM in the ultraviolet region, and (ii quadratic contributions of Feynman loop diagrams in quantum field theories are physically meaningful, we show that the SM electroweak symmetry breaking is induced by the quadratic contributions from loop effects. As the quadratic running of Higgs mass parameter leads to an additive renormalization, which distinguishes from the logarithmic running with a multiplicative renormalization, the symmetry breaking occurs once the sliding energy scale μ moves from Mc down to a transition scale μ=ΛEW at which the additive renormalized Higgs mass parameter mH2(Mc/μ gets to change the sign. With the input of current experimental data, this symmetry breaking energy scale is found to be ΛEW≃760 GeV, which provides another basic energy scale for the SM besides Mc. Studying such a symmetry breaking mechanism could play an important role in understanding both the hierarchy problem and naturalness problem. It also provides a possible way to explore the experimental implications of the quadratic contributions as ΛEW lies within the probing reach of the LHC and the future Great Collider.

  7. Physical Model of Cellular Symmetry Breaking

    Science.gov (United States)

    van der Gucht, Jasper; Sykes, Cécile

    2009-01-01

    Cells can polarize in response to external signals, such as chemical gradients, cell–cell contacts, and electromagnetic fields. However, cells can also polarize in the absence of an external cue. For example, a motile cell, which initially has a more or less round shape, can lose its symmetry spontaneously even in a homogeneous environment and start moving in random directions. One of the principal determinants of cell polarity is the cortical actin network that underlies the plasma membrane. Tension in this network generated by myosin motors can be relaxed by rupture of the shell, leading to polarization. In this article, we discuss how simplified model systems can help us to understand the physics that underlie the mechanics of symmetry breaking. PMID:20066077

  8. Electroweak Symmetry Breaking (3/3)

    CERN Multimedia

    CERN. Geneva

    2012-01-01

    The focus of the lectures will be on the role of the Higgs boson in the mechanism of electroweak symmetry breaking, both in the Standard Model and in models of New Physics. In particular, I will discuss how a determination of its couplings to matter and gauge fields can give important information on the nature and origin of the Higgs boson. I will thus review the picture on Higgs couplings implied by the current experimental data and examine further interesting processes that can be measured in the future.

  9. Electroweak Symmetry Breaking (1/3)

    CERN Multimedia

    CERN. Geneva

    2012-01-01

    The focus of the lectures will be on the role of the Higgs boson in the mechanism of electroweak symmetry breaking, both in the Standard Model and in models of New Physics. In particular, I will discuss how a determination of its couplings to matter and gauge fields can give important information on the nature and origin of the Higgs boson. I will thus review the picture on Higgs couplings implied by the current experimental data and examine further interesting processes that can be measured in the future.

  10. Electroweak Symmetry Breaking (2/3)

    CERN Multimedia

    CERN. Geneva

    2012-01-01

    The focus of the lectures will be on the role of the Higgs boson in the mechanism of electroweak symmetry breaking, both in the Standard Model and in models of New Physics. In particular, I will discuss how a determination of its couplings to matter and gauge fields can give important information on the nature and origin of the Higgs boson. I will thus review the picture on Higgs couplings implied by the current experimental data and examine further interesting processes that can be measured in the future.

  11. Symmetry associated with symmetry break: Revisiting ants and humans escaping from multiple-exit rooms

    Science.gov (United States)

    Ji, Q.; Xin, C.; Tang, S. X.; Huang, J. P.

    2018-02-01

    Crowd panic has incurred massive injuries or deaths throughout the world, and thus understanding it is particularly important. It is now a common knowledge that crowd panic induces "symmetry break" in which some exits are jammed while others are underutilized. Amazingly, here we show, by experiment, simulation and theory, that a class of symmetry patterns come to appear for ants and humans escaping from multiple-exit rooms while the symmetry break exists. Our symmetry pattern is described by the fact that the ratio between the ensemble-averaging numbers of ants or humans escaping from different exits is equal to the ratio between the widths of the exits. The mechanism lies in the effect of heterogeneous preferences of agents with limited information for achieving the Nash equilibrium. This work offers new insights into how to improve public safety because large public areas are always equipped with multiple exits, and it also brings an ensemble-averaging method for seeking symmetry associated with symmetry breaking.

  12. Chiral symmetry breakings in supersymmetric QCD

    Energy Technology Data Exchange (ETDEWEB)

    Shinmura, Mamoru; Yamawaki, Koichi (Nagoya Univ. (Japan). Dept. of Physics)

    1984-05-01

    It is argued that spontaneous chiral symmetry breaking in supersymmetric QCD is due to the boson pair condensation instead of the fermion pair condensation in sharp contrast to the ordinary QCD. We further construct a low energy effective Lagrangian for supersymmetric QCD, which realizes the symmetry breaking, SU(N) sub(L) x SU(N) sub(R) x U(1) sub(V) x U(1) sub(X) down to SU(N) sub(V) x U(1) sub(V), in the massless limit. Our Lagrangian has no singular behaviour in the massless limit, supersymmetry being preserved independently of the quark mass m. It is shown that linear masses (instead of quadratic masses) of the pseudo-Nambu-Goldstone bosons are proportional to the quark mass and supersymmetric variants of Dashen's formulae are all saturated by the condensations -- O(m..lambda../sup 2/) and -- O (..lambda../sup 2/) for m -- 0.

  13. Chiral symmetry breaking in unstirred crystallization

    Energy Technology Data Exchange (ETDEWEB)

    Szurgot, M. [Center of Mathematics and Physics, Technical University of Lodz (Poland)

    2012-01-15

    Statistics of nucleation of chiral forms of sodium bromate from unstirred aqueous solutions was studied. It was established that bimodal, trimodal and unimodal distributions of enantiomers are obtained in unstirred crystallization. It was also found out that probabilities of the creation of L or D crystals and racemates R, as well as the presence of D, L, and R peaks in distributions depend on crystallizer size, supersaturation and temperature. Nucleation at low supersaturations in small, closed crystallizers leads to the formation of pure enantiomers, and to bimodal distributions with D and L peaks at any temperature. At high supersaturations in large, open crystallizers the formation of racemates and unimodal distributions with racemate R peaks results. In open crystallizers at the lowest temperatures and at the highest temperatures used in crystallization from aqueous solution racemates of sodium bromate are preferentially formed, but in a wide range of intermediate-temperatures apart from racemates, pure enantiomers are efficiently formed which leads to trimodal distributions. The spontaneous formation of pure enantiomers in crystallization from unstirred, unseeded solutions is caused by the chiral symmetry breaking phenomenon, the same as that discovered in stirred crystallization. The conservation of chiral symmetry is, in unstirred crystallization, one of the two possibilities, and the other one is the breakage of symmetry. Both of them occur in nature. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  14. Ras activation and symmetry breaking during Dictyostelium chemotaxis.

    Science.gov (United States)

    Kortholt, Arjan; Keizer-Gunnink, Ineke; Kataria, Rama; Van Haastert, Peter J M

    2013-10-01

    Central to chemotaxis is the molecular mechanism by which a shallow spatial gradient of chemoattractant induces symmetry breaking of activated signaling molecules. Previously, we have used Dictyostelium mutants to investigate the minimal requirements for chemotaxis, and identified a basal signaling module providing activation of Ras and F-actin at the leading edge. Here, we show that Ras activation after application of a pipette releasing the chemoattractant cAMP has three phases, each depending on specific guanine-nucleotide-exchange factors (GEFs). Initially a transient activation of Ras occurs at the entire cell boundary, which is proportional to the local cAMP concentrations and therefore slightly stronger at the front than in the rear of the cell. This transient Ras activation is present in gα2 (gpbB)-null cells but not in gβ (gpbA)-null cells, suggesting that Gβγ mediates the initial activation of Ras. The second phase is symmetry breaking: Ras is activated only at the side of the cell closest to the pipette. Symmetry breaking absolutely requires Gα2 and Gβγ, but not the cytoskeleton or four cAMP-induced signaling pathways, those dependent on phosphatidylinositol (3,4,5)-triphosphate [PtdIns(3,4,5)P3], cGMP, TorC2 and PLA2. As cells move in the gradient, the crescent of activated Ras in the front half of the cell becomes confined to a small area at the utmost front of the cell. Confinement of Ras activation leads to cell polarization, and depends on cGMP formation, myosin and F-actin. The experiments show that activation, symmetry breaking and confinement of Ras during Dictyostelium chemotaxis uses different G-protein subunits and a multitude of Ras GEFs and GTPase-activating proteins (GAPs).

  15. Quantum Measurement Driven by Spontaneous Symmetry Breaking

    Science.gov (United States)

    Morikawa, M.; Nakamichi, A.

    2006-10-01

    Quantum mechanics cannot be applied within a closed system. Inevitable measurement process in quantum mechanics is usually treated separately from the basic principles of the framework and requires outside observer of the system. In this paper, we propose that the quantum measurement process is actually a physical process associated with the ubiquitous mechanism of spontaneous symmetry breaking. Based on this proposal, we construct a quantum measurement model in which the mixed state evolves into a pure state as the dynamical pro-coherence process. Furthermore, the classically distinguishable pointer parameter emerges as the c-number order parameter in the formalism of closed time-path quantum field theory. We also discuss the precision of the measurement and the possible deduction of the Born probability postulate.

  16. Symmetry breaking: The standard model and superstrings

    Energy Technology Data Exchange (ETDEWEB)

    Gaillard, M.K.

    1988-08-31

    The outstanding unresolved issue of the highly successful standard model is the origin of electroweak symmetry breaking and of the mechanism that determines its scale, namely the vacuum expectation value (vev)v that is fixed by experiment at the value v = 4m//sub w//sup 2///g/sup 2/ = (..sqrt..2G/sub F/)/sup /minus/1/ approx. = 1/4 TeV. In this talk I will discuss aspects of two approaches to this problem. One approach is straightforward and down to earth: the search for experimental signatures, as discussed previously by Pierre Darriulat. This approach covers the energy scales accessible to future and present laboratory experiments: roughly (10/sup /minus/9/ /minus/ 10/sup 3/)GeV. The second approach involves theoretical speculations, such as technicolor and supersymmetry, that attempt to explain the TeV scale. 23 refs., 5 figs.

  17. Golden Probe of Electroweak Symmetry Breaking

    CERN Document Server

    Chen, Yi; Spiropulu, Maria; Stolarski, Daniel; Vega-Morales, Roberto

    2016-12-09

    The ratio of the Higgs couplings to $WW$ and $ZZ$ pairs, $\\lambda_{WZ}$, is a fundamental parameter in electroweak symmetry breaking as well as a measure of the (approximate) custodial symmetry possessed by the gauge boson mass matrix. We show that Higgs decays to four leptons are sensitive, via tree level/1-loop interference effects, to both the magnitude and, in particular, overall sign of $\\lambda_{WZ}$. Determining this sign requires interference effects, as it is nearly impossible to measure with rate information. Furthermore, simply determining the sign effectively establishes the custodial representation of the Higgs boson. We find that $h\\to4\\ell$ ($4\\ell \\equiv 2e2\\mu, 4e, 4\\mu$) decays have excellent prospects of directly establishing the overall sign at a high luminosity 13 TeV LHC. We also examine the ultimate LHC sensitivity in $h\\to4\\ell$ to the magnitude of $\\lambda_{WZ}$. Our results are independent of other measurements of the Higgs boson couplings and, in particular, largely free of assumpti...

  18. Effects of symmetry breaking in finite quantum systems

    Energy Technology Data Exchange (ETDEWEB)

    Birman, J.L. [Department of Physics, City College, City University of New York, New York, NY 10031 (United States); Nazmitdinov, R.G. [Departament de Fisica, Universitat de les Illes Balears, Palma de Mallorca 07122 (Spain); Bogolubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, Dubna 141980 (Russian Federation); Yukalov, V.I., E-mail: yukalov@theor.jinr.ru [Bogolubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, Dubna 141980 (Russian Federation)

    2013-05-15

    The review considers the peculiarities of symmetry breaking and symmetry transformations and the related physical effects in finite quantum systems. Some types of symmetry in finite systems can be broken only asymptotically. However, with a sufficiently large number of particles, crossover transitions become sharp, so that symmetry breaking happens similarly to that in macroscopic systems. This concerns, in particular, global gauge symmetry breaking, related to Bose–Einstein condensation and superconductivity, or isotropy breaking, related to the generation of quantum vortices, and the stratification in multicomponent mixtures. A special type of symmetry transformation, characteristic only for finite systems, is the change of shape symmetry. These phenomena are illustrated by the examples of several typical mesoscopic systems, such as trapped atoms, quantum dots, atomic nuclei, and metallic grains. The specific features of the review are: (i) the emphasis on the peculiarities of the symmetry breaking in finite mesoscopic systems; (ii) the analysis of common properties of physically different finite quantum systems; (iii) the manifestations of symmetry breaking in the spectra of collective excitations in finite quantum systems. The analysis of these features allows for the better understanding of the intimate relation between the type of symmetry and other physical properties of quantum systems. This also makes it possible to predict new effects by employing the analogies between finite quantum systems of different physical nature.

  19. Radiative symmetry breaking from interacting UV fixed points

    Science.gov (United States)

    Abel, Steven; Sannino, Francesco

    2017-09-01

    It is shown that the addition of positive mass-squared terms to asymptotically safe gauge-Yukawa theories with perturbative UV fixed points leads to calculable radiative symmetry breaking in the IR. This phenomenon, and the multiplicative running of the operators that lies behind it, is akin to the radiative symmetry breaking that occurs in the supersymmetric standard model.

  20. Stochastic chiral symmetry breaking process besides the deterministic one.

    Science.gov (United States)

    Silva-Dias, L; López-Castillo, A

    2017-11-08

    In chiral symmetry breaking, populations with initial enantiomeric excess (EE) are probabilistically favored if statistical fluctuation is present, as in nature. Stochastic methods correctly describe chiral symmetry breaking by taking into account the quantitative enantiomeric difference (excess or deficiency) and the statistical fluctuation amplitude, which is inversely proportional to the absolute size of the populations involved. From this, we obtain a law, which indicates that such a favoring probability decreases exponentially [P(EE) = 1/(e(αEE) + 1)] with an initial enantiomeric deficiency mediated by statistical fluctuation. Obviously, chiral symmetry breaking equally favors populations without enantiomeric excess [P(0) = 1/2]. However, if deterministic methods are considered, chiral symmetry breaking will strictly favor the population with an initial enantiomeric excess (EE). To study these stochastic chiral symmetry breaking processes the autocatalytic Frank model was considered. Summarizing, our results show that the initial enantiomeric excesses are not entirely responsible for the final state configuration of autocatalytic finite systems.

  1. Lorentz symmetry breaking effects on relativistic EPR correlations

    Energy Technology Data Exchange (ETDEWEB)

    Belich, H. [Universidade Federal do Espirito Santo, Departamento de Fisica e Quimica, Vitoria, ES (Brazil); Furtado, C.; Bakke, K. [Universidade Federal da Paraiba, Departamento de Fisica, Caixa Postal 5008, Joao Pessoa, PB (Brazil)

    2015-09-15

    Lorentz symmetry breaking effects on relativistic EPR (Einstein-Podolsky-Rosen) correlations are discussed. From the modified Maxwell theory coupled to gravity, we establish a possible scenario of the Lorentz symmetry violation and write an effective metric for the Minkowski spacetime. Then we obtain the Wigner rotation angle via the Fermi-Walker transport of spinors and consider the WKB (Wentzel-Kramers-Brillouin) approximation in order to study the influence of Lorentz symmetry breaking effects on the relativistic EPR correlations. (orig.)

  2. Warped Electroweak Breaking Without Custodial Symmetry

    CERN Document Server

    Cabrer, Joan A; Quiros, Mariano

    2010-01-01

    We propose an alternative to the introduction of an extra gauge (custodial) symmetry to suppress the contribution of KK modes to the T parameter in warped theories of electroweak breaking. The mechanism is based on a general class of warped 5D metrics and a Higgs propagating in the bulk. The metrics are nearly AdS in the UV region but depart from AdS in the IR region, towards where KK fluctuations are mainly localized, and have a singularity outside the slice between the UV and IR branes. This gravitational background is generated by a bulk stabilizing scalar field which triggers a natural solution to the hierarchy problem. Depending on the model parameters, gauge-boson KK modes can be consistent with present bounds on EWPT for m > 1 TeV at 95% CL. The model contains a light Higgs mode which unitarizes the four-dimensional theory. The reduction in the precision observables can be traced back to a large wave function renormalization for this mode.

  3. Dynamical Local Chirality and Chiral Symmetry Breaking

    CERN Document Server

    Alexandru, Andrei

    2013-01-01

    We present some of the reasoning and results substantiating the notion that spontaneous chiral symmetry breaking (SChSB) in QCD is encoded in local chiral properties of Dirac eigenmodes. Such association is possible when viewing chirality as a dynamical effect, measured with respect to the benchmark of statistically independent left-right components. Following this rationale leads to describing local chiral behavior by a taylor-made correlation, namely the recently introduced correlation coefficient of polarization C_A. In this language, correlated modes (C_A>0) show dynamical preference for local chirality while anti-correlated modes (C_A<0) favor anti-chirality. Our conclusion is that SChSB in QCD can be viewed as dominance of low-energy correlation (chirality) over anti-correlation (anti-chirality) of Dirac sea. The spectral range of local chirality, chiral polarization scale Lambda_ch, is a dynamically generated scale in the theory associated with SChSB. One implication of these findings is briefly dis...

  4. Cilia in Left-Right Symmetry Breaking.

    Science.gov (United States)

    Shinohara, Kyosuke; Hamada, Hiroshi

    2017-10-03

    Visceral organs of vertebrates show left-right (L-R) asymmetry with regard to their position and morphology. Cilia play essential role in generating L-R asymmetry. A number of genes required for L-R asymmetry have now been identified in vertebrates, including human, many of which contribute to the formation and motility of cilia. In the mouse embryo, breaking of L-R symmetry occurs in the ventral node, where two types of cilia (motile and immotile) are present. Motile cilia are located at the central region of the node, and generate a leftward fluid flow. These motile cilia at the node are unique in that they rotate in the clockwise direction, unlike other immotile cilia such as airway cilia that show planar beating. The second type of cilia essential for L-R asymmetry is immotile cilia that are peripherally located immotile cilia. They sense a flow-dependent signal, which is either chemical or mechanical in nature. Although Ca 2+ signaling is implicated in flow sensing, the precise mechanism remains unknown. Copyright © 2017 Cold Spring Harbor Laboratory Press; all rights reserved.

  5. Explicit symmetry breaking in electrodynamic systems and electromagnetic radiation

    CERN Document Server

    Sinha, Dhiraj

    2016-01-01

    This book is an introduction to the concept of symmetries in electromagnetism and explicit symmetry breaking. It begins with a brief background on the origin of the concept of symmetry and its meaning in fields such as architecture, mathematics and physics. Despite the extensive developments of symmetry in these fields, it has yet to be applied to the context of classical electromagnetism and related engineering applications. This book unravels the beauty and excitement of this area to scientists and engineers.

  6. Spontaneous Breaking of Spatial and Spin Symmetry in Spinor Condensates

    DEFF Research Database (Denmark)

    Scherer, M.; Lücke, B.; Gebreyesus, G.

    2010-01-01

    Parametric amplification of quantum fluctuations constitutes a fundamental mechanism for spontaneous symmetry breaking. In our experiments, a spinor condensate acts as a parametric amplifier of spin modes, resulting in a twofold spontaneous breaking of spatial and spin symmetry in the amplified...... broken, but phase squeezing prevents spin-symmetry breaking. If, however, nondegenerate spin modes contribute to the amplification, quantum interferences lead to spin-dependent density profiles and hence spontaneously formed patterns in the longitudinal magnetization....... clouds. Our experiments permit a precise analysis of the amplification in specific spatial Bessel-like modes, allowing for the detailed understanding of the double symmetry breaking. On resonances that create vortex-antivortex superpositions, we show that the cylindrical spatial symmetry is spontaneously...

  7. Introduction to symmetry-breaking phenomena in physics

    CERN Multimedia

    CERN. Geneva. Audiovisual Unit

    2001-01-01

    The notion of broken symmetries started slowly to emerge in the 19th century. The early studies of Pasteur on the parity asymmetry of life, the studies of Curie on piezoelectricity and on the symmetries of effects versus the symmetry of causes ( which clearly excluded spontaneous symmetry breaking), are important historical landmarks. However the possibility of spontaneous symmetry breaking within the usual principles of statistical mechanics, waited for the work of Peierls and Onsager. The whole theory of phase transitions and critical phenomena, as well as the construction of field theoretic models as long distance limit of yet unknown physics, relies nowadays on the concept of criticality associated to spontaneous symmetry breaking. The phenomena of Goldstone bosons, of Meissner-Higgs effects, are central to the theory of condensed matter as well as to particle physics. In cosmology as well, the various inflationary scenarios begin similarly with this same concept. The three lectures will provide a simple ...

  8. Spontaneous symmetry breaking in spinor Bose-Einstein condensates

    DEFF Research Database (Denmark)

    Scherer, Manuel; Lücke, Bernd; Peise, Jan

    2013-01-01

    We present an analytical model for the theoretical analysis of spin dynamics and spontaneous symmetry breaking in a spinor Bose-Einstein condensate (BEC). This allows for an excellent intuitive understanding of the processes and provides good quantitative agreement with the experimental results...... in the creation efficiency of these atom pairs can be traced back to excitation modes of this confinement. The understanding of these excitation modes allows for a detailed characterization of the symmetry-breaking mechanism, showing how a twofold spontaneous breaking of spatial and spin symmetry can occur....... In addition, a detailed account of the experimental methods for the preparation and analysis of spinor quantum gases is given....

  9. Spontaneous symmetry breaking, self-trapping, and Josephson oscillations

    CERN Document Server

    2013-01-01

    This volume collects a a number of contributions on spontaneous symmetry breaking. Current studies in this general field are going ahead at a full speed. The book present review chapters which give an overview on the major break throughs of recent years. It covers a number of different physical settings which are introduced when a nonlinearity is added to the underlying symmetric problems and its strength exceeds a certain critical value. The corresponding loss of symmetry, called spontaneous symmetry breaking, alias self-trapping into asymmetric states is extensively discussed in this book.

  10. Positive Disintegration as a Process of Symmetry Breaking.

    Science.gov (United States)

    Laycraft, Krystyna

    2017-04-01

    This article presents an analysis of the positive disintegration as a process of symmetry breaking. Symmetry breaking plays a major role in self-organized patterns formation and correlates directly to increasing complexity and function specialization. According to Dabrowski, a creator of the Theory of Positive Disintegration, the change from lower to higher levels of human development requires a major restructuring of an individual's psychological makeup. Each level of human development is a relatively stable and coherent configuration of emotional-cognitive patterns called developmental dynamisms. Their main function is to restructure a mental structure by breaking the symmetry of a low level and bringing differentiation and then integration to higher levels. The positive disintegration is then the process of transitions from a lower level of high symmetry and low complexity to higher levels of low symmetry and high complexity of mental structure.

  11. Concepts of Electroweak Symmetry Breaking and Higgs Physics

    CERN Document Server

    Gomez-Bock, M; Mühlleitner, M; Spira, M; Zerwas, P M

    2008-01-01

    We present an introduction to the basic concepts of electroweak symmetry breaking and Higgs physics within the Standard Model and its supersymmetric extensions. A brief overview will also be given on alternative mechanisms of electroweak symmetry breaking. In addition to the theoretical basis, the present experimental status of Higgs physics and prospects at the Tevatron, the LHC and e+e- linear colliders are discussed.

  12. Concepts of electroweak symmetry breaking and Higgs physics

    Energy Technology Data Exchange (ETDEWEB)

    Gomez-Bock, M. [Benemerita Univ., Puebla (Mexico). Inst. de Fisica; Mondragon, M. [Universidad Nacional Autonoma de Mexico, Mexico City (Mexico). Inst. de Fisica; Muehlleitner, M. [Laboratoire d' Annecy-Le-Vieux de Physique Theorique, 74 (France)]|[CERN - European Organization for Nuclear Research, Geneva (Switzerland). Theory Div.; Spira, M. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Zerwas, P.M. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)]|[RWTH Aachen (Germany). Inst. Theor. Physik E]|[Univ. Paris- Sud, Orsay (France). Laboratoire de Physique Theorique

    2007-12-15

    We present an introduction to the basic concepts of electroweak symmetry breaking and Higgs physics within the Standard Model and its supersymmetric extensions. A brief overview will also be given on alternative mechanisms of electroweak symmetry breaking. In addition to the theoretical basis, the present experimental status of Higgs physics and prospects at the Tevatron, the LHC and e{sup +}e{sup -} linear colliders are discussed. (orig.)

  13. Gauge symmetry breaking in gauge theories -- in search of clarification

    NARCIS (Netherlands)

    Friederich, Simon

    2013-01-01

    The paper investigates the spontaneous breaking of gauge symmetries in gauge theories from a philosophical angle, taking into account the fact that the notion of a spontaneously broken local gauge symmetry, though widely employed in textbook expositions of the Higgs mechanism, is not supported by

  14. Matter Mass Generation and Theta Vacuum: Dynamical Spontaneous Symmetry Breaking

    OpenAIRE

    Roh, Heui-Seol

    2001-01-01

    This work proposes a stringent concept of matter mass generation and Theta vacuum in the context of local gauge theory for the strong force under the constraint of the flat universe. The matter mass is generated as the consequence of dynamical spontaneous symmetry breaking (DSSB) of gauge symmetry and discrete symmetries, which is motivated by the parameter Theta representing the surface term. Matter mass generation introduces the typical features of constituent particle mass, dual Meissner e...

  15. Hartree-Fock symmetry breaking around conical intersections.

    Science.gov (United States)

    Jake, Lena C; Henderson, Thomas M; Scuseria, Gustavo E

    2018-01-14

    We study the behavior of Hartree-Fock (HF) solutions in the vicinity of conical intersections. These are here understood as regions of a molecular potential energy surface characterized by degenerate or nearly degenerate eigenfunctions with identical quantum numbers (point group, spin, and electron numbers). Accidental degeneracies between states with different quantum numbers are known to induce symmetry breaking in HF. The most common closed-shell restricted HF instability is related to singlet-triplet spin degeneracies that lead to collinear unrestricted HF solutions. Adding geometric frustration to the mix usually results in noncollinear generalized HF (GHF) solutions, identified by orbitals that are linear combinations of up and down spins. Near conical intersections, we observe the appearance of coplanar GHF solutions that break all symmetries, including complex conjugation and time-reversal, which do not carry good quantum numbers. We discuss several prototypical examples taken from the conical intersection literature. Additionally, we utilize a recently introduced magnetization diagnostic to characterize these solutions, as well as a solution of a Jahn-Teller active geometry of H8+2.

  16. A model for chiral symmetry breaking in QCD

    Science.gov (United States)

    Govaerts, J.; Mandula, J. E.; Weyers, J.

    1984-04-01

    A recently proposed model for dynamical breaking of chiral symmetry in QCD is extended and developed for the calculation of pion and chiral symmetry breaking parameters. The pion is explicitly realized as a massless Goldstone boson and as a bound state of the constituent quarks. We compute, in the limit of exact chiral symmetry, MQ, the constituent quark mass ƒ π the pion decay coupling, , the constituent quark loop density, μπ2/ mq, the ratio of the Goldstone boson mass squared to the bare quark mass, and π, the pion electromagnetic charge radius squared.

  17. Local Activity Principle:. the Cause of Complexity and Symmetry Breaking

    Science.gov (United States)

    Mainzer, Klaus

    2013-01-01

    The principle of local activity is precisely the missing concept to explain the emergence of complex patterns in a homogeneous medium. Leon O. Chua discovered and defined this principle in the theory of nonlinear electronic circuits in a mathematically rigorous way. The local principle can be generalized and proven at least for the class of nonlinear reaction-diffusion systems in physics, chemistry, biology and brain research. Recently, it was realized by memristors for nanoelectronic device applications in technical brains. In general, the emergence of complex patterns and structures is explained by symmetry breaking in homogeneous media. The principle of local activity is the cause of symmetry breaking in homogeneous media. We argue that the principle of local activity is really fundamental in science and can even be identified in quantum cosmology as symmetry breaking of local gauge symmetries generating the complexity of matter and forces in our universe. Finally, we consider applications in economic, financial, and social systems with the emergence of equilibrium states, symmetry breaking at critical points of phase transitions and risky acting at the edge of chaos. In any case, the driving causes of symmetry breaking and the emergence of complexity are locally active elements, cells, units, or agents.

  18. Perturbation treatment of symmetry breaking within random matrix theory

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho, J.X. de [Max-Planck-Institut fuer Physik komplexer Systeme, Noethnitzer Strasse 38, D-01187 Dresden (Germany); Instituto de Fisica, Universidade de Sao Paulo, C.P. 66318, 05315-970 Sao Paulo, S.P. (Brazil); Hussein, M.S. [Max-Planck-Institut fuer Physik komplexer Systeme, Noethnitzer Strasse 38, D-01187 Dresden (Germany); Instituto de Fisica, Universidade de Sao Paulo, C.P. 66318, 05315-970 Sao Paulo, S.P. (Brazil)], E-mail: mhussein@mpipks-dresden.mpg.de; Pato, M.P.; Sargeant, A.J. [Instituto de Fisica, Universidade de Sao Paulo, C.P. 66318, 05315-970 Sao Paulo, S.P. (Brazil)

    2008-07-07

    We discuss the applicability, within the random matrix theory, of perturbative treatment of symmetry breaking to the experimental data on the flip symmetry breaking in quartz crystal. We found that the values of the parameter that measures this breaking are different for the spacing distribution as compared to those for the spectral rigidity. We consider both two-fold and three-fold symmetries. The latter was found to account better for the spectral rigidity than the former. Both cases, however, underestimate the experimental spectral rigidity at large L. This discrepancy can be resolved if an appropriate number of eigenfrequencies is considered to be missing in the sample. Our findings are relevant for symmetry violation studies in general.

  19. Emergent Electroweak Symmetry Breaking with Composite W, Z Bosons

    CERN Document Server

    Cui, Yanou; Wells, James D

    2009-01-01

    We present a model of electroweak symmetry breaking in a warped extra dimension where electroweak symmetry is broken at the UV (or Planck) scale. An underlying conformal symmetry is broken at the IR (or TeV) scale generating masses for the electroweak gauge bosons without invoking a Higgs mechanism. By the AdS/CFT correspondence the W,Z bosons are identified as composite states of a strongly-coupled gauge theory, suggesting that electroweak symmetry breaking is an emergent phenomenon at the IR scale. The model satisfies electroweak precision tests with reasonable fits to the S and T parameter. In particular the T parameter is sufficiently suppressed since the model naturally admits a custodial SU(2) symmetry. The composite nature of the W,Z-bosons provide a novel possibility of unitarizing WW scattering via form factor suppression. Constraints from LEP and the Tevatron as well as discovery opportunities at the LHC are discussed for these composite electroweak gauge bosons.

  20. Cobimaximal lepton mixing from soft symmetry breaking

    Science.gov (United States)

    Grimus, W.; Lavoura, L.

    2017-11-01

    Cobimaximal lepton mixing, i.e.θ23 = 45 ° and δ = ± 90 ° in the lepton mixing matrix V, arises as a consequence of SV =V* P, where S is the permutation matrix that interchanges the second and third rows of V and P is a diagonal matrix of phase factors. We prove that any such V may be written in the form V = URP, where U is any predefined unitary matrix satisfying SU =U*, R is an orthogonal, i.e. real, matrix, and P is a diagonal matrix satisfying P2 = P. Using this theorem, we demonstrate the equivalence of two ways of constructing models for cobimaximal mixing-one way that uses a standard CP symmetry and a different way that uses a CP symmetry including μ-τ interchange. We also present two simple seesaw models to illustrate this equivalence; those models have, in addition to the CP symmetry, flavour symmetries broken softly by the Majorana mass terms of the right-handed neutrino singlets. Since each of the two models needs four scalar doublets, we investigate how to accommodate the Standard Model Higgs particle in them.

  1. Cobimaximal lepton mixing from soft symmetry breaking

    Directory of Open Access Journals (Sweden)

    W. Grimus

    2017-11-01

    Full Text Available Cobimaximal lepton mixing, i.e. θ23=45° and δ=±90° in the lepton mixing matrix V, arises as a consequence of SV=V⁎P, where S is the permutation matrix that interchanges the second and third rows of V and P is a diagonal matrix of phase factors. We prove that any such V may be written in the form V=URP, where U is any predefined unitary matrix satisfying SU=U⁎, R is an orthogonal, i.e. real, matrix, and P is a diagonal matrix satisfying P2=P. Using this theorem, we demonstrate the equivalence of two ways of constructing models for cobimaximal mixing—one way that uses a standard CP symmetry and a different way that uses a CP symmetry including μ–τ interchange. We also present two simple seesaw models to illustrate this equivalence; those models have, in addition to the CP symmetry, flavour symmetries broken softly by the Majorana mass terms of the right-handed neutrino singlets. Since each of the two models needs four scalar doublets, we investigate how to accommodate the Standard Model Higgs particle in them.

  2. Symmetry Breaking in a random passive scalar

    Science.gov (United States)

    Kilic, Zeliha; McLaughlin, Richard; Camassa, Roberto

    2017-11-01

    We consider the evolution of a decaying passive scalar in the presence of a gaussian white noise fluctuating shear flow. We focus on deterministic initial data and establish the short, intermediate, and long time symmetry properties of the evolving point wise probability measure for the random passive scalar. Analytical results are compared directly to Monte Carlo simulations. Time permitting we will compare the predictions to experimental observations.

  3. Spontaneous symmetry breaking in the composite-vector-boson model

    Energy Technology Data Exchange (ETDEWEB)

    Garavaglia, T.

    1986-11-15

    Spontaneous symmetry breaking is discussed in the Abelian, QED-like, composite-vector-boson model. When the auxiliary vector field has a nonzero vacuum expectation value, a global symmetry, Lorentz invariance, is broken. It is shown that the regularization of the saddle-point conditions for the quantum fluctuation generating functional is consistent only with a spacelike vacuum expectation value for the auxiliary vector field.

  4. Holographic Ward identities for symmetry breaking in two dimensions

    Energy Technology Data Exchange (ETDEWEB)

    Argurio, Riccardo [Physique Théorique et Mathématique and International Solvay Institutes,Université Libre de Bruxelles,C.P. 231, 1050 Brussels (Belgium); Giribet, Gaston [Martin Fisher School of Physics, Brandeis University,Waltham, Massachusetts 02453 (United States); Physics Department, University of Buenos Aires FCEN-UBA and IFIBA-CONICET,Ciudad Universitaria, Pabellón I, 1428, Buenos Aires (Argentina); Marzolla, Andrea; Naegels, Daniel [Physique Théorique et Mathématique and International Solvay Institutes,Université Libre de Bruxelles,C.P. 231, 1050 Brussels (Belgium); Sierra-Garcia, J. Anibal [Department of Particle Physics and IGFAE, University of Santiago de Compostela,E-15782 Santiago de Compostela (Spain)

    2017-04-03

    We investigate symmetry breaking in two-dimensional field theories which have a holographic gravity dual. Being at large N, the Coleman theorem does not hold and Goldstone bosons are expected. We consider the minimal setup to describe a conserved current and a charged operator, and we perform holographic renormalization in order to find the correct Ward identities describing symmetry breaking. This involves some subtleties related to the different boundary conditions that a vector can have in the three-dimensional bulk. We establish which is the correct prescription that yields, after renormalization, the same Ward identities as in higher dimensions.

  5. Symmetry-Breaking Plasmonic Metasurfaces for Broadband Light Bending

    DEFF Research Database (Denmark)

    Ni, Xingjie; Emani, Naresh K.; Kildishev, Alexander V.

    2012-01-01

    We experimentally demonstrate unparalleled wave-front control in a broadband, optical wavelength range from 1.0 μm to 1.9 μm, using a thin plasmonic layer (metasurface) consisting of a nanoantenna array that breaks the symmetry along the interface.......We experimentally demonstrate unparalleled wave-front control in a broadband, optical wavelength range from 1.0 μm to 1.9 μm, using a thin plasmonic layer (metasurface) consisting of a nanoantenna array that breaks the symmetry along the interface....

  6. Spontaneous breaking of non-relativistic scale symmetry

    Science.gov (United States)

    Arav, Igal; Hason, Itamar; Oz, Yaron

    2017-10-01

    We analyze the mechanism of spontaneous symmetry breaking of scale invariance in Galilean invariant field theories. We show that the existence of a dynamic gapless dilaton mode depends on whether the U(1) particle number or the Galilean boost symmetry are spontaneously broken. When both scale and particle number symmetries are spontaneously broken there is one propagating gapless Nambu-Goldstone mode. Its dispersion relation is linear if the chemical potential is nonzero and quadratic otherwise. We discuss the reversibility of RG flows in such theories.

  7. Relativistic symmetry breaking in light kaonic nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Rong-Yao; Jiang, Wei-Zhou; Zhang, Dong-Rui; Wei, Si-Na [Southeast University, Department of Physics, Nanjing (China); Xiang, Qian-Fei [Chinese Academy of Sciences, Institute of High Energy Physics, Beijing (China)

    2014-12-01

    As the experimental data from kaonic atoms and K{sup -}N scatterings imply that the K{sup -} -nucleon intenraction is strongly attractive at saturation density, there is a possibility to form K{sup -} -nuclear bound states or kaonic nuclei. In this work, we investigate the ground-state properties of the light kaonic nuclei with the relativistic mean-field theory. It is found that the strong attraction between K{sup -} and nucleons reshapes the scalar and vector meson fields, leading to the remarkable enhancement of the nuclear density in the interior of light kaonic nuclei and the manifest shift of the single-nucleon energy spectra and magic numbers therein. As a consequence, the pseudospin symmetry is shown to be violated together with enlarged spin-orbit splittings in these kaonic nuclei. (orig.)

  8. The origin of a primordial genome through spontaneous symmetry breaking

    NARCIS (Netherlands)

    Takeuchi, Nobuto|info:eu-repo/dai/nl/304836966; Hogeweg, P|info:eu-repo/dai/nl/073710725; Kaneko, Kunihiko

    2017-01-01

    The heredity of a cell is provided by a small number of non-catalytic templates-The genome. How did genomes originate? Here, we demonstrate the possibility that genome-like molecules arise from symmetry breaking between complementary strands of self-replicating molecules. Our model assumes a

  9. Spontaneous Symmetry Breaking in Quantum Systems. A review for Scholarpedia

    CERN Document Server

    Strocchi, F

    2012-01-01

    The mechanism of spontaneous symmetry breaking in quantum systems is briefly reviewed, rectifying part of the standard wisdom on logical and mathematical grounds. The crucial role of the localization properties of the time evolution for the conclusion of the Goldstone theorem is emphasized.

  10. Electroweak Symmetry Breaking without the $\\mu^2$ Term

    CERN Document Server

    Goertz, Florian

    2016-01-01

    We demonstrate that from a low energy perspective a viable electroweak symmetry breaking can be achieved without the (negative sign) $\\mu^2$ mass term in the Higgs potential, thereby avoiding completely the appearance of relevant operators. We show that such a setup is self consistent and not ruled out by Higgs physics. In particular, we point out that it is the lightness of the Higgs boson that allows for the electroweak symmetry to be broken dynamically via operators of $D\\geq 4$, consistent with the power expansion. Beyond that, we entertain how this scenario might even be preferred phenomenologically compared to the ordinary mechanism of electroweak symmetry breaking, as realized in the Standard Model, and argue that it can be fully tested at the LHC. In an appendix, we classify UV completions that could lead to such a setup, considering also the option of generating all scales dynamically.

  11. Dynamical chiral symmetry breaking and Bethe-Salpeter equation

    Energy Technology Data Exchange (ETDEWEB)

    Naito, Kenichi [Tokyo Inst. of Tech. (Japan)

    1998-08-01

    {pi} meson, (pseudo) Nambu-Goldstone particle caused by a spontaneous breaking of chiral symmetry, was studied by use of Bethe-Salpeter (BS) equation in the limits of effective model as a bound state of quark and antiquark. The effective model has nonlocal interaction and proved to satisfy the Gell-Mann-Oaks-Renner (GMOR) mass formula by treating correct Noether current in spite of loss of local chiral invariance of interaction term. GMOR mass formula: M{sub {pi}}{sup 2}f{sub {pi}}{sup 2}{approx_equal}-2m{sub 0} was realized as the result of the dynamical breaking and the clear breaking of chiral symmetry. M{sub {pi}}, f{sub {pi}}, m{sub 0}, and indicate mass of pseudo scalar meson, decay constant, mass of quark and vacuum condensation of quark and antiquark. (S.Y.)

  12. Cracking up: symmetry breaking in cellular systems

    Science.gov (United States)

    Paluch, Ewa; van der Gucht, Jasper; Sykes, Cécile

    2006-01-01

    The shape of animal cells is, to a large extent, determined by the cortical actin network that underlies the cell membrane. Because of the presence of myosin motors, the actin cortex is under tension, and local relaxation of this tension can result in cortical flows that lead to deformation and polarization of the cell. Cortex relaxation is often regulated by polarizing signals, but the cortex can also rupture and relax spontaneously. A similar tension-induced polarization is observed in actin gels growing around beads, and we propose that a common mechanism governs actin gel rupture in both systems. PMID:17145960

  13. Effective photon mass by Super and Lorentz symmetry breaking

    Science.gov (United States)

    Bonetti, Luca; dos Santos Filho, Luís R.; Helayël-Neto, José A.; Spallicci, Alessandro D. A. M.

    2017-01-01

    In the context of Standard Model Extensions (SMEs), we analyse four general classes of Super Symmetry (SuSy) and Lorentz Symmetry (LoSy) breaking, leading to observable imprints at our energy scales. The photon dispersion relations show a non-Maxwellian behaviour for the CPT (Charge-Parity-Time reversal symmetry) odd and even sectors. The group velocities exhibit also a directional dependence with respect to the breaking background vector (odd CPT) or tensor (even CPT). In the former sector, the group velocity may decay following an inverse squared frequency behaviour. Thus, we extract a massive Carroll-Field-Jackiw photon term in the Lagrangian and show that the effective mass is proportional to the breaking vector and moderately dependent on the direction of observation. The breaking vector absolute value is estimated by ground measurements and leads to a photon mass upper limit of 10-19 eV or 2 ×10-55 kg, and thereby to a potentially measurable delay at low radio frequencies.

  14. Effective photon mass by Super and Lorentz symmetry breaking

    Directory of Open Access Journals (Sweden)

    Luca Bonetti

    2017-01-01

    Full Text Available In the context of Standard Model Extensions (SMEs, we analyse four general classes of Super Symmetry (SuSy and Lorentz Symmetry (LoSy breaking, leading to observable imprints at our energy scales. The photon dispersion relations show a non-Maxwellian behaviour for the CPT (Charge-Parity-Time reversal symmetry odd and even sectors. The group velocities exhibit also a directional dependence with respect to the breaking background vector (odd CPT or tensor (even CPT. In the former sector, the group velocity may decay following an inverse squared frequency behaviour. Thus, we extract a massive Carroll–Field–Jackiw photon term in the Lagrangian and show that the effective mass is proportional to the breaking vector and moderately dependent on the direction of observation. The breaking vector absolute value is estimated by ground measurements and leads to a photon mass upper limit of 10−19 eV or 2×10−55 kg, and thereby to a potentially measurable delay at low radio frequencies.

  15. Noncritically squeezed light via spontaneous rotational symmetry breaking.

    Science.gov (United States)

    Navarrete-Benlloch, Carlos; Roldán, Eugenio; de Valcárcel, Germán J

    2008-05-23

    We predict squeezed light generation through the spontaneous rotational symmetry breaking occurring in a degenerate optical parametric oscillator (DOPO) pumped above threshold. We show, within the linearized theory, that a DOPO with spherical mirrors, in which the signal and idler fields correspond to first-order Laguerre-Gauss modes, produces a perfectly squeezed vacuum with the shape of a Hermite-Gauss mode. This occurs at any pumping level above threshold; hence, the phenomenon is noncritical. Imperfections of the rotational symmetry, due, e.g., to cavity anisotropy, are shown to have a small impact.

  16. Natural Cold Baryogenesis from Strongly Interacting Electroweak Symmetry Breaking

    CERN Document Server

    Konstandin, Thomas

    2011-01-01

    The mechanism of "cold electroweak baryogenesis" has been so far unpopular because its proposal has relied on the ad-hoc assumption of a period of hybrid inflation at the electroweak scale with the Higgs acting as the waterfall field. We argue here that cold baryogenesis can be naturally realized without the need to introduce any slow-roll potential. Our point is that composite Higgs models where electroweak symmetry breaking arises via a strongly first-order phase transition provide a well-motivated framework for cold baryogenesis. In this case, reheating proceeds by bubble collisions and we argue that this can induce changes in Chern-Simons number, which in the presence of new sources of CP violation commonly lead to baryogenesis. We illustrate this mechanism using as a source of CP violation an effective dimension-six operator which is free from EDM constraints, another advantage of cold baryogenesis compared to the standard theory of electroweak baryogenesis. Our results are general as they do not rely on...

  17. Polarized growth in fungi: symmetry breaking and hyphal formation.

    Science.gov (United States)

    Arkowitz, Robert A; Bassilana, Martine

    2011-10-01

    Cell shape is a critical determinant for function. The baker's yeast Saccharomyces cerevisiae changes shape in response to its environment, growing by budding in rich nutrients, forming invasive pseudohyphal filaments in nutrient poor conditions and pear shaped shmoos for growth towards a partner during mating. The human opportunistic pathogen Candida albicans can switch from budding to hyphal growth, in response to numerous environmental stimuli to colonize and invade its host. Hyphal growth, typical of filamentous fungi, is not observed in S. cerevisiae. A number of internal cues regulate when and where yeast cells break symmetry leading to polarized growth and ultimately distinct cell shapes. This review discusses how cells break symmetry using the yeast S. cerevisiae paradigm and how polarized growth is initiated and maintained to result in dramatic morphological changes during C. albicans hyphal growth. Copyright © 2011 Elsevier Ltd. All rights reserved.

  18. Stochastic recruitment leads to symmetry breaking in foraging populations

    Science.gov (United States)

    Biancalani, Tommaso; Dyson, Louise; McKane, Alan

    2014-03-01

    When an ant colony is faced with two identical equidistant food sources, the foraging ants are found to concentrate more on one source than the other. Analogous symmetry-breaking behaviours have been reported in various population systems, (such as queueing or stock market trading) suggesting the existence of a simple universal mechanism. Past studies have neglected the effect of demographic noise and required rather complicated models to qualitatively reproduce this behaviour. I will show how including the effects of demographic noise leads to a radically different conclusion. The symmetry-breaking arises solely due to the process of recruitment and ceases to occur for large population sizes. The latter fact provides a testable prediction for a real system.

  19. Breaking of PT Symmetry in Bounded and Unbounded Scattering Systems

    Directory of Open Access Journals (Sweden)

    Philipp Ambichl

    2013-12-01

    Full Text Available PT-symmetric scattering systems with balanced gain and loss can undergo a symmetry-breaking transition in which the eigenvalues of the nonunitary scattering matrix change their phase shifts from real to complex values. We relate the PT-symmetry-breaking points of such an unbounded scattering system to those of the underlying bounded systems. In particular, we show how the PT thresholds in the scattering matrix of the unbounded system translate into analogous transitions in the Robin boundary conditions of the corresponding bounded systems. Based on this relation, we argue and then confirm that the PT transitions in the scattering matrix are, under very general conditions, entirely insensitive to a variable coupling strength between the bounded region and the unbounded asymptotic region, a result that can be tested experimentally and visualized using the concept of Smith charts.

  20. Breaking of PT Symmetry in Bounded and Unbounded Scattering Systems

    Science.gov (United States)

    Ambichl, Philipp; Makris, Konstantinos G.; Ge, Li; Chong, Yidong; Stone, A. Douglas; Rotter, Stefan

    2013-12-01

    PT-symmetric scattering systems with balanced gain and loss can undergo a symmetry-breaking transition in which the eigenvalues of the non-unitary scattering matrix change their phase shifts from real to complex values. We relate the PT-symmetry breaking points of such an unbounded scattering system to those of underlying bounded systems. In particular, we show how the PT-thresholds in the scattering matrix of the unbounded system translate into analogous transitions in the Robin boundary conditions of the corresponding bounded systems. Based on this relation, we argue and then confirm that the PT-transitions in the scattering matrix are, under very general conditions, entirely insensitive to a variable coupling strength between the bounded region and the unbounded asymptotic region, a result that can be tested experimentally and visualized using the concept of Smith charts.

  1. Breaking discrete symmetries in the effective field theory of inflation

    Energy Technology Data Exchange (ETDEWEB)

    Cannone, Dario [Dipartimento di Fisica e Astronomia “G. Galilei”, Università degli Studi di Padova,Padova, I-35131 (Italy); INFN, Sezione di Padova,Padova, I-35131 (Italy); Gong, Jinn-Ouk [Asia Pacific Center for Theoretical Physics,Pohang, 790-784 (Korea, Republic of); Department of Physics,Postech, Pohang, 790-784 (Korea, Republic of); Tasinato, Gianmassimo [Department of Physics, Swansea University,Swansea, SA2 8PP (United Kingdom)

    2015-08-03

    We study the phenomenon of discrete symmetry breaking during the inflationary epoch, using a model-independent approach based on the effective field theory of inflation. We work in a context where both time reparameterization symmetry and spatial diffeomorphism invariance can be broken during inflation. We determine the leading derivative operators in the quadratic action for fluctuations that break parity and time-reversal. Within suitable approximations, we study their consequences for the dynamics of linearized fluctuations. Both in the scalar and tensor sectors, we show that such operators can lead to new direction-dependent phases for the modes involved. They do not affect the power spectra, but can have consequences for higher correlation functions. Moreover, a small quadrupole contribution to the sound speed can be generated.

  2. Curling Liquid Crystal Microswimmers: A Cascade of Spontaneous Symmetry Breaking.

    Science.gov (United States)

    Krüger, Carsten; Klös, Gunnar; Bahr, Christian; Maass, Corinna C

    2016-07-22

    We report curling self-propulsion in aqueous emulsions of common mesogenic compounds. Nematic liquid crystal droplets self-propel in a surfactant solution with concentrations above the critical micelle concentration while undergoing micellar solubilization [Herminghaus et al., Soft Matter 10, 7008 (2014)]. We analyzed trajectories both in a Hele-Shaw geometry and in a 3D setup at variable buoyancy. The coupling between the nematic director field and the convective flow inside the droplet leads to a second symmetry breaking which gives rise to curling motion in 2D. This is demonstrated through a reversible transition to nonhelical persistent swimming by heating to the isotropic phase. Furthermore, autochemotaxis can spontaneously break the inversion symmetry, leading to helical trajectories in 3D.

  3. Radiative electroweak symmetry breaking in standard model extensions

    Science.gov (United States)

    Babu, K. S.; Gogoladze, Ilia; Khan, S.

    2017-05-01

    We study the possibility of radiative electroweak symmetry breaking where loop corrections to the mass parameter of the Higgs boson trigger the symmetry breaking in various extensions of the Standard Model (SM). Although the mechanism fails in the SM, it is shown to be quite successful in several extensions which share a common feature of having an additional scalar around the TeV scale. The positive Higgs mass parameter at a high energy scale is turned negative in the renormalization group flow to lower energy by the cross couplings between the scalars in the Higgs potential. The type-II seesaw model with a TeV scale weak scalar triplet, a two-loop radiative neutrino mass model with new scalars at the TeV scale, the inert doublet model, scalar singlet dark matter model, and a universal seesaw model with an additional U (1 ) broken at the TeV scale are studied and shown to exhibit successful radiative electroweak symmetry breaking.

  4. Planar cell polarity breaks bilateral symmetry by controlling ciliary positioning.

    Science.gov (United States)

    Song, Hai; Hu, Jianxin; Chen, Wen; Elliott, Gene; Andre, Philipp; Gao, Bo; Yang, Yingzi

    2010-07-15

    Defining the three body axes is a central event of vertebrate morphogenesis. Establishment of left-right (L-R) asymmetry in development follows the determination of dorsal-ventral and anterior-posterior (A-P) body axes, although the molecular mechanism underlying precise L-R symmetry breaking in reference to the other two axes is still poorly understood. Here, by removing both Vangl1 and Vangl2, the two mouse homologues of a Drosophila core planar cell polarity (PCP) gene Van Gogh (Vang), we reveal a previously unrecognized function of PCP in the initial breaking of lateral symmetry. The leftward nodal flow across the posterior notochord (PNC) has been identified as the earliest event in the de novo formation of L-R asymmetry. We show that PCP is essential in interpreting the A-P patterning information and linking it to L-R asymmetry. In the absence of Vangl1 and Vangl2, cilia are positioned randomly around the centre of the PNC cells and nodal flow is turbulent, which results in disrupted L-R asymmetry. PCP in mouse, unlike what has been implicated in other vertebrate species, is not required for ciliogenesis, cilium motility, Sonic hedgehog (Shh) signalling or apical docking of basal bodies in ciliated tracheal epithelial cells. Our data suggest that PCP acts earlier than the unidirectional nodal flow during bilateral symmetry breaking in vertebrates and provide insight into the functional mechanism of PCP in organizing the vertebrate tissues in development.

  5. Dynamical quantum phase transitions in systems with continuous symmetry breaking

    Science.gov (United States)

    Weidinger, Simon A.; Heyl, Markus; Silva, Alessandro; Knap, Michael

    2017-10-01

    Interacting many-body systems that are driven far away from equilibrium can exhibit phase transitions between dynamically emerging quantum phases, which manifest as singularities in the Loschmidt echo. Whether and under which conditions such dynamical transitions occur in higher-dimensional systems with spontaneously broken continuous symmetries is largely elusive thus far. Here, we study the dynamics of the Loschmidt echo in the three-dimensional O(N ) model following a quantum quench from a symmetry-breaking initial state. The O(N ) model exhibits a dynamical transition in the asymptotic steady state, separating two phases with a finite and vanishing order parameter, that is associated with the broken symmetry. We analytically calculate the rate function of the Loschmidt echo and find that it exhibits periodic kink singularities when this dynamical steady-state transition is crossed. The singularities arise exactly at the zero crossings of the oscillating order parameter. As a consequence, the appearance of the kink singularities in the transient dynamics is directly linked to a dynamical transition in the order parameter. Furthermore, we argue, that our results for dynamical quantum phase transitions in the O(N ) model are general and apply to generic systems with continuous symmetry breaking.

  6. Spontaneous chiral symmetry breaking in early molecular networks

    Directory of Open Access Journals (Sweden)

    Markovitch Omer

    2010-05-01

    Full Text Available Abstract Background An important facet of early biological evolution is the selection of chiral enantiomers for molecules such as amino acids and sugars. The origin of this symmetry breaking is a long-standing question in molecular evolution. Previous models addressing this question include particular kinetic properties such as autocatalysis or negative cross catalysis. Results We propose here a more general kinetic formalism for early enantioselection, based on our previously described Graded Autocatalysis Replication Domain (GARD model for prebiotic evolution in molecular assemblies. This model is adapted here to the case of chiral molecules by applying symmetry constraints to mutual molecular recognition within the assembly. The ensuing dynamics shows spontaneous chiral symmetry breaking, with transitions towards stationary compositional states (composomes enriched with one of the two enantiomers for some of the constituent molecule types. Furthermore, one or the other of the two antipodal compositional states of the assembly also shows time-dependent selection. Conclusion It follows that chiral selection may be an emergent consequence of early catalytic molecular networks rather than a prerequisite for the initiation of primeval life processes. Elaborations of this model could help explain the prevalent chiral homogeneity in present-day living cells. Reviewers This article was reviewed by Boris Rubinstein (nominated by Arcady Mushegian, Arcady Mushegian, Meir Lahav (nominated by Yitzhak Pilpel and Sergei Maslov.

  7. Lateralization as a symmetry breaking process in birdsong

    Science.gov (United States)

    Trevisan, M. A.; Cooper, B.; Goller, F.; Mindlin, G. B.

    2007-03-01

    The singing by songbirds is a most convincing example in the animal kingdom of functional lateralization of the brain, a feature usually associated with human language. Lateralization is expressed as one or both of the bird’s sound sources being active during the vocalization. Normal songs require high coordination between the vocal organ and respiratory activity, which is bilaterally symmetric. Moreover, the physical and neural substrate used to produce the song lack obvious asymmetries. In this work we show that complex spatiotemporal patterns of motor activity controlling airflow through the sound sources can be explained in terms of spontaneous symmetry breaking bifurcations. This analysis also provides a framework from which to study the effects of imperfections in the system’ s symmetries. A physical model of the avian vocal organ is used to generate synthetic sounds, which allows us to predict acoustical signatures of the song and compare the predictions of the model with experimental data.

  8. Gauge Invariance and Symmetry Breaking by Topology and Energy Gap

    Directory of Open Access Journals (Sweden)

    Franco Strocchi

    2015-10-01

    Full Text Available For the description of observables and states of a quantum system, it may be convenient to use a canonical Weyl algebra of which only a subalgebra A, with a non-trivial center Z, describes observables, the other Weyl operators playing the role of intertwiners between inequivalent representations of A. In particular, this gives rise to a gauge symmetry described by the action of Z. A distinguished case is when the center of the observables arises from the fundamental group of the manifold of the positions of the quantum system. Symmetries that do not commute with the topological invariants represented by elements of Z are then spontaneously broken in each irreducible representation of the observable algebra, compatibly with an energy gap; such a breaking exhibits a mechanism radically different from Goldstone and Higgs mechanisms. This is clearly displayed by the quantum particle on a circle, the Bloch electron and the two body problem.

  9. Minimal but non-minimal inflation and electroweak symmetry breaking

    Energy Technology Data Exchange (ETDEWEB)

    Marzola, Luca [National Institute of Chemical Physics and Biophysics,Rävala 10, 10143 Tallinn (Estonia); Institute of Physics, University of Tartu,Ravila 14c, 50411 Tartu (Estonia); Racioppi, Antonio [National Institute of Chemical Physics and Biophysics,Rävala 10, 10143 Tallinn (Estonia)

    2016-10-07

    We consider the most minimal scale invariant extension of the standard model that allows for successful radiative electroweak symmetry breaking and inflation. The framework involves an extra scalar singlet, that plays the rôle of the inflaton, and is compatibile with current experimental bounds owing to the non-minimal coupling of the latter to gravity. This inflationary scenario predicts a very low tensor-to-scalar ratio r≈10{sup −3}, typical of Higgs-inflation models, but in contrast yields a scalar spectral index n{sub s}≃0.97 which departs from the Starobinsky limit. We briefly discuss the collider phenomenology of the framework.

  10. Introduction to weak interaction theories with dynamical symmetry breaking

    Energy Technology Data Exchange (ETDEWEB)

    Lane, K.D.; Peskin, M.E.

    1980-07-01

    A straightforward introduction to theories of the weak interactions with dynamical symmetry breaking-theories of technicolor or hypercolor is presented. The intent is to inform experimentalists, but also to goad theorists. The motivation for considering theories of this type is described. The structure that such a theory must possess, including new gauge interactions at mass scales of 1-100 TeV is then outlined. Despite their reliance on phenomena at such enormous energies, these theories contain new phenomena observable at currently accessible energies. Three such effects which are especially likely to be observed are described.

  11. Probing dynamical symmetry breaking using quantum-entangled photons

    Science.gov (United States)

    Li, Hao; Piryatinski, Andrei; Jerke, Jonathan; Ram Srimath Kandada, Ajay; Silva, Carlos; Bittner, Eric R.

    2018-01-01

    We present an input/output analysis of photon-correlation experiments whereby a quantum mechanically entangled bi-photon state interacts with a material sample placed in one arm of a Hong–Ou–Mandel apparatus. We show that the output signal contains detailed information about subsequent entanglement with the microscopic quantum states in the sample. In particular, we apply the method to an ensemble of emitters interacting with a common photon mode within the open-system Dicke model. Our results indicate considerable dynamical information concerning spontaneous symmetry breaking can be revealed with such an experimental system.

  12. Cosmological constraints on spontaneous R-symmetry breaking models

    Energy Technology Data Exchange (ETDEWEB)

    Hamada, Yuta; Kobayashi, Tatsuo [Kyoto Univ. (Japan). Dept. of Physics; Kamada, Kohei [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Ookouchi, Yutaka [Kyoto Univ. (Japan). Dept. of Physics; Kyoto Univ. (Japan). The Hakubi Center for Advanced Research and Dept. of Physics

    2012-11-15

    We study general constraints on spontaneous R-symmetry breaking models coming from the cosmological effects of the pseudo Nambu-Goldstone bosons, R-axions. They are substantially produced in the early Universe and may cause several cosmological problems. We focus on relatively long-lived R-axions and find that in a wide range of parameter space, models are severely constrained. In particular, R-axions with mass less than 1 MeV are generally ruled out for relatively high reheating temperature, T{sub R}>10 GeV.

  13. Spontaneous Symmetry Breaking as a Basis of Particle Mass

    Energy Technology Data Exchange (ETDEWEB)

    Quigg, Chris; /Fermilab /CERN

    2007-04-01

    Electroweak theory joins electromagnetism with the weak force in a single quantum field theory, ascribing the two fundamental interactions--so different in their manifestations--to a common symmetry principle. How the electroweak gauge symmetry is hidden is one of the most urgent and challenging questions facing particle physics. The provisional answer incorporated in the ''standard model'' of particle physics was formulated in the 1960s by Higgs, by Brout & Englert, and by Guralnik, Hagen, & Kibble: The agent of electroweak symmetry breaking is an elementary scalar field whose self-interactions select a vacuum state in which the full electroweak symmetry is hidden, leaving a residual phase symmetry of electromagnetism. By analogy with the Meissner effect of the superconducting phase transition, the Higgs mechanism, as it is commonly known, confers masses on the weak force carriers W{sup {+-}} and Z. It also opens the door to masses for the quarks and leptons, and shapes the world around us. It is a good story--though an incomplete story--and we do not know how much of the story is true. Experiments that explore the Fermi scale (the energy regime around 1 TeV) during the next decade will put the electroweak theory to decisive test, and may uncover new elements needed to construct a more satisfying completion of the electroweak theory. The aim of this article is to set the stage by reporting what we know and what we need to know, and to set some ''Big Questions'' that will guide our explorations.

  14. Spontaneous breaking of time-reversal symmetry in topological insulators

    Energy Technology Data Exchange (ETDEWEB)

    Karnaukhov, Igor N., E-mail: karnaui@yahoo.com

    2017-06-21

    Highlights: • Proposed a new approach for description of phase transitions in topological insulators. • Considered the mechanism of spontaneous breaking of time-reversal symmetry in topological insulators. • The Haldane model can be implemented in real compounds of the condensed matter physics. - Abstract: The system of spinless fermions on a hexagonal lattice is studied. We have considered tight-binding model with the hopping integrals between the nearest-neighbor and next-nearest-neighbor lattice sites, that depend on the direction of the link. The links are divided on three types depending on the direction, the hopping integrals are defined by different phases along the links. The energy of the system depends on the phase differences, the solutions for the phases, that correspond to the minimums of the energy, lead to a topological insulator state with the nontrivial Chern numbers. We have analyzed distinct topological states and phase transitions, the behavior of the chiral gapless edge modes, have defined the Chern numbers. The band structure of topological insulator (TI) is calculated, the ground-state phase diagram in the parameter space is obtained. We propose a novel mechanism of realization of TI, when the TI state is result of spontaneous breaking of time-reversal symmetry due to nontrivial stable solutions for the phases that determine the hopping integrals along the links and show that the Haldane model can be implemented in real compounds of the condensed matter physics.

  15. 3D toroidal physics: testing the boundaries of symmetry breaking

    Science.gov (United States)

    Spong, Don

    2014-10-01

    Toroidal symmetry is an important concept for plasma confinement; it allows the existence of nested flux surface MHD equilibria and conserved invariants for particle motion. However, perfect symmetry is unachievable in realistic toroidal plasma devices. For example, tokamaks have toroidal ripple due to discrete field coils, optimized stellarators do not achieve exact quasi-symmetry, the plasma itself continually seeks lower energy states through helical 3D deformations, and reactors will likely have non-uniform distributions of ferritic steel near the plasma. Also, some level of designed-in 3D magnetic field structure is now anticipated for most concepts in order to lead to a stable, steady-state fusion reactor. Such planned 3D field structures can take many forms, ranging from tokamaks with weak 3D ELM-suppression fields to stellarators with more dominant 3D field structures. There is considerable interest in the development of unified physics models for the full range of 3D effects. Ultimately, the questions of how much symmetry breaking can be tolerated and how to optimize its design must be addressed for all fusion concepts. Fortunately, significant progress is underway in theory, computation and plasma diagnostics on many issues such as magnetic surface quality, plasma screening vs. amplification of 3D perturbations, 3D transport, influence on edge pedestal structures, MHD stability effects, modification of fast ion-driven instabilities, prediction of energetic particle heat loads on plasma-facing materials, effects of 3D fields on turbulence, and magnetic coil design. A closely coupled program of simulation, experimental validation, and design optimization is required to determine what forms and amplitudes of 3D shaping and symmetry breaking will be compatible with future fusion reactors. The development of models to address 3D physics and progress in these areas will be described. This work is supported both by the US Department of Energy under Contract DE

  16. Stock market speculation: Spontaneous symmetry breaking of economic valuation

    Science.gov (United States)

    Sornette, Didier

    2000-09-01

    Firm foundation theory estimates a security's firm fundamental value based on four determinants: expected growth rate, expected dividend payout, the market interest rate and the degree of risk. In contrast, other views of decision-making in the stock market, using alternatives such as human psychology and behavior, bounded rationality, agent-based modeling and evolutionary game theory, expound that speculative and crowd behavior of investors may play a major role in shaping market prices. Here, we propose that the two views refer to two classes of companies connected through a "phase transition". Our theory is based on (1) the identification of the fundamental parity symmetry of prices (p→-p), which results from the relative direction of payment flux compared to commodity flux and (2) the observation that a company's risk-adjusted growth rate discounted by the market interest rate behaves as a control parameter for the observable price. We find a critical value of this control parameter at which a spontaneous symmetry-breaking of prices occurs, leading to a spontaneous valuation in absence of earnings, similarly to the emergence of a spontaneous magnetization in Ising models in absence of a magnetic field. The low growth rate phase is described by the firm foundation theory while the large growth rate phase is the regime of speculation and crowd behavior. In practice, while large "finite-time horizon" effects round off the predicted singularities, our symmetry-breaking speculation theory accounts for the apparent over-pricing and the high volatility of fast growing companies on the stock markets.

  17. Supersymmetry in a sector of Higgsless electroweak symmetry breaking

    Energy Technology Data Exchange (ETDEWEB)

    Knochel, Alexander Karl

    2009-05-11

    In this thesis we have investigated phenomenological implications which arise for cosmology and collider physics when the electroweak symmetry breaking sector of warped higgsless models is extended to include warped supersymmetry with conserved R parity. The goal was to find the simplest supersymmetric extension of these models which still has a realistic light spectrum including a viable dark matter candidate. To accomplish this, we have used the same mechanism which is already at work for symmetry breaking in the electroweak sector to break supersymmetry as well, namely symmetry breaking by boundary conditions. While supersymmetry in five dimensions contains four supercharges and is therefore directly related to 4D N=2 supersymmetry, half of them are broken by the background leaving us with ordinary N=1 theory in the massless sector after Kaluza-Klein expansion. We thus use boundary conditions to model the effects of a breaking mechanism for the remaining two supercharges. The simplest viable scenario to investigate is a supersymmetric bulk and IR brane without supersymmetry on the UV brane. Even though parts of the light spectrum are effectively projected out by this mechanism, we retain the rich phenomenology of complete N=2 supermultiplets in the Kaluza-Klein sector. While the light supersymmetric spectrum consists of electroweak gauginos which get their O(100 GeV) masses from IR brane electroweak symmetry breaking, the light gluinos and squarks are projected out on the UV brane. The neutralinos, as mass eigenstates of the neutral bino-wino sector, are automatically the lightest gauginos, making them LSP dark matter candidates with a relic density that can be brought to agreement withWMAP measurements without extensive tuning of parameters. For chargino masses close to the experimental lower bounds at around m{sub {chi}{sup +}}{approx}100.. 110 GeV, the dark matter relic density points to LSP masses of around m{sub {chi}}{approx}90 GeV. At the LHC, the

  18. SU(3)F gauge family model and new symmetry breaking scale from FCNC processes

    National Research Council Canada - National Science Library

    Shou-Shan Bao; Zhuo Liu; Yue-Liang Wu

    2016-01-01

    Based on the SU(3)F gauge family symmetry model which was proposed to explain the observed mass and mixing pattern of neutrinos, we investigate the symmetry breaking, the mixing pattern in quark and lepton sectors...

  19. Evolution of the genetic code through progressive symmetry breaking.

    Science.gov (United States)

    Lenstra, Reijer

    2014-04-21

    Evolution of the genetic code in an early RNA world is dependent on the steadily improving specificity of the coevolving protein synthesis machinery for codons, anticodons, tRNAs and amino acids. In the beginning, there is RNA but the machinery does not distinguish yet between the codons, which therefore all encode the same information. Synonymous codons are equivalent under a symmetry group that exchanges (permutes) the codons without affecting the code. The initial group changes any codon into any other by permuting the order of the bases in the triplet as well as by replacing the four RNA bases with each other at every codon position. This group preserves the differences between codons, known as Hamming distances, with a 1-distance corresponding to a single point mutation. Stepwise breaking of the group into subgroups divides the 64 codons into progressively smaller subsets - blocks of equivalent codons under the smaller symmetry groups, with each block able to encode a different message. This formalism prescribes how the evolving machinery increasingly differentiates between codons. The model indicates that primitive ribosomes first identified a unique mRNA reading frame to break the group permuting the order of the bases and subsequently enforced increasingly stringent codon-anticodon basepairing rules to break the subgroups permuting the four bases at each codon position. The modern basepairing rules evolve in five steps and at each step the number of codon blocks doubles. The fourth step generates 16 codon blocks corresponding with the 16 family boxes of the standard code and the last step splits these boxes into 32 blocks of commonly two, but rarely one or three, synonymous codons. The evolving codes transmit at most one message per codon block and as the number of messages increases so does the specificity of the code and of protein synthesis. The selective advantage conferred by better functioning proteins drives the symmetry breaking process. Over time

  20. A Clifford algebra approach to chiral symmetry breaking and fermion mass hierarchies

    Science.gov (United States)

    Lu, Wei

    2017-09-01

    We propose a Clifford algebra approach to chiral symmetry breaking and fermion mass hierarchies in the context of composite Higgs bosons. Standard model fermions are represented by algebraic spinors of six-dimensional binary Clifford algebra, while ternary Clifford algebra-related flavor projection operators control allowable flavor-mixing interactions. There are three composite electroweak Higgs bosons resulted from top quark, tau neutrino, and tau lepton condensations. Each of the three condensations gives rise to masses of four different fermions. The fermion mass hierarchies within these three groups are determined by four-fermion condensations, which break two global chiral symmetries. The four-fermion condensations induce axion-like pseudo-Nambu-Goldstone bosons and can be dark matter candidates. In addition to the 125 GeV Higgs boson observed at the Large Hadron Collider, we anticipate detection of tau neutrino composite Higgs boson via the charm quark decay channel.

  1. Emergent spontaneous symmetry breaking and emergent symmetry restoration in rippling gravitational background

    Energy Technology Data Exchange (ETDEWEB)

    Kurkov, Maxim A. [Universidade Federal do ABC, CMCC, Santo Andre, SP (Brazil)

    2016-06-15

    We study effects of a rippling gravitational background on a scalar field with a double well potential, focusing on the analogy with the well known dynamics of the Kapitza's pendulum. The ripples are rendered as infinitesimal but rapidly oscillating perturbations of the scale factor. We find that the resulting dynamics crucially depends on a value of the parameter ξ in the ξRφ{sup 2} vertex. For the time-dependent perturbations of a proper form the resulting effective action is generally covariant, and at a high enough frequency at ξ < 0 and at ξ > 1/6 the effective potential has a single minimum at zero, thereby restoring spontaneously broken symmetry of the ground state. On the other side, at 0 < ξ < 1/6 spontaneous symmetry breaking emerges even when it is absent in the unperturbed case. (orig.)

  2. Inertial Spontaneous Symmetry Breaking and Quantum Scale Invariance

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Pedro G. [Oxford U.; Hill, Christopher T. [Fermilab; Ross, Graham G. [Oxford U., Theor. Phys.

    2018-01-23

    Weyl invariant theories of scalars and gravity can generate all mass scales spontaneously, initiated by a dynamical process of "inertial spontaneous symmetry breaking" that does not involve a potential. This is dictated by the structure of the Weyl current, $K_\\mu$, and a cosmological phase during which the universe expands and the Einstein-Hilbert effective action is formed. Maintaining exact Weyl invariance in the renormalised quantum theory is straightforward when renormalisation conditions are referred back to the VEV's of fields in the action of the theory, which implies a conserved Weyl current. We do not require scale invariant regulators. We illustrate the computation of a Weyl invariant Coleman-Weinberg potential.

  3. Symmetry breaking of zero energy landau level in monolayer graphene

    Science.gov (United States)

    Zhao, Yue; Cadden-Zimansky, Paul; Ghahari, Fereshte; Kim, Philip

    2011-03-01

    We experimentally study the nature of the symmetry breaking of the zero energy landau level (LL) in monolayer graphene using Corbino geometry and Hall bar geometry devices. At high magnetic fields, in the absence of the edge state channel connection in Corbino devices, we observe a gap opening in ν = 0 QH state whose gap is independent of in-plane magnetic field. In Hall-bar geometry devices where edge state connection is allowed, we observe similar QH Insulator behavior independent of the in-plane magnetic field, indicating that the observed insulating behavior at the charge neutrality point of monolayer graphene at high magnetic field is originated from the degeneracy lifting of the zero LL via the valley pseudospin polarization rather spin polarization.

  4. Further Study of BRST-Symmetry Breaking on the Lattice

    CERN Document Server

    Cucchieri, Attilio

    2016-01-01

    We evaluate the so-called Bose-ghost propagator Q(p^2) for SU(2) gauge theory in minimal Landau gauge, considering lattice volumes up to 120^4 and physical lattice extents up to 13.5 f. In particular, we investigate discretization effects, as well as the infinite-volume and continuum limits. We recall that a nonzero value for this quantity provides direct evidence of BRST-symmetry breaking, related to the restriction of the functional measure to the first Gribov region. Our results show that the prediction (from cluster decomposition) for Q(p^2) in terms of gluon and ghost propagators is better satisfied as the continuum limit is approached.

  5. Fermion masses without symmetry breaking in two spacetime dimensions

    Energy Technology Data Exchange (ETDEWEB)

    BenTov, Yoni [Department of Physics, University of California,Santa Barbara, CA 93106 (United States)

    2015-07-08

    I study the prospect of generating mass for symmetry-protected fermions without breaking the symmetry that forbids quadratic mass terms in the Lagrangian. I focus on 1+1 spacetime dimensions in the hope that this can provide guidance for interacting fermions in 3+1 dimensions. I first review the SO(8) Gross-Neveu model and emphasize a subtlety in the triality transformation. Then I focus on the “m=0” manifold of the SO(7) Kitaev-Fidkowski model. I argue that this theory exhibits a phenomenon similar to “parity doubling” in hadronic physics, and this leads to the conclusion that the fermion propagator vanishes when p{sup μ}=0. I also briefly explore a connection between this model and the two-channel, single-impurity Kondo effect. This paper may serve as an introduction to topological superconductors for high energy theorists, and perhaps as a taste of elementary particle physics for condensed matter theorists.

  6. A perfectly conducting surface in electrodynamics with Lorentz symmetry breaking

    Energy Technology Data Exchange (ETDEWEB)

    Borges, L.H.C. [UNESP, Campus de Guaratingueta, DFQ, Guaratingueta, SP (Brazil); Barone, F.A. [IFQ, Universidade Federal de Itajuba, Itajuba, MG (Brazil)

    2017-10-15

    In this paper we consider a model which exhibits explicit Lorentz symmetry breaking due to the presence of a single background vector v{sup μ} coupled to the gauge field. We investigate such a theory in the vicinity of a perfectly conducting plate for different configurations of v{sup μ}. First we consider no restrictions on the components of the background vector and we treat it perturbatively up to second order. Next, we treat v{sup μ} exactly for two special cases: the first one is when it has only components parallel to the plate, and the second one when it has a single component perpendicular to the plate. For all these configurations, the propagator for the gauge field and the interaction force between the plate and a point-like electric charge are computed. Surprisingly, it is shown that the image method is valid in our model and we argue that it is a non-trivial result. We show there arises a torque on the mirror with respect to its positioning in the background field when it interacts with a point-like charge. It is a new effect with no counterpart in theories with Lorentz symmetry in the presence of a perfect mirror. (orig.)

  7. Rotation Breaking Induced by ELMs on EAST

    DEFF Research Database (Denmark)

    Xiong, H.; Xu, G.; Sun, Y.

    Spontaneous rotation has been observed in LHCD H-mode plasmas with type III ELMs (edge localized modes) on EAST, and it revealed that type III ELMs can induce the loss of both core and edge toroidal rotation. Here we work on the breaking mechanism during the ELMs. Several large tokamaks have...... discovered ELMs' filamentary structures. It revealed that the ELMs are filamentary perturbations of positive density formed along the local field lines close to the LCFS. Currents flowing in the filaments induce magnetic perturbations, which break symmetry of magnetic field strength and lead to deformation...... of magnetic surface, thus generate NTV (neoclassical toroidal viscosity) torque that affects toroidal rotation. We adopt 1cm maximum edge magnetic surface displacement from experimental observation, and our calculation shows that the edge torque is about 0.35 N/m2, and the core very small. The expected...

  8. Modeling outer-sphere disorder in the symmetry breaking of PPV.

    Science.gov (United States)

    Liu, L Angela; Yaron, David J

    2009-04-21

    Disorder plays an important role in the photophysics of conjugated polymers such as poly(para-phenylene vinylene) (PPV). The dipole moments measured by electroabsorption spectroscopy for a centrosymmetric system such as PPV provide a direct quantitative measure of disorder-induced symmetry breaking. Although inner-sphere (structural) disorder is present, outer-sphere (environmental) disorder dominates the symmetry breaking in PPV. This paper develops and compares six models of outer-sphere disorder that differ in their representation of the electrostatic environment of PPV in glassy solvents. The most detailed model is an all-atom description of the solvent glass and this model forms the basis for comparison of the less detailed models. Four models are constructed in which multipoles are placed at points on a lattice. These lattice models differ in the degree to which they include correlation between the lattice spacings and the orientations of the multipoles. A simple model that assigns random Gaussian-distributed electrostatic potentials to each atom in the PPV molecule is also considered. Comparison of electronic structure calculations of PPV in these electrostatic environments using the all-atom model as a benchmark reveals that dipole and quadrupole lattices provide reasonable models of organic glassy solvents. Including orientational correlation among the solvent molecules decreases the effects of outer-sphere disorder, whereas including correlation in the lattice spacings increases the effects. Both the dipole and quadrupole moments of the solvent molecules can have significant effects on the symmetry breaking and these effects are additive. This additivity provides a convenient means for predicting the effects of various glassy solvents based on their multipole moments. The results presented here suggest that electrostatic disorder can account for the observed symmetry breaking in organic glasses. Furthermore, the lattice models are in general agreement

  9. Symmetry breaking on density in escaping ants: experiment and alarm pheromone model.

    Science.gov (United States)

    Li, Geng; Huan, Di; Roehner, Bertrand; Xu, Yijuan; Zeng, Ling; Di, Zengru; Han, Zhangang

    2014-01-01

    The symmetry breaking observed in nature is fascinating. This symmetry breaking is observed in both human crowds and ant colonies. In such cases, when escaping from a closed space with two symmetrically located exits, one exit is used more often than the other. Group size and density have been reported as having no significant impact on symmetry breaking, and the alignment rule has been used to model symmetry breaking. Density usually plays important roles in collective behavior. However, density is not well-studied in symmetry breaking, which forms the major basis of this paper. The experiment described in this paper on an ant colony displays an increase then decrease of symmetry breaking versus ant density. This result suggests that a Vicsek-like model with an alignment rule may not be the correct model for escaping ants. Based on biological facts that ants use pheromones to communicate, rather than seeing how other individuals move, we propose a simple yet effective alarm pheromone model. The model results agree well with the experimental outcomes. As a measure, this paper redefines symmetry breaking as the collective asymmetry by deducing the random fluctuations. This research indicates that ants deposit and respond to the alarm pheromone, and the accumulation of this biased information sharing leads to symmetry breaking, which suggests true fundamental rules of collective escape behavior in ants.

  10. arXiv Radiative symmetry breaking from interacting UV fixed points

    CERN Document Server

    Abel, Steven

    2017-09-28

    It is shown that the addition of positive mass-squared terms to asymptotically safe gauge-Yukawa theories with perturbative UV fixed points leads to calculable radiative symmetry breaking in the IR. This phenomenon, and the multiplicative running of the operators that lies behind it, is akin to the radiative symmetry breaking that occurs in the supersymmetric standard model.

  11. Symmetry breaking on density in escaping ants: experiment and alarm pheromone model.

    Directory of Open Access Journals (Sweden)

    Geng Li

    Full Text Available The symmetry breaking observed in nature is fascinating. This symmetry breaking is observed in both human crowds and ant colonies. In such cases, when escaping from a closed space with two symmetrically located exits, one exit is used more often than the other. Group size and density have been reported as having no significant impact on symmetry breaking, and the alignment rule has been used to model symmetry breaking. Density usually plays important roles in collective behavior. However, density is not well-studied in symmetry breaking, which forms the major basis of this paper. The experiment described in this paper on an ant colony displays an increase then decrease of symmetry breaking versus ant density. This result suggests that a Vicsek-like model with an alignment rule may not be the correct model for escaping ants. Based on biological facts that ants use pheromones to communicate, rather than seeing how other individuals move, we propose a simple yet effective alarm pheromone model. The model results agree well with the experimental outcomes. As a measure, this paper redefines symmetry breaking as the collective asymmetry by deducing the random fluctuations. This research indicates that ants deposit and respond to the alarm pheromone, and the accumulation of this biased information sharing leads to symmetry breaking, which suggests true fundamental rules of collective escape behavior in ants.

  12. Symmetry breaking and un-breaking in microhydrodynamical systems: Swimming, pumping and bio-ballistics

    Science.gov (United States)

    Roper, Marcus Leigh

    This thesis describes the numerical and asymptotic analysis of symmetry breaking phenomena in three fluid dynamical systems. The first part concerns modeling of a micrometer sized swimming device, comprising a filament composed of superparamagnetic micron-sized beads and driven by an applied magnetic field. The swimming mechanics are deciphered in order to show how actuation by a spatially-homogeneous but temporally-varying torque leads to propagation of a bending wave along the filament and thence to propulsion. Absence of swimming unless the lateral symmetry of the filament is broken by tethering one end to a high drag body is explained. The model is used to determine whether, and to what extent, the micro-swimmer behaves like a flagellated eukaryotic cell. The second part concerns modeling of locomotion using a reversible stroke. Although forbidden at low Reynolds numbers, such symmetric gaits are favored by some microscopic planktonic swimmers. We analyze the constraints upon generation of propulsive force by such swimmers using a numerical model for a flapped limb. Effective locomotion is shown to be possible at arbitrarily low rates of energy expenditure, escaping a formerly postulated time-symmetry constraint, if the limb is shaped in order to exploit slow inertial-streaming eddies. Finally we consider the evolution of explosively launched ascomycete spores toward perfect projectile shapes---bodies that are designed to experience minimum drag in flight---using the variance of spore shapes between species in order to quantify the stiffness of the drag minimization constraint. A surprising observation about the persistent fore-aft symmetry of perfect projectiles, even up to Reynolds numbers great enough that the flow around the projectile is highly asymmetric, points both toward a model for spore ontogeny and to a novel linear approximation for moderate Reynolds flows.

  13. Artificial Symmetry-Breaking for Morphogenetic Engineering Bacterial Colonies.

    Science.gov (United States)

    Nuñez, Isaac N; Matute, Tamara F; Del Valle, Ilenne D; Kan, Anton; Choksi, Atri; Endy, Drew; Haseloff, Jim; Rudge, Timothy J; Federici, Fernan

    2017-02-17

    Morphogenetic engineering is an emerging field that explores the design and implementation of self-organized patterns, morphologies, and architectures in systems composed of multiple agents such as cells and swarm robots. Synthetic biology, on the other hand, aims to develop tools and formalisms that increase reproducibility, tractability, and efficiency in the engineering of biological systems. We seek to apply synthetic biology approaches to the engineering of morphologies in multicellular systems. Here, we describe the engineering of two mechanisms, symmetry-breaking and domain-specific cell regulation, as elementary functions for the prototyping of morphogenetic instructions in bacterial colonies. The former represents an artificial patterning mechanism based on plasmid segregation while the latter plays the role of artificial cell differentiation by spatial colocalization of ubiquitous and segregated components. This separation of patterning from actuation facilitates the design-build-test-improve engineering cycle. We created computational modules for CellModeller representing these basic functions and used it to guide the design process and explore the design space in silico. We applied these tools to encode spatially structured functions such as metabolic complementation, RNAPT7 gene expression, and CRISPRi/Cas9 regulation. Finally, as a proof of concept, we used CRISPRi/Cas technology to regulate cell growth by controlling methionine synthesis. These mechanisms start from single cells enabling the study of morphogenetic principles and the engineering of novel population scale structures from the bottom up.

  14. Studies of strong electroweak symmetry breaking at photon colliders

    Science.gov (United States)

    Cheung, Kingman

    1994-10-01

    It has recently been shown that the studies of strongly interacting electroweak symmetry breaking (EWSB) at photon colliders, via photon splitting into a W pair followed by longitudinal W-boson scattering, could be possible. Here we present a signal-background analysis for the scattering channels W+LW-L-->ZLZL and W+LW-L-->W+LW-L with the background coming from the standard model (SM) production of γγ-->WWZZ and WWWW, respectively. We illustrate the analysis using the SM with a heavy Higgs boson (mH~=1 TeV) to represent a typical strongly interacting EWSB model and the SM with a light Higgs boson (mH~=0.1 TeV) to represent the background. We come up with a set of kinematic acceptance to enhance the signal-to-background ratio. The extension of the kinematic acceptance to other strongly interacting EWSB models is then trivial, and the signal cross sections for various EWSB models are calculated. We found that it is very feasible to probe the EWSB sector at a photon collider of center-of-mass energy of 2 TeV with a luminosity of just 10 fb-1.

  15. Localization and Symmetry Breaking in the Quantum Quasiperiodic Ising Glass

    Science.gov (United States)

    Chandran, A.; Laumann, C. R.

    2017-07-01

    Quasiperiodic modulation can prevent isolated quantum systems from equilibrating by localizing their degrees of freedom. In this article, we show that such systems can exhibit dynamically stable long-range orders forbidden in equilibrium. Specifically, we show that the interplay of symmetry breaking and localization in the quasiperiodic quantum Ising chain produces a quasiperiodic Ising glass stable at all energy densities. The glass order parameter vanishes with an essential singularity at the melting transition with no signatures in the equilibrium properties. The zero-temperature phase diagram is also surprisingly rich, consisting of paramagnetic, ferromagnetic, and quasiperiodically alternating ground-state phases with extended, localized, and critically delocalized low-energy excitations. The system exhibits an unusual quantum Ising transition whose properties are intermediate between those of the clean and infinite randomness Ising transitions. Many of these results follow from a geometric generalization of the Aubry-André duality that we develop. The quasiperiodic Ising glass may be realized in near-term quantum optical experiments.

  16. Spontaneous breaking of time-reversal symmetry in topological insulators

    Science.gov (United States)

    Karnaukhov, Igor N.

    2017-06-01

    The system of spinless fermions on a hexagonal lattice is studied. We have considered tight-binding model with the hopping integrals between the nearest-neighbor and next-nearest-neighbor lattice sites, that depend on the direction of the link. The links are divided on three types depending on the direction, the hopping integrals are defined by different phases along the links. The energy of the system depends on the phase differences, the solutions for the phases, that correspond to the minimums of the energy, lead to a topological insulator state with the nontrivial Chern numbers. We have analyzed distinct topological states and phase transitions, the behavior of the chiral gapless edge modes, have defined the Chern numbers. The band structure of topological insulator (TI) is calculated, the ground-state phase diagram in the parameter space is obtained. We propose a novel mechanism of realization of TI, when the TI state is result of spontaneous breaking of time-reversal symmetry due to nontrivial stable solutions for the phases that determine the hopping integrals along the links and show that the Haldane model [1] can be implemented in real compounds of the condensed matter physics.

  17. Localization and Symmetry Breaking in the Quantum Quasiperiodic Ising Glass

    Directory of Open Access Journals (Sweden)

    A. Chandran

    2017-09-01

    Full Text Available Quasiperiodic modulation can prevent isolated quantum systems from equilibrating by localizing their degrees of freedom. In this article, we show that such systems can exhibit dynamically stable long-range orders forbidden in equilibrium. Specifically, we show that the interplay of symmetry breaking and localization in the quasiperiodic quantum Ising chain produces a quasiperiodic Ising glass stable at all energy densities. The glass order parameter vanishes with an essential singularity at the melting transition with no signatures in the equilibrium properties. The zero-temperature phase diagram is also surprisingly rich, consisting of paramagnetic, ferromagnetic, and quasiperiodically alternating ground-state phases with extended, localized, and critically delocalized low-energy excitations. The system exhibits an unusual quantum Ising transition whose properties are intermediate between those of the clean and infinite randomness Ising transitions. Many of these results follow from a geometric generalization of the Aubry-André duality that we develop. The quasiperiodic Ising glass may be realized in near-term quantum optical experiments.

  18. Symmetry breaking and finite size scaling in antiferromagnets

    Science.gov (United States)

    Azaria, P.; Delamotte, B.; Mouhanna, D.

    1993-02-01

    We show that the finite size scaling analysis of the quantum non linear sigma model O(3)/O(2) associated with antiferromagnets justifies the existence of the tower of excited states first proposed by Anderson to explain the symmetry breaking of quantum antiferromagnets in the thermodynamical limit. Finite size formulas for the ground state energy and for the ground state expectation value of the order parameter are explicitly given. Nous montrons que l'analyse du comportement à taille finie du modèle sigma non linéaire quantique O(3)/O(2) adapté aux antiferromagnétiques justifie l'existence d'une tour d'états excités proposée pour la première fois par Anderson pour expliquer la brisure de symétrie des antiferromagnétiques quantiques dans la limite thermodynamique. Nous donnons également les formules de taille finie pour l'énergie du fondamental et pour la valeur moyenne dans le vide du paramètre d'ordre.

  19. Superallowed nuclear β decay: symmetry breaking, CVC and CKM unitarity

    Science.gov (United States)

    Hardy, J. C.; Towner, I. S.

    2010-11-01

    Currently, the most restrictive test of the unitarity of the Cabibbo-Kobayashi-Maskawa (CKM) matrix is anchored by nuclear beta decay. Precise measurements of the ft-values for superallowed beta transitions between analog 0+ states are used to determine G, the vector coupling constant; this, in turn, yields V, the up-down element of the Cabibbo-Kobayashi-Maskawa (CKM) matrix. When the value for V obtained from the latest survey of world data is combined with V and V, the other top-row elements, it leads to the most demanding test available of the unitarity of that matrix. Important ingredients required in the extraction of V from experiment are calculated radiative corrections as well as corrections to account for the isospin symmetry breaking that occurs between the analog parent and daughter states of each superallowed transition. The latter are well supported by comparison with experiment. The current value for the unitarity sum is 0.99995(61), a result that is in remarkable agreement with Standard Model expectations.

  20. Sea quark transverse momentum distributions and dynamical chiral symmetry breaking

    Energy Technology Data Exchange (ETDEWEB)

    Schweitzer, Peter [Univ. of Connecticut, Storrs, CT (United States); Strikman, Mark [Penn State Univ., State College, PA (United States); Weiss, Christian [JLAB Newport News, VA (United States)

    2014-01-01

    Recent theoretical studies have provided new insight into the intrinsic transverse momentum distributions of valence and sea quarks in the nucleon at a low scale. The valence quark transverse momentum distributions (q - qbar) are governed by the nucleon's inverse hadronic size R{sup -1} ~ 0.2 GeV and drop steeply at large p{sub T}. The sea quark distributions (qbar) are in large part generated by non-perturbative chiral-symmetry breaking interactions and extend up to the scale rho{sup -1} ~ 0.6 GeV. These findings have many implications for modeling the initial conditions of perturbative QCD evolution of TMD distributions (starting scale, shape of p{sub T}. distributions, coordinate-space correlation functions). The qualitative difference between valence and sea quark intrinsic p{sub T}. distributions could be observed experimentally, by comparing the transverse momentum distributions of selected hadrons in semi-inclusive deep-inelastic scattering, or those of dileptons produced in pp and pbar-p scattering.

  1. Robustness of replica symmetry breaking phenomenology in random laser.

    Science.gov (United States)

    Tommasi, Federico; Ignesti, Emilio; Lepri, Stefano; Cavalieri, Stefano

    2016-11-16

    Random lasers are optical sources where light is amplified by stimulated emission along random paths through an amplifying scattering medium. Connections between their physics and the one of quenched disordered nonlinear systems, notably spin glasses, have been recently suggested. Here we report a first experimental study of correlations of spectral fluctuations intensity in a random laser medium where the scatterers displacement significantly changes among consecutive shots. Remarkably, our results reveal that the replica symmetry breaking (RSB) phenomenology is robust with respect to an averaging over different realizations of the disorder. Moreover, besides opening new intriguing questions about the understanding of such a phenomenon, this work aims to clarify the connection between the RSB with the onset of the Lévy regime, i.e. the fluctuations regime that is a peculiar feature of the random lasing under critical conditions. Our results suggest that the former occurs independently of the latter and then the RSB phenomenology is a generic feature linked to the random laser threshold.

  2. Symmetry Breaking and Adaptation Evidence from a Toy Model of a Virus

    CERN Document Server

    Mora, J; Waelbroeck, H

    1997-01-01

    We argue that the phenomenon of symmetry breaking in genetics can enhance the adaptability of a species to changes in the environment. In the case of a virus, the claim is that the codon bias in the neutralization epitope improves the virus' ability to generate mutants that evade the induced immune response. We support our claim with a simple ``toy model'' of a viral epitope evolving in competition with the immune system. The effective selective advantage of a higher mutability leads to a dominance of codons that favour non-synonymous mutations. The results in this paper suggest the possibility of emergence of an algorithmic language in more complicated systems.

  3. Unconventional superconductivity in generalized Hubbard model: role of electron-hole symmetry breaking terms.

    Science.gov (United States)

    Wysokiński, Marcin M; Kaczmarczyk, Jan

    2017-03-01

    We investigate the effect of the electron-hole (e-h) symmetry breaking on d-wave superconductivity induced by non-local effects of correlations in the generalized Hubbard model. The symmetry breaking is introduced in a two-fold manner: by the next-to-nearest neighbor hopping of electrons and by the charge-bond interaction-the off-diagonal term of the Coulomb potential. Both terms lead to a pronounced asymmetry of the superconducting order parameter. The next-to-nearest neighbor hopping enhances superconductivity for h-doping, while diminishes it for e-doping. The charge-bond interaction alone leads to the opposite effect and, additionally, to the kinetic-energy gain upon condensation in the underdoped regime. With both terms included, with similar amplitudes, the height of the superconducting dome and the critical doping remain in favor of h-doping. The influence of the charge-bond interaction on deviations from [Formula: see text] symmetry of the shape of the gap at the Fermi surface in the momentum space is briefly discussed.

  4. Universality of phase transition dynamics: topological defects from symmetry breaking

    Energy Technology Data Exchange (ETDEWEB)

    Zurek, Wojciech H. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Del Campo, Adolfo [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-02-13

    In the course of a non-equilibrium continuous phase transition, the dynamics ceases to be adiabatic in the vicinity of the critical point as a result of the critical slowing down (the divergence of the relaxation time in the neighborhood of the critical point). This enforces a local choice of the broken symmetry and can lead to the formation of topological defects. The Kibble-Zurek mechanism (KZM) was developed to describe the associated nonequilibrium dynamics and to estimate the density of defects as a function of the quench rate through the transition. During recent years, several new experiments investigating formation of defects in phase transitions induced by a quench both in classical and quantum mechanical systems were carried out. At the same time, some established results were called into question. We review and analyze the Kibble-Zurek mechanism focusing in particular on this surge of activity, and suggest possible directions for further progress.

  5. Phase segregation and spontaneous symmetry breaking in a bidirectional two-channel non-conserving model with narrow entrances

    Science.gov (United States)

    Sharma, Natasha; Gupta, A. K.

    2017-04-01

    Motivated by connections between the inputs and outputs of several transport mechanisms and multi-species functionalities, we studied an open system of a two-species totally asymmetric simple exclusion process with narrow entrances, which assimilate the synergy of the particles with the surrounding environment through Langmuir kinetics (LK). We analyzed the model within the framework of mean-field theory, and examined complex phenomena such as boundary-induced phase transitions and spontaneous symmetry breaking for variant conditions of attachment and detachment rates. Based on the theoretical investigations we obtained the phase boundaries for various symmetric and asymmetric phases. Our finding displays a prolific behavior, highlighting the significant effect of LK rates on symmetry breaking. It is found that for lower orders of LK rates, the number of symmetrical and asymmetrical phases increases notably, while for their higher orders symmetry breaking disappears, revealing that the presence of bulk non-conserving processes can resume/break the uniformity between two species. The critical value of LK rates beyond which the asymmetrical phases disappears is identified. The theoretical findings are explored by extensive Monte Carlo simulations. The effect of the system size and symmetry breaking incident on the Monte Carlo simulation results has also been examined based on particle density histograms.

  6. Chiral symmetry breaking in QCD with two light flavors.

    Science.gov (United States)

    Engel, Georg P; Giusti, Leonardo; Lottini, Stefano; Sommer, Rainer

    2015-03-20

    A distinctive feature of the presence of spontaneous chiral symmetry breaking in QCD is the condensation of low modes of the Dirac operator near the origin. The rate of condensation must be equal to the slope of M(π)(2)F(π)(2)/2 with respect to the quark mass m in the chiral limit, where M(π) and F(π) are the mass and the decay constant of the Nambu-Goldstone bosons. We compute the spectral density of the (Hermitian) Dirac operator, the quark mass, the pseudoscalar meson mass, and decay constant by numerical simulations of lattice QCD with two light degenerate Wilson quarks. We use lattices generated by the Coordinated Lattice Simulation (CLS) group at three values of the lattice spacing in the range 0.05-0.08 fm, and for several quark masses corresponding to pseudoscalar mesons masses down to 190 MeV. Thanks to this coverage of parameters space, we can extrapolate all quantities to the chiral and continuum limits with confidence. The results show that the low quark modes do condense in the continuum as expected by the Banks-Casher mechanism, and the rate of condensation agrees with the Gell-Mann-Oakes-Renner relation. For the renormalization-group-invariant ratios we obtain [Σ(RGI)](1/3)/F=2.77(2)(4) and Λ(M̅S)/F=3.6(2), which correspond to [Σ(M̅S)(2  GeV)](1/3)=263(3)(4)  MeV and F=85.8(7)(20)  MeV if F(K) is used to set the scale by supplementing the theory with a quenched strange quark.

  7. Spontaneous breaking of the left-right symmetry and quantum corrections

    Science.gov (United States)

    Cvetič, M.

    1984-03-01

    In this paper we study new features of spontaneous symmetry breaking (SSB) of the left-right (LR) symmetry based on a model with gauge symmetry SU(2) R × SU(2) L × U(1) B- L that arise when we include quantum corrections to the tree-level Higgs potential. First, an instructive toy model, with fermions remaining massless, is considered in which the gauge symmetry breaks via SU(2) L × U(1) Y down to U(1) EM through the vacuum expectation value (VEV) of just two scalar doublet fields φ L ˜ ( 2, 1, 1) and φ R ˜ ( 1, 2, 1) . We show that while the tree-level solution yields ≠ 0 and = 0, inclusion of quantum corrections can induce ≠ 0 and provide a hierarchy mW R > mW L ≠ 0 for masses of the left-handed and right-handed vector bosons. The striking prediction of the model, following from the minimization of the potential, is a result of R = mW R/ mW L being bounded above the expression exp(1+ β/2 α2 where α= g2/4 π with g a gauge coupling constant and β depends on the tree-level Higgs potential parameter and βmodel there is a natural bound for R ≲ 2 to 4. The model also predicts a light neutral pseudo-Goldstone particle, which is indeed a Higgs particle of the Weinberg-Salam model, and whose mass cannot exceed 10 GeV. This approach represents a viable way for breaking a discrete LR symmetry by quantum corrections and evades a constraint which states: the symmetry of the VEV obtained at the tree level cannot be broken by quantum corrections unless some "accidental" symmetry is present at the tree-level Higgs potential. We also consider a realistic model where we include together with the doublet fields φL,R, also the field ξ ˜ ( 2, 2, 0) giving Dirac masses to fermions. In this model we observe that the LR symmetry can be broken spontaneously at the tree level as before, but in contrast to the toy model, also SU(2) L symmetry is necessarily broken at the tree level consistent with a hierarchy requirement mW R > mW L ≠ 0. Including quantum

  8. Silicene nanomeshes: bandgap opening by bond symmetry breaking and uniaxial strain.

    Science.gov (United States)

    Jia, Tian-Tian; Fan, Xin-Yu; Zheng, Meng-Meng; Chen, Gang

    2016-02-10

    Based on the first-principles calculations, we have investigated in detail the bandgap opening of silicene nanomeshes. Different to the mechanism of bandgap opening induced by the sublattice equivalence breaking, the method of degenerate perturbation through breaking the bond symmetry could split the π-like bands in the inversion symmetry preserved silicene nanomeshes, resulting into the πa1 - πa2 and πz1 - πz2 band sets with sizable energy intervals. Besides the bandgap opening in the nanomeshes with Dirac point being folded to Γ point, the split energy intervals are however apart away from Fermi level to leave the semimetal nature unchanged for the other nanomeshes with Dirac points located at opposite sides of Γ point as opposite pseudo spin wave valleys. A mass bandgap could be then opened at the aid of uniaxial strain to transfer the nanomesh to be semiconducting, whose width could be continuously enlarged until reaching its maximum Emax. Moreover, the Emax could also be tuned by controlling the defect density in silicene nanomeshes. These studies could contribute to the understanding of the bandgap engineering of silicene-based nanomaterials to call for further investigations on both theory and experiment.

  9. Spontaneous cell polarization: Feedback control of Cdc42 GTPase breaks cellular symmetry.

    Science.gov (United States)

    Martin, Sophie G

    2015-11-01

    Spontaneous polarization without spatial cues, or symmetry breaking, is a fundamental problem of spatial organization in biological systems. This question has been extensively studied using yeast models, which revealed the central role of the small GTPase switch Cdc42. Active Cdc42-GTP forms a coherent patch at the cell cortex, thought to result from amplification of a small initial stochastic inhomogeneity through positive feedback mechanisms, which induces cell polarization. Here, I review and discuss the mechanisms of Cdc42 activity self-amplification and dynamic turnover. A robust Cdc42 patch is formed through the combined effects of Cdc42 activity promoting its own activation and active Cdc42-GTP displaying reduced membrane detachment and lateral diffusion compared to inactive Cdc42-GDP. I argue the role of the actin cytoskeleton in symmetry breaking is not primarily to transport Cdc42 to the active site. Finally, negative feedback and competition mechanisms serve to control the number of polarization sites. © 2015 WILEY Periodicals, Inc.

  10. Maximal Rashba-like spin splitting via kinetic-energy-coupled inversion-symmetry breaking

    Science.gov (United States)

    Sunko, Veronika; Rosner, H.; Kushwaha, P.; Khim, S.; Mazzola, F.; Bawden, L.; Clark, O. J.; Riley, J. M.; Kasinathan, D.; Haverkort, M. W.; Kim, T. K.; Hoesch, M.; Fujii, J.; Vobornik, I.; MacKenzie, A. P.; King, P. D. C.

    2017-09-01

    Engineering and enhancing the breaking of inversion symmetry in solids—that is, allowing electrons to differentiate between ‘up’ and ‘down’—is a key goal in condensed-matter physics and materials science because it can be used to stabilize states that are of fundamental interest and also have potential practical applications. Examples include improved ferroelectrics for memory devices and materials that host Majorana zero modes for quantum computing. Although inversion symmetry is naturally broken in several crystalline environments, such as at surfaces and interfaces, maximizing the influence of this effect on the electronic states of interest remains a challenge. Here we present a mechanism for realizing a much larger coupling of inversion-symmetry breaking to itinerant surface electrons than is typically achieved. The key element is a pronounced asymmetry of surface hopping energies—that is, a kinetic-energy-coupled inversion-symmetry breaking, the energy scale of which is a substantial fraction of the bandwidth. Using spin- and angle-resolved photoemission spectroscopy, we demonstrate that such a strong inversion-symmetry breaking, when combined with spin–orbit interactions, can mediate Rashba-like spin splittings that are much larger than would typically be expected. The energy scale of the inversion-symmetry breaking that we achieve is so large that the spin splitting in the CoO2- and RhO2-derived surface states of delafossite oxides becomes controlled by the full atomic spin–orbit coupling of the 3d and 4d transition metals, resulting in some of the largest known Rashba-like spin splittings. The core structural building blocks that facilitate the bandwidth-scaled inversion-symmetry breaking are common to numerous materials. Our findings therefore provide opportunities for creating spin-textured states and suggest routes to interfacial control of inversion-symmetry breaking in designer heterostructures of oxides and other material classes.

  11. Anomalous breaking of anisotropic scaling symmetry in the quantum lifshitz model

    NARCIS (Netherlands)

    Baggio, M.; de Boer, J.; Holsheimer, K.

    2012-01-01

    In this note we investigate the anomalous breaking of anisotropic scaling symmetry (t, x) → (λ z t, λ x) in a non-relativistic field theory with dynamical exponent z = 2. On general grounds, one can show that there exist two possible "central charges" which characterize the breaking of scale

  12. Symmetry-Breaking as a Paradigm to Design Highly-Sensitive Sensor Systems

    Directory of Open Access Journals (Sweden)

    Antonio Palacios

    2015-06-01

    Full Text Available A large class of dynamic sensors have nonlinear input-output characteristics, often corresponding to a bistable potential energy function that controls the evolution of the sensor dynamics. These sensors include magnetic field sensors, e.g., the simple fluxgate magnetometer and the superconducting quantum interference device (SQUID, ferroelectric sensors and mechanical sensors, e.g., acoustic transducers, made with piezoelectric materials. Recently, the possibilities offered by new technologies and materials in realizing miniaturized devices with improved performance have led to renewed interest in a new generation of inexpensive, compact and low-power fluxgate magnetometers and electric-field sensors. In this article, we review the analysis of an alternative approach: a symmetry-based design for highly-sensitive sensor systems. The design incorporates a network architecture that produces collective oscillations induced by the coupling topology, i.e., which sensors are coupled to each other. Under certain symmetry groups, the oscillations in the network emerge via an infinite-period bifurcation, so that at birth, they exhibit a very large period of oscillation. This characteristic renders the oscillatory wave highly sensitive to symmetry-breaking effects, thus leading to a new detection mechanism. Model equations and bifurcation analysis are discussed in great detail. Results from experimental works on networks of fluxgate magnetometers are also included.

  13. Isospin Symmetry Breaking within the HLS Model A Full ($\\rho, \\omega, \\phi$) Mixing Scheme

    CERN Document Server

    Benayoun, Maurice

    2001-01-01

    We study the way isospin symmetry violation can be generated within the Hidden Local Symmetry (HLS) Model. We show that isospin symmetry breaking effects on pseudoscalar mesons naturally induces correspondingly effects within the physics of vector mesons, through kaon loops. In this way, one recovers all features traditionally expected from $\\rho-\\omg$ mixing and one finds support for the Orsay phase modelling of the $e^+e^- \\ra \\pi^+ \\pi^-$ amplitude. We then examine an effective procedure which generates mixing in the whole $\\rho$, $\\omg$, $\\phi$ sector of the HLS Model. The corresponding model allows us to account for all two body decays of light mesons accessible to the HLS model in modulus and phase, leaving aside the $\\rho \\ra \\pi \\pi$ and $K^* \\ra K \\pi$ modes only, which raise a specific problem. Comparison with experimental data is performed and covers modulus and phase information; this represents 26 physical quantities successfully described with very good fit quality within a constrained model whi...

  14. Analysis of symmetry breaking in quartz blocks using superstatistical random-matrix theory

    Science.gov (United States)

    Abul-Magd, A. Y.; Mazen, S. A.; Abdel-Mageed, M.

    2012-06-01

    We study the symmetry breaking of acoustic resonances measured by Ellegaard et al. (1996) [1] in quartz blocks. The observed resonance spectra show a gradual transition from a superposition of two uncoupled components, one for each symmetry realization, to a single component that is well represented by a Gaussian orthogonal ensemble (GOE) of random matrices. We discuss the applicability of superstatistical random-matrix theory to the final stages of the symmetry-breaking transition. A comparison is made between the formula from superstatistics and that from a previous work by Abd El-Hady et al. (2002) [7], which describes the same data by introducing a third GOE component. Our results suggest that the inverse chi-squared superstatistics could be used for studying the whole symmetry-breaking process.

  15. Explicit chiral symmetry breaking in Gross-Neveu type models

    Energy Technology Data Exchange (ETDEWEB)

    Boehmer, Christian

    2011-07-25

    This thesis is devoted to the study of a 1+1-dimensional, fermionic quantum field theory with Lagrangian L= anti {psi}i{gamma}{sup {mu}}{partial_derivative}{sub {mu}}{psi}-m{sub 0} anti {psi}{psi}+(g{sup 2})/(2)(anti {psi}{psi}){sup 2}+(G{sup 2})/(2)(anti {psi}i{gamma}{sub 5}{psi}){sup 2} in the limit of an infinite number of flavors, using semiclassical methods. The main goal of the present work was to see what changes if we allow for explicit chiral symmetry breaking, either by a bare mass term, or a splitting of the scalar and pseudo-scalar coupling constants, or both. In the first case, this becomes the massive NJL{sub 2} model. In the 2nd and 3rd cases we are dealing with a model largely unexplored so far. The first half of this thesis deals with the massive NJL{sub 2} model. Before attacking the phase diagram, it was necessary to determine the baryons of the model. We have carried out full numerical Hartree-Fock calculations including the Dirac sea. The most important result is the first complete phase diagram of the massive NJL{sub 2} model in ({mu},T,{gamma}) space, where {gamma} arises from m{sub 0} through mass renormalization. In the 2nd half of the thesis we have studied a generalization of the massless NJL{sub 2} model with two different (scalar and pseudoscalar) coupling constants, first in the massless version. Renormalization of the 2 coupling constants leads to the usual dynamical mass by dynamical transmutation, but in addition to a novel {xi} parameter interpreted as chiral quenching parameter. As far as baryon structure is concerned, the most interesting result is the fact that the new baryons interpolate between the kink of the GN model and the massless baryon of the NJL{sub 2} model, always carrying fractional baryon number 1/2. The phase diagram of the massless model with 2 coupling constants has again been determined numerically. At zero temperature we have also investigated the massive, generalized GN model with 3 parameters. It is well

  16. Chiral Symmetry Breaking in Peptide Systems During Formation of Life on Earth

    Science.gov (United States)

    Konstantinov, Konstantin K.; Konstantinova, Alisa F.

    2017-11-01

    Chiral symmetry breaking in complex chemical systems with a large number of amino acids and a large number of similar reactions was considered. It was shown that effective averaging over similar reaction channels may result in very weak effective enantioselectivity of forward reactions, which does not allow most of the known models to result in chiral symmetry breaking during formation of life on Earth. Models with simple and catalytic synthesis of a single amino acid, formation of peptides up to length five, and sedimentation of insoluble pair of substances were considered. It was shown that depending on the model and the values of the parameters, chiral symmetry breaking may occur in up to about 10% out of all possible unique insoluble pair combinations even in the absence of any catalytic synthesis and that minimum total number of amino acids in the pair is 5. If weak enantioselective forward catalytic synthesis of amino acids is present, then the number of possible variants, in which chiral symmetry breaking may occur, increases substantially. It was shown that that the most interesting catalysts have zero or one amino acid of "incorrect" chirality. If the parameters of the model are adjusted in such a way to result in an increase of concentration of longer peptides, then catalysts with two amino acids of incorrect chirality start to appear at peptides of length five. Models of chiral symmetry breaking in the presence of epimerization were considered for peptides up to length three. It was shown that the range of parameters in which chiral symmetry breaking could occur significantly shrinks in comparison to previously considered models with peptides up to length two. An experiment of chiral symmetry breaking was proposed. The experiment consists of a three-step cycle: reversible catalytic synthesis of amino acids, reversible synthesis of peptides, and irreversible sedimentation of insoluble substances.

  17. Spontaneous symmetry breaking in the $S_3$-symmetric scalar sector

    CERN Document Server

    Emmanuel-Costa, D.; Osland, P.; Rebelo, M.N.

    2016-02-23

    We present a detailed study of the vacua of the $S_3$-symmetric three-Higgs-doublet potential, specifying the region of parameters where these minimisation solutions occur. We work with a CP conserving scalar potential and analyse the possible real and complex vacua with emphasis on the cases in which the CP symmetry can be spontaneously broken. Results are presented both in the reducible-representation framework of Derman, and in the irreducible-representation framework. Mappings between these are given. Some of these implementations can in principle accommodate dark matter and for that purpose it is important to identify the residual symmetries of the potential after spontaneous symmetry breakdown. We are also concerned with constraints from vacuum stability.

  18. Effective photon mass by Super and Lorentz symmetry breaking

    National Research Council Canada - National Science Library

    Bonetti, Luca; dos Santos Filho, Luís R; Helayël-Neto, José A; Spallicci, Alessandro D.A.M

    2017-01-01

    .... Thus, we extract a massive Carroll–Field–Jackiw photon term in the Lagrangian and show that the effective mass is proportional to the breaking vector and moderately dependent on the direction of observation...

  19. Topological Insulators and Nematic Phases from Spontaneous Symmetry Breaking in

    Energy Technology Data Exchange (ETDEWEB)

    Sun, K.

    2010-05-26

    We investigate the stability of a quadratic band-crossing point (QBCP) in 2D fermionic systems. At the non-interacting level, we show that a QBCP exists and is topologically stable for a Berry flux {-+}2{pi}, if the point symmetry group has either fourfold or sixfold rotational symmetries. This putative topologically stable free-fermion QBCP is marginally unstable to arbitrarily weak shortrange repulsive interactions. We consider both spinless and spin-1/2 fermions. Four possible ordered states result: a quantum anomalous Hall phase, a quantum spin Hall phase, a nematic phase, and a nematic-spin-nematic phase.

  20. Is radiative electroweak symmetry breaking consistent with a 125 GeV Higgs mass?

    Science.gov (United States)

    Steele, T G; Wang, Zhi-Wei

    2013-04-12

    The mechanism of radiative electroweak symmetry breaking occurs through loop corrections, and unlike conventional symmetry breaking where the Higgs mass is a parameter, the radiatively generated Higgs mass is dynamically predicted. Padé approximations and an averaging method are developed to extend the Higgs mass predictions in radiative electroweak symmetry breaking from five- to nine-loop order in the scalar sector of the standard model, resulting in an upper bound on the Higgs mass of 141 GeV. The mass predictions are well described by a geometric series behavior, converging to an asymptotic Higgs mass of 124 GeV consistent with the recent ATLAS and CMS Collaborations observations. Similarly, we find that the Higgs self-coupling converges to λ=0.23, which is significantly larger than its conventional symmetry breaking counterpart for a 124 GeV Higgs mass. In addition to this significant enhancement of the Higgs self-coupling and HH→HH scattering, we find that Higgs decays to gauge bosons are unaltered and the scattering processes WL(+)WL(+)→HH, ZLZL→HH are also enhanced, providing signals to distinguish conventional and radiative electroweak symmetry breaking mechanisms.

  1. A model of electroweak symmetry breaking from a fifth dimension

    Energy Technology Data Exchange (ETDEWEB)

    Panico, Giuliano [ISAS-SISSA and INFN, Via Beirut 2-4, I-34013 Trieste (Italy); Serone, Marco [ISAS-SISSA and INFN, Via Beirut 2-4, I-34013 Trieste (Italy)]. E-mail: serone@sissa.it; Wulzer, Andrea [ISAS-SISSA and INFN, Via Beirut 2-4, I-34013 Trieste (Italy) and IFAE, Universitat Autonoma de Barcelona, 08193 Bellaterra, Barcelona (Spain)

    2006-04-03

    We reconsider the idea of identifying the Higgs field as the internal component of a gauge field in the flat space R{sup 4}xS{sup 1}/Z{sub 2}, by relaxing the constraint of having unbroken SO(4,1) Lorentz symmetry in the bulk. In this way, we show that the main common problems of previous models of this sort, namely the prediction of a too light Higgs and top mass, as well as of a too low compactification scale, are all solved. We mainly focus our attention on a previously constructed model. We show how, with few minor modifications and by relaxing the requirement of SO(4,1) symmetry, a potentially realistic model can be obtained with a moderate tuning in the parameter space of the theory. In this model, the Higgs potential is stabilized and the hierarchy of fermion masses explained.

  2. Quasi-homologous spherically symmetric branes and their symmetry breaking

    Energy Technology Data Exchange (ETDEWEB)

    Abdalla, M.C.B.; Carlesso, P.F. [UNESP - Universidade Estadual Paulista, Instituto de Fisica Teorica, Rua Dr. Bento Teobaldo Ferraz, 271, Bloco II, Barra-Funda, Caixa Postal 70532-2, Sao Paulo, SP (Brazil); Hoff da Silva, J.M. [UNESP - Universidade Estadual Paulista, Departamento de Fisica e Quimica, Guaratingueta, SP (Brazil)

    2013-06-15

    We revisit the dynamical system-based approach of spherically symmetric vacuum braneworlds, pointing out and studying the existence of a transcritical bifurcation as the dark pressure parameter changes its sign, we analyze some consequences of not discard the brane cosmological constant. For instance, it is noteworthy that the existence of an isothermal state equation between the dark fluid parameters cannot be obtained via the requirement of a quasi-homologous symmetry of the vacuum. (orig.)

  3. Some Relations for Quark Confinement and Chiral Symmetry Breaking in QCD

    Directory of Open Access Journals (Sweden)

    Suganuma Hideo

    2017-01-01

    Full Text Available We analytically study the relation between quark confinement and spontaneous chiral-symmetry breaking in QCD. In terms of the Dirac eigenmodes, we derive some formulae for the Polyakov loop, its fluctuations, and the string tension from the Wilson loop. We also investigate the Polyakov loop in terms of the eigenmodes of theWilson, the clover and the domain wall fermion kernels, respectively. For the confinement quantities, the low-lying Dirac/fermion eigenmodes are found to give negligible contribution, while they are essential for chiral symmetry breaking. These relations indicate no direct one-to-one correspondence between confinement and chiral symmetry breaking in QCD, which seems to be natural because confinement is realized independently of the quark mass.

  4. A new dynamics of electroweak symmetry breaking with classically scale invariance

    Energy Technology Data Exchange (ETDEWEB)

    Haba, Naoyuki [Graduate School of Science and Engineering, Shimane University, Matsue 690-8504 (Japan); Ishida, Hiroyuki, E-mail: ishida@riko.shimane-u.ac.jp [Graduate School of Science and Engineering, Shimane University, Matsue 690-8504 (Japan); Kitazawa, Noriaki [Department of Physics, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397 (Japan); Yamaguchi, Yuya [Graduate School of Science and Engineering, Shimane University, Matsue 690-8504 (Japan); Department of Physics, Faculty of Science, Hokkaido University, Sapporo 060-0810 (Japan)

    2016-04-10

    We propose a new dynamics of the electroweak symmetry breaking in a classically scale invariant version of the standard model. The scale invariance is broken by the condensations of additional fermions under a strong coupling dynamics. The electroweak symmetry breaking is triggered by negative mass squared of the elementary Higgs doublet, which is dynamically generated through the bosonic seesaw mechanism. We introduce a real pseudo-scalar singlet field interacting with additional fermions and Higgs doublet in order to avoid massless Nambu–Goldstone bosons from the chiral symmetry breaking in a strong coupling sector. We investigate the mass spectra and decay rates of these pseudo-Nambu–Goldstone bosons, and show they can decay fast enough without cosmological problems. We further show that our model can make the electroweak vacuum stable.

  5. A new dynamics of electroweak symmetry breaking with classically scale invariance

    Directory of Open Access Journals (Sweden)

    Naoyuki Haba

    2016-04-01

    Full Text Available We propose a new dynamics of the electroweak symmetry breaking in a classically scale invariant version of the standard model. The scale invariance is broken by the condensations of additional fermions under a strong coupling dynamics. The electroweak symmetry breaking is triggered by negative mass squared of the elementary Higgs doublet, which is dynamically generated through the bosonic seesaw mechanism. We introduce a real pseudo-scalar singlet field interacting with additional fermions and Higgs doublet in order to avoid massless Nambu–Goldstone bosons from the chiral symmetry breaking in a strong coupling sector. We investigate the mass spectra and decay rates of these pseudo-Nambu–Goldstone bosons, and show they can decay fast enough without cosmological problems. We further show that our model can make the electroweak vacuum stable.

  6. Nodeless superconductivity and time-reversal symmetry breaking in the noncentrosymmetric superconductor Re24Ti5

    Science.gov (United States)

    Shang, T.; Pang, G. M.; Baines, C.; Jiang, W. B.; Xie, W.; Wang, A.; Medarde, M.; Pomjakushina, E.; Shi, M.; Mesot, J.; Yuan, H. Q.; Shiroka, T.

    2018-01-01

    The noncentrosymmetric superconductor Re24Ti5 , a time-reversal symmetry- (TRS-) breaking candidate with Tc=6 K , was studied by means of muon-spin rotation/relaxation (μ SR ) and tunnel-diode oscillator techniques. At the macroscopic level, its bulk superconductivity was investigated via electrical resistivity, magnetic susceptibility, and heat-capacity measurements. The low-temperature penetration depth, superfluid density, and electronic heat capacity all evidence an s -wave coupling with an enhanced superconducting gap. The spontaneous magnetic fields revealed by zero-field μ SR below Tc indicate a time-reversal symmetry breaking and thus the unconventional nature of superconductivity in Re24Ti5 . The concomitant occurrence of TRS breaking also in the isostructural Re6(Zr ,Hf ) compounds hints at its common origin in this superconducting family and that an enhanced spin-orbital coupling does not affect pairing symmetry.

  7. Symmetry breaking in MAST plasma turbulence due to toroidal flow shear

    CERN Document Server

    Fox, M F J; Field, A R; Ghim, Y -c; Parra, F I; Schekochihin, A A

    2016-01-01

    The flow shear associated with the differential toroidal rotation of tokamak plasmas breaks an underlying symmetry of the turbulent fluctuations imposed by the up-down symmetry of the magnetic equilibrium. Using experimental Beam-Emission-Spectroscopy (BES) measurements and gyrokinetic simulations, this symmetry breaking in ion-scale turbulence in MAST is shown to manifest itself as a tilt of the spatial correlation function and a finite skew in the distribution of the fluctuating density field. The tilt is a statistical expression of the "shearing" of the turbulent structures by the mean flow. The skewness of the distribution is related to the emergence of long-lived density structures in sheared, near-marginal plasma turbulence. The extent to which these effects are pronounced is argued (with the aid of the simulations) to depend on the distance from the nonlinear stability threshold. Away from the threshold, the symmetry is effectively restored.

  8. Spontaneous Symmetry Breaking and Nambu–Goldstone Bosons in Quantum Many-Body Systems

    Directory of Open Access Journals (Sweden)

    Tomáš Brauner

    2010-04-01

    Full Text Available Spontaneous symmetry breaking is a general principle that constitutes the underlying concept of a vast number of physical phenomena ranging from ferromagnetism and superconductivity in condensed matter physics to the Higgs mechanism in the standard model of elementary particles. I focus on manifestations of spontaneously broken symmetries in systems that are not Lorentz invariant, which include both nonrelativistic systems as well as relativistic systems at nonzero density, providing a self-contained review of the properties of spontaneously broken symmetries specific to such theories. Topics covered include: (i Introduction to the mathematics of spontaneous symmetry breaking and the Goldstone theorem. (ii Minimization of Higgs-type potentials for higher-dimensional representations. (iii Counting rules for Nambu–Goldstone bosons and their dispersion relations. (iv Construction of effective Lagrangians. Specific examples in both relativistic and nonrelativistic physics are worked out in detail.

  9. Weyl-invariant Higher Curvature Gravity Theories in n Dimensions and Mass Generation by Symmetry Breaking

    OpenAIRE

    Dengiz, Suat

    2014-01-01

    Weyl-invariant extensions of three-dimensional New Massive Gravity, generic n-dimensional Quadratic Curvature Gravity theories and three-dimensional Born-Infeld gravity theory are analyzed in details. As required by Weyl-invariance, the actions of these gauge theories do not contain any dimensionful parameter; therefore the local symmetry is spontaneously broken in (Anti) de Sitter vacua in analogy with the Standard Model Higgs mechanism. About the flat vacuum, symmetry breaking mechanism is ...

  10. Cosmological baryon-number domain structure from symmetry breaking in grand unified field theories

    Science.gov (United States)

    Brown, R. W.; Stecker, F. W.

    1979-01-01

    It is suggested that grand unified field theories with spontaneous symmetry breaking in the very early big bang can lead more naturally to a baryon-symmetric cosmology with a domain structure than to a totally baryon-asymmetric cosmology. The symmetry is broken in a randomized manner in causally independent domains, favoring neither a baryon nor an antibaryon excess on a universal scale. Arguments in favor of this cosmology and observational tests are discussed.

  11. Cosmological baryon number domain structure from symmetry-breaking in grand unified field theories

    Science.gov (United States)

    Brown, R. W.; Stecker, F. W.

    1979-01-01

    It is suggested that grand unified field theories with spontaneous symmetry breaking in the very early big-bang can lead more naturally to a baryon symmetric cosmology with a domain structure than to a totally baryon asymmetric cosmology. The symmetry is broken in a randomized manner in causally independent domains, favoring neither a baryon nor an antibaryon excess on a universal scale. Arguments in favor of this cosmology and observational tests are discussed.

  12. Symmetry and symmetry breaking in quantum mechanics; Symetrie et brisure de symetrie en mechanique quantique

    Energy Technology Data Exchange (ETDEWEB)

    Chomaz, Philippe [Grand Accelerateur National d`Ions Lourds (GANIL), 14 - Caen (France)

    1998-12-31

    In the world of infinitely small, the world of atoms, nuclei and particles, the quantum mechanics enforces its laws. The discovery of Quanta, this unbelievable castration of the Possible in grains of matter and radiation, in discrete energy levels compels us of thinking the Single to comprehend the Universal. Quantum Numbers, magic Numbers and Numbers sign the wave. The matter is vibration. To describe the music of the world one needs keys, measures, notes, rules and partition: one needs quantum mechanics. The particles reduce themselves not in material points as the scholars of the past centuries thought, but they must be conceived throughout the space, in the accomplishment of shapes of volumes. When Einstein asked himself whether God plays dice, there was no doubt among its contemporaries that if He exists He is a geometer. In a Nature reduced to Geometry, the symmetries assume their role in servicing the Harmony. The symmetries allow ordering the energy levels to make them understandable. They impose there geometrical rules to the matter waves, giving them properties which sometimes astonish us. Hidden symmetries, internal symmetries and newly conceived symmetries have to be adopted subsequently to the observation of some order in this world of Quanta. In turn, the symmetries provide new observables which open new spaces of observation 17 refs., 16 figs.

  13. Two-mode bosonic squeezing and symmetry breaking

    Energy Technology Data Exchange (ETDEWEB)

    Ocak, Sema Bilge [Ankara Nuclear Research and Training Center, 06100 Besevler, Ankara (Turkey)]. E-mail: semamuzo@yahoo.com

    2005-02-21

    The squeezed states of two-mode boson systems are defined through canonical transformation. The defined concept of squeezed boson systems has been applied the Hamiltonian H={gamma}Sz2-BSx. The ground-state energy of boson systems is investigated by means of squeezed states. We analyze coherent and squeezed Hamiltonian in the group-theoretic method. It is found that squeezing acts as asymmetry breaking.

  14. Double Field Theory description of heterotic gauge symmetry enhancing-breaking

    Science.gov (United States)

    Aldazabal, G.; Andrés, E.; Mayo, M.; Penas, V.

    2017-10-01

    A Double Field Theory (DFT) description of gauge symmetry enhancing-breaking in the heterotic string is presented. The construction, based on previous results for the bosonic string, relies on the extension of the tangent frame of DFT. The fluxes of a Scherk-Schwarz like generalized toroidal compactification are moduli dependent and become identified with the structure constants of the enhanced group at fixed "self-dual" points in moduli space. Slight displacements from such points provide the breaking of the symmetry, gauge bosons acquiring masses proportional to fluxes. The inclusion of fermions is also discussed.

  15. Comments on the Chiral Symmetry Breaking in Soft Wall Holographic QCD

    DEFF Research Database (Denmark)

    Bechi, Jacopo

    2009-01-01

    In this paper we describe qualitatively some aspects of the holographic QCD. Inspired by a successfull 4D description, we try to separate the Confinement and the Chiral Symmetry Breaking dynamics. We also discuss the realization of the baryons as skyrmions in Soft Wall Holographic QCD, and the is......In this paper we describe qualitatively some aspects of the holographic QCD. Inspired by a successfull 4D description, we try to separate the Confinement and the Chiral Symmetry Breaking dynamics. We also discuss the realization of the baryons as skyrmions in Soft Wall Holographic QCD...

  16. Experimental Validation of the Largest Calculated Isospin-Symmetry-Breaking Effect in a Superallowed Fermi Decay

    Science.gov (United States)

    Melconian, D.; Triambak, S.; Bordeanu, C.; García, A.; Hardy, J. C.; Iacob, V. E.; Nica, N.; Park, H. I.; Tabacaru, G.; Trache, L.; Towner, I. S.; Tribble, R. E.; Zhai, Y.

    2011-10-01

    A precision measurement of the γ yields following the β decay of Cl32 has determined its isobaric-analogue branch to be (22.47-0.18+0.21)%. Since it is an almost pure-Fermi decay, we can also determine the amount of isospin-symmetry breaking in this superallowed transition. We find a very large value, δC=5.3(9)%, in agreement with a shell-model calculation. This result sets a benchmark for isospin-symmetry-breaking calculations and lends support for similarly calculated, yet smaller, corrections that are currently applied to 0+→0+ transitions for tests of the standard model.

  17. Symmetry Breaking and Adaptation The Genetic Code of Retroviral Env Proteins

    CERN Document Server

    Vera, S

    1996-01-01

    Although several synonymous codons can encode the same aminoacid, this symmetry is generally broken in natural genetic systems. In this article, we show that the symmetry breaking can result from selective pressures due to the violation of the synonym symmetry by mutation and recombination. We conjecture that this enhances the probability to produce mutants that are well-adapted to the current environment. Evidence is found in the codon frequencies of the HIV resistant to the current immunological attack, are found with a greater frequency than their less mutable synonyms.

  18. Ultra-large distance modification of gravity from Lorentz symmetry breaking at the Planck scale

    OpenAIRE

    Gorbunov, D. S.; Sibiryakov, S. M.

    2005-01-01

    We present an extension of the Randall--Sundrum model in which, due to spontaneous Lorentz symmetry breaking, graviton mixes with bulk vector fields and becomes quasilocalized. The masses of KK modes comprising the four-dimensional graviton are naturally exponentially small. This allows to push the Lorentz breaking scale to as high as a few tenth of the Planck mass. The model does not contain ghosts or tachyons and does not exhibit the van Dam--Veltman--Zakharov discontinuity. The gravitation...

  19. Surface symmetry-breaking and strain effects on orbital occupancy in transition metal perovskite epitaxial films.

    Science.gov (United States)

    Pesquera, D; Herranz, G; Barla, A; Pellegrin, E; Bondino, F; Magnano, E; Sánchez, F; Fontcuberta, J

    2012-01-01

    The electron occupancy of 3d-orbitals determines the properties of transition metal oxides. This can be achieved, for example, through thin-film heterostructure engineering of ABO(3) oxides, enabling emerging properties at interfaces. Interestingly, epitaxial strain may break the degeneracy of 3d-e(g) and t(2g) orbitals, thus favoring a particular orbital filling with consequences for functional properties. Here we disclose the effects of symmetry breaking at free surfaces of ABO(3) perovskite epitaxial films and show that it can be combined with substrate-induced epitaxial strain to tailor at will the electron occupancy of in-plane and out-of-plane surface electronic orbitals. We use X-ray linear dichroism to monitor the relative contributions of surface, strain and atomic terminations to the occupancy of 3z(2)-r(2) and x(2)-y(2) orbitals in La(2/3)Sr(1/3)MnO(3) films. These findings open the possibility of an active tuning of surface electronic and magnetic properties as well as chemical properties (catalytic reactivity, wettability and so on).

  20. Twisted Spectral Triple for the Standard Model and Spontaneous Breaking of the Grand Symmetry

    Energy Technology Data Exchange (ETDEWEB)

    Devastato, Agostino, E-mail: agostino.devastato@na.infn.it; Martinetti, Pierre, E-mail: martinetti@dima.unige.it [Università di Napoli Federico II, Dipartimento di Fisica (Italy)

    2017-03-15

    Grand symmetry models in noncommutative geometry, characterized by a non-trivial action of functions on spinors, have been introduced to generate minimally (i.e. without adding new fermions) and in agreement with the first order condition an extra scalar field beyond the standard model, which both stabilizes the electroweak vacuum and makes the computation of the mass of the Higgs compatible with its experimental value. In this paper, we use a twist in the sense of Connes-Moscovici to cure a technical problem due to the non-trivial action on spinors, that is the appearance together with the extra scalar field of unbounded vectorial terms. The twist makes these terms bounded and - thanks to a twisted version of the first-order condition that we introduce here - also permits to understand the breaking to the standard model as a dynamical process induced by the spectral action, as conjectured in [24]. This is a spontaneous breaking from a pre-geometric Pati-Salam model to the almost-commutativegeometryofthestandardmodel,withtwoHiggs-likefields: scalar and vector.

  1. Spontaneous Time Symmetry Breaking in System with Mixed Strategy Nash Equilibrium: Evidences in Experimental Economics Data

    Science.gov (United States)

    Wang, Zhijian; Xu, Bin; Zhejiang Collaboration

    2011-03-01

    In social science, laboratory experiment with human subjects' interaction is a standard test-bed for studying social processes in micro level. Usually, as in physics, the processes near equilibrium are suggested as stochastic processes with time-reversal symmetry (TRS). To the best of our knowledge, near equilibrium, the breaking time symmetry, as well as the existence of robust time anti-symmetry processes, has not been reported clearly in experimental economics till now. By employing Markov transition method to analysis the data from human subject 2x2 Games with wide parameters and mixed Nash equilibrium, we study the time symmetry of the social interaction process near Nash equilibrium. We find that, the time symmetry is broken, and there exists a robust time anti-symmetry processes. We also report the weight of the time anti-symmetry processes in the total processes of each the games. Evidences in laboratory marketing experiments, at the same time, are provided as one-dimension cases. In these cases, time anti-symmetry cycles can also be captured. The proposition of time anti-symmetry processes is small, but the cycles are distinguishable.

  2. Order and Symmetry Breaking in the Fluctuations of Driven Systems

    Science.gov (United States)

    Tizón-Escamilla, N.; Pérez-Espigares, C.; Garrido, P. L.; Hurtado, P. I.

    2017-09-01

    Dynamical phase transitions (DPTs) in the space of trajectories are one of the most intriguing phenomena of nonequilibrium physics, but their nature in realistic high-dimensional systems remains puzzling. Here we observe for the first time a DPT in the current vector statistics of an archetypal two-dimensional (2D) driven diffusive system and characterize its properties using the macroscopic fluctuation theory. The complex interplay among the external field, anisotropy, and vector currents in 2D leads to a rich phase diagram, with different symmetry-broken fluctuation phases separated by lines of first- and second-order DPTs. Remarkably, different types of 1D order in the form of jammed density waves emerge to hinder transport for low-current fluctuations, revealing a connection between rare events and self-organized structures which enhance their probability.

  3. Quark pair condensation and chiral symmetry breaking in QCD

    Energy Technology Data Exchange (ETDEWEB)

    Finger, J.R. (Massachusetts Inst. of Tech., Cambridge (USA)); Mandula, J.E. (Washington Univ., St. Louis, MO (USA))

    1982-05-17

    If the effective qanti q interaction strength due to gluon exchange becomes at least moderately strong beyond some distance g/sup 2//4..pi.. > 9/8, the perturbative vacuum becomes unstable to the creation of color singlet qanti q pairs, which indicates that the true vacuum contains a condensate of such pairs. We analyze the condensation by a coherent state variational procedure modeled after the BCS superconductor, and show that this method is equivalent to a self-consistent Hartree-Fock approximation to the Schwinger-Dyson equation for the quark propagator. The condensate leads to a spontaneous breakdown of chiral symmetry in the manner discussed by Nambu and Jona-Lasinio. The massive pseudoparticles with quark quantum numbers are identified with the 'constituent' quarks.

  4. Quark pair condensation and chiral symmetry breaking in QCD

    Science.gov (United States)

    Finger, Jonathan R.; Mandula, Jeffrey E.

    1982-05-01

    If the effective qoverlineq interaction strength due to gluon exchange becomes at least moderately strong beyond some distance g 2/4π > {9}/{8}, the perturbative vacuum becomes unstable to the creation of color singlet qoverlineq pairs, which indicates that the true vacuum contains a condensate of such pairs. We analyze the condensation by a coherent state variational procedure modeled after the BCS superconductor, and show that this method is equivalent to a self-consistent Hartree-Fock approximation to the Schwinger-Dyson equation for the quark propagator. The condensate leads to a spontaneous breakdown of chiral symmetry in the manner discussed by Nambu and Jona-Lasinio. The massive pseudoparticles with quark quantum numbers are identified with the "constituent" quarks.

  5. Unitarity in gauge symmetry breaking on an orbifold

    CERN Document Server

    Abe, Y; Higashide, Y; Kobayashi, K; Matsunaga, M

    2003-01-01

    We study the unitarity bounds of scattering amplitudes in extra-dimensional gauge theory, in which the gauge symmetry is broken by the boundary conditions. The evaluation of the amplitude of the diagram including four massive gauge bosons in the external lines shows that the asymptotic power behavior of the amplitude is canceled. The calculation is carried out with the 5-dimensional standard model and the SU(5) grand unified theory, whose 5th dimensional coordinate is compactified on S sup 1 /Z sub 2. The gauge theories broken through the orbifolding preserve unitarity a high energies, similarly to the broken gauge theories in which the gauge bosons acquire masses through the Higgs mechanism. We show that the contributions of the Kaluza-Klein states play a crucial role in conserving the unitarity. (author)

  6. Chiral-symmetry breaking and confinement in Minkowski space

    Energy Technology Data Exchange (ETDEWEB)

    Biernat, Elmar P. [Centro de Física Teórica de Partículas (CFTP), Instituto Superior Técnico (IST), Universidade de Lisboa, 1049-001 Lisboa (Portugal); Peña, M. T. [Centro de Física Teórica de Partículas (CFTP), Instituto Superior Técnico (IST), Universidade de Lisboa, 1049-001 Lisboa (Portugal); Departamento de Física, Instituto Superior Técnico (IST), Universidadede Lisboa, 1049-001 Lisboa (Portugal); Ribeiro, J. E. [Centro de Física das Interações Fundamentais (CFIF), Instituto Superior Técnico (IST), Universidade de Lisboa, 1049-001 Lisboa (Portugal); Stadler, Alfred [Departamento de Física, Universidade de Évora, 7000-671 Évora (Portugal); Centro de Física Teórica de Partículas (CFTP), Instituto Superior Técnico (IST), Universidade de Lisboa, 1049-001 Lisboa (Portugal); Gross, Franz [Thomas Jefferson National Accelerator Facility (JLab), Newport News, Virginia 23606 (United States)

    2016-01-22

    We present a model for the quark-antiquark interaction formulated in Minkowski space using the Covariant Spectator Theory. The quark propagators are dressed with the same kernel that describes the interaction between different quarks. By applying the axial-vector Ward-Takahashi identity we show that our model satisfies the Adler-zero constraint imposed by chiral symmetry. For this model, our Minkowski-space results of the dressed quark mass function are compared to lattice QCD data obtained in Euclidean space. The mass function is then used in the calculation of the electromagnetic pion form factor in relativistic impulse approximation, and the results are presented and compared with the experimental data from JLab.

  7. Chiral-symmetry breaking and confinement in Minkowski space

    Energy Technology Data Exchange (ETDEWEB)

    Biernat, Elmer P. [Unibersidade de Lisboa, 104-001, Lisboa, Portugal; Pena, M. T. [Universidade de Lisboa, 1049-001, Lisboa, Portugal; Ribiero, J. E. [Universidade de Lisboa, 1049-001 Lisboa, Portugal; Stadler, Alfred [Universidade de Évora, 7000-671 Évora, Portugal; Universidade de Lisboa, 1049-001 Lisboa, Portugal; Gross, Franz [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

    2016-01-01

    We present a model for the quark-antiquark interaction formulated in Minkowski space using the Covariant Spectator Theory. The quark propagators are dressed with the same kernel that describes the interaction between different quarks. By applying the axial-vector Ward-Takahashi identity we show that our model satisfies the Adler-zero constraint imposed by chiral symmetry. For this model, our Minkowski-space results of the dressed quark mass function are compared to lattice QCD data obtained in Euclidean space. The mass function is then used in the calculation of the electromagnetic pion form factor in relativistic impulse approximation, and the results are presented and compared with the experimental data from JLab.

  8. Probing symmetry and symmetry breaking in resonant soft-x-ray fluorescence spectra of molecules

    Energy Technology Data Exchange (ETDEWEB)

    Glans, P.; Gunnelin, K.; Guo, J. [Uppsala Univ. (Sweden)] [and others

    1997-04-01

    Conventional non-resonant soft X-ray emission brings about information about electronic structure through its symmetry and polarization selectivity, the character of which is governed by simple dipole rules. For centro-symmetric molecules with the emitting atom at the inversion center these rules lead to selective emission through the required parity change. For the more common classes of molecules which have lower symmetry or for systems with degenerate core orbitals (delocalized over identical sites), it is merely the local symmetry selectivity that provides a probe of the local atomic orbital contribution to the molecular orbital. For instance, in X-ray spectra of first row species the intensities essentially map the p-density at each particular atomic site, and, in a molecular orbital picture, the contribution of the local p-type atomic orbitals in the LCAO description of the molecular orbitals. The situation is different for resonant X-ray fluorescence spectra. Here strict parity and symmetry selectivity gives rise to a strong frequency dependence for all molecules with an element of symmetry. In addition to symmetry selectivity the strong frequency dependence of resonant X-ray emission is caused by the interplay between the shape of a narrow X-ray excitation energy function and the lifetime and vibrational broadenings of the resonantly excited core states. This interplay leads to various observable effects, such as linear dispersion, resonance narrowing and emission line (Stokes) doubling. Also from the point of view of polarization selectivity, the resonantly excited X-ray spectra are much more informative than the corresponding non-resonant spectra. Examples are presented for nitrogen, oxygen, and carbon dioxide molecules.

  9. {\\mathscr{P}}{\\mathscr{T}}-symmetry breaking in the steady state of microscopic gain-loss systems

    Science.gov (United States)

    Kepesidis, Kosmas V.; Milburn, Thomas J.; Huber, Julian; Makris, Konstantinos G.; Rotter, Stefan; Rabl, Peter

    2016-09-01

    The phenomenon of { P }{ T } (parity- and time-reversal) symmetry breaking is conventionally associated with a change in the complex mode spectrum of a non-Hermitian system that marks a transition from a purely oscillatory to an exponentially amplified dynamical regime. In this work we describe a new type of { P }{ T }-symmetry breaking, which occurs in the steady-state energy distribution of open systems with balanced gain and loss. In particular, we show that the combination of nonlinear saturation effects and the presence of thermal or quantum noise in actual experiments results in unexpected behavior that differs significantly from the usual dynamical picture. We observe additional phases with preserved or ‘weakly’ broken { P }{ T }-symmetry, and an unconventional transition from a high-noise thermal state to a low-amplitude lasing state with broken symmetry and strongly reduced fluctuations. We illustrate these effects here for the specific example of coupled mechanical resonators with optically induced loss and gain, but the described mechanisms will be essential for a general understanding of the steady-state properties of actual { P }{ T }-symmetric systems operated at low amplitudes or close to the quantum regime.

  10. Supersolid formation in a quantum gas breaking a continuous translational symmetry

    Science.gov (United States)

    Léonard, Julian; Morales, Andrea; Zupancic, Philip; Esslinger, Tilman; Donner, Tobias

    2017-03-01

    The concept of a supersolid state combines the crystallization of a many-body system with dissipationless flow of the atoms from which it is built. This quantum phase requires the breaking of two continuous symmetries: the phase invariance of a superfluid and the continuous translational invariance to form the crystal. Despite having been proposed for helium almost 50 years ago, experimental verification of supersolidity remains elusive. A variant with only discrete translational symmetry breaking on a preimposed lattice structure—the ‘lattice supersolid’—has been realized, based on self-organization of a Bose-Einstein condensate. However, lattice supersolids do not feature the continuous ground-state degeneracy that characterizes the supersolid state as originally proposed. Here we report the realization of a supersolid with continuous translational symmetry breaking along one direction in a quantum gas. The continuous symmetry that is broken emerges from two discrete spatial symmetries by symmetrically coupling a Bose-Einstein condensate to the modes of two optical cavities. We establish the phase coherence of the supersolid and find a high ground-state degeneracy by measuring the crystal position over many realizations through the light fields that leak from the cavities. These light fields are also used to monitor the position fluctuations in real time. Our concept provides a route to creating and studying glassy many-body systems with controllably lifted ground-state degeneracies, such as supersolids in the presence of disorder.

  11. Scale symmetry breaking from total derivative densities and the cosmological constant problem

    Energy Technology Data Exchange (ETDEWEB)

    Guendelman, Eduardo I., E-mail: guendel@bgu.ac.il [Department of Physics, Ben-Gurion University, Beer-Sheva (Israel); Nishino, Hitoshi, E-mail: hnishino@csulb.edu [California State University at Long Beach, Long Beach, CA (United States); Rajpoot, Subhash, E-mail: Subhash.Rajpoot@csulb.edu [California State University at Long Beach, Long Beach, CA (United States)

    2014-05-01

    The use in the action integral of totally divergent densities in generally coordinate invariant theories can lead to interesting mechanisms of spontaneous symmetry breaking of scale invariance. With dependence in the action on a metric independent density Φ, in 4D, we can define Φ=ε{sup μναβ}∂{sub μ}A{sub ναβ} that gives a new interesting mechanism for breaking scale symmetry in 4D theories of gravity plus matter fields, through the A{sub ναβ} equations of motion which lead to an integration constant the breaks the scale symmetry, while introducing terms of the form eGlnK, e being the determinant of the vierbein, G being the Gauss–Bonnet scalar and K being scalar functions of the fields transforming like K→cK (where c is a constant) under a scale transformation. Such a term is invariant only up to a total divergence and therefore leads to breaking of scale invariance due to gravitational instantons. The topological density constructed out of gauge field strengths ε{sup μναβ}F{sub μν}{sup a}F{sub αβ}{sup a} can be coupled to the dilaton field linearly to produce a scale invariant term up to a total divergence. The scale symmetry can be broken by Yang–Mills instantons which lead to a very small vacuum energy for our Universe.

  12. Symmetry breaking in amorphous solids undergoing martensitic phase transformation - a relation to Landau's theory

    Science.gov (United States)

    Fischlschweiger, Michael; Oberaigner, Eduard

    2011-03-01

    Martensitic phase transformation can be classified as displacive solid -solid phase transformations, where the symmetry of the high temperature phase (austenite) breaks when phase transformation occurs. The martensitic phase (low temperature phase) and its variants are products of symmetry breaking in solids. Based on a quasiparticle statistical mechanics approach the canonical free energy of a representative solid volume element consisting of several quasiparticles (representative mole number) can be derived. The symmetry breaking order parameter of the system is the total strain which is an ensemble mean value in the statistical mechanics concept. In the current theory the order parameter is a macroscopic strain in a sense that the representative volume element stands for the macroscopic level, whereas the lattice parameter changes are considered in the hamiltonian definition of each quasiparticle. Computational results of the developed theory correspond to experimentally observed phenomena in materials undergoing martensitic phase transformation. The present study is focusing the region nearby the phase transformation and shows how the developed theory for describing symmetry breaking and order parameter changes correspond to Landau's phenomenological theory of phase transitions.

  13. Geometric phase effects in dynamics near conical intersections: symmetry breaking and spatial localization.

    Science.gov (United States)

    Ryabinkin, Ilya G; Izmaylov, Artur F

    2013-11-27

    We show that finite systems with conical intersections can exhibit spontaneous symmetry breaking which manifests itself in spatial localization of eigenstates. This localization has a geometric phase origin and is robust against variation of model parameters. The transition between localized and delocalized eigenstate regimes resembles a continuous phase transition. The localization slows down the low-energy quantum nuclear dynamics at low temperatures.

  14. Aspects of semilocal BPS vortex in systems with Lorentz symmetry breaking

    Energy Technology Data Exchange (ETDEWEB)

    Villalobos, C.H.C.; Silva, J.M.H. da; Hott, M.B. [UNESP, Univ Estadual Paulista, Departamento de Fisica e Quimica, Guaratingueta, SP (Brazil); Belich, H. [Universidade Federal do Espi rito Santo (UFES), Departamento de Fisica e Quimica, Vitoria, ES (Brazil)

    2014-03-15

    The existence is shown of a static self-dual semilocal vortex configuration for the Maxwell-Higgs system with a Lorentz-violating CPT-even term. The dependence of the vorticity upper limit on the Lorentz-symmetry-breaking term is also investigated. (orig.)

  15. Large-radius Holstein polaron and the problem of spontaneous symmetry breaking

    Science.gov (United States)

    Lakhno, V. D.

    2014-07-01

    A translation-invariant solution is found for a large-radius Holstein polaron whose energy in the strong coupling limit is lower than that obtained by Holstein [T. Holstein, Annals Phys., 8, 325 (1959)]. The wave function corresponding to this solution is delocalized. A conclusion is drawn about the absence of spontaneous symmetry breaking in the quantum system discussed.

  16. Symmetry-breaking intramolecular charge transfer in the excited state of meso-linked BODIPY dyads

    KAUST Repository

    Whited, Matthew T.

    2012-01-01

    We report the synthesis and characterization of symmetric BODIPY dyads where the chromophores are attached at the meso position, using either a phenylene bridge or direct linkage. Both molecules undergo symmetry-breaking intramolecular charge transfer in the excited state, and the directly linked dyad serves as a visible-light-absorbing analogue of 9,9′-bianthryl.

  17. Electroweak symmetry breaking and precision tests with a fifth dimension

    Energy Technology Data Exchange (ETDEWEB)

    Panico, Giuliano [ISAS-SISSA and INFN, Via Beirut 2-4, I-34013 Trieste (Italy); Serone, Marco [ISAS-SISSA and INFN, Via Beirut 2-4, I-34013 Trieste (Italy); Wulzer, Andrea [IFAE, Universitat Autonoma de Barcelona, 08193 Bellaterra, Barcelona (Spain)]. E-mail: wulzer@ifae.es

    2007-01-29

    We perform a complete study of flavor and CP conserving electroweak observables in a slight refinement of a recently proposed five-dimensional model on R{sup 4}xS{sup 1}/Z{sub 2}, where the Higgs is the internal component of a gauge field and the Lorentz symmetry is broken in the fifth dimension. Interestingly enough, the relevant corrections to the electroweak observables turn out to be of universal type and essentially depend only on the value of the Higgs mass and on the scale of new physics, in our case the compactification scale 1/R. The model passes all constraints for 1/R>=4.7 TeV at 90% C.L., with a moderate fine-tuning in the parameters. The Higgs mass turns out to be always smaller than 200 GeV although higher values would be allowed, due to a large correction to the T parameter. The lightest non-SM states in the model are typically colored fermions with a mass of order 1-2 TeV.

  18. Inversion symmetry breaking of atomic bound states in strong and short laser fields

    CERN Document Server

    Stooß, Veit; Ott, Christian; Blättermann, Alexander; Ding, Thomas; Pfeifer, Thomas

    2015-01-01

    In any atomic species, the spherically symmetric potential originating from the charged nucleus results in fundamental symmetry properties governing the structure of atomic states and transition rules between them. If atoms are exposed to external electric fields, these properties are modified giving rise to energy shifts such as the AC Stark-effect in varying fields and, contrary to this in a constant (DC) electric field for high enough field strengths, the breaking of the atomic symmetry which causes fundamental changes in the atom's properties. This has already been observed for atomic Rydberg states with high principal quantum numbers. Here, we report on the observation of symmetry breaking effects in Helium atoms for states with principal quantum number n=2 utilizing strong visible laser fields. These findings were enabled by temporally resolving the dynamics better than the sub-optical cycle of the applied laser field, utilizing the method of attosecond transient absorption spectroscopy (ATAS). We ident...

  19. Progress gauge symmetry breaking in SU(6) x SU(2) sub R model

    CERN Document Server

    Hayashi, T; Matsuda, M; Matsuoka, T

    2003-01-01

    In the SU(6) x SU(2) sub R string-inspired model, we describe the evolution of the couplings and the masses down from the string scale M sub s using the renormalization group equations and minimize the effective potential. This model possesses the flavor symmetry, including the binary dihedral group D tilde sub 4. We show that the scalar mass squared of the gauge non-singlet matter field possibly becomes negative slightly below the string scale. As a consequence, the precocious radiative breaking of the gauge symmetry down to the standard model gauge group can be realized. In the present model, the large Yukawa coupling, which plays an important role in the symmetry breaking, is identical to the colored Higgs coupling related to the longevity of the proton. (author)

  20. Confinement/deconfinement transition from symmetry breaking in gauge/gravity duality

    Energy Technology Data Exchange (ETDEWEB)

    Čubrović, Mihailo [Institute for Theoretical Physics, University of Cologne,Zülpicher Strasse 77, D-50937, Cologne (Germany)

    2016-10-19

    We study the confinement/deconfinement transition in a strongly coupled system triggered by an independent symmetry-breaking quantum phase transition in gauge/gravity duality. The gravity dual is an Einstein-scalar-dilaton system with AdS near-boundary behavior and soft wall interior at zero scalar condensate. We study the cases of neutral and charged condensate separately. In the former case the condensation breaks the discrete ℤ{sub 2} symmetry while a charged condensate breaks the continuous U(1) symmetry. After the condensation of the order parameter, the non-zero vacuum expectation value of the scalar couples to the dilaton, changing the soft wall geometry into a non-confining and anisotropically scale-invariant infrared metric. In other words, the formation of long-range order is immediately followed by the deconfinement transition and the two critical points coincide. The confined phase has a scale — the confinement scale (energy gap) which vanishes in the deconfined case. Therefore, the breaking of the symmetry of the scalar (ℤ{sub 2} or U(1)) in turn restores the scaling symmetry in the system and neither phase has a higher overall symmetry than the other. When the scalar is charged the phase transition is continuous which goes against the Ginzburg-Landau theory where such transitions generically only occur discontinuously. This phenomenon has some commonalities with the scenario of deconfined criticality. The mechanism we have found has applications mainly in effective field theories such as quantum magnetic systems. We briefly discuss these applications and the relation to real-world systems.

  1. Symmetry-breaking polarization driven by a Cdc42p GEF-PAK complex.

    Science.gov (United States)

    Kozubowski, Lukasz; Saito, Koji; Johnson, Jayme M; Howell, Audrey S; Zyla, Trevin R; Lew, Daniel J

    2008-11-25

    In 1952, Alan Turing suggested that spatial patterns could arise from homogeneous starting conditions by feedback amplification of stochastic fluctuations. One example of such self-organization, called symmetry breaking, involves spontaneous cell polarization in the absence of spatial cues. The conserved GTPase Cdc42p is essential for both guided and spontaneous polarization, and in budding yeast cells Cdc42p concentrates at a single site (the presumptive bud site) at the cortex. Cdc42p concentrates at a random cortical site during symmetry breaking in a manner that requires the scaffold protein Bem1p. The mechanism whereby Bem1p promotes this polarization was unknown. Here we show that Bem1p promotes symmetry breaking by assembling a complex in which both a Cdc42p-directed guanine nucleotide exchange factor (GEF) and a Cdc42p effector p21-activated kinase (PAK) associate with Bem1p. Analysis of Bem1p mutants indicates that both GEF and PAK must bind to the same molecule of Bem1p, and a protein fusion linking the yeast GEF and PAK bypasses the need for Bem1p. Although mammalian cells lack a Bem1p ortholog, they contain more complex multidomain GEFs that in some cases can directly interact with PAKs, and we show that yeast containing an artificial GEF with similar architecture can break symmetry even without Bem1p. Yeast symmetry-breaking polarization involves a GEF-PAK complex that binds GTP-Cdc42p via the PAK and promotes local Cdc42p GTP-loading via the GEF. By generating fresh GTP-Cdc42p near pre-existing GTP-Cdc42p, the complex amplifies clusters of GTP-Cdc42p at the cortex. Our findings provide mechanistic insight into an evolutionarily conserved pattern-forming positive-feedback pathway.

  2. More on cosmological constraints on spontaneous R-symmetry breaking models

    Energy Technology Data Exchange (ETDEWEB)

    Hamada, Yuta; Kobayashi, Tatsuo [Kyoto Univ. (Japan). Dept. of Physics; Kamada, Kohei [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Ecole Polytechnique Federale de Lausanne (Switzerland). Inst. de Theorie des Phenomenes Physiques; Ookouchi, Yutaka [Kyushu Univ., Fukuoka (Japan). Faculty of Arts and Science

    2013-10-15

    We study the spontaneous R-symmetry breaking model and investigate the cosmological constraints on this model due to the pseudo Nambu-Goldstone boson, R-axion. We consider the R-axion which has relatively heavy mass in order to complement our previous work. In this regime, model parameters, R-axions mass and R-symmetry breaking scale, are constrained by Big Bang Nucleosynthesis and overproduction of the gravitino produced from R-axion decay and thermal plasma. We find that the allowed parameter space is very small for high reheating temperature. For low reheating temperature, the U(1){sub R} breaking scale f{sub a} is constrained as f{sub a}<10{sup 12-14} GeV regardless of the value of R-axion mass.

  3. Determination of time-reversal symmetry breaking lengths in an InGaAs interferometer array.

    Science.gov (United States)

    Ren, S L; Heremans, J J; Vijeyaragunathan, S; Mishima, T D; Santos, M B

    2015-05-13

    Quantum interference oscillations due to the Aharonov-Bohm phase were measured in a ring interferometer array fabricated on a two-dimensional electron system in an InGaAs/InAlAs heterostructure. Coexisting oscillations with magnetic flux periodicity h/e and h/2e were observed and their amplitudes compared as function of applied magnetic field. The h/2e oscillations originate in time-reversed trajectories with the ring interferometers operating in Sagnac-type mode, while the h/e oscillations result from Mach-Zehnder operation. The h/2e oscillations require time-reversal symmetry and hence can be used to quantify time-reversal symmetry breaking, more particularly the fundamental mesoscopic dephasing length associated with time-reversal symmetry breaking under applied magnetic field, an effective magnetic length. The oscillation amplitudes were investigated over magnetic fields spanning 2.2 T, using Fourier transforms over short segments of 40 mT. As the magnetic field increased, the h/2e oscillation amplitude decreased due to time-reversal symmetry breaking by the local magnetic flux in the interferometer arms. A dephasing model for quantum-coherent arrays was used to experimentally quantify effective magnetic lengths. The data was then compared with analytical expressions for diffusive, ballistic and confined systems.

  4. Spontaneous PT -symmetry breaking in non-Hermitian coupled-cavity array

    Science.gov (United States)

    Xing, Yan; Qi, Lu; Cao, Ji; Wang, Dong-Yang; Bai, Cheng-Hua; Wang, Hong-Fu; Zhu, Ai-Dong; Zhang, Shou

    2017-10-01

    We study the effects of the position of the passive and active cavities on the spontaneous parity-time- (PT -) symmetry-breaking behavior in a non-Hermitian coupled-cavity-array model. We analyze and discuss the energy eigenvalue spectra and PT symmetry in the topologically trivial and nontrivial regimes under three different cases in detail; that is, the passive and active cavities are located at, respectively, the two end positions, the second and penultimate positions, and each position in the coupled-cavity array. The odevity of the number of cavities is further considered to check the effects of the non-Hermitian terms applied on the PT -symmetric and -asymmetric systems. We find that the position of the passive and active cavities has remarkable impacts on the spontaneous PT -symmetry-breaking behavior, and in each case the system exhibits distinguishable and novel spontaneous PT -symmetry-breaking characteristics. The effects of the non-Hermitian terms on the PT -symmetric and -asymmetric systems due to the odevity are comparatively different in the first case but qualitatively the same in the second case.

  5. Conformal symmetry breaking operators for differential forms on spheres

    CERN Document Server

    Kobayashi, Toshiyuki; Pevzner, Michael

    2016-01-01

    This work is the first systematic study of all possible conformally covariant differential operators transforming differential forms on a Riemannian manifold X into those on a submanifold Y with focus on the model space (X, Y) = (Sn, Sn-1). The authors give a complete classification of all such conformally covariant differential operators, and find their explicit formulæ in the flat coordinates in terms of basic operators in differential geometry and classical hypergeometric polynomials. Resulting families of operators are natural generalizations of the Rankin–Cohen brackets for modular forms and Juhl's operators from conformal holography. The matrix-valued factorization identities among all possible combinations of conformally covariant differential operators are also established. The main machinery of the proof relies on the "F-method" recently introduced and developed by the authors. It is a general method to construct intertwining operators between C∞-induced representations or to find singular vecto...

  6. Break up of the azimuthal symmetry of higher order fiber modes

    DEFF Research Database (Denmark)

    Israelsen, Stine Møller; Rishøj, Lars Søgaard; Rottwitt, Karsten

    2014-01-01

    We investigate Bessel-like modes guided in a double cladding fiber where the outer cladding is an aircladding. For very high order LP0 X-modes, the azimuthal symmetry is broken and the mode is no longer linearly polarized. This is observed experimentally and confirmed numerically. The effect is i...... mode. The free space properties of modes suffering from break up of azimuthal symmetry are also investigated experimentally by measuring the free space propagation of a LP016-mode excited in the double cladding fiber. © 2014 Optical Society of America....

  7. Spectra of massive QCD Dirac operators from random matrix theory: all three chiral symmetry breaking patterns

    Energy Technology Data Exchange (ETDEWEB)

    Akemann, G.; Kanzieper, E

    2001-03-01

    The microscopic spectral eigenvalue correlations of QCD Dirac operators in the presence of dynamical fermions are calculated within the framework of Random Matrix Theory (RMT). Our approach treats the low-energy correlation functions of all three chiral symmetry breaking patterns (labeled by the Dyson index {beta} = 1, 2 and 4) on the same footing, offering a unifying description of massive QCD Dirac spectra. RMT universality is explicitly proven for all three symmetry classes and the results are compared to the available lattice data for {beta} = 4.

  8. Nonlinear delayed symmetry breaking in a solid excited by hard x-ray free electron laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Ferrer, A., E-mail: aferrer@phys.ethz.ch [Institute for Quantum Electronics, ETH Zurich, CH-8093 Zurich (Switzerland); Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Johnson, J. A., E-mail: jjohnson@chem.byu.edu; Mariager, S. O.; Grübel, S.; Staub, U. [Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Huber, T.; Trant, M.; Johnson, S. L., E-mail: johnson@phys.ethz.ch [Institute for Quantum Electronics, ETH Zurich, CH-8093 Zurich (Switzerland); Zhu, D.; Chollet, M.; Robinson, J.; Lemke, H. T. [LCLS, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Ingold, G.; Beaud, P. [Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); SwissFEL, Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Milne, C. [SwissFEL, Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland)

    2015-04-13

    We have studied the ultrafast changes of electronic states in bulk ZnO upon intense hard x-ray excitation from a free electron laser. By monitoring the transient anisotropy induced in an optical probe beam, we observe a delayed breaking of the initial c-plane symmetry of the crystal that lasts for several picoseconds. Interaction with the intense x-ray pulses modifies the electronic state filling in a manner inconsistent with a simple increase in electronic temperature. These results may indicate a way to use intense ultrashort x-ray pulses to investigate high-energy carrier dynamics and to control certain properties of solid-state materials.

  9. Tunable symmetry breaking and helical edge transport in a graphene quantum spin Hall state.

    Science.gov (United States)

    Young, A F; Sanchez-Yamagishi, J D; Hunt, B; Choi, S H; Watanabe, K; Taniguchi, T; Ashoori, R C; Jarillo-Herrero, P

    2014-01-23

    Low-dimensional electronic systems have traditionally been obtained by electrostatically confining electrons, either in heterostructures or in intrinsically nanoscale materials such as single molecules, nanowires and graphene. Recently, a new method has emerged with the recognition that symmetry-protected topological (SPT) phases, which occur in systems with an energy gap to quasiparticle excitations (such as insulators or superconductors), can host robust surface states that remain gapless as long as the relevant global symmetry remains unbroken. The nature of the charge carriers in SPT surface states is intimately tied to the symmetry of the bulk, resulting in one- and two-dimensional electronic systems with novel properties. For example, time reversal symmetry endows the massless charge carriers on the surface of a three-dimensional topological insulator with helicity, fixing the orientation of their spin relative to their momentum. Weakly breaking this symmetry generates a gap on the surface, resulting in charge carriers with finite effective mass and exotic spin textures. Analogous manipulations have yet to be demonstrated in two-dimensional topological insulators, where the primary example of a SPT phase is the quantum spin Hall state. Here we demonstrate experimentally that charge-neutral monolayer graphene has a quantum spin Hall state when it is subjected to a very large magnetic field angled with respect to the graphene plane. In contrast to time-reversal-symmetric systems, this state is protected by a symmetry of planar spin rotations that emerges as electron spins in a half-filled Landau level are polarized by the large magnetic field. The properties of the resulting helical edge states can be modulated by balancing the applied field against an intrinsic antiferromagnetic instability, which tends to spontaneously break the spin-rotation symmetry. In the resulting canted antiferromagnetic state, we observe transport signatures of gapped edge states

  10. Bimanual training in stroke: How do coupling and symmetry-breaking matter?

    Directory of Open Access Journals (Sweden)

    Berton Eric

    2011-01-01

    Full Text Available Abstract Background The dramatic consequences of stroke on patient autonomy in daily living activities urged the need for new reliable therapeutic strategies. Recently, bimanual training has emerged as a promising tool to improve the functional recovery of upper-limbs in stroke patients. However, who could benefit from bimanual therapy and how it could be used as a part of a more complete rehabilitation protocol remain largely unknown. A possible reason explaining this situation is that coupling and symmetry-breaking mechanisms, two fundamental principles governing bimanual behaviour, have been largely under-explored in both research and rehabilitation in stroke. Discussion Bimanual coordination emerges as an active, task-specific assembling process where the limbs are constrained to act as a single unit by virtue of mutual coupling. Consequently, exploring, assessing, re-establishing and exploiting functional bimanual synergies following stroke, require moving beyond the classical characterization of performance of each limb in separate and isolated fashion, to study coupling signatures at both neural and behavioural levels. Grounded on the conceptual framework of the dynamic system approach to bimanual coordination, we debated on two main assumptions: 1 stroke-induced impairment of bimanual coordination might be anticipated/understood by comparing, in join protocols, changes in coupling strength and asymmetry of bimanual discrete movements observed in healthy people and those observed in stroke; 2 understanding/predicting behavioural manifestations of decrease in bimanual coupling strength and/or increase in interlimb asymmetry might constitute an operational prerequisite to adapt therapy and better target training at the specific needs of each patient. We believe that these statements draw new directions for experimental and clinical studies and contribute in promoting bimanual training as an efficient and adequate tool to facilitate the

  11. On Laplace-Runge-Lenz Vector as Symmetry Breaking order parameter in Kepler Orbit and Goldstone Boson

    CERN Document Server

    Amiri, Manouchehr

    2014-01-01

    We introduce a type of symmetry breaking and associated order parameter in connection with Laplace-Runge-Lenz vector of Kepler orbit through an extended spatial dimension and Ensemble view. By implementation of a small extra spatial dimension and embedded infinitesimal toral manifold, it has been shown that emerging of LRL vector under SO(4)symmetry is in analogy with a variety of explicit and spontaneous symmetry breaking situations and related Goldstone bosons such as phonons and spin waves. A theorem introduced to generalize this concept of breaking symmetry. The diffeomorphism of circular orbit(geodesic)to elliptic one proved to be equivalent with a covariant derivative and related parallel displacement in this extended four dimensional spatial space.Respect to ensemble definition this diffeomorphism breaks the O(2) symmetry of initial orbit and Hamiltonian to Z2 resulting in broken generators in quotient space and associated Goldstone boson as perturbing Hamiltonian term leading to a perpetual circular m...

  12. Ultra-large distance modification of gravity from Lorentz symmetry breaking at the Planck scale

    Energy Technology Data Exchange (ETDEWEB)

    Gorbunov, Dmitry S. [Institute for Nuclear Research of the Russian Academy of Sciences, 60th October Anniversary prospect, 7a, 117312 Moscow (Russian Federation); Sibiryakov, Sergei M. [Institute for Nuclear Research of the Russian Academy of Sciences, 60th October Anniversary prospect, 7a, 117312 Moscow (Russian Federation)

    2005-09-15

    We present an extension of the Randall-Sundrum model in which, due to spontaneous Lorentz symmetry breaking, graviton mixes with bulk vector fields and becomes quasilocalized. The masses of KK modes comprising the four-dimensional graviton are naturally exponentially small. This allows to push the Lorentz breaking scale to as high as a few tenth of the Planck mass. The model does not contain ghosts or tachyons and does not exhibit the van Dam-Veltman-Zakharov discontinuity. The gravitational attraction between static point masses becomes gradually weaker with increasing of separation and gets replaced by repulsion (antigravity) at exponentially large distances.

  13. Dynamical Electroweak Symmetry Breaking with a Heavy Fermion in Light of Recent LHC Results

    Directory of Open Access Journals (Sweden)

    Pham Q. Hung

    2013-01-01

    Full Text Available The recent announcement of a discovery of a possible Higgs-like particle—its spin and parity are yet to be determined—at the LHC with a mass of 126 GeV necessitates a fresh look at the nature of the electroweak symmetry breaking, in particular if this newly-discovered particle will turn out to have the quantum numbers of a Standard Model Higgs boson. Even if it were a 0+ scalar with the properties expected for a SM Higgs boson, there is still the quintessential hierarchy problem that one has to deal with and which, by itself, suggests a new physics energy scale around 1 TeV. This paper presents a minireview of one possible scenario: the formation of a fermion-antifermion condensate coming from a very heavy fourth generation, carrying the quantum number of the SM Higgs field, and thus breaking the electroweak symmetry.

  14. Symmetry Breaking of Frequency Comb in Varying Normal Dispersion Fiber Ring Cavity

    CERN Document Server

    Afzal, Muhammad Imran; Lee, Yong Tak

    2016-01-01

    We build on a previously reported frequency comb of mode spacing 0.136 nm in a fiber ring cavity of varying normal dispersion [1], to generate, for the first time, a frequency comb of mode spacing 0.144 nm centered at 978.544 nm to demonstrate the symmetry-breaking. By controlling the birefringence of the optical cavity through fiber stretching and polarization control, the spacing of the comb lines increases from 0.136 nm to 0.144 nm, and this small change in mode spacing generates very different spectral symmetry-breaking in the frequency comb relative to the frequency comb of mode spacing 0.136 nm. Interestingly, non-uniform depletion of primary modes is also observed. The experimental results are an important contribution in the continuing effort of understanding the dynamics of frequency combs involving large number of modes, nontrivial nonlinear waves and deterministic chaos.

  15. The influence of pairing correlations on the isospin symmetry breaking corrections of superallowed Fermi beta decays

    Energy Technology Data Exchange (ETDEWEB)

    Cal Latin-Small-Letter-Dotless-I k, A. E., E-mail: engincalik@yahoo.com [Dumlupinar University, Department of Physics, Faculty of Arts and Sciences (Turkey); Gerceklioglu, M. [Ege University, Department of Physics, Faculty of Science (Turkey); Selam, C. [Mus Alparslan University, Department of Physics, Faculty of Arts and Sciences (Turkey)

    2013-05-15

    Within the framework of quasi-particle random phase approximation, the isospin breaking correction of superallowed 0{sup +} {yields} 0{sup +} beta decay and unitarity of Cabibbo-Kobayashi-Maskawa mixing matrix have been investigated. The broken isotopic symmetry of nuclear part of Hamiltonian has been restored by Pyatov's method. The isospin symmetry breaking correction with pairing correlations has been compared with the previous results without pairing. The effect of pairing interactions has been examined for nine superallowed Fermi beta decays; their parent nuclei are {sup 26}Al, {sup 34}Cl, {sup 38}K, {sup 42}Sc, {sup 46}V, {sup 50}Mn, {sup 54}Co, {sup 62}Ga, {sup 74}Rb.

  16. Noncritical generation of nonclassical frequency combs via spontaneous rotational symmetry breaking

    Science.gov (United States)

    Navarrete-Benlloch, Carlos; Patera, Giuseppe; de Valcárcel, Germán J.

    2017-10-01

    Synchronously pumped optical parametric oscillators (SPOPOs) are optical cavities driven by mode-locked lasers, and containing a nonlinear crystal capable of down-converting a frequency comb to lower frequencies. SPOPOs have received a lot of attention lately because their intrinsic multimode nature makes them compact sources of quantum correlated light with promising applications in modern quantum information technologies. In this work we show that SPOPOs are also capable of accessing the challenging and interesting regime where spontaneous symmetry breaking confers strong nonclassical properties to the emitted light, which has eluded experimental observation so far. Apart from opening the possibility of studying experimentally this elusive regime of dissipative phase transitions, our predictions will have a practical impact, since we show that spontaneous symmetry breaking provides a specific spatiotemporal mode with large quadrature squeezing for any value of the system parameters, turning SPOPOs into robust sources of highly nonclassical light above threshold.

  17. Local symmetry breaking and spin–phonon coupling in SmCrO{sub 3} orthochromite

    Energy Technology Data Exchange (ETDEWEB)

    El Amrani, M. [GREMAN CNRS UMR 7347, Université F. Rabelais, IUT de Blois, 15 rue de la Chocolatrie 41029 Blois cedex (France); Zaghrioui, M., E-mail: zaghrioui@univ-tours.fr [GREMAN CNRS UMR 7347, Université F. Rabelais, IUT de Blois, 15 rue de la Chocolatrie 41029 Blois cedex (France); Ta Phuoc, V.; Gervais, F. [GREMAN CNRS UMR 7347, Université F. Rabelais, IUT de Blois, 15 rue de la Chocolatrie 41029 Blois cedex (France); Massa, Néstor E. [Laboratorio Nacional de Investigacion y Servicios en Espectroscopia Optica-Centro CEQUINOR, Universidad Nacional de La Plata, C. C. 962, 1900 La Plata (Argentina)

    2014-06-01

    Raman scattering and infrared reflectivity performed on polycrystalline SmCrO{sub 3} support strong influence of the antiferromagnetic order on phonon modes. Both measurements show softening of some modes below T{sub N}. Such a behavior is explained by spin–phonon coupling in this compound. Furthermore, temperature dependence of the infrared spectra has demonstrated important changes compared to the Raman spectra, suggesting strong structural modifications due to the cation displacements rather to those of the oxygen ions. Our results reveal that polar distortions originating in local symmetry breaking, i.e. local non-centrosymmetry, resulting in Cr off-centring. - Highlights: • We investigated Raman and infrared phonon modes of SmCrO{sub 3} versus temperature. • Results reveal strong influence of the antiferromagnetic order on phonon modes. • Temperature dependence of the infrared spectra shows strong structural modifications suggesting local symmetry breaking.

  18. Magnetism and local symmetry breaking in a Mott insulator with strong spin orbit interactions.

    Science.gov (United States)

    Lu, L; Song, M; Liu, W; Reyes, A P; Kuhns, P; Lee, H O; Fisher, I R; Mitrović, V F

    2017-02-09

    Study of the combined effects of strong electronic correlations with spin-orbit coupling (SOC) represents a central issue in quantum materials research. Predicting emergent properties represents a huge theoretical problem since the presence of SOC implies that the spin is not a good quantum number. Existing theories propose the emergence of a multitude of exotic quantum phases, distinguishable by either local point symmetry breaking or local spin expectation values, even in materials with simple cubic crystal structure such as Ba 2 NaOsO 6 . Experimental tests of these theories by local probes are highly sought for. Our local measurements designed to concurrently probe spin and orbital/lattice degrees of freedom of Ba 2 NaOsO 6 provide such tests. Here we show that a canted ferromagnetic phase which is preceded by local point symmetry breaking is stabilized at low temperatures, as predicted by quantum theories involving multipolar spin interactions.

  19. Unidirectional molecular assembly alignment on graphene enabled by nanomechanical symmetry breaking.

    Science.gov (United States)

    Hong, Liu; Nishihara, Taishi; Hijikata, Yuh; Miyauchi, Yuhei; Itami, Kenichiro

    2018-02-05

    Precise fabrication of molecular assemblies on a solid surface has long been of central interest in surface science. Their perfectly oriented growth only along a desired in-plane direction, however, remains a challenge, because of the thermodynamical equivalence of multiple axis directions on a solid-surface lattice. Here we demonstrate the successful fabrication of an in-plane, unidirectional molecular assembly on graphene. Our methodology relies on nanomechanical symmetry breaking effects under atomic force microscopy tip scanning, which has never been used in molecular alignment. Individual one-dimensional (1D) molecular assemblies were aligned along a selected symmetry axis of the graphene lattice under finely-tuned scanning conditions after removing initially-adsorbed molecules. Experimental statistics and computational simulations suggest that the anisotropic tip scanning locally breaks the directional equivalence of the graphene surface, which enables nucleation of the unidirectional 1D assemblies. Our findings will open new opportunities in the molecular alignment control on various atomically flat surfaces.

  20. CERN LHC sensitivity to the resonance spectrum of a minimal strongly interacting electroweak symmetry breaking sector

    CERN Document Server

    Dobado, A; Peláez, J R; Ruiz-Morales, Ester

    2000-01-01

    We present a unified analysis of the two main production processes of vector boson pairs at the CERN LHC, VV-fusion and qq annihilation, in a minimal strongly interacting electroweak symmetry breaking sector. Using a unitarized electroweak chiral Lagrangian formalism and modeling the final V/sub L/V/sub L/ strong rescattering effects by a form factor, we describe qq annihilation processes in terms of the two chiral parameters that govern elastic V/sub L/V/sub L/ scattering. Depending on the values of these two chiral parameters, the unitarized amplitudes may present resonant enhancements in different angular momentum-isospin channels. Scanning this two parameter space, we generate the general resonance spectrum of a minimal strongly interacting electroweak symmetry breaking sector and determine the regions that can be probed at the CERN LHC. (47 refs).

  1. Benchmarking Density Functional Theory Approaches for the Description of Symmetry-Breaking in Long Polymethine Dyes

    KAUST Repository

    Gieseking, Rebecca L.

    2016-04-25

    Long polymethines are well-known experimentally to symmetry-break, which dramatically modifies their linear and nonlinear optical properties. Computational modeling could be very useful to provide insight into the symmetry-breaking process, which is not readily available experimentally; however, accurately predicting the crossover point from symmetric to symmetry-broken structures has proven challenging. Here, we benchmark the accuracy of several DFT approaches relative to CCSD(T) geometries. In particular, we compare analogous hybrid and long-range corrected (LRC) functionals to clearly show the influence of the functional exchange term. Although both hybrid and LRC functionals can be tuned to reproduce the CCSD(T) geometries, the LRC functionals are better performing at reproducing the geometry evolution with chain length and provide a finite upper limit for the gas-phase crossover point; these methods also provide good agreement with the experimental crossover points for more complex polymethines in polar solvents. Using an approach based on LRC functionals, a reduction in the crossover length is found with increasing medium dielectric constant, which is related to localization of the excess charge on the end groups. Symmetry-breaking is associated with the appearance of an imaginary frequency of b2 symmetry involving a large change in the degree of bond-length alternation. Examination of the IR spectra show that short, isolated streptocyanines have a mode at ~1200 cm-1 involving a large change in bond-length alternation; as the polymethine length or the medium dielectric increases, the frequency of this mode decreases before becoming imaginary at the crossover point.

  2. Parity symmetry-breaking phase transition in a nonlinear Rabi-Hubbard lattice

    OpenAIRE

    Pyykkönen, A. (Ari)

    2015-01-01

    Abstract Lattices consisting of cavity QED and circuit QED elements have come under focus as a platform for studying several novel quantum phenomena. In particular, a lattice of Rabi systems described by the Rabi-Hubbard model is expected to display a new Z2 parity symmetry-breaking phase transition of light between a Rabi insulator and a delocalized superradiant phase. In this thesis, we examine a superconducting circuit c...

  3. Dynamical Symmetry Breaking on Langevin Equation : Nambu-Jona-Lasinio Model : Particles and Fields

    OpenAIRE

    Kenji, IKEGAMI; Riuji, MOCHIZUKI; Kazuhiro, YOSHIDA; Graduate School of Science and Technology, Chiba University; Department of Physics, Faculty of Science, Chiba University; Department of Physics, Faculty of Science, Chiba University

    1993-01-01

    In order to investigate dynamical symmetry breaking,we study Nambu-Jona-Lasinio model in the large-N limit in the stochastic quantization method. Here in order to solve the Langevin equation, we impose specified initial conditions and construct "effective Langevin equation" in the large-N limit and give the same non-perturbative results as path-integral approach gives. Moreover we discuss stability of vacuum by means of "effective potential"

  4. In silico reconstitution of actin-based symmetry breaking and motility.

    Directory of Open Access Journals (Sweden)

    Mark J Dayel

    2009-09-01

    Full Text Available Eukaryotic cells assemble viscoelastic networks of crosslinked actin filaments to control their shape, mechanical properties, and motility. One important class of actin network is nucleated by the Arp2/3 complex and drives both membrane protrusion at the leading edge of motile cells and intracellular motility of pathogens such as Listeria monocytogenes. These networks can be reconstituted in vitro from purified components to drive the motility of spherical micron-sized beads. An Elastic Gel model has been successful in explaining how these networks break symmetry, but how they produce directed motile force has been less clear. We have combined numerical simulations with in vitro experiments to reconstitute the behavior of these motile actin networks in silico using an Accumulative Particle-Spring (APS model that builds on the Elastic Gel model, and demonstrates simple intuitive mechanisms for both symmetry breaking and sustained motility. The APS model explains observed transitions between smooth and pulsatile motion as well as subtle variations in network architecture caused by differences in geometry and conditions. Our findings also explain sideways symmetry breaking and motility of elongated beads, and show that elastic recoil, though important for symmetry breaking and pulsatile motion, is not necessary for smooth directional motility. The APS model demonstrates how a small number of viscoelastic network parameters and construction rules suffice to recapture the complex behavior of motile actin networks. The fact that the model not only mirrors our in vitro observations, but also makes novel predictions that we confirm by experiment, suggests that the model captures much of the essence of actin-based motility in this system.

  5. Symmetry breaking in homo-oligomers: the curious case of mega-hemocyanin.

    Science.gov (United States)

    Garcia Seisdedos, Hector; Steinberg, Avital; Levy, Emmanuel D

    2015-01-06

    Mega-hemocyanin is a 13.5 MDa oxygen transporter found in snails. It is built from three stacked rings involving ten subunits each. The cryo-EM structure of the complex presented by Gatsogiannis and colleagues in this issue of Structure revealed an unexpected breaking of 5-fold symmetry in the central ring and a nonequivalent packing of the subunits. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. Rotational Symmetry Breaking in a Trigonal Superconductor Nb-doped Bi_{2}Se_{3}

    Directory of Open Access Journals (Sweden)

    Tomoya Asaba

    2017-01-01

    Full Text Available The search for unconventional superconductivity has been focused on materials with strong spin-orbit coupling and unique crystal lattices. Doped bismuth selenide (Bi_{2}Se_{3} is a strong candidate, given the topological insulator nature of the parent compound and its triangular lattice. The coupling between the physical properties in the superconducting state and its underlying crystal symmetry is a crucial test for unconventional superconductivity. In this paper, we report direct evidence that the superconducting magnetic response couples strongly to the underlying trigonal crystal symmetry in the recently discovered superconductor with trigonal crystal structure, niobium (Nb-doped Bi_{2}Se_{3}. As a result, the in-plane magnetic torque signal vanishes every 60°. More importantly, the superconducting hysteresis loop amplitude is enhanced along one preferred direction, spontaneously breaking the rotational symmetry. This observation indicates the presence of nematic order in the superconducting ground state of Nb-doped Bi_{2}Se_{3}.

  7. Radiative electroweak symmetry breaking in non-supersymmetric extensions of standard model

    Science.gov (United States)

    Khan, Saki

    2017-11-01

    In this talk, I discuss the possibility of radiative electroweak symmetry breaking where loop corrections to the mass parameter of the Higgs boson trigger the symmetry breaking in various non-supersymmetric extensions of the Standard Model (SM). Although the mechanism fails in the SM, it is shown to be quite successful in several extensions which share a common feature of having an additional scalar around the TeV scale. Due to the cross couplings between the scalars in the Higgs potential, the positive Higgs mass parameter at a high energy scale is turned negative in the renormalization group flow to lower energy. The type-II seesaw model, a two-loop radiative neutrino mass model, the inert doublet model, scalar singlet dark matter model, and a universal seesaw model with an additional U(1) broken at the TeV scale are studied and shown to exhibit successful radiative electroweak symmetry breaking when the additional scalars are at TeV scale. Large Hadron Collider (LHC) may be able to detect some of these TeV scale particles in near future.

  8. Spontaneous mirror left-right symmetry breaking for leptogenesis parametrized by Majorana neutrino mass matrix

    Science.gov (United States)

    Gu, Pei-Hong

    2017-10-01

    We introduce a mirror copy of the ordinary fermions and Higgs scalars for embedding the SU(2) L × U(1) Y electroweak gauge symmetry into an SU(2) L × SU(2) R × U(1) B-L left-right gauge symmetry. We then show the spontaneous left-right symmetry breaking can automatically break the parity symmetry motivated by solving the strong CP problem. Through the SU(2) R gauge interactions, a mirror Majorana neutrino can decay into a mirror charged lepton and two mirror quarks. Consequently we can obtain a lepton asymmetry stored in the mirror charged leptons. The Yukawa couplings of the mirror and ordinary charged fermions to a dark matter scalar then can transfer the mirror lepton asymmetry to an ordinary lepton asymmetry which provides a solution to the cosmic baryon asymmetry in association with the SU(2) L sphaleron processes. In this scenario, the baryon asymmetry can be well described by the neutrino mass matrix up to an overall factor.

  9. { Z}_N symmetry breaking in projected entangled pair state models

    Science.gov (United States)

    Rispler, Manuel; Duivenvoorden, Kasper; Schuch, Norbert

    2017-09-01

    We consider projected entangled pair state (PEPS) models with a global { Z}N symmetry, which are constructed from { Z}N -symmetric tensors and are thus { Z}N -invariant wavefunctions, and study the occurence of long-range order and symmetry breaking in these systems. First, we show that long-range order in those models is accompanied by a degeneracy in the so-called transfer operator of the system. We subsequently use this degeneracy to determine the nature of the symmetry broken states, i.e. those stable under arbitrary perturbations, and provide a succinct characterization in terms of the fixed points of the transfer operator (i.e. the different boundary conditions) in the individual symmetry sectors. We verify our findings numerically through the study of a { Z}3 -symmetric model, and show that the entanglement Hamiltonian derived from the symmetry broken states is quasi-local (unlike the one derived from the symmetric state), reinforcing the locality of the entanglement Hamiltonian for gapped phases.

  10. Spontaneous Symmetry-Breaking in a Network Model for Quadruped Locomotion

    Science.gov (United States)

    Stewart, Ian

    2017-12-01

    Spontaneous symmetry-breaking proves a mechanism for pattern generation in legged locomotion of animals. The basic timing patterns of animal gaits are produced by a network of spinal neurons known as a Central Pattern Generator (CPG). Animal gaits are primarily characterized by phase differences between leg movements in a periodic gait cycle. Many different gaits occur, often having spatial or spatiotemporal symmetries. A natural way to explain gait patterns is to assume that the CPG is symmetric, and to classify the possible symmetry-breaking periodic motions. Pinto and Golubitsky have discussed a four-node model CPG network for biped gaits with ℤ2 × ℤ2 symmetry, classifying the possible periodic states that can arise. A more specific rate model with this structure has been analyzed in detail by Stewart. Here we extend these methods to quadruped gaits, using an eight-node network with ℤ4 × ℤ2 symmetry proposed by Golubitsky and coworkers. We formulate a rate model and calculate how the first steady or Hopf bifurcation depends on its parameters, which represent four connection strengths. The calculations involve a distinction between “real” gaits with one or two phase shifts (pronk, bound, pace, trot) and “complex” gaits with four phase shifts (forward and reverse walk, forward and reverse buck). The former correspond to real eigenvalues of the connection matrix, the latter to complex conjugate pairs. The partition of parameter space according to the first bifurcation, ignoring complex gaits, is described explicitly. The complex gaits introduce further complications, not yet fully understood. All eight gaits can occur as the first bifurcation from a fully synchronous equilibrium, for suitable parameters, and numerical simulations indicate that they can be asymptotically stable.

  11. Symmetry breaking in nematic liquid crystals: analogy with cosmology and magnetism.

    Science.gov (United States)

    Repnik, R; Ranjkesh, A; Simonka, V; Ambrozic, M; Bradac, Z; Kralj, S

    2013-10-09

    Universal behavior related to continuous symmetry breaking in nematic liquid crystals is studied using Brownian molecular dynamics. A three-dimensional lattice system of rod-like objects interacting via the Lebwohl-Lasher interaction is considered. We test the applicability of predictions originally derived in cosmology and magnetism. In the first part we focus on coarsening dynamics following the temperature driven isotropic-nematic phase transition for different quench rates. The behavior in the early coarsening regime supports predictions made originally by Kibble in cosmology. For fast enough quenches, symmetry breaking and causality give rise to a dense tangle of defects. When the degree of orientational ordering is large enough, well defined protodomains characterized by a single average domain length are formed. With time subcritical domains gradually vanish and supercritical domains grow with time, exhibiting a universal scaling law. In the second part of the paper we study the impact of random-field-type disorder on a range of ordering in the (symmetry broken) nematic phase. We demonstrate that short-range order is observed even for a minute concentration of impurities, giving rise to disorder in line with the Imry-Ma theorem prediction only for the appropriate history of systems.

  12. Spontaneous chiral symmetry breaking in QCD:a finite-size scaling study on the lattice

    CERN Document Server

    Giusti, Leonardo; Giusti, Leonardo; Necco, Silvia

    2007-01-01

    Spontaneous chiral symmetry breaking in QCD with massless quarks at infinite volume can be seen in a finite box by studying, for instance, the dependence of the chiral condensate from the volume and the quark mass. We perform a feasibility study of this program by computing the quark condensate on the lattice in the quenched approximation of QCD at small quark masses. We carry out simulations in various topological sectors of the theory at several volumes, quark masses and lattice spacings by employing fermions with an exact chiral symmetry, and we focus on observables which are infrared stable and free from mass-dependent ultraviolet divergences. The numerical calculation is carried out with an exact variance-reduction technique, which is designed to be particularly efficient when spontaneous symmetry breaking is at work in generating a few very small low-lying eigenvalues of the Dirac operator. The finite-size scaling behaviour of the condensate in the topological sectors considered agrees, within our stati...

  13. Continuous Symmetry Breaking in 1D Long-Range Interacting Quantum Systems

    Science.gov (United States)

    Maghrebi, Mohammad F.; Gong, Zhe-Xuan; Gorshkov, Alexey V.

    2017-07-01

    Continuous symmetry breaking (CSB) in low-dimensional systems, forbidden by the Mermin-Wagner theorem for short-range interactions, may take place in the presence of slowly decaying long-range interactions. Nevertheless, there is no stringent bound on how slowly interactions should decay to give rise to CSB in 1D quantum systems at zero temperature. Here, we study a long-range interacting spin chain with U (1 ) symmetry and power-law interactions V (r )˜1 /rα. Using a number of analytical and numerical techniques, we find CSB for α smaller than a critical exponent αc(≤3 ) that depends on the microscopic parameters of the model. Furthermore, the transition from the gapless X Y phase to the gapless CSB phase is mediated by the breaking of conformal and Lorentz symmetries due to long-range interactions, and is described by a universality class akin to, but distinct from, the Berezinskii-Kosterlitz-Thouless transition. Signatures of the CSB phase should be accessible in existing trapped-ion experiments.

  14. Symmetry breaking in the opinion dynamics of a multi-group project organization

    Science.gov (United States)

    Zhu, Zhen-Tao; Zhou, Jing; Li, Ping; Chen, Xing-Guang

    2012-10-01

    A bounded confidence model of opinion dynamics in multi-group projects is presented in which each group's opinion evolution is driven by two types of forces: (i) the group's cohesive force which tends to restore the opinion back towards the initial status because of its company culture; and (ii) nonlinear coupling forces with other groups which attempt to bring opinions closer due to collaboration willingness. Bifurcation analysis for the case of a two-group project shows a cusp catastrophe phenomenon and three distinctive evolutionary regimes, i.e., a deadlock regime, a convergence regime, and a bifurcation regime in opinion dynamics. The critical value of initial discord between the two groups is derived to discriminate which regime the opinion evolution belongs to. In the case of a three-group project with a symmetric social network, both bifurcation analysis and simulation results demonstrate that if each pair has a high initial discord, instead of symmetrically converging to consensus with the increase of coupling scale as expected by Gabbay's result (Physica A 378 (2007) p. 125 Fig. 5), project organization (PO) may be split into two distinct clusters because of the symmetry breaking phenomenon caused by pitchfork bifurcations, which urges that apart from divergence in participants' interests, nonlinear interaction can also make conflict inevitable in the PO. The effects of two asymmetric level parameters are tested in order to explore the ways of inducing dominant opinion in the whole PO. It is found that the strong influence imposed by a leader group with firm faith on the flexible and open minded follower groups can promote the formation of a positive dominant opinion in the PO.

  15. Actin polymerization or myosin contraction: two ways to build up cortical tension for symmetry breaking

    Science.gov (United States)

    Carvalho, Kevin; Lemière, Joël; Faqir, Fahima; Manzi, John; Blanchoin, Laurent; Plastino, Julie; Betz, Timo; Sykes, Cécile

    2013-01-01

    Cells use complex biochemical pathways to drive shape changes for polarization and movement. One of these pathways is the self-assembly of actin filaments and myosin motors that together produce the forces and tensions that drive cell shape changes. Whereas the role of actin and myosin motors in cell polarization is clear, the exact mechanism of how the cortex, a thin shell of actin that is underneath the plasma membrane, can drive cell shape changes is still an open question. Here, we address this issue using biomimetic systems: the actin cortex is reconstituted on liposome membranes, in an ‘outside geometry’. The actin shell is either grown from an activator of actin polymerization immobilized at the membrane by a biotin–streptavidin link, or built by simple adsorption of biotinylated actin filaments to the membrane, in the presence or absence of myosin motors. We show that tension in the actin network can be induced either by active actin polymerization on the membrane via the Arp2/3 complex or by myosin II filament pulling activity. Symmetry breaking and spontaneous polarization occur above a critical tension that opens up a crack in the actin shell. We show that this critical tension is reached by growing branched networks, nucleated by the Arp2/3 complex, in a concentration window of capping protein that limits actin filament growth and by a sufficient number of motors that pull on actin filaments. Our study provides the groundwork to understanding the physical mechanisms at work during polarization prior to cell shape modifications. PMID:24062578

  16. Polar Kerr effect studies of time reversal symmetry breaking states in heavy fermion superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Schemm, E.R., E-mail: eschemm@alumni.stanford.edu [Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA 94305 (United States); Levenson-Falk, E.M. [Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA 94305 (United States); Department of Physics, Stanford University, Stanford, CA 94305 (United States); Kapitulnik, A. [Geballe Laboratory for Advanced Materials, Stanford University, Stanford, CA 94305 (United States); Department of Physics, Stanford University, Stanford, CA 94305 (United States); Department of Applied Physics, Stanford University, Stanford, CA 94305 (United States); Stanford Institute of Energy and Materials Science, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States)

    2017-04-15

    Highlights: • Polar Kerr effect (PKE) probes broken time-reversal symmetry (TRS) in superconductors. • Absence of PKE below Tc in CeCoIn{sub 5} is consistent with dx2-y2 order parameter symmetry. • PKE in the B phase of the multiphase superconductor UPt3 agrees with an E2u model. • Data on URu2Si2 show broken TRS and additional structure in the superconducting state. - Abstract: The connection between chiral superconductivity and topological order has emerged as an active direction in research as more instances of both have been identified in condensed matter systems. With the notable exception of {sup 3}He-B, all of the known or suspected chiral – that is to say time-reversal symmetry-breaking (TRSB) – superfluids arise in heavy fermion superconductors, although the vast majority of heavy fermion superconductors preserve time-reversal symmetry. Here we review recent experimental efforts to identify TRSB states in heavy fermion systems via measurement of polar Kerr effect, which is a direct consequence of TRSB.

  17. Bose-Einstein condensation and symmetry breaking of a complex charged scalar field

    Energy Technology Data Exchange (ETDEWEB)

    Matos, Tonatiuh [Centro de Investigacion y de Estudios Avanzados del IPN, Departamento de Fisica, Mexico, DF (Mexico); Castellanos, Elias [Centro de Investigacion y de Estudios Avanzados del IPN, Departamento de Fisica, Mexico, DF (Mexico); Universidad Autonoma de Chiapas, Mesoamerican Centre for Theoretical Physics, Tuxtla Gutierrez, Chiapas (Mexico); Suarez, Abril [Centro de Investigacion y de Estudios Avanzados del IPN, Departamento de Fisica, Mexico, DF (Mexico); Universidad Politecnica Metropolitana de Hidalgo, Departamento de Aeronautica, Tolcayuca, Hidalgo (Mexico)

    2017-08-15

    In this work the Klein-Gordon equation for a complex scalar field with U(1) symmetry endowed in a mexican-hat scalar field potential with thermal and electromagnetic contributions is written as a Gross-Pitaevskii (GP)-like equation. This equation is interpreted as a charged generalization of the GP equation at finite temperatures found in previous works. Its hydrodynamical representation is obtained and the corresponding thermodynamical properties are derived and related to measurable quantities. The condensation temperature in the non-relativistic regime associated with the aforementioned system within the semiclassical approximation is calculated. Also, a generalized equation for the conservation of energy for a charged bosonic gas is found when electromagnetic fields are introduced, and it is studied how under certain circumstances its breaking of symmetry can give some insight on the phase transition of the system not just into the condensed phase but also on other related systems. (orig.)

  18. Dual-Band Perfect Absorption by Breaking the Symmetry of Metamaterial Structure

    Science.gov (United States)

    Hai, Le Dinh; Qui, Vu Dinh; Dinh, Tiep Hong; Hai, Pham; Giang, Trinh Thị; Cuong, Tran Manh; Tung, Bui Son; Lam, Vu Dinh

    2017-06-01

    Since the first proposal of Landy et al. (Phys Rev Lett 100:207402, 2008), the metamaterial perfect absorber (MPA) has rapidly become one of the most crucial research trends. Recently, dual-band, multi-band and broadband MPA have been highly desirable in electronic applications. In this paper, we demonstrate and evaluate a MPA structure which can generate dual-band absorption operating at the microwave frequency by breaking the symmetry of structure. There is an agreement between simulation and experimental results. The results can be explained by using the equivalent LC circuit and the electric field distribution of this structure. In addition, various structures with different symmetry configurations were studied to gain greater insight into the absorption.

  19. Is the Higgs boson associated with Coleman-Weinberg dynamical symmetry breaking?

    Energy Technology Data Exchange (ETDEWEB)

    Hill, Christopher T. [Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States)

    2014-04-01

    The Higgs mechanism may be a quantum phenomenon, i.e., a Coleman-Weinberg potential generated by the explicit breaking of scale symmetry in Feynman loops. We review the relationship of scale symmetry, trace anomalies, and emphasize the role of the renormalization group in determining Coleman- Weinberg potentials. We propose a simple phenomenological model with "maximal visibility" at the LHC containing a "dormant" Higgs doublet (no VEV, coupled to standard model gauge interactions $SU(2)\\times U(1)$) with a mass of $\\sim 380$ GeV. We discuss the LHC phenomenology and UV challenges of such a model. We also give a schematic model in which new heavy fermions, with masses $\\sim 230$ GeV, can drive a Coleman-Weinberg potential at two-loops. The role of the "improved stress tensor" is emphasized, and we propose a non-gravitational term, analogous to the $\\theta$-term in QCD, which generates it from a scalar action.

  20. Lattice Symmetry Breaking of Spin Wave Propagation in Two-Dimensional Magnonic Crystals

    Science.gov (United States)

    Sietsema, Glade; Flatté, Michael E.

    2014-03-01

    We solve the Landau-Lifshitz-Gilbert equation for spin waves in a two-dimensional magnonic crystal using the plane wave expansion method. In doing this we have found that the inclusion of the dipolar field in the LLG equation results in the dispersion relations and linewidths having a lower symmetry than the crystal latice. The magnitude of this symmetry breaking is determined by the strength of the dipolar field relative to the exchange field. Adjusting the crystal parameters can change the relative strength of these fields, thereby allowing this effect to be enhanced or reduced. We have also calculated the Green's functions for this system, which show highly directional propagation of the spin waves depending on the excitation frequency. This work was supported in part by C-SPIN, one of six centers of STARnet, a Semiconductor Research Corporation program, sponsored by MARCO and DARPA.

  1. Spontaneous symmetry breaking and neutral stability in the noncanonical Hamiltonian formalism

    Energy Technology Data Exchange (ETDEWEB)

    Morrison, P.J.; Eliezer, S.

    1985-10-01

    The noncanonical Hamiltonian formalism is based upon a generalization of the Poisson bracket, a particular form of which is possessed by continuous media fields. Associated with this generalization are special constants of motion called Casimirs. These are constants that can be viewed as being built into the phase space, for they are invariant for all Hamiltonians. Casimirs are important because when added to the Hamiltonian they yield an effective Hamiltonian that produces equilibrium states upon variation. The stability of these states can be ascertained by a second variation. Goldstone's theorem, in its usual context, determines zero eigenvalues of the mass matrix for a given vacuum state, the equilibrium with minimum energy. Here, since for fluids and plasmas the vacuum state is uninteresting, we examine symmetry breaking for general equilibria. Broken symmetries imply directions of neutral stability. Two examples are presented: the nonlinear Alfven wave of plasma physics and the Korteweg-de Vries soliton. 46 refs.

  2. Spontaneous symmetry breaking and neutral stability in the noncanonical Hamiltonian formalism

    Energy Technology Data Exchange (ETDEWEB)

    Morrison, P.J.; Eliezer, S.

    1986-06-01

    The noncanonical Hamiltonian formalism is based upon a generalization of the Poisson bracket, a particular form of which is possessed by continuous media fields. Associated with this generalization are special constants of motion called Casimir invariants. These are constants that can be viewed as being built into the phase space, for they are invariant for all Hamiltonians. Casimir invariants are important because when added to the Hamiltonian they yield an effective Hamiltonian that produces equilibrium states upon variation. The stability of these states can be ascertained by a second variation. Goldstone's theorem, in its usual context, determines zero eigenvalues of the mass matrix for a given vacuum state, the equilibrium with minimum energy. Here, since for fluids and plasmas the vacuum state is uninteresting, we examine symmetry breaking for general equilibria. Broken symmetries imply directions of neutral stability. Two examples are presented: the nonlinear Alfven wave of plasma physics and the Korteweg-de Vries soliton.

  3. Chiral symmetry breaking and the Banks-Casher relation in lattice QCD with Wilson quarks

    CERN Document Server

    Giusti, Leonardo

    2009-01-01

    The Banks--Casher relation links the spontaneous breaking of chiral symmetry in QCD to the presence of a non-zero density of quark modes at the low end of the spectrum of the Dirac operator. Spectral observables like the number of modes in a given energy interval are renormalizable and can therefore be computed using the Wilson formulation of lattice QCD even though the latter violates chiral symmetry at energies on the order of the inverse lattice spacing. Using numerical simulations, we find (in two-flavour QCD) that the low quark modes do condense in the expected way. In particular, the chiral condensate can be accurately calculated simply by counting the low modes on large lattices. Other spectral observables can be considered as well and have a potentially wide range of uses.

  4. Symmetry breaking and restoring wave transmission in diode-antidiode double chains.

    Science.gov (United States)

    Lepri, Stefano; Malomed, Boris A

    2013-04-01

    We introduce a system of two parallel-coupled discrete nonlinear Schrödinger inhomogeneous chains. Each one favors the unidirectional transmission of incident packets, in the opposite directions with respect to each other. Two different configurations of the diode-antidiode pair are considered, i.e., a ladder and a plaquette. They feature, respectively, the uniform transverse linear coupling or the coupling limited to the central nonlinear segment of the system. In the case of weak linear coupling, the symmetry breaking is observed (i.e., the pair still features the diode behavior), while the moderately strong coupling restores the symmetry, making the transmission effectively bidirectional. In the case of the ladder, an oscillatory dependence of the transmission on the strength of the coupling is observed and qualitatively explained.

  5. Neutrino masses and LFV from minimal breaking of U(3)^5 and U(2)^5 flavor symmetries

    CERN Document Server

    Blankenburg, Gianluca; Jones-Perez, Joel

    2012-01-01

    We analyze neutrino masses and Lepton Flavor Violation (LFV) in charged leptons with a minimal ansatz about the breaking of the U(3)^5 flavor symmetry, consistent with the U(2)^3 breaking pattern of quark Yukawa couplings, in the context of supersymmetry. Neutrino masses are expected to be almost degenerate, close to present bounds from cosmology and $0\

  6. Electronic in-plane symmetry breaking at field-tuned quantum criticality in CeRhIn5

    Energy Technology Data Exchange (ETDEWEB)

    Helm, T. [MPI-CPFS (Germany); Bachmann, M. [MPI-CPFS (Germany); Moll, P.J.W. [MPI-CPFS (Germany); Balicas, L. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States). National High Magnetic Field Lab. (MagLab); Chan, Mun Keat [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Ramshaw, Brad [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Mcdonald, Ross David [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Balakirev, Fedor Fedorovich [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Bauer, Eric Dietzgen [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Ronning, Filip [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-03-23

    Electronic nematicity appears in proximity to unconventional high-temperature superconductivity in the cuprates and iron-arsenides, yet whether they cooperate or compete is widely discussed. While many parallels are drawn between high-Tc and heavy fermion superconductors, electronic nematicity was not believed to be an important aspect in their superconductivity. We have found evidence for a field-induced strong electronic in-plane symmetry breaking in the tetragonal heavy fermion superconductor CeRhIn5. At ambient pressure and zero field, it hosts an anti-ferromagnetic order (AFM) of nominally localized 4f electrons at TN=3.8K(1). Moderate pressure of 17kBar suppresses the AFM order and a dome of superconductivity appears around the quantum critical point. Similarly, a density-wave-like correlated phase appears centered around the field-induced AFM quantum critical point. In this phase, we have now observed electronic nematic behavior.

  7. Theories of Electroweak Symmetry Breaking : A Post LHC Run-I Perspective (1/3)

    CERN Multimedia

    CERN. Geneva

    2015-01-01

    Lecture 1 : The Brout-Englert-Higgs Theory of Electroweak Symmetry Breaking The goal of this lecture is to put the discovery of the Higgs boson in historical context and qualitatively discuss the importance and meaning of its discovery. Claims that the BEH theory has its roots in the theory developments of superconductivity will be considered. Viability of the theory from several points of view will be assessed. First, has the theory been established yet as correct? Second, is the theory stable to vacuum fluctuations? And finally, is the theory natural?

  8. Light bullets in waveguide arrays: spacetime-coupling, spectral symmetry breaking and superluminal decay [Invited].

    Science.gov (United States)

    Eilenberger, Falk; Minardi, Stefano; Szameit, Alexander; Röpke, Ulrich; Kobelke, Jens; Schuster, Kay; Bartelt, Hartmut; Nolte, Stefan; Tünnermann, Andreas; Pertsch, Thomas

    2011-11-07

    We investigate the effects of the space-time coupling (STC) on the nonlinear formation and propagation of Light Bullets, spatiotemporal solitons in which dispersion and diffraction along all dimensions are balanced by nonlinearity, through periodic media with a weak transverse modulation of the refractive index, i.e. waveguide arrays. The STC arises from wavelength dependence of the strength of inter-waveguide coupling and can be tuned by variation of the array geometry. We show experimentally and numerically that the STC breaks the spectral symmetry of Light Bullets to a considerable degree and modifies their group velocity, leading to superluminal propagation when the Light Bullets decay.

  9. Symmetry breaking perturbative flows to retrieve resonant modes in plane shear layers

    CERN Document Server

    Akinaga, Takeshi; Generalis, Sotos

    2015-01-01

    We propose a simple computational procedure in order to resolve the degeneracy, which invariably exists on the background of fluid motion associated with a channel of infinite extent. The procedure is applied to elucidate the bifurcation structure for the particular case of laterally heated flow with the addition of a perturbative Poiseuille flow component. The introduction of a symmetry breaking perturbation as the simplest imperfection alters the bifurcation tree of the original shear flow. As a result, the previously unknown higher order nonlinear solutions for the unperturbed flow are discovered, without implementing classical stability theory.

  10. Hybrid dynamical electroweak symmetry breaking with heavy quarks and the 125 GeV Higgs

    OpenAIRE

    Geller, Michael; Bar-Shalom, Shaouly; Soni, Amarjit

    2013-01-01

    Existing models of dynamical electroweak symmetry breaking (EWSB) find it very difficult to get a Higgs of mass lighter than $m_t$. Consequently, in light of the LHC discovery of the ~125 GeV Higgs, such models face a significant obstacle. Moreover, with three generations those models have a superheavy cut-off around $10^{17}$ GeV, requiring a significant fine-tuning. To overcome these twin difficulties, we propose a hybrid framework for EWSB, in which the Higgs mechanism is combined with a N...

  11. Shock wave evolution and discontinuity propagation for relativistic superfluid hydrodynamics with spontaneous symmetry breaking

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Sun, E-mail: szhang@pmo.ac.cn [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China); Key Laboratory of Dark Matter and Space Astronomy, Chinese Academy of Sciences, Nanjing 210008 (China); Joint Center for Particle, Nuclear Physics and Cosmology (J-CPNPC), PMO-NJU, Nanjing 210008 (China)

    2014-02-05

    In this Letter, we have studied the shock wave and discontinuity propagation for relativistic superfluid with spontaneous U(1) symmetry breaking in the framework of hydrodynamics. General features of shock waves are provided, the propagation of discontinuity and the sound modes of shock waves are also presented. The first sound and the second sound are identified as the propagation of discontinuity, and the results are in agreement with earlier theoretical studies. Moreover, a differential equation, called the growth equation, is obtained to describe the decay and growth of the discontinuity propagating along its normal trajectory. The solution is in an integral form and special cases of diverging waves are also discussed.

  12. Radiative symmetry breaking from flat potential in various U(1)' models

    Science.gov (United States)

    Hashimoto, Michio; Iso, Satoshi; Orikasa, Yuta

    2014-03-01

    We investigate a radiative electroweak gauge symmetry breaking scenario via the Coleman-Weinberg mechanism starting from a completely flat Higgs potential at the Planck scale ("flatland scenario"). In our previous paper, we showed that the flatland scenario is possible only when an inequality K <1 among the coefficients of the β functions is satisfied. In this paper, we calculate the number K in various models with an extra U(1) gauge sector in addition to the standard model particles. We also show the renormalization group behaviors of a couple of the models as examples.

  13. Symmetry breaking and uniqueness for the incompressible Navier-Stokes equations

    Energy Technology Data Exchange (ETDEWEB)

    Dascaliuc, Radu; Thomann, Enrique; Waymire, Edward C., E-mail: waymire@math.oregonstate.edu [Department of Mathematics, Oregon State University, Corvallis, Oregon 97331 (United States); Michalowski, Nicholas [Department of Mathematics, New Mexico State University, Las Cruces, New Mexico 88003 (United States)

    2015-07-15

    The present article establishes connections between the structure of the deterministic Navier-Stokes equations and the structure of (similarity) equations that govern self-similar solutions as expected values of certain naturally associated stochastic cascades. A principle result is that explosion criteria for the stochastic cascades involved in the probabilistic representations of solutions to the respective equations coincide. While the uniqueness problem itself remains unresolved, these connections provide interesting problems and possible methods for investigating symmetry breaking and the uniqueness problem for Navier-Stokes equations. In particular, new branching Markov chains, including a dilogarithmic branching random walk on the multiplicative group (0, ∞), naturally arise as a result of this investigation.

  14. Symmetry breaking and uniqueness for the incompressible Navier-Stokes equations

    Science.gov (United States)

    Dascaliuc, Radu; Michalowski, Nicholas; Thomann, Enrique; Waymire, Edward C.

    2015-07-01

    The present article establishes connections between the structure of the deterministic Navier-Stokes equations and the structure of (similarity) equations that govern self-similar solutions as expected values of certain naturally associated stochastic cascades. A principle result is that explosion criteria for the stochastic cascades involved in the probabilistic representations of solutions to the respective equations coincide. While the uniqueness problem itself remains unresolved, these connections provide interesting problems and possible methods for investigating symmetry breaking and the uniqueness problem for Navier-Stokes equations. In particular, new branching Markov chains, including a dilogarithmic branching random walk on the multiplicative group (0, ∞), naturally arise as a result of this investigation.

  15. Symmetry-breaking for a restricted n-body problem in the Maxwell-ring configuration

    Science.gov (United States)

    Calleja, Renato; Doedel, Eusebius; García-Azpeitia, Carlos

    2016-11-01

    We investigate the motion of a massless body interacting with the Maxwell relative equilibrium, which consists of n bodies of equal mass at the vertices of a regular polygon that rotates around a central mass. The massless body has three equilibrium ℤn-orbits from which families of Lyapunov orbits emerge. Numerical continuation of these families using a boundary value formulation is used to construct the bifurcation diagram for the case n = 7, also including some secondary and tertiary bifurcating families. We observe symmetry-breaking bifurcations in this system, as well as certain period-doubling bifurcations.

  16. New Calculation of the Isospin-Symmetry Breaking Correction to Superallowed Fermi Beta Decay

    Science.gov (United States)

    Towner, I. S.; Hardy, J. C.

    2009-01-01

    We report new shell-model calculations of the isospin-symmetry-breaking correction, δC, to superallowed Fermi β decay. The most important improvement is the inclusion of core orbitals, which are demonstrated to have a significant impact on the mismatch in the radial wave functions of the parent and daughter states. These new calculations lead to a lower average corrected 𝓕t value and a higher value for Vud. The sum of the squares of the top-row elements of the CKM matrix agrees with unitarity.

  17. Comparative tests of isospin-symmetry-breaking corrections to superallowed 0+→0+ nuclear β decay

    Science.gov (United States)

    Towner, I. S.; Hardy, J. C.

    2010-12-01

    We present a test with which to evaluate the calculated isospin-symmetry-breaking corrections to superallowed 0+→0+ nuclear β decay. The test is based on the corrected experimental Ft values being required to satisfy conservation of the vector current (CVC). When applied to six sets of published calculations, the test demonstrates quantitatively that only one set, the one based on the shell model with Saxon-Woods radial wave functions, provides satisfactory agreement with CVC. This test can easily be applied to any sets of calculated correction terms that are produced in future.

  18. Charge independence, charge symmetry breaking in the S-wave nucleon-nucleon interaction, and renormalization

    Energy Technology Data Exchange (ETDEWEB)

    Alvaro Calle Cordon,Manuel Pavon Valderrama,Enrique Ruiz Arriola

    2012-02-01

    We study the interplay between charge symmetry breaking and renormalization in the NN system for S-waves. We find a set of universality relations which disentangle explicitly the known long distance dynamics from low energy parameters and extend them to the Coulomb case. We analyze within such an approach the One-Boson-Exchange potential and the theoretical conditions which allow to relate the proton-neutron, proton-proton and neutron-neutron scattering observables without the introduction of extra new parameters and providing good phenomenological success.

  19. Spontaneous Symmetry Breaking and Strong Deformations in Metal Adsorbed Graphene Sheets

    CERN Document Server

    Jalbout, A F; Seligman, T H

    2013-01-01

    We study the adsorption of Li to graphene flakes described as aromatic molecules. Surprisingly the out of plane deformation is much stronger for the double adsorption from both sides to the same ring than for a single adsorption, although a symmetric solution seems possible. We thus have an interesting case of spontaneous symmetry breaking. While we cannot rule out a Jahn Teller deformation with certainty, this explanation seems unlikely and other options are discussed. We find a similar behavior for Boron-Nitrogen sheets, and also for other light alkalines.

  20. Imaging dynamical chiral-symmetry breaking: pion wave function on the light front.

    Science.gov (United States)

    Chang, Lei; Cloët, I C; Cobos-Martinez, J J; Roberts, C D; Schmidt, S M; Tandy, P C

    2013-03-29

    We project onto the light front the pion's Poincaré-covariant Bethe-Salpeter wave function obtained using two different approximations to the kernels of quantum chromodynamics' Dyson-Schwinger equations. At an hadronic scale, both computed results are concave and significantly broader than the asymptotic distribution amplitude, φ(π)(asy)(x)=6x(1-x); e.g., the integral of φ(π)(x)/φ(π)(asy)(x) is 1.8 using the simplest kernel and 1.5 with the more sophisticated kernel. Independent of the kernels, the emergent phenomenon of dynamical chiral-symmetry breaking is responsible for hardening the amplitude.

  1. Universality in random matrix theory and chiral symmetry breaking in QCD

    Energy Technology Data Exchange (ETDEWEB)

    Akemann, G.

    2000-05-01

    In this work we review the topic of random matrix model universality with particular stress on its application to the study of chiral symmetry breaking in QCD. We highlight the role of microscopic and macroscopic matrix model correlation functions played in the description of the deep infrared eigenvalue spectrum of the Dirac operator. The universal microscopic correlation functions are presented for all three chiral symmetry breaking patterns, and the corresponding random matrix universality proofs are given for massless and massive fermions in a unified way. These analytic results have been widely confirmed from QCD lattice data and we present a comparison with the most recent analytic calculations describing data for dynamical SU(2) staggered fermions. The microscopic matrix model results are then re-expressed in terms of the finite-volume partition functions of Leutwyler and Smilga, where some of these expressions have been recently obtained using field theory only. The macroscopic random matrix universality is reviewed for the most simplest examples of bosonic and supersymmetric models. We also give an example for a non-universal deformation of a random matrix model - the restricted trace ensemble. (orig.)

  2. TYPE Ia SUPERNOVAE: CAN CORIOLIS FORCE BREAK THE SYMMETRY OF THE GRAVITATIONAL CONFINED DETONATION EXPLOSION MECHANISM?

    Energy Technology Data Exchange (ETDEWEB)

    García-Senz, D. [Departament de Física, UPC, Comte d’Urgell 187, E-08036 Barcelona (Spain); Cabezón, R. M.; Thielemann, F. K. [Departement Physik, Universität Basel. Klingelbergstrasse, 82, 4056 Basel (Switzerland); Domínguez, I., E-mail: domingo.garcia@upc.edu, E-mail: ruben.cabezon@unibas.ch [Departamento de Física, Teórica y del Cosmos, Universidad de Granada, E-18071 Granada (Spain)

    2016-03-10

    Currently the number of models aimed at explaining the phenomena of type Ia supernovae is high and distinguishing between them is a must. In this work we explore the influence of rotation on the evolution of the nuclear flame that drives the explosion in the so-called gravitational confined detonation models. Assuming that the flame starts in a pointlike region slightly above the center of the white dwarf (WD) and adding a moderate amount of angular velocity to the star we follow the evolution of the deflagration using a smoothed particle hydrodynamics code. We find that the results are very dependent on the angle between the rotational axis and the line connecting the initial bubble of burned material with the center of the WD at the moment of ignition. The impact of rotation is larger for angles close to 90° because the Coriolis force on a floating element of fluid is maximum and its principal effect is to break the symmetry of the deflagration. Such symmetry breaking weakens the convergence of the nuclear flame at the antipodes of the initial ignition volume, changing the environmental conditions around the convergence region with respect to non-rotating models. These changes seem to disfavor the emergence of a detonation in the compressed volume at the antipodes and may compromise the viability of the so-called gravitational confined detonation mechanism.

  3. Dirac mass generation from crystal symmetry breaking on the surfaces of topological crystalline insulators.

    Science.gov (United States)

    Zeljkovic, Ilija; Okada, Yoshinori; Serbyn, Maksym; Sankar, R; Walkup, Daniel; Zhou, Wenwen; Liu, Junwei; Chang, Guoqing; Wang, Yung Jui; Hasan, M Zahid; Chou, Fangcheng; Lin, Hsin; Bansil, Arun; Fu, Liang; Madhavan, Vidya

    2015-03-01

    The tunability of topological surface states and controllable opening of the Dirac gap are of fundamental and practical interest in the field of topological materials. In the newly discovered topological crystalline insulators (TCIs), theory predicts that the Dirac node is protected by a crystalline symmetry and that the surface state electrons can acquire a mass if this symmetry is broken. Recent studies have detected signatures of a spontaneously generated Dirac gap in TCIs; however, the mechanism of mass formation remains elusive. In this work, we present scanning tunnelling microscopy (STM) measurements of the TCI Pb1-xSnxSe for a wide range of alloy compositions spanning the topological and non-topological regimes. The STM topographies reveal a symmetry-breaking distortion on the surface, which imparts mass to the otherwise massless Dirac electrons-a mechanism analogous to the long sought-after Higgs mechanism in particle physics. Interestingly, the measured Dirac gap decreases on approaching the trivial phase, whereas the magnitude of the distortion remains nearly constant. Our data and calculations reveal that the penetration depth of Dirac surface states controls the magnitude of the Dirac mass. At the limit of the critical composition, the penetration depth is predicted to go to infinity, resulting in zero mass, consistent with our measurements. Finally, we discover the existence of surface states in the non-topological regime, which have the characteristics of gapped, double-branched Dirac fermions and could be exploited in realizing superconductivity in these materials.

  4. Spontaneous symmetry breaking, and strings defects in hypercomplex gauge field theories

    Energy Technology Data Exchange (ETDEWEB)

    Cartas-Fuentevilla, R. [Universidad Autonoma de Puebla, Instituto de Fisica, Puebla, Pue. (Mexico); Meza-Aldama, O. [Universidad Autonoma de Puebla, Facultad de Ciencias Fisico-Matematicas, Puebla, Pue. (Mexico)

    2016-02-15

    Inspired by the appearance of split-complex structures in the dimensional reduction of string theory, and in the theories emerging as byproducts, we study the hypercomplex formulation of Abelian gauge field theories by incorporating a new complex unit to the usual complex one. The hypercomplex version of the traditional Mexican hat potential associated with the U(1) gauge field theory, corresponds to a hybrid potential with two real components, and with U(1) x SO(1,1) as symmetry group. Each component corresponds to a deformation of the hat potential, with the appearance of a new degenerate vacuum. Hypercomplex electrodynamics will show novel properties, such as spontaneous symmetry breaking scenarios with running masses for the vectorial and scalar Higgs fields, and such as Aharonov-Bohm type strings defects as exact solutions; these topological defects may be detected only by quantum interference of charged particles through gauge invariant loop integrals. In a particular limit, the hyperbolic electrodynamics does not admit topological defects associated with continuous symmetries. (orig.)

  5. Rotational symmetry breaking in the topological superconductor SrxBi2Se3 probed by upper-critical field experiments.

    Science.gov (United States)

    Pan, Y; Nikitin, A M; Araizi, G K; Huang, Y K; Matsushita, Y; Naka, T; de Visser, A

    2016-06-28

    Recently it was demonstrated that Sr intercalation provides a new route to induce superconductivity in the topological insulator Bi2Se3. Topological superconductors are predicted to be unconventional with an odd-parity pairing symmetry. An adequate probe to test for unconventional superconductivity is the upper critical field, Bc2. For a standard BCS layered superconductor Bc2 shows an anisotropy when the magnetic field is applied parallel and perpendicular to the layers, but is isotropic when the field is rotated in the plane of the layers. Here we report measurements of the upper critical field of superconducting SrxBi2Se3 crystals (Tc = 3.0 K). Surprisingly, field-angle dependent magnetotransport measurements reveal a large anisotropy of Bc2 when the magnet field is rotated in the basal plane. The large two-fold anisotropy, while six-fold is anticipated, cannot be explained with the Ginzburg-Landau anisotropic effective mass model or flux flow induced by the Lorentz force. The rotational symmetry breaking of Bc2 indicates unconventional superconductivity with odd-parity spin-triplet Cooper pairs (Δ4-pairing) recently proposed for rhombohedral topological superconductors, or might have a structural nature, such as self-organized stripe ordering of Sr atoms.

  6. Epithelial rotation is preceded by planar symmetry breaking of actomyosin and protects epithelial tissue from cell deformations.

    Directory of Open Access Journals (Sweden)

    Ivana Viktorinová

    2017-11-01

    Full Text Available Symmetry breaking is involved in many developmental processes that form bodies and organs. One of them is the epithelial rotation of developing tubular and acinar organs. However, how epithelial cells move, how they break symmetry to define their common direction, and what function rotational epithelial motions have remains elusive. Here, we identify a dynamic actomyosin network that breaks symmetry at the basal surface of the Drosophila follicle epithelium of acinar-like primitive organs, called egg chambers, and may represent a candidate force-generation mechanism that underlies the unidirectional motion of this epithelial tissue. We provide evidence that the atypical cadherin Fat2, a key planar cell polarity regulator in Drosophila oogenesis, directs and orchestrates transmission of the intracellular actomyosin asymmetry cue onto a tissue plane in order to break planar actomyosin symmetry, facilitate epithelial rotation in the opposite direction, and direct the elongation of follicle cells. In contrast, loss of this rotational motion results in anisotropic non-muscle Myosin II pulses that are disorganized in plane and causes cell deformations in the epithelial tissue of Drosophila eggs. Our work demonstrates that atypical cadherins play an important role in the control of symmetry breaking of cellular mechanics in order to facilitate tissue motion and model epithelial tissue. We propose that their functions may be evolutionarily conserved in tubular/acinar vertebrate organs.

  7. Epithelial rotation is preceded by planar symmetry breaking of actomyosin and protects epithelial tissue from cell deformations.

    Science.gov (United States)

    Viktorinová, Ivana; Henry, Ian; Tomancak, Pavel

    2017-11-01

    Symmetry breaking is involved in many developmental processes that form bodies and organs. One of them is the epithelial rotation of developing tubular and acinar organs. However, how epithelial cells move, how they break symmetry to define their common direction, and what function rotational epithelial motions have remains elusive. Here, we identify a dynamic actomyosin network that breaks symmetry at the basal surface of the Drosophila follicle epithelium of acinar-like primitive organs, called egg chambers, and may represent a candidate force-generation mechanism that underlies the unidirectional motion of this epithelial tissue. We provide evidence that the atypical cadherin Fat2, a key planar cell polarity regulator in Drosophila oogenesis, directs and orchestrates transmission of the intracellular actomyosin asymmetry cue onto a tissue plane in order to break planar actomyosin symmetry, facilitate epithelial rotation in the opposite direction, and direct the elongation of follicle cells. In contrast, loss of this rotational motion results in anisotropic non-muscle Myosin II pulses that are disorganized in plane and causes cell deformations in the epithelial tissue of Drosophila eggs. Our work demonstrates that atypical cadherins play an important role in the control of symmetry breaking of cellular mechanics in order to facilitate tissue motion and model epithelial tissue. We propose that their functions may be evolutionarily conserved in tubular/acinar vertebrate organs.

  8. Photonic ferromagnetic-like spontaneous mode-locking phase transition with replica symmetry breaking in multimode Nd:YAG laser

    CERN Document Server

    Moura, André L; Raposo, Ernesto P; Gomes, Anderson S L; de Araújo, Cid B

    2016-01-01

    The recent reports of the replica symmetry breaking (RSB) phenomenon in photonic experiments [1-5] boosted the understanding of the role of disorder in multimode lasers, as well as helped to settle enlightening connections [6-13] with the statistical physics of complex systems. RSB manifests when identically-prepared system replicas reach distinct states, yielding different measures of observable quantities [14]. Here we demonstrate the RSB in the spontaneous mode-locking regime of a conventional multimode Nd:YAG laser in a closed cavity. The underlying mechanism is quite distinct from that of the RSB spinglass phase in cavityless random lasers with incoherently-oscillating modes. Here, a specific nonuniform distribution of the gain takes place in each pulse, and frustration is induced since the coherent oscillation of a given subset of longitudinal modes dominates and simultaneously inhibits the others. Nevertheless, when high losses are introduced only the replica-symmetric amplified stimulation emission is...

  9. On the harmonic-type and linear-type confinement of a relativistic scalar particle yielded by Lorentz symmetry breaking effects

    Energy Technology Data Exchange (ETDEWEB)

    Bakke, K., E-mail: kbakke@fisica.ufpb.br [Departamento de Física, Universidade Federal da Paraíba, Caixa Postal 5008, 58051-900, João Pessoa-PB (Brazil); Belich, H., E-mail: belichjr@gmail.com [Departamento de Física e Química, Universidade Federal do Espírito Santo, Av. Fernando Ferrari, 514, Goiabeiras, 29060-900, Vitória, ES (Brazil)

    2016-10-15

    Based on the Standard Model Extension, we investigate relativistic quantum effects on a scalar particle in backgrounds of the Lorentz symmetry violation defined by a tensor field. We show that harmonic-type and linear-type confining potentials can stem from Lorentz symmetry breaking effects, and thus, relativistic bound state solutions can be achieved. We first analyse a possible scenario of the violation of the Lorentz symmetry that gives rise to a harmonic-type potential. In the following, we analyse another possible scenario of the breaking of the Lorentz symmetry that induces both harmonic-type and linear-type confining potentials. In this second case, we also show that not all values of the parameter associated with the intensity of the electric field are permitted in the search for polynomial solutions to the radial equation, where the possible values of this parameter are determined by the quantum numbers of the system and the parameters associated with the violation of the Lorentz symmetry.

  10. Symmetry Breaking in the Supramolecular Gels of an Achiral Gelator Exclusively Driven by π-π Stacking.

    Science.gov (United States)

    Shen, Zhaocun; Jiang, Yuqian; Wang, Tianyu; Liu, Minghua

    2015-12-30

    Supramolecular symmetry breaking, in which chiral assemblies with imbalanced right- and left-handedness emerge from achiral molecular building blocks, has been achieved in the organogels of a C3-symmetric molecule only via π-π stacking. Specifically, an achiral C3-symmetric benzene-1,3,5-tricarboxylate substituted with methyl cinnamate through ester bond was found to form organogels in various organic solvents. More interestingly, when gels formed in cyclohexane, symmetry breaking occurred; i.e., optically active organogels together with the helical nanofibers with predominant handedness were obtained. Furthermore, the stochastically appeared imbalanced helicity could be driven to desired handedness by utilizing slight chiral solvents such as (R)- or (S)-terpinen-4-ol. Remarkably, the handedness of supramolecular assemblies thus formed could be kept even when the chiral solvents were removed. For the first time, we show that symmetry breaking can occur in supramolecular gel system driven exclusively through π-π stacking.

  11. Relation between PT -symmetry breaking and topologically nontrivial phases in the Su-Schrieffer-Heeger and Kitaev models

    Science.gov (United States)

    Klett, Marcel; Cartarius, Holger; Dast, Dennis; Main, Jörg; Wunner, Günter

    2017-05-01

    Non-Hermitian systems with PT symmetry can possess purely real eigenvalue spectra. In this work two one-dimensional systems with two different topological phases, the topological nontrivial phase (TNP) and the topological trivial phase (TTP), combined with PT -symmetric non-Hermitian potentials are investigated. The models of choice are the Su-Schrieffer-Heeger (SSH) model and the Kitaev chain. The interplay of a spontaneous PT -symmetry breaking due to gain and loss with the topological phase is different for the two models. The SSH model undergoes a PT -symmetry breaking transition in the TNP immediately with the presence of a nonvanishing gain and loss strength γ , whereas the TTP exhibits a parameter regime in which a purely real eigenvalue spectrum exists. For the Kitaev chain the PT -symmetry breaking is independent of the topological phase. We show that the topologically interesting states—the edge states—are the reason for the different behaviors of the two models and that the intrinsic particle-hole symmetry of the edge states in the Kitaev chain is responsible for a conservation of PT symmetry in the TNP.

  12. Optical probes of symmetry breaking in magnetic and superconducting BaFe2(As1-xPx)2

    Science.gov (United States)

    Orenstein, Joseph

    The discovery of iron pnictide superconductors has opened promising new directions in the effort to fully understand the phenomenon of high-Tc, with a focus on the connections between superconductivity, magnetism, and electronic nematicity. The BaFe2(As1-xPx)2 (P:Ba122) system in particular has received attention because isovalent substitution of As for P generates less disorder than doping on the Fe site. The phase diagram of P:Ba122 is characterized by a line of simultaneous antiferromagnetic (AF) and tetragonal-to-orthorhombic transitions, Ts (x) , that penetrates the superconducting dome at x =0.28, just below optimal doping (xopt = 0.30). In this work, we use spatially-resolved optical polarimetry and photomodulated reflectance to detect linear birefringence and therefore breaking of 4-fold rotational (C4) symmetry. In underdoped (xTsand grows continuously with decreasing T . The birefringence is unidirectional in a large (300 μm x300 μm) field of view, suggesting that C4 breaking in this range of T is caused by residual strain that couples to a diverging nematic susceptibility. Birefringence maps just below Ts (x) show the appearance of domains, indicating the onset of spontaneous symmetry breaking to an AF ground state. Surprisingly, in samples with x>0.28, in which the low T phase is superconducting/ tetragonal rather than AF/orthorhombic, C4 breaking is observed as well, with an abrupt onset and domain formation at 55 K. We tentatively associate these features with a transition to an AF phase induced by residual strain, as previously proposed [H.-H. Kuo et al. Phys. Rev. B86, 134507 (2012)] to account for structure in resistivity vs. T. Time-resolved photomodulation allow us to follow the amplitude of the AF order with time following pulsed photoexcitation. Below Tc the AF order at first weakens , but then strengthens in response to the photoinduced weakening of superconductivity. This complex time evolution is accounted for quantitatively by a model

  13. Effect of Lorentz symmetry breaking on the deflection of light in a cosmic string spacetime

    Science.gov (United States)

    Kimet, Jusufi; Izzet, Sakallı; Ali, Övgün

    2017-07-01

    We investigate the Lorentz symmetry breaking effects (LSBE) on the deflection of light by a rotating cosmic string spacetime in the weak limit approximation. We first calculate the deflection angle by a static cosmic string for a fixed spacelike 4-vector case (FSL) with the corresponding effective-string optical metric using the Gauss-Bonnet theorem (GBT). Then, we focus on a more general scenario, namely we calculate the deflection angle by a rotating cosmic string applying the GBT to Randers effective-string metric. We obtain a significant modification in the deflection angle because of the LSBE parameter. We find first and second order correction terms due to the global effective topology which are proportional to the cosmic string and LSBE parameter, respectively. Finally, for a fixed time-like 4-vector (FTL) case, we show that the deflection angle is not affected by LSBE parameter.

  14. Sequence selection by dynamical symmetry breaking in an autocatalytic binary polymer model

    Science.gov (United States)

    Fellermann, Harold; Tanaka, Shinpei; Rasmussen, Steen

    2017-12-01

    Template-directed replication of nucleic acids is at the essence of all living beings and a major milestone for any origin of life scenario. We present an idealized model of prebiotic sequence replication, where binary polymers act as templates for their autocatalytic replication, thereby serving as each others reactants and products in an intertwined molecular ecology. Our model demonstrates how autocatalysis alters the qualitative and quantitative system dynamics in counterintuitive ways. Most notably, numerical simulations reveal a very strong intrinsic selection mechanism that favors the appearance of a few population structures with highly ordered and repetitive sequence patterns when starting from a pool of monomers. We demonstrate both analytically and through simulation how this "selection of the dullest" is caused by continued symmetry breaking through random fluctuations in the transient dynamics that are amplified by autocatalysis and eventually propagate to the population level. The impact of these observations on related prebiotic mathematical models is discussed.

  15. Nonreciprocal transmission in a photonic-crystal Fano structure enabled by symmetry breaking

    CERN Document Server

    Yu, Yi; Hu, Hao; Xue, Weiqi; Yvind, Kresten; Mørk, Jesper

    2014-01-01

    Nanostructures that feature nonreciprocal light transmission are highly desirable building blocks for realizing photonic integrated circuits. Here, a simple and ultra-compact photonic-crystal structure, where a waveguide is coupled to a single nanocavity, is proposed and experimentally demonstrated, showing very efficient optical diode functionality. The key novelty of the structure is the use of a Fano resonance in combination with spatial symmetry breaking and cavity enhanced material nonlinearities to realize non-reciprocal propagation effects at ultra-low power and with a good wavelength tunability. The nonlinearity of the device relies on ultrafast carrier dynamics, rather than the thermal effects usually considered, allowing the demonstration of nonreciprocal operation at a bit-rate of 10 Gbit/s with a low energy consumption of 4.5 fJ/bit.

  16. Accretion of a symmetry-breaking scalar field by a Schwarzschild black hole.

    Science.gov (United States)

    Traykova, Dina; Braden, Jonathan; Peiris, Hiranya V

    2018-03-06

    We simulate the behaviour of a Higgs-like field in the vicinity of a Schwarzschild black hole using a highly accurate numerical framework. We consider both the limit of the zero-temperature Higgs potential and a toy model for the time-dependent evolution of the potential when immersed in a slowly cooling radiation bath. Through these numerical investigations, we aim to improve our understanding of the non-equilibrium dynamics of a symmetry-breaking field (such as the Higgs) in the vicinity of a compact object such as a black hole. Understanding this dynamics may suggest new approaches for studying properties of scalar fields using black holes as a laboratory.This article is part of the Theo Murphy meeting issue 'Higgs Cosmology'. © 2018 The Author(s).

  17. Chiral symmetry breaking during the self-assembly of monolayers from achiral purine molecules.

    Science.gov (United States)

    Sowerby, S J; Heckl, W M; Petersen, G B

    1996-11-01

    Scanning tunneling microscopy was used to investigate the structure of the two-dimensional adsorbate formed by molecular self-assembly of the purine base, adenine, on the surfaces of the naturally occurring mineral molybdenite and the synthetic crystal highly oriented pyrolytic graphite. Although formed from adenine, which is achiral, the observed adsorbate surface structures were enantiomorphic on molybdenite. This phenomenon suggests a mechanism for the introduction of a localized chiral symmetry break by the spontaneous crystallization of these prebiotically available molecules on inorganic surfaces and may have some role in the origin of biomolecular optical asymmetry. The possibility that purine-pyrimidine arrays assembled on naturally occurring mineral surfaces might act as possible templates for biomolecular assembly is discussed.

  18. Recent Results from CMS and ATLAS: Electroweak Symmetry, Breaking and Beyond

    CERN Document Server

    Azzurri, Paolo

    2016-01-01

    The discovery of the Higgs boson, announced by the CMS and ATLAS collaborations in 2012, unearthed the final cornerstone of the standard electroweak model of particle physics, and repre- sents the main legacy of the LHC Run 1. With Run 1 data the mass of the Higgs boson has been determined with 0.2pct precision, while coupling properties are only established at the 10pct level or worse. As the picture of the minimal standard model is now complete, unsettled difficulties and open questions remain on its stage. The LHC Run 2 has successfully started in 2015, opening a new period of particle physics exploration, at higher energy and intensity it will undoubtedly de- liver more insight on the electroweak model, its symmetry breaking mechanism, and on possible solutions to its difficulties.

  19. Rencontres de Moriond EW 2012: Addressing symmetry breaking and mass hierarchy

    CERN Multimedia

    Pauline Gagnon

    2012-01-01

    Last Friday at the Moriond conference in La Thuile in Italy, Lisa Randall from Harvard University reminded the audience how all fields are related: electroweak symmetry breaking must take into account flavour physics for example. Every good model should address this intrinsic connection.   Despite many expectations, no signs for supersymmetry (SUSY) of any type has been found to date. So Lisa Randall worked with Csaba Csaki and John Terning to explore alternatives and developed a version of supersymmetry built on the Minimal Composite Supersymmetry Standard Model (MCSSM) that Csaki, Shirman, and Terning had developed, incorporating a strongly interacting theory with compositeness that addresses among other things the fact that the top quark is so much heavier than all other quarks. Randall and collaborators showed that this model, when supersymmetry is incorporated, naturally accommodates both a Higgs boson around 125 GeV and a light stop, the supersymmetric partner to the top quark. &a...

  20. Sequence selection by dynamical symmetry breaking in an autocatalytic binary polymer model

    DEFF Research Database (Denmark)

    Fellermann, Harold; Tanaka, Shinpei; Rasmussen, Steen

    2017-01-01

    as each others reactants and products in an intertwined molecular ecology. Our model demonstrates how autocatalysis alters the qualitative and quantitative system dynamics in counterintuitive ways. Most notably, numerical simulations reveal a very strong intrinsic selection mechanism that favors......Template-directed replication of nucleic acids is at the essence of all living beings and a major milestone for any origin of life scenario. We present an idealized model of prebiotic sequence replication, where binary polymers act as templates for their autocatalytic replication, thereby serving...... the appearance of a few population structures with highly ordered and repetitive sequence patterns when starting from a pool of monomers. We demonstrate both analytically and through simulation how this "selection of the dullest" is caused by continued symmetry breaking through random fluctuations...

  1. Accretion of a symmetry-breaking scalar field by a Schwarzschild black hole

    Science.gov (United States)

    Traykova, Dina; Braden, Jonathan; Peiris, Hiranya V.

    2018-01-01

    We simulate the behaviour of a Higgs-like field in the vicinity of a Schwarzschild black hole using a highly accurate numerical framework. We consider both the limit of the zero-temperature Higgs potential and a toy model for the time-dependent evolution of the potential when immersed in a slowly cooling radiation bath. Through these numerical investigations, we aim to improve our understanding of the non-equilibrium dynamics of a symmetry-breaking field (such as the Higgs) in the vicinity of a compact object such as a black hole. Understanding this dynamics may suggest new approaches for studying properties of scalar fields using black holes as a laboratory. This article is part of the Theo Murphy meeting issue `Higgs Cosmology'.

  2. Breaking the symmetry. The first steps of a new way of thinking

    CERN Document Server

    Sardella, Ignazio A

    2010-01-01

    The concept of Spontaneous Symmetry Breaking (SSB) represents a real breakthrough for present description of fundamental interactions by means of gauge theories. Although the underlying ideas were ancient, their formalization required a long time, due to epistemological obstacles and technical difficulties. In this paper, the main steps of SSB evolution are briefly outlined, from the introduction of the order parameter in the Thirties to the birth of the many-body theory at the end of the Fifties. In this context, the contribute of the capital L.Landau's works on phase transitions and quantum fluids, as well as of the seminal ideas of F. London, is highlighted, and the phenomenological approach in theoretical physics (whose features are schematically underlined) is showed to be crucial in the rising field of complex systems.

  3. Symmetry-breaking phase transition without a Peierls instability in conducting monoatomic chains.

    Science.gov (United States)

    Blumenstein, C; Schäfer, J; Morresi, M; Mietke, S; Matzdorf, R; Claessen, R

    2011-10-14

    The one-dimensional (1D) model system Au/Ge(001), consisting of linear chains of single atoms on a surface, is scrutinized for lattice instabilities predicted in the Peierls paradigm. By scanning tunneling microscopy and electron diffraction we reveal a second-order phase transition at 585 K. It leads to charge ordering with transversal and vertical displacements and complex interchain correlations. However, the structural phase transition is not accompanied by the electronic signatures of a charge density wave, thus precluding a Peierls instability as origin. Instead, this symmetry-breaking transition exhibits three-dimensional critical behavior. This reflects a dichotomy between the decoupled 1D electron system and the structural elements that interact via the substrate. Such substrate-mediated coupling between the wires thus appears to have been underestimated also in related chain systems.

  4. Origin of maximal symmetry breaking in even PT-symmetric lattices

    Energy Technology Data Exchange (ETDEWEB)

    Joglekar, Yogesh N.; Barnett, Jacob L. [Department of Physics, Indiana University Purdue University Indianapolis (IUPUI), Indianapolis, Indiana 46202 (United States)

    2011-08-15

    By investigating a parity- and time-reversal- (PT-) symmetric, N-site lattice with impurities {+-}i{gamma} and hopping amplitudes t{sub 0} (t{sub b}) for regions outside (between) the impurity locations, we probe the interimpurity-distance dependence of the critical impurity strength and the origin of maximal PT-symmetry breaking that occurs when the impurities are nearest neighbors. Through a simple and exact derivation, we prove that the critical impurity strength is equal to the hopping amplitude between the impurities, {gamma}{sub c}=t{sub b}, and the simultaneous emergence of N complex eigenvalues is a robust feature of any PT-symmetric hopping profile. Our results show that the threshold strength {gamma}{sub c} can be widely tuned by a small change in the global profile of the lattice and thus have experimental implications.

  5. Quantum gases. Critical dynamics of spontaneous symmetry breaking in a homogeneous Bose gas.

    Science.gov (United States)

    Navon, Nir; Gaunt, Alexander L; Smith, Robert P; Hadzibabic, Zoran

    2015-01-09

    Kibble-Zurek theory models the dynamics of spontaneous symmetry breaking, which plays an important role in a wide variety of physical contexts, ranging from cosmology to superconductors. We explored these dynamics in a homogeneous system by thermally quenching an atomic gas with short-range interactions through the Bose-Einstein phase transition. Using homodyne matter-wave interferometry to measure first-order correlation functions, we verified the central quantitative prediction of the Kibble-Zurek theory, namely the homogeneous-system power-law scaling of the coherence length with the quench rate. Moreover, we directly confirmed its underlying hypothesis, the freezing of the correlation length near the transition. Our measurements agree with a beyond-mean-field theory and support the expectation that the dynamical critical exponent for this universality class is z = 3/2. Copyright © 2015, American Association for the Advancement of Science.

  6. Critical dynamics of spontaneous symmetry breaking in a homogeneous Bose gas

    Science.gov (United States)

    Gaunt, Alexander; Navon, Nir; Smith, Robert; Hadzibabic, Zoran

    2015-05-01

    Kibble-Zurek theory models the dynamics of spontaneous symmetry breaking, which plays an important role in a wide variety of physical contexts, ranging from cosmology to superconductors. We explored these dynamics in a homogeneous system by thermally quenching an atomic gas with short-range interactions through the Bose-Einstein phase transition. Using homodyne matter-wave interferometry to measure first-order correlation functions, we verified the central quantitative prediction of the Kibble-Zurek theory, namely the homogeneous-system power-law scaling of the coherence length with the quench rate. Moreover, we directly confirmed its underlying hypothesis, the freezing of the correlation length near the transition. Our measurements agree with a beyond-mean-field theory and support the expectation that the dynamical critical exponent for this universality class is z=3/2.

  7. Sum rules for the spontaneous-chiral-symmetry-breaking parameters of quantum chromodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Craigie, N.S.; Stern, J.

    1982-11-01

    We discuss in the spirit of the work of Shifman, Vainshtein, and Zakharov (SVZ), sum rules involving current-current vacuum correlation functions, whose Wilson expansion start off with the operators q-barq or (q-barq)/sup 2/, and thus provide information about the chiral-symmetry-breaking parameters of QCD. We point out that under the type of crude approximations made by SVZ, a value of /sub vac/ = (250 MeV)/sup 3/ is obtained from one of these sum rules, in agreement with current expectations. Further, we show that a Borel-transformed version of the Weinberg sum rule for VV-AA current products seems only to make sense for an A/sub 1/ mass close to 1.3 GeV and it makes little sense with the current-algebra mass M/sub A/ = 2M. We also give an estimate for the chiral-symmetry-breaking parameters ..mu../sub 1/ /sup 6/ = 2/sub vac/, entering in the Weinberg sum rules, and ..mu../sub 2/ /sup 6/ = g/sup 2/<(q-bar/sub R/lambda/sup a/sigma/sub munu/q/sub L/) (q-bar/sub R/lambda/sup a/sigma/sup munu/q/sub L/)>/sub vac/, entering in a new sum rule we propose, involving antisymmetric tensor currents J = q-barsigma/sub munu/q.

  8. Modeling finite-volume effects and chiral symmetry breaking in two-flavor QCD thermodynamics

    Science.gov (United States)

    Klein, Bertram

    2017-11-01

    Finite-volume effects in Quantum Chromodynamics (QCD) have been a subject of much theoretical interest for more than two decades. They are in particular important for the analysis and interpretation of QCD simulations on a finite, discrete space-time lattice. Most of these effects are closely related to the phenomenon of spontaneous breaking of the chiral flavor symmetry and the emergence of pions as light Goldstone bosons. These long-range fluctuations are strongly affected by putting the system into a finite box, and an analysis with different methods can be organized according to the interplay between pion mass and box size. The finite volume also affects critical behavior at the chiral phase transition in QCD. In the present review, I will be mainly concerned with modeling such finite volume effects as they affect the thermodynamics of the chiral phase transition for two quark flavors. I review recent work on the analysis of finite-volume effects which makes use of the quark-meson model for dynamical chiral symmetry breaking. To account for the effects of critical long-range fluctuations close to the phase transition, most of the calculations have been performed using non-perturbative Renormalization Group (RG) methods. I give an overview over the application of these methods to a finite volume. The method, the model and the results are put into the context of related work in random matrix theory for very small volumes, chiral perturbation theory for larger volumes, and related methods and approaches. They are applied towards the analysis of finite-volume effects in lattice QCD simulations and their interpretation, mainly in the context of the chiral phase transition for two quark flavors.

  9. Relativistic Anandan quantum phase and the Aharonov–Casher effect under Lorentz symmetry breaking effects in the cosmic string spacetime

    Energy Technology Data Exchange (ETDEWEB)

    Bakke, K., E-mail: kbakke@fisica.ufpb.br [Departamento de Física, Universidade Federal da Paraíba, Caixa Postal 5008, 58051-900, João Pessoa-PB (Brazil); Furtado, C., E-mail: furtado@fisica.ufpb.br [Departamento de Física, Universidade Federal da Paraíba, Caixa Postal 5008, 58051-900, João Pessoa-PB (Brazil); Belich, H., E-mail: belichjr@gmail.com [Departamento de Física e Química, Universidade Federal do Espírito Santo, Av. Fernando Ferrari, 514, Goiabeiras, 29060-900, Vitória, ES (Brazil)

    2016-09-15

    From the modified Maxwell theory coupled to gravity, we establish a possible scenario of the violation of the Lorentz symmetry and write an effective metric for the cosmic string spacetime. Then, we investigate the arising of an analogue of the Anandan quantum phase for a relativistic Dirac neutral particle with a permanent magnetic dipole moment in the cosmic string spacetime under Lorentz symmetry breaking effects. Besides, we analyse the influence of the effects of the Lorentz symmetry violation and the topology of the defect on the Aharonov–Casher geometric quantum phase in the nonrelativistic limit.

  10. Relativistic Anandan quantum phase and the Aharonov-Casher effect under Lorentz symmetry breaking effects in the cosmic string spacetime

    Science.gov (United States)

    Bakke, K.; Furtado, C.; Belich, H.

    2016-09-01

    From the modified Maxwell theory coupled to gravity, we establish a possible scenario of the violation of the Lorentz symmetry and write an effective metric for the cosmic string spacetime. Then, we investigate the arising of an analogue of the Anandan quantum phase for a relativistic Dirac neutral particle with a permanent magnetic dipole moment in the cosmic string spacetime under Lorentz symmetry breaking effects. Besides, we analyse the influence of the effects of the Lorentz symmetry violation and the topology of the defect on the Aharonov-Casher geometric quantum phase in the nonrelativistic limit.

  11. Moving vortex phases, dynamical symmetry breaking, and jamming for vortices in honeycomb pinning arrays

    Energy Technology Data Exchange (ETDEWEB)

    Reichhardt, Charles [Los Alamos National Laboratory; Reichhardt, Cynthia [Los Alamos National Laboratory

    2008-01-01

    We show using numerical simulations that vortices in honeycomb pinning arrays can exhibit a remarkable variety of dynamical phases that are distinct from those found for triangular and square pinning arrays. In the honeycomb arrays, it is possible for the interstitial vortices to form dimer or higher n-mer states which have an additional orientational degree of freedom that can lead to the formation of vortex molecular crystals. For filling fractions where dimer states appear, a dynamical symmetry breaking can occur when the dimers flow in one of two possible alignment directions. This leads to transport in the direction transverse to the applied drive. We show that dimerization produces distinct types of moving phases which depend on the direction of the driving force with respect to the pinning lattice symmetry. When the dimers are driven along certain directions, a reorientation of the dimers can produce a jamming phenomenon which results in a strong enhancement in the critical depinning force. The jamming can also cause unusual effects such as an increase in the critical depinning force when the size of the pinning sites is reduced.

  12. Charge Symmetry Breaking In Neutron Proton Scattering To Deuteron And Neutral Pion Close To Threshold

    CERN Document Server

    Reitzner, S D

    2001-01-01

    The charge symmetry breaking (CSB) experiment using the CHARGEX facility and the SASP magnetic spectrometer at TRIUMF has measured the forward-backward scattering asymmetry (Afb) for np→dπ 0 at a neutron beam energy of 279.5 MeV. This reaction is sensitive to contributions not present in elastic scattering and therefore will complement previous measurements of CSB. Contributions to CSB in np→dπ 0 are predicted to be an order of magnitude greater than those found for elastic scattering. These contributions, which include η − π 0 and η′ − π0 mixing and the u - d quark mass difference in pion- nucleon scattering, are predicted to give values for Afb that range from (−35 to +60) × 10−4. A fb can be non-zero only if charge-symmetry is violated. Due to the nature of the observable and the realities of the experiment, Afb is obtained from a χ2 minimization procedure which compares data w...

  13. Symmetry Breaking in NMR Spectroscopy: The Elucidation of Hidden Molecular Rearrangement Processes

    Directory of Open Access Journals (Sweden)

    Michael J. McGlinchey

    2014-08-01

    Full Text Available Variable-temperature NMR spectroscopy is probably the most convenient and sensitive technique to monitor changes in molecular structure in solution. Rearrangements that are rapid on the NMR time-scale exhibit simplified spectra, whereby non-equivalent nuclear environments yield time-averaged resonances. At lower temperatures, when the rate of exchange is sufficiently reduced, these degeneracies are split and the underlying “static” molecular symmetry, as seen by X-ray crystallography, becomes apparent. Frequently, however, such rearrangement processes are hidden, even when they become slow on the NMR time-scale, because the molecular point group remains unchanged. Judicious symmetry breaking, such as by substitution of a molecular fragment by a similar, but not identical moiety, or by the incorporation of potentially diastereotopic (chemically non-equivalent nuclei, allows the elucidation of the kinetics and energetics of such processes. Examples are chosen that include a wide range of rotations, migrations and other rearrangements in organic, inorganic and organometallic chemistry.

  14. Mirror Symmetry Breaking in Helical Polysilanes: Preference between Left and Right of Chemical and Physical Origin

    Directory of Open Access Journals (Sweden)

    Michiya Fujiki

    2010-08-01

    Full Text Available From elemental particles to human beings, matter is dissymmetric with respect to mirror symmetry. In 1860, Pasteur conjectured that biomolecular handedness— homochirality—may originate from certain inherent dissymmetric forces existing in the universe. Kipping, a pioneer of organosilicon chemistry, was interested in the handedness of sodium chlorate during his early research life. Since Kipping first synthesized several Si-Si bonded oligomers bearing phenyl groups, Si-Si bonded high polymers carrying various organic groups—polysilanes—can be prepared by sodium-mediated condensation of the corresponding organodichlorosilanes. Among these polysilanes, optically active helical polysilanes with enantiomeric pairs of organic side groups may be used for testing the mirror symmetry-breaking hypothesis by weak neutral current (WNC origin in the realm of chemistry and material science. Several theoretical studies have predicted that WNC-existing chiral molecules with stereogenic centers and/or stereogenic bonds allow for distinguishing between image and mirror image molecules. Based on several amplification mechanisms, theorists claimed that minute differences, though still very subtle, may be detectable by precise spectroscopic and physicochemical measurements if proper chiral molecular pairs were employed. The present paper reports comprehensively an inequality between six pairs of helical polysilane high polymers, presumably, detectable by (chiroptical and achiral 29Si-/13C- NMR spectra, and viscometric measurements.

  15. Breaking of axial symmetry in excited nuclei as identified in experimental data

    Science.gov (United States)

    Junghans, Arnd R.; Grosse, Eckart; Massarczyk, Ralph

    2017-09-01

    A phenomenological prediction for radiative neutron capture is presented and compared to recent compilations of Maxwellian averaged cross sections and average radiative widths. Photon strength functions and nuclear level densities near the neutron separation energy are extracted from data without the assumption of axial symmetry - at variance to common usage. A satisfactory description is reached with a small number of global parameters when theoretical predictions on triaxiality (from constrained HFB calculations with the Gogny D1S interaction) are inserted into conventional calculations of radiative neutron capture. The photon strength is parametrized using the sum of three Lorentzians (TLO) in accordance to the dipole sum rule. The positions and widths are accounted for by the droplet model with surface dissipation without locally adjusted parameters. Level densities are influenced strongly by the significant collective enhancement based on the breaking of axial symmetry. With the less stringent requirement of invariance against rotation by 180∘ a global set of parameters which allows to describe the photon strength function and the level densities in the nuclear mass range from mass number 50 < A < 250 is found.

  16. Discriminative phenomenological features of scale invariant models for electroweak symmetry breaking

    Directory of Open Access Journals (Sweden)

    Katsuya Hashino

    2016-01-01

    Full Text Available Classical scale invariance (CSI may be one of the solutions for the hierarchy problem. Realistic models for electroweak symmetry breaking based on CSI require extended scalar sectors without mass terms, and the electroweak symmetry is broken dynamically at the quantum level by the Coleman–Weinberg mechanism. We discuss discriminative features of these models. First, using the experimental value of the mass of the discovered Higgs boson h(125, we obtain an upper bound on the mass of the lightest additional scalar boson (≃543 GeV, which does not depend on its isospin and hypercharge. Second, a discriminative prediction on the Higgs-photon–photon coupling is given as a function of the number of charged scalar bosons, by which we can narrow down possible models using current and future data for the di-photon decay of h(125. Finally, for the triple Higgs boson coupling a large deviation (∼+70% from the SM prediction is universally predicted, which is independent of masses, quantum numbers and even the number of additional scalars. These models based on CSI can be well tested at LHC Run II and at future lepton colliders.

  17. Role of Symmetry Breaking on the Optical Transitions in Lead-Salt Quantum Dots

    KAUST Repository

    Nootz, Gero

    2010-09-08

    The influence of quantum confinement on the one- and two-photon absorption spectra (1PA and 2PA) of PbS and PbSe semiconductor quantum dots (QDs) is investigated. The results show 2PA peaks at energies where only 1PA transitions are predicted and 1PA peaks where only 2PA transitions are predicted by the often used isotropic k•p four-band envelope function formalism. The first experimentally identified two-photon absorption peak coincides with the energy of the first one photon allowed transition. This first two-photon peak cannot be explained by band anisotropy, verifying that the inversion symmetry of the wave functions is broken and relaxation of the parity selection rules has to be taken into account to explain optical transitions in lead-salt QDs. Thus, while the band anisotropy of the bulk semiconductor plays a role in the absorption spectra, especially for the more anisotropic PbSe QDs, a complete model of the absorption spectra, for both 1PA and 2PA, must also include symmetry breaking of the quantum confined wave functions. These studies clarify the controversy of the origin of spectral features in lead-salt QDs. © 2010 American Chemical Society.

  18. Breaking of axial symmetry in excited nuclei as identified in experimental data

    Directory of Open Access Journals (Sweden)

    Junghans Arnd R.

    2017-01-01

    Full Text Available A phenomenological prediction for radiative neutron capture is presented and compared to recent compilations of Maxwellian averaged cross sections and average radiative widths. Photon strength functions and nuclear level densities near the neutron separation energy are extracted from data without the assumption of axial symmetry – at variance to common usage. A satisfactory description is reached with a small number of global parameters when theoretical predictions on triaxiality (from constrained HFB calculations with the Gogny D1S interaction are inserted into conventional calculations of radiative neutron capture. The photon strength is parametrized using the sum of three Lorentzians (TLO in accordance to the dipole sum rule. The positions and widths are accounted for by the droplet model with surface dissipation without locally adjusted parameters. Level densities are influenced strongly by the significant collective enhancement based on the breaking of axial symmetry. With the less stringent requirement of invariance against rotation by 180∘ a global set of parameters which allows to describe the photon strength function and the level densities in the nuclear mass range from mass number 50 < A < 250 is found.

  19. Chiral symmetry breaking and chiral polarization: Tests for finite temperature and many flavors

    Directory of Open Access Journals (Sweden)

    Andrei Alexandru

    2015-02-01

    Full Text Available It was recently conjectured that, in SU(3 gauge theories with fundamental quarks, valence spontaneous chiral symmetry breaking is equivalent to condensation of local dynamical chirality and appearance of chiral polarization scale Λch. Here we consider more general association involving the low-energy layer of chirally polarized modes which, in addition to its width (Λch, is also characterized by volume density of participating modes (Ω and the volume density of total chirality (Ωch. Few possible forms of the correspondence are discussed, paying particular attention to singular cases where Ω emerges as the most versatile characteristic. The notion of finite-volume “order parameter”, capturing the nature of these connections, is proposed. We study the effects of temperature (in Nf=0 QCD and light quarks (in Nf=12, both in the regime of possible symmetry restoration, and find agreement with these ideas. In Nf=0 QCD, results from several volumes indicate that, at the lattice cutoff studied, the deconfinement temperature Tc is strictly smaller than the overlap–valence chiral transition temperature Tch in real Polyakov line vacuum. Somewhat similar intermediate phase (in quark mass is also seen in Nf=12. It is suggested that deconfinement in Nf=0 is related to indefinite convexity of absolute X-distributions.

  20. Electric-Field Switchable Second-Harmonic Generation in Bilayer MoS2 by Inversion Symmetry Breaking.

    Science.gov (United States)

    Klein, J; Wierzbowski, J; Steinhoff, A; Florian, M; Rösner, M; Heimbach, F; Müller, K; Jahnke, F; Wehling, T O; Finley, J J; Kaniber, M

    2017-01-11

    We demonstrate pronounced electric-field-induced second-harmonic generation in naturally inversion symmetric 2H stacked bilayer MoS2 embedded into microcapacitor devices. By applying strong external electric field perturbations (|F| = ±2.6 MV cm-1) perpendicular to the basal plane of the crystal, we control the inversion symmetry breaking and, hereby, tune the nonlinear conversion efficiency. Strong tunability of the nonlinear response is observed throughout the energy range (Eω ∼ 1.25-1.47 eV) probed by measuring the second-harmonic response at E2ω, spectrally detuned from both the A- and B-exciton resonances. A 60-fold enhancement of the second-order nonlinear signal is obtained for emission at E2ω = 2.49 eV, energetically detuned by ΔE = E2ω - EC = -0.26 eV from the C-resonance (EC = 2.75 eV). The pronounced spectral dependence of the electric-field-induced second-harmonic generation signal reflects the bandstructure and wave function admixture and exhibits particularly strong tunability below the C-resonance, in good agreement with density functional theory calculations. Moreover, we show that the field-induced second-harmonic generation relies on the interlayer coupling in the bilayer. Our findings strongly suggest that the strong tunability of the electric-field-induced second-harmonic generation signal in bilayer transition metal dichalcogenides may find applications in miniaturized electrically switchable nonlinear devices.

  1. Zurek–Kibble Symmetry Breaking Process in Superconducting Rings; Spontaneous Fluxon Formation in Annular Josephson Tunnel Junctions

    DEFF Research Database (Denmark)

    Aarøe, Morten; Monaco, Roberto; Dmitriev, P

    2007-01-01

    We report on new investigations of spontaneous symmetry breaking in non-adiabatic phase transitions. This Zurek-Kibble (ZK) process is mimicked in solid state systems by trapping of magnetic flux quanta, fluxons, in a long annular Josephson tunnel junction quenched through the normal...

  2. Thermoelectric Signatures of Time-Reversal Symmetry Breaking States in Multiband Superconductors.

    Science.gov (United States)

    Garaud, Julien; Silaev, Mihail; Babaev, Egor

    2016-03-04

    We show that superconductors with broken time-reversal symmetry have very specific magnetic and electric responses to inhomogeneous heating. A local heating of such superconductors induces a magnetic field with a profile that is sensitive to the presence of domain walls and crystalline anisotropy of superconducting states. A nonstationary heating process produces an electric field and a charge imbalance in different bands. These effects can be measured and used to distinguish s+is and s+id superconducting states in the candidate materials such as Ba_{1-x}K_{x}Fe_{2}As_{2}.

  3. Applications of Computational Quantum Chemistry: Conformational Analysis, Physical Predictions, and Circumvention of Symmetry-Breaking

    Science.gov (United States)

    Blahous, Charles Paul, III

    Advanced computational methods are applied to a variety of chemical problems, most prominently the study of potential high energy density materials. Two possible high energy species (O_6 and N _6H_6) are examined with self-consistent-field methods (SCF), whose reliability is discussed in terms of the electronic structures of the subjects of investigation. The adaptation of method to problem is further exemplified in the study of two species (NO_2 and trimethylenemethane) which require higher-level theoretical treatments. Symmetry -breaking in NO_2 is avoided by multi -configuration (CAS-SCF) calculations, and spin polarization in trimethylenemethane is accounted for by configuration interaction (CISD). O_6 is predicted to exhibit chair, twist, and boat conformations along an energy surface analogous to that of cyclohexane. Six symmetrically equivalent oxygen atoms are predicted to comprise the lowest-energy chair form, 15.9 kcal/mole below the twist and 17.5 kcal/mole below the boat at the DZP-SCF level of theory. The boat is not found to be an energy minimum but rather exhibits one imaginary vibrational frequency. Rough predictions are made (~130 kcal/mole) of the heat of formation of O_6. N_6H_6 is predicted to also assume a chair shape in its lowest energy form. The thirteen symmetrically distinct conformations of chair-N_6H_6 are found to cover a range of 37.0 kcal/mole with DZP-SCF methods, the lowest in energy being that with all hydrogens axial. Analytic SCF second-derivative methods reveal each of the thirteen conformations to be a local energy minimum with this basis. The cyclic N_6H _6 system is exploited for the information it reveals concerning the steric requirements of lone pairs in amino-type systems. These conformational trends are quantified in general rules of thumb for estimating the energies of these types of molecules. SCF methods are found to be inadequate to describe the two lowest-energy electronic states (^2 B_2 and ^2 A_1) of NO_2

  4. Scattering in PT - and RT -symmetric multimode waveguides: Generalized conservation laws and spontaneous symmetry breaking beyond one dimension

    Science.gov (United States)

    Ge, Li; Makris, Konstantinos G.; Christodoulides, Demetrios N.; Feng, Liang

    2015-12-01

    We extend the generalized conservation law of light propagating in a one-dimensional PT -symmetric system, i.e., |T -1 | =√{RLRR } for the transmittance T and the reflectance RL ,R from the left and right, to a multimode waveguide with either PT or RT symmetry, in which higher dimensional investigations are necessary. These conservation laws exist not only in a matrix form for the transmission and reflection matrices; they also exist in a scalar form for real-valued quantities by defining generalized transmittance and reflectance. We then discuss how a multimode PT -symmetric waveguide can be used to observe spontaneous symmetry breaking of the scattering matrix, which typically requires tuning the non-Hermiticity of the system (i.e., the strength of gain and loss). Here the advantage of using a multimode waveguide is the elimination of tuning any system parameters: the transverse mode order m plays the role of the symmetry-breaking parameter, and one observes the symmetry breaking by simply performing a scattering experiment in each waveguide channel at a single frequency and fixed strength of gain and loss.

  5. One step replica symmetry breaking and extreme order statistics of logarithmic REMs

    Directory of Open Access Journals (Sweden)

    Xiangyu Cao, Yan V. Fyodorov, Pierre Le Doussal

    2016-12-01

    Full Text Available Building upon the one-step replica symmetry breaking formalism, duly understood and ramified, we show that the sequence of ordered extreme values of a general class of Euclidean-space logarithmically correlated random energy models (logREMs behave in the thermodynamic limit as a randomly shifted decorated exponential Poisson point process. The distribution of the random shift is determined solely by the large-distance ("infra-red", IR limit of the model, and is equal to the free energy distribution at the critical temperature up to a translation. the decoration process is determined solely by the small-distance ("ultraviolet", UV limit, in terms of the biased minimal process. Our approach provides connections of the replica framework to results in the probability literature and sheds further light on the freezing/duality conjecture which was the source of many previous results for log-REMs. In this way we derive the general and explicit formulae for the joint probability density of depths of the first and second minima (as well its higher-order generalizations in terms of model-specific contributions from UV as well as IR limits. In particular, we show that the second min statistics is largely independent of details of UV data, whose influence is seen only through the mean value of the gap. For a given log-correlated field this parameter can be evaluated numerically, and we provide several numerical tests of our theory using the circular model of $1/f$-noise.

  6. Inverse cascade and symmetry breaking in rapidly-rotating Boussinesq convection

    CERN Document Server

    Favier, B; Proctor, M R E

    2014-01-01

    In this paper we present numerical simulations of rapidly-rotating Rayleigh-B\\'enard convection in the Boussinesq approximation with stress-free boundary conditions. At moderately low Rossby number and large Rayleigh number, we show that a large-scale depth-invariant flow is formed, reminiscent of the condensate state observed in two-dimensional flows. We show that the large-scale circulation shares many similarities with the so-called vortex, or slow-mode, of forced rotating turbulence. Our investigations show that at a fixed rotation rate the large-scale vortex is only observed for a finite range of Rayleigh numbers, as the quasi-two-dimensional nature of the flow disappears at very high Rayleigh numbers. We observe slow vortex merging events and find a non-local inverse cascade of energy in addition to the regular direct cascade associated with fast small-scale turbulent motions. Finally, we show that cyclonic structures are dominant in the small-scale turbulent flow and this symmetry breaking persists in ...

  7. Spontaneous onset of magnetic reconnection in toroidal plasma caused by breaking of 2D symmetry

    Energy Technology Data Exchange (ETDEWEB)

    Egedal, Jan; Katz, Noam; Bonde, Jeff; Fox, Will; Le, Ari; Porkolab, Miklos; Vrublevskis, Arturs [Department of Physics/Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2011-11-15

    Magnetic reconnection is studied in the collisionless limit at the Versatile Toroidal Facility (VTF) at MIT. Two distinct magnetic configurations are applied in the experiments; an open magnetic cusp and a closed cusp. In the open cusp configurations, the field lines intersect the the vacuum vessel walls and here axisymmetric oscillatory reconnection is observed. Meanwhile, in the closed cusp configuration, where the field lines are confined inside the experiment, the coupling between global modes and a current sheet leads to powerful bursts of 3D spontaneous reconnection. These spontaneous events start at one toroidal location, and then propagate around the toroidal direction at the Alfven speed (calculated with the strength of the dominant guide field). The three dimensional measurements include the detailed time evolution of the plasma density, current density, the magnetic flux function, the electrostatic potential, and the reconnection rate. The vastly different plasma behavior in the two configurations can be described using a simple theoretical framework, linking together the interdependencies of the reconnection rate, the in-plane electrostatic potential, and the parallel electron currents. We find that it is the breaking of toroidal symmetry by the global mode that allows for a localized disruption of the x-line current and hereby facilitates the onset of spontaneous reconnection.

  8. Chiral symmetry breaking by spatial confinement in tactoidal droplets of lyotropic chromonic liquid crystals.

    Science.gov (United States)

    Tortora, Luana; Lavrentovich, Oleg D

    2011-03-29

    In many colloidal systems, an orientationally ordered nematic (N) phase emerges from the isotropic (I) melt in the form of spindle-like birefringent tactoids. In cases studied so far, the tactoids always reveal a mirror-symmetric nonchiral structure, sometimes even when the building units are chiral. We report on chiral symmetry breaking in the nematic tactoids formed in molecularly nonchiral polymer-crowded aqueous solutions of low-molecular weight disodium cromoglycate. The parity is broken by twisted packing of self-assembled molecular aggregates within the tactoids as manifested by the observed optical activity. Fluorescent confocal microscopy reveals that the chiral N tactoids are located at the boundaries of cells. We explain the chirality induction as a replacement of energetically costly splay packing of the aggregates within the curved bipolar tactoidal shape with twisted packing. The effect represents a simple pathway of macroscopic chirality induction in an organic system with no molecular chirality, as the only requirements are orientational order and curved shape of confinement.

  9. Chiral symmetry breaking and surface faceting in chromonic liquid crystal droplets with giant elastic anisotropy.

    Science.gov (United States)

    Jeong, Joonwoo; Davidson, Zoey S; Collings, Peter J; Lubensky, Tom C; Yodh, A G

    2014-02-04

    Confined liquid crystals (LC) provide a unique platform for technological applications and for the study of LC properties, such as bulk elasticity, surface anchoring, and topological defects. In this work, lyotropic chromonic liquid crystals (LCLCs) are confined in spherical droplets, and their director configurations are investigated as a function of mesogen concentration using bright-field and polarized optical microscopy. Because of the unusually small twist elastic modulus of the nematic phase of LCLCs, droplets of this phase exhibit a twisted bipolar configuration with remarkably large chiral symmetry breaking. Further, the hexagonal ordering of columns and the resultant strong suppression of twist and splay but not bend deformation in the columnar phase, cause droplets of this phase to adopt a concentric director configuration around a central bend disclination line and, at sufficiently high mesogen concentration, to exhibit surface faceting. Observations of director configurations are consistent with Jones matrix calculations and are understood theoretically to be a result of the giant elastic anisotropy of LCLCs.

  10. Symmetry breaking and morphological instabilities in core-shell metallic nanoparticles.

    Science.gov (United States)

    Ferrando, Riccardo

    2015-01-14

    Nanoalloys are bi- or multi-component metallic particles in the size range between 1 and 100 nm. Nanoalloys present a wide variety of structures and properties, which make them suitable for many applications in catalysis, optics, magnetism and biomedicine. This topical review is devoted to the structural properties of nanoalloys of weakly miscible metals, which are expected to present phase-separated arrangements of their components, such as core-shell and Janus arrangements. The focus is on singling out size- and composition-dependent transitions between these arrangements, showing that several transitions can be rationalized by a unifying concept, that is symmetry breaking, caused by the accumulation of strain at the atomic level and its subsequent release. The driving forces that rule the interplay between core-shell and other structures and determine the actual shapes of core and shell, and the placement of the core inside the shell are analyzed. Several systems, such as Ag-Cu, Ag-Co, Ag-Ni, Au-Co, Au-Pt, and Ir-Pt are treated, comparing computational results to experimental observations and simple analytical models. After treating the lowest-energy structures, which are representative of the equilibrium configurations at sufficiently low temperatures, high-temperature and growth kinetics effects are considered.

  11. Break-induced replication is highly inaccurate.

    Directory of Open Access Journals (Sweden)

    Angela Deem

    2011-02-01

    Full Text Available DNA must be synthesized for purposes of genome duplication and DNA repair. While the former is a highly accurate process, short-patch synthesis associated with repair of DNA damage is often error-prone. Break-induced replication (BIR is a unique cellular process that mimics normal DNA replication in its processivity, rate, and capacity to duplicate hundreds of kilobases, but is initiated at double-strand breaks (DSBs rather than at replication origins. Here we employed a series of frameshift reporters to measure mutagenesis associated with BIR in Saccharomyces cerevisiae. We demonstrate that BIR DNA synthesis is intrinsically inaccurate over the entire path of the replication fork, as the rate of frameshift mutagenesis during BIR is up to 2,800-fold higher than during normal replication. Importantly, this high rate of mutagenesis was observed not only close to the DSB where BIR is less stable, but also far from the DSB where the BIR replication fork is fast and stabilized. We established that polymerase proofreading and mismatch repair correct BIR errors. Also, dNTP levels were elevated during BIR, and this contributed to BIR-related mutagenesis. We propose that a high level of DNA polymerase errors that is not fully compensated by error-correction mechanisms is largely responsible for mutagenesis during BIR, with Pol δ generating many of the mutagenic errors. We further postulate that activation of BIR in eukaryotic cells may significantly contribute to accumulation of mutations that fuel cancer and evolution.

  12. Odd-parity superconductivity in the vicinity of inversion symmetry breaking in spin-orbit-coupled systems

    Science.gov (United States)

    Kozii, Vladyslav; Fu, Liang; Massachusetts institute of technology Team

    We study superconductivity in spin-orbit-coupled systems in the vicinity of inversion symmetry breaking. We find that due to the presence of spin-orbit coupling, fluctuations of the incipient parity-breaking order generate an attractive pairing interaction in an odd-parity pairing channel, which competes with the s-wave pairing. We show that Coulomb repulsion or an external Zeeman field suppresses the s-wave pairing and promotes the odd-parity superconducting state. Our work provides a new mechanism for odd-parity pairing and opens a route to novel topological superconductivity. This work is supported by the David and Lucile Packard foundation.

  13. The lithium superoxide radical: Symmetry breaking phenomena and potential energy surfaces

    Science.gov (United States)

    Allen, Wesley D.; Horner, David A.; Dekock, Roger L.; Remington, Richard B.; Schaefer, Henry F.

    1989-05-01

    The two lowest electronic states of the lithium superoxide radical, LiO 2, have been investigated using ab initio theoretical techniques, including RHF SCF, CISD, Davidson-corrected CISD [CISD + (Q)], UHF SCF, UMP2, UMP3, UMP4(SDTQ), spin-projected UHF and UMP, valence and extravalence CASSCF (CASSCF-v and CASSCF-π), and CISD based on CASSCF natural orbitals (CISD-π). Four basis sets ranging in quality from Li (9s4p/5s2p), O (9s5pld/5s3pld) to Li (10s5pld/6s4pld), O(11s7p2dlf/6s5p2dlf) were employed, these being designated TZP, QZ2P, QZ2P+R, and QZ2P+R+f. The investigation encompassed dissociation energies, relative energies of various conformations, geometrical structures, vibrational frequencies, infrared and Raman intensities, dipole moments, cubic force fields, vibration-rotation interaction constants, and symmetry breaking phenomena. The onset of spatial symmetry breaking in the electronic orbitals of the TZP RHF reference wavefunction for overlineX2A 2 LiO 2 leads to an irremovable singularity in the quadratic force constant for antisymmetric LiO stretching at the isosceles-triangle (C 2v) geometry d(OO) = 1.3266 Å and r(LiO) = 1.7737 Å. This anomalous lowering of spatial symmetry from C 2v to C s, makes the two oxygen atoms inequivalent, and thus it becomes necessary to avert the symmetry dilemma in the reference wavefunction to provide unequivocal evidence for a C 2v geometrical structure of overlineX2A 2 LiO 2 which is consistent with the ionic model. This task is achieved with the CASSCF-π and CISD-π wavefunctions, the latter yielding d(OO) = 1.3405 Å, r(LiO) = 1.7937 Å, ω 1(a 1) = 1263 cm -1, ω 2(a 1) = 740 cm -1, and ω 3(b 2) = 519 cm -1 at the C 2v equilibrium geometry. Final proposals of d(OO) = 1.335 Å, r(LiO) = 1.76 Å, and D0(LiO 2) = 62 kcal/mol are made for overlineX2A 2 LiO 2, as indicated by appurtenant studies of overlineX2Π gO 2-1 and overlineX2Π LiO. Improved predictions are thereby provided for gas

  14. Topological Fermi-liquid theory for interacting Weyl metals with time reversal symmetry breaking

    Science.gov (United States)

    Jho, Yong-Soo; Han, Jae-Ho; Kim, Ki-Seok

    2017-05-01

    superconducting transition temperatures, justifying the topological Fermi-liquid theory of interacting Weyl metals with time reversal symmetry breaking. The topological Fermi-liquid theory serves a theoretical platform for us to investigate the role of Fermi-liquid interactions in anomalous transport phenomena of interacting Weyl metals such as anomalous Hall effects, chiral magnetic and vortical effects, and negative longitudinal magnetoresistivity properties. In addition, it allows us to study how thermodynamic properties such as the Wilson's ratio and spectra of collective excitations such as zero sound modes in the Landau's Fermi-liquid state are modified due to the Berry curvature and the chiral anomaly.

  15. Stability of effective thin-shell wormholes under Lorentz symmetry breaking supported by dark matter and dark energy

    Science.gov (United States)

    Övgün, Ali; Jusufi, Kimet

    2017-12-01

    In this paper, we construct generic, spherically symmetric thin-shell wormholes and check their stabilities using the unified dark sector, including dark energy and dark matter. We give a master equation, from which one can recover, as a special case, other stability solutions for generic spherically symmetric thin-shell wormholes. In this context, we consider a particular solution; namely we construct an effective thin-shell wormhole under Lorentz symmetry breaking. We explore stability analyses using different models of the modified Chaplygin gas with constraints from cosmological observations, such as seventh-year full Wilkinson microwave anisotropy probe data points, type Ia supernovae, and baryon acoustic oscillation. In all these models we find stable solutions by choosing suitable values for the parameters of the Lorentz symmetry breaking effect.

  16. Academic Training Lectures | Theories of Electroweak Symmetry Breaking: A Post LHC Run-I Perspective | 26, 27 and 29 May

    CERN Multimedia

    2015-01-01

    Please note that our next series of Academic Training Lectures will take place on the 26, 27 and 29 May 2015.   Theories of Electroweak Symmetry Breaking: A Post LHC Run-I Perspective, by James Daniel Wells (University of Michigan (US)) from 11.00 a.m. to 12.00 p.m. in the Council Chamber (503-1-001) https://indico.cern.ch/event/383514/

  17. Improved calculation of the isospin-symmetry-breaking corrections to superallowed Fermi β decay

    Science.gov (United States)

    Towner, I. S.; Hardy, J. C.

    2008-02-01

    We report new shell-model calculations of the isospin-symmetry-breaking correction δC to superallowed 0+→0+ nuclear β decay. The most important improvement is the inclusion of core orbitals, which are demonstrated to have a significant impact on the mismatch in the radial wave functions of the parent and daughter states. We determine which core orbitals are important to include from an examination of measured spectroscopic factors in single-nucleon pickup reactions. In addition, where new sets of effective interactions have become available since our last calculation, we now include them; this leads to small changes in δNS as well. We also examine the new radiative-correction calculation by Marciano and Sirlin and, by a simple reorganization, show that it is possible to preserve the conventional separation into a nucleus-independent “inner” radiative term, ΔRV, and a nucleus-dependent “outer” term, δR'. We tabulate the new values for δC,δNS, and δR' for 20 superallowed transitions, including the 13 currently well-studied cases. With these new correction terms, the corrected Ft values for the 13 cases are statistically consistent with one another, and the anomalousness of the V46 result disappears. These new calculations lead to a lower average Ft¯ value and a higher value for Vud. The sum of squares of the top-row elements of the Cabibbo-Kobayashi-Maskawa matrix now agrees exactly with unitarity.

  18. Entropic chiral symmetry breaking in self-organized two-dimensional colloidal crystals.

    Science.gov (United States)

    Mayoral, Kenny; Mason, Thomas G

    2014-07-07

    Long-range chiral symmetry breaking (CSB) has been recently observed in 2D self-organized rhombic crystals of hard, achiral, 72 degree rhombic microparticles. However, purely entropic selection of a CSB crystal in an idealized system of hard achiral shapes, in which attractions are entirely absent and the shape does not dictate a chiral tiling, has not yet been quantitatively predicted. Overcoming limitations of a purely rotational cage model, we investigate a translational-rotational cage model (TRCM) of dense systems of hard achiral rhombs and quantitatively demonstrate that entropy can spontaneously drive the preferential self-organization of a chiral crystal composed of achiral shapes that also tile into an achiral crystal. At different particle area fractions, ϕA, we calculate the number of accessible translational-rotational microstates, Ω, of a mobile central rhomb in a static cage of neighboring rhombs, which can have different orientation angles, γ, relative to the bisector of the crystalline axes. As we raise ϕA, two maxima emerge in Ω(γ) at non-zero cage orientation angles, ±γmax. These maxima correspond to additional translational microstates that become accessible in the CSB crystalline polymorph through reduced translational tip-tip interference. Thus, entropy, often associated with structural disorder, can drive CSB in condensed phase systems of non-attractive achiral objects that do not tile into chiral structures. The success of the TRCM in explaining the entropic origin of CSB in systems of hard rhombs indicates that the TRCM will have significant utility in predicting the self-organized behavior of dense systems of other hard shapes in 2D.

  19. Amplification of enantiomeric excess, mirror-image symmetry breaking and kinetic proofreading in Soai reaction models with different oligomeric orders.

    Science.gov (United States)

    Micheau, Jean-Claude; Coudret, Christophe; Cruz, José-Manuel; Buhse, Thomas

    2012-10-14

    A comprehensive kinetic analysis of three prototypical autocatalytic cycle models based on the absolute asymmetric Soai reaction is presented. The three models, which can give rise to amplification of enantiomeric excess and mirror-image symmetry breaking, vary by their monomeric, dimeric or trimeric order of the assumed catalytic species. Our numerical approach considered the entire chiral combinatorics of the diastereomeric interactions in the models as well as the multiplicity of coupled reversible reactions without applying fast equilibration or quasi-steady state approximations. For the simplest monomeric model, an extensive range of parameters was explored employing a random grid parameter scanning method that revealed the influence of the parameter values on the product distribution, the reaction-time, the attenuation or amplification of enantiomeric excess as well as on the presence or absence of mirror-image symmetry breaking. A symmetry breaking test was imposed on the three models showing that an increase in the catalytic oligomer size from one to three leads to a higher tolerance to poorer chiral recognition between the diastereoisomers and identifies the greater impact of the diastereoisomeric energy difference over an imperfect stereoselectivity in the catalytic step. This robustness is understood as a particular case of so-called kinetic proofreading in asymmetric autocatalysis.

  20. Viable dark matter via radiative symmetry breaking in a scalar singlet Higgs portal extension of the standard model.

    Science.gov (United States)

    Steele, T G; Wang, Zhi-Wei; Contreras, D; Mann, R B

    2014-05-02

    We consider the generation of dark matter mass via radiative electroweak symmetry breaking in an extension of the conformal standard model containing a singlet scalar field with a Higgs portal interaction. Generating the mass from a sequential process of radiative electroweak symmetry breaking followed by a conventional Higgs mechanism can account for less than 35% of the cosmological dark matter abundance for dark matter mass M(s)>80 GeV. However, in a dynamical approach where both Higgs and scalar singlet masses are generated via radiative electroweak symmetry breaking, we obtain much higher levels of dark matter abundance. At one-loop level we find abundances of 10%-100% with 106 GeVdark matter mass. The dynamical approach also predicts a small scalar-singlet self-coupling, providing a natural explanation for the astrophysical observations that place upper bounds on dark matter self-interaction. The predictions in all three approaches are within the M(s)>80 GeV detection region of the next generation XENON experiment.

  1. Symmetries and symmetry breaking beyond the electroweak theory; Symetries et brisures de symetries au-dela de la theorie electrofaible

    Energy Technology Data Exchange (ETDEWEB)

    Grojean, Ch

    1999-05-04

    The Glashow-Salam-Weinberg theory describing electroweak interactions is one of the best successes of quantum field theory; it has passed all the experimental tests of particles physics with a high accuracy. However, this theory suffers from some deficiencies in the sense that some parameters, especially those involved in the generation of the mass of the elementary particles, are fixed to unnatural values. Moreover gravitation whose quantization cannot be achieved in ordinary quantum filed theory is hot taken into account. The aim of this PhD dissertation is to study some theories beyond the Standard Model and inspired by superstring theories. My endeavour has been to develop theoretical aspects of an effective dynamical description of one of the soltonic states of the strongly coupled strings. An important part of my results is also devoted to a more phenomenological analysis of the low energy effects of the symmetries that assure the coherence of the theories at high energy: these symmetries could explain the fermion mass hierarchy and could be directly observable in collider experiments. It is also shown how the geometrical properties of compactified spaces characterize the vacuum of string theory in a non-perturbative regime; such a vacuum can be used to construct a unified theory of gauge and gravitational interactions with a supersymmetry softy broken at a TcV scale. (author)

  2. Proceedings of the 1992 workshops on high-energy physics with colliding beams. Volume 3, Electroweak symmetry breaking at colliding-beam facilities

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, J. [ed.

    1992-12-31

    This report contains viewgraphs on the following topics: Introduction to Electroweak Symmetry Breaking: Intermediate-Mass Higgs Bosons; Extended Higgs Sectors and Novel Searches; and Heavy Higgs Bosons and Strong WW Scattering.

  3. Hopf Symmetry and its breaking; Braid Statistics and Confinement in Planar Physics

    NARCIS (Netherlands)

    Slingerland, J.K.

    2002-01-01

    Dit proefschrift gaat over symmetrie en statistiek. Bij symmetrie moeten we hier denken aan symmetrieen van de natuurwetten, zoals translatiesymmetrie; de natuurwetten zijn hier hetzelfde als een eind verderop. Bij statistiek gaat het om zgn. topologische wisselwerkingen tussen deeltjes in het

  4. Image charge effects in single-molecule junctions: Breaking of symmetries and negative-differential resistance in a benzene single-electron transistor

    DEFF Research Database (Denmark)

    Kaasbjerg, Kristen; Flensberg, K.

    2011-01-01

    and molecular symmetries remain unclear. Using a theoretical framework developed for semiconductor-nanostructure-based single-electron transistors (SETs), we demonstrate that the image charge interaction breaks the molecular symmetries in a benzene-based single-molecule transistor operating in the Coulomb...

  5. Replica Symmetry Breaking in the Photonic Ferromagneticlike Spontaneous Mode-Locking Phase of a Multimode Nd:YAG Laser

    Science.gov (United States)

    Moura, André L.; Pincheira, Pablo I. R.; Reyna, Albert S.; Raposo, Ernesto P.; Gomes, Anderson S. L.; de Araújo, Cid B.

    2017-10-01

    We demonstrate the replica symmetry breaking (RSB) phenomenon in the spontaneous mode-locking regime of a multimode Q -switched Nd:YAG laser. The underlying mechanism is quite distinct from that of the RSB recently observed in random lasers. Here, there is no random medium and the phase is not glassy with incoherently oscillating modes as in random lasers. Instead, in each pulse a specific subset of longitudinal modes are activated in a nondeterministic way, whose coherent oscillation dominates and frustrates the others. The emergence of RSB coincides with the onset of ultrashort pulse generation typical of the spontaneous mode-locking regime, both occurring at the laser threshold. On the other hand, when high losses are introduced, RSB is inhibited and only the amplified stimulated emission with replica symmetry is observed. Our results disclose the only theoretically predicted photonic phase with RSB that remained unobserved so far.

  6. Phonons in the multiferroic langasite Ba3NbFe3Si2O14 : Evidence for symmetry breaking

    Science.gov (United States)

    Toulouse, C.; Cazayous, M.; de Brion, S.; Levy-Bertrand, F.; Barkaoui, H.; Lejay, P.; Chaix, L.; Lepetit, M. B.; Brubach, J. B.; Roy, P.

    2015-09-01

    The chiral langasite Ba3NbFe3Si2O14 is a multiferroic compound. While its magnetic order below TN=27 K is now well characterized, its polar order is still controversial. We thus looked at the phonon spectrum and its temperature dependence to unravel possible crystal symmetry breaking. We combine optical measurements (both infrared and Raman spectroscopy) with ab initio calculations and show that the signatures of a polar state are clearly present in the phonon spectrum even at room temperature. An additional symmetry lowering occurs below 120 K as seen from the emergence of softer phonon modes in the terahertz range. These results confirm the multiferroic nature of this langasite and open new routes to understand the origin of the polar state.

  7. PT -breaking threshold in spatially asymmetric Aubry-André and Harper models: Hidden symmetry and topological states

    Science.gov (United States)

    Harter, Andrew K.; Lee, Tony E.; Joglekar, Yogesh N.

    2016-06-01

    Aubry-André-Harper lattice models, characterized by a reflection-asymmetric sinusoidally varying nearest-neighbor tunneling profile, are well known for their topological properties. We consider the fate of such models in the presence of balanced gain and loss potentials ±i γ located at reflection-symmetric sites. We predict that these models have a finite PT -breaking threshold only for specific locations of the gain-loss potential and uncover a hidden symmetry that is instrumental to the finite threshold strength. We also show that the topological edge states remain robust in the PT -symmetry-broken phase. Our predictions substantially broaden the possible experimental realizations of a PT -symmetric system.

  8. Bilateral symmetry breaking in a nonlinear Fabry-Perot cavity exhibiting optical tristability

    CERN Document Server

    Torres, J P; Chiao, R Y; Torres, Juan P.; Boyce, Jack; Chiao, Raymond Y.

    1999-01-01

    We show the existence of a region in the parameter space that defines the field dynamics in a Fabry-Perot cylindrical cavity, where three output stable stationary states of the light are possible for a given localized incident field. Two of these states do not preserve the bilateral (i.e. left-right) symmetry of the entire system. These broken-symmetry states are the high-transmission nonlinear modes of the system. We also discuss how to excite these states.

  9. Comment on "Spontaneous breaking of permutation symmetry in pseudo-Hermitian quantum mechanics"

    Science.gov (United States)

    Fernández, Francisco M.

    2017-10-01

    Li and Miao [Phys. Rev. A 85, 042110 (2012), 10.1103/PhysRevA.85.042110] proposed a non-Hermitian Hamiltonian that is neither Hermitian nor P T symmetric but exhibits real eigenvalues for some values of the model parameters. In order to explain this fact, they resorted to P T -pseudo Hermiticity and to a so-called permutation symmetry. Here we show that the spectrum of this Hamiltonian can be easily analyzed in the usual way in terms of exact or broken antiunitary symmetries that appear to be more relevant than the permutation symmetry. In addition, we show why the authors' Hamiltonian and the well-known Pais-Uhlenbeck oscillator lead to the same fourth-order differential equation for the coordinates.

  10. “Electroweak symmetry breaking: to Higgs or not to Higgs” (2/3)

    CERN Multimedia

    CERN. Geneva

    2009-01-01

    How do elementary particles acquire their mass? What is making the photon different from the Z boson? In a word: How is electroweak symmetry broken? This is one of the pressing questions in particle physics that the LHC will answer soon. The aim of this lectures is, after briefly introducing SM physics and the conventional Higgs mechanism, to give a survey of recent attempts to go beyond a simple elementary Higgs. In particular, I will describe composite models (where the Higgs boson emerges from a strongly-interacting sector) and Higsless models. Distinctive signatures at the LHC are expected and will reveal the true nature of the electroweak symmetry sector.

  11. “Electroweak symmetry breaking: to Higgs or not to Higgs” (1/3)

    CERN Multimedia

    CERN. Geneva

    2009-01-01

    How do elementary particles acquire their mass? What is making the photon different from the Z boson? In a word: How is electroweak symmetry broken? This is one of the pressing questions in particle physics that the LHC will answer soon. The aim of this lectures is, after briefly introducing SM physics and the conventional Higgs mechanism, to give a survey of recent attempts to go beyond a simple elementary Higgs. In particular, I will describe composite models (where the Higgs boson emerges from a strongly-interacting sector) and Higsless models. Distinctive signatures at the LHC are expected and will reveal the true nature of the electroweak symmetry sector.

  12. “Electroweak symmetry breaking: to Higgs or not to Higgs” (3/3)

    CERN Multimedia

    CERN. Geneva

    2009-01-01

    How do elementary particles acquire their mass? What is making the photon different from the Z boson? In a word: How is electroweak symmetry broken? This is one of the pressing questions in particle physics that the LHC will answer soon. The aim of this lectures is, after briefly introducing SM physics and the conventional Higgs mechanism, to give a survey of recent attempts to go beyond a simple elementary Higgs. In particular, I will describe composite models (where the Higgs boson emerges from a strongly-interacting sector) and Higsless models. Distinctive signatures at the LHC are expected and will reveal the true nature of the electroweak symmetry sector.

  13. PT-symmetry breaking and laser-absorber modes in optical scattering systems.

    Science.gov (United States)

    Chong, Y D; Ge, Li; Stone, A Douglas

    2011-03-04

    Using a scattering matrix formalism, we derive the general scattering properties of optical structures that are symmetric under a combination of parity and time reversal (PT). We demonstrate the existence of a transition between PT-symmetric scattering eigenstates, which are norm preserving, and symmetry-broken pairs of eigenstates exhibiting net amplification and loss. The system proposed by Longhi [Phys. Rev. A 82, 031801 (2010).], which can act simultaneously as a laser and coherent perfect absorber, occurs at discrete points in the broken-symmetry phase, when a pole and zero of the S matrix coincide.

  14. Higgs bosons, electroweak symmetry breaking, and the physics of the Large Hadron Collider

    Energy Technology Data Exchange (ETDEWEB)

    Quigg, Chris; /Fermilab /CERN

    2007-02-01

    The Large Hadron Collider, a 7 {circle_plus} 7 TeV proton-proton collider under construction at CERN (the European Laboratory for Particle Physics in Geneva), will take experiments squarely into a new energy domain where mysteries of the electroweak interaction will be unveiled. What marks the 1-TeV scale as an important target? Why is understanding how the electroweak symmetry is hidden important to our conception of the world around us? What expectations do we have for the agent that hides the electroweak symmetry? Why do particle physicists anticipate a great harvest of discoveries within reach of the LHC?

  15. Opening a band gap without breaking lattice symmetry: a new route toward robust graphene-based nanoelectronics.

    Science.gov (United States)

    Kou, Liangzhi; Hu, Feiming; Yan, Binghai; Frauenheim, Thomas; Chen, Changfeng

    2014-07-07

    Developing graphene-based nanoelectronics hinges on opening a band gap in the electronic structure of graphene, which is commonly achieved by breaking the inversion symmetry of the graphene lattice via an electric field (gate bias) or asymmetric doping of graphene layers. Here we introduce a new design strategy that places a bilayer graphene sheet sandwiched between two cladding layers of materials that possess strong spin-orbit coupling (e.g., Bi2Te3). Our ab initio and tight-binding calculations show that a proximity enhanced spin-orbit coupling effect opens a large (44 meV) band gap in bilayer graphene without breaking its lattice symmetry, and the band gap can be effectively tuned by an interlayer stacking pattern and significantly enhanced by interlayer compression. The feasibility of this quantum-well structure is demonstrated by recent experimental realization of high-quality heterojunctions between graphene and Bi2Te3, and this design also conforms to existing fabrication techniques in the semiconductor industry. The proposed quantum-well structure is expected to be especially robust since it does not require an external power supply to open and maintain a band gap, and the cladding layers provide protection against environmental degradation of the graphene layer in its device applications.

  16. Dynamical symmetry breaking of lambda- and vee-type three-level ...

    Indian Academy of Sciences (India)

    between the SU(N) symmetry and the N-level system in general, was investigated extensively in the recent past .... Proceeding in the same way, the semiclassical vee-type three-level system can be written as. HV = HV ...... dimensional Bloch equations and non-linear constants for different configurations of the three-level ...

  17. Composite-meson--quark interactions under the condition of dynamical breaking of chiral symmetry

    Energy Technology Data Exchange (ETDEWEB)

    Hirata, M.

    1989-03-01

    Starting from the QCD-inspired model Hamiltonian which can lead to the dynamical breakdown of chiral symmetry, we describe a vacuum consisting of a condensate of q-barq pairs and furthermore meson states and composite-meson field operators within the new Tamm-Dancoff approximation. Using these fields operators and the Hamiltonian we construct composite-meson--quark interactions.

  18. Radiative symmetry breaking at the Fermi scale and flat potential at the Planck scale

    Science.gov (United States)

    Hashimoto, Michio; Iso, Satoshi; Orikasa, Yuta

    2014-01-01

    We investigate a possibility of the "flatland scenario," in which the electroweak gauge symmetry is radiatively broken via the Coleman-Weinberg mechanism starting from a completely flat Higgs potential at the Planck scale. We show that the flatland scenario is realizable only when an inequality K<1 among the coefficients of the β functions is satisfied. We show several models satisfying the condition.

  19. Symmetry-Breaking in a Rate Model for a Biped Locomotion Central Pattern Generator

    Directory of Open Access Journals (Sweden)

    Ian Stewart

    2014-01-01

    Full Text Available The timing patterns of animal gaits are produced by a network of spinal neurons called a Central Pattern Generator (CPG. Pinto and Golubitsky studied a four-node CPG for biped dynamics in which each leg is associated with one flexor node and one extensor node, with Ζ2 x Ζ2 symmetry. They used symmetric bifurcation theory to predict the existence of four primary gaits and seven secondary gaits. We use methods from symmetric bifurcation theory to investigate local bifurcation, both steady-state and Hopf, for their network architecture in a rate model. Rate models incorporate parameters corresponding to the strengths of connections in the CPG: positive for excitatory connections and negative for inhibitory ones. The three-dimensional space of connection strengths is partitioned into regions that correspond to the first local bifurcation from a fully symmetric equilibrium. The partition is polyhedral, and its symmetry group is that of a tetrahedron. It comprises two concentric tetrahedra, subdivided by various symmetry planes. The tetrahedral symmetry arises from the structure of the eigenvalues of the connection matrix, which is involved in, but not equal to, the Jacobian of the rate model at bifurcation points. Some of the results apply to rate equations on more general networks.

  20. Phases with modular ground states for symmetry breaking by rank 3 and rank 2 antisymmetric tensor scalars

    Directory of Open Access Journals (Sweden)

    Stephen L. Adler

    2015-03-01

    Full Text Available Working with explicit examples given by the 56 representation in SU(8, and the 10 representation in SU(5, we show that symmetry breaking of a group G⊃G1×G2 by a scalar in a rank three or two antisymmetric tensor representation leads to a number of distinct modular ground states. For these broken symmetry phases, the ground state is periodic in an integer divisor p of N, where N>0 is the absolute value of the nonzero U(1 generator of the scalar component Φ that is a singlet under the simple subgroups G1 and G2. Ground state expectations of fractional powers Φp/N provide order parameters that distinguish the different phases. For the case of period p=1, this reduces to the usual Higgs mechanism, but for divisors N≥p>1 of N it leads to a modular ground state with periodicity p, implementing a discrete Abelian symmetry group U(1/Zp. This observation may allow new approaches to grand unification and family unification.

  1. The meso Helix: Symmetry and Symmetry-Breaking in Dynamic Oligourea Foldamers with Reversible Hydrogen-Bond Polarity.

    Science.gov (United States)

    Wechsel, Romina; Raftery, James; Cavagnat, Dominique; Guichard, Gilles; Clayden, Jonathan

    2016-08-08

    Oligoureas (up to n=6) of meso cyclohexane-1,2-diamine were synthesized by chain extension with an enzymatically desymmetrized monomer 2. Despite being achiral, the meso oligomers adopt chiral canonical 2.5-helical conformations, the equally populated enantiomeric screw-sense conformers of which are in slow exchange on the NMR timescale, with a barrier to screw-sense inversion of about 70 kJ mol(-1) . Screw-sense inversion in these helical foldamers is coupled with cyclohexane ring-flipping, and results in a reversal of the directionality of the hydrogen bonding in the helix. The termini of the meso oligomers are enantiotopic, and desymmetrized analogues of the oligoureas with differentially and enantioselectively protected termini display moderate screw-sense preferences. A screw-sense preference may furthermore be induced in the achiral, meso oligoureas by formation of a 1:1 hydrogen-bonded complex with the carboxylate anion of Boc-d-proline. The meso oligoureas are the first examples of hydrogen-bonded foldamers with reversible hydrogen-bond directionality. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Flux States and Topological Phases from Spontaneous Time-Reversal Symmetry Breaking in CrSi (Ge )Te3 -Based Systems

    Science.gov (United States)

    Liu, Jianpeng; Park, Se Young; Garrity, Kevin F.; Vanderbilt, David

    2016-12-01

    We study adatom-covered single layers of CrSiTe3 and CrGeTe3 using first-principles calculations based on hybrid functionals. We find that the insulating ground state of a monolayer of La (Lu) deposited on single-layer CrSiTe3 (CrGeTe3 ) carries spontaneously generated current loops around the Cr sites. These "flux states" induce antiferromagnetically ordered orbital moments on the Cr sites and are also associated with nontrivial topological properties. The calculated Chern numbers for these systems are predicted to be ±1 even in the absence of spin-orbit coupling, with sizable gaps on the order of 100 meV. The flux states and the associated topological phases result from spontaneous time-reversal symmetry breaking due to the presence of nonlocal Coulomb interactions.

  3. SU(4) flavor symmetry breaking in D-meson couplings to light hadrons

    Energy Technology Data Exchange (ETDEWEB)

    Fontoura, C.E. [Instituto Tecnologico da Aeronautica, DCTA, Sao Jose dos Campos, SP (Brazil); Universidade Estadual Paulista, Instituto de Fisica Teorica, Sao Paulo, SP (Brazil); Haidenbauer, J. [Institute for Advanced Simulation, Institut fuer Kernphysik, and Juelich Center for Hadron Physics, Forschungszentrum Juelich, Juelich (Germany); Krein, G. [Universidade Estadual Paulista, Instituto de Fisica Teorica, Sao Paulo, SP (Brazil)

    2017-05-15

    The validity of SU(4)-flavor symmetry relations of couplings of charmed D-mesons to light mesons and baryons is examined with the use of {sup 3}P{sub 0} quark-pair creation model and nonrelativistic quark-model wave functions. We focus on the three-meson couplings ππρ, KKρ and DDρ and baryon-baryon-meson couplings NNπ, NΛK and NΛ{sub c}D. It is found that SU(4)-flavor symmetry is broken at the level of 30% in the DDρ tree-meson couplings and 20% in the baryon-baryon-meson couplings. Consequences of these findings for DN cross sections and existence of bound states D-mesons in nuclei are discussed. (orig.)

  4. Quark model with chiral-symmetry breaking and confinement in the Covariant Spectator Theory

    Energy Technology Data Exchange (ETDEWEB)

    Biernat, Elmer P. [CFTP, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal; Pena, Maria Teresa [CFTP, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal; Departamento de Física, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal; Ribiero, Jose' Emilio F. [CeFEMA, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal; Stadler, Alfred [Departamento de Física, Universidade de Évora, 7000-671 Évora, Portugal; Gross, Franz L. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

    2016-03-01

    We propose a model for the quark-antiquark interaction in Minkowski space using the Covariant Spectator Theory. We show that with an equal-weighted scalar-pseudoscalar structure for the confining part of our interaction kernel the axial-vector Ward-Takahashi identity is preserved and our model complies with the Adler-zero constraint for pi-pi-scattering imposed by chiral symmetry.

  5. Symmetry breaking in ligand-protected gold clusters probed by nonlinear optics.

    Science.gov (United States)

    Van Steerteghem, Nick; Van Cleuvenbergen, Stijn; Deckers, Steven; Kumara, Chanaka; Dass, Amala; Häkkinen, Hannu; Clays, Koen; Verbiest, Thierry; Knoppe, Stefan

    2016-06-16

    The first hyperpolarizabilities of [Au25(SR)18](-1/0) and Au38(SR)24 clusters were determined by Hyper-Rayleigh Scattering. A strong dependence on the molecular symmetry was observed, and we explore two strategies to destroy the center of inversion in [Au25(SR)18](-1/0), protection by chiral ligands and alloying of the cluster with silver. This may open new avenues to applications of Au : SR clusters in second-order nonlinear optics.

  6. Bulk Rotational Symmetry Breaking in Kondo Insulator SmB_{6}

    Directory of Open Access Journals (Sweden)

    Z. Xiang

    2017-09-01

    Full Text Available The Kondo insulator samarium hexaboride (SmB_{6} has been intensely studied in recent years as a potential candidate of a strongly correlated topological insulator. One of the most exciting phenomena observed in SmB_{6} is the clear quantum oscillations appearing in magnetic torque at a low temperature despite the insulating behavior in resistance. These quantum oscillations show multiple frequencies and varied effective masses. The origin of quantum oscillation is, however, still under debate with evidence of both two-dimensional Fermi surfaces and three-dimensional Fermi surfaces. Here, we carry out angle-resolved torque magnetometry measurements in a magnetic field up to 45 T and a temperature range down to 40 mK. With the magnetic field rotated in the (010 plane, the quantum oscillation frequency of the strongest oscillation branch shows a fourfold rotational symmetry. However, in the angular dependence of the amplitude of the same branch, this fourfold symmetry is broken and, instead, a twofold symmetry shows up, which is consistent with the prediction of a two-dimensional Lifshitz-Kosevich model. No deviation of Lifshitz-Kosevich behavior is observed down to 40 mK. Our results suggest the existence of multiple light-mass surface states in SmB_{6}, with their mobility significantly depending on the surface disorder level.

  7. Break-induced telomere synthesis underlies alternative telomere maintenance.

    Science.gov (United States)

    Dilley, Robert L; Verma, Priyanka; Cho, Nam Woo; Winters, Harrison D; Wondisford, Anne R; Greenberg, Roger A

    2016-11-03

    Homology-directed DNA repair is essential for genome maintenance through templated DNA synthesis. Alternative lengthening of telomeres (ALT) necessitates homology-directed DNA repair to maintain telomeres in about 10-15% of human cancers. How DNA damage induces assembly and execution of a DNA replication complex (break-induced replisome) at telomeres or elsewhere in the mammalian genome is poorly understood. Here we define break-induced telomere synthesis and demonstrate that it utilizes a specialized replisome, which underlies ALT telomere maintenance. DNA double-strand breaks enact nascent telomere synthesis by long-tract unidirectional replication. Proliferating cell nuclear antigen (PCNA) loading by replication factor C (RFC) acts as the initial sensor of telomere damage to establish predominance of DNA polymerase δ (Pol δ) through its POLD3 subunit. Break-induced telomere synthesis requires the RFC-PCNA-Pol δ axis, but is independent of other canonical replisome components, ATM and ATR, or the homologous recombination protein Rad51. Thus, the inception of telomere damage recognition by the break-induced replisome orchestrates homology-directed telomere maintenance.

  8. Gauge fields emerging from time-reversal symmetry breaking for spin-5/2 fermions in a honeycomb lattice

    Energy Technology Data Exchange (ETDEWEB)

    Szirmai, G.; Szirmai, E. [ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, E-08860 Castelldefels (Barcelona) (Spain); Research Institute for Solid State Physics and Optics, P.O. Box 49, H-1525 Budapest (Hungary); Zamora, A. [ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, E-08860 Castelldefels (Barcelona) (Spain); Lewenstein, M. [ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, E-08860 Castelldefels (Barcelona) (Spain); ICREA-Institucio Catalana de Recerca i Estudis Avancats, Lluis Companys 23, E-08010 Barcelona (Spain)

    2011-07-15

    We propose an experimentally feasible setup with ultracold alkaline-earth-metal atoms to simulate the dynamics of U(1) lattice gauge theories in 2 + 1 dimensions with a Chern-Simons term. To this end we consider the ground-state properties of spin-5/2 alkaline-earth-metal fermions in a honeycomb lattice. We use the Gutzwiller projected variational approach in the strongly repulsive regime in the case of filling 1/6. The ground state of the system is a chiral spin-liquid state with 2{pi}/3 flux per plaquette, which violates time-reversal invariance. We demonstrate that due to the breaking of time-reversal symmetry the system exhibits quantum Hall effect and chiral edge states. We relate the experimentally accessible spin fluctuations to the emerging gauge-field dynamics. We discuss also properties of the lowest energy competing orders.

  9. The impact of propagation and processing delays on amplitude and oscillation deaths in the presence of symmetry-breaking coupling

    Science.gov (United States)

    Zou, Wei; Zhan, Meng; Kurths, Jürgen

    2017-11-01

    We numerically investigate the impacts of both propagation and processing delays on the emergences of amplitude death (AD) and oscillation death (OD) in one system of two Stuart-Landau oscillators with symmetry-breaking coupling. In either the absence of or the presence of propagation delay, the processing delay destabilizes both AD and OD by revoking the stability of the stable homogenous and inhomogenous steady states. In the AD to OD transition, the processing delay destabilizes first OD from large values of coupling strength until its stable regime completely disappears and then AD from both the upper and lower bounds of the stable coupling interval. Our numerical study sheds new insight lights on the understanding of nontrivial effects of time delays on dynamic activity of coupled nonlinear systems.

  10. Binding energy of (Lambda)He-7 and test of charge symmetry breaking in the Lambda N interaction potential

    Energy Technology Data Exchange (ETDEWEB)

    Hashimoto, O; Honda, D; Kaneta, M; Kato, F; Kawama, D; Maruyama, N; Matsumura, A; Nakamura, S N; Nomura, H; Nonaka, K; Ohtani, A; Okayasu, Y; Osaka, M; Oyamada, M; Sumihama, M; Tamura, H; Baker, O K; Cole, L; Christy, M; Gueye, P; Keppel, C; Tang, L; Yuan, L; Acha, A; Baturin, P; Boeglin, W; Kramer, L; Markowitz, P; Pamela, P; Perez, N; Raue, B; Reinhold, J; Rivera, R; Kato, S; Sato, Y; Takahashi, T; Daniel, A; Hungerford, Ed V; Ispiryan, M; Kalantarians, N; Lan, K J; Li, Y; Miyoshi, T; Randeniya, S; Rodriguez, V M; Bosted, P; Carlini, R; Ent, R; Fenker, H; Gaskell, D; Jones, M; Mack, D; Roche, J; Smith, G; Tvaskis, V; Vulcan, W; Wood, S; Yan, C; Asaturyan, A; Asaturyan, R; Egiyan, K; Mkrtchyan, H; Margaryan, A; Navasardyan, T; Tadevosyan, V; Zamkochian, S; Hu, B; Song, Y; Luo, W; Androic, D; Furic, M; Petkovic, T; Seva, T; Ahmidouch, A; Danagoulian, S; Gasparian, A; Halkyard, R; Johnson, K; Simicevic, N; Wells, S; Niculescu, G; Niculescu, M I; Gan, L; Benmokhtar, F; Horn, T; Elassar, M

    2011-09-01

    The binding energy of 7LambdaHe has been obtained for the first time with reaction spectroscopy using the (e, e'K+) reaction at Jefferson Lab's Hall C. A comparison among the binding energies of the A = 7 T = l iso-triplet hypernuclei, 7LambdaHe, 7LambdaLi*and 7LambdaBe, is made and possible charge symmetry breaking (CSB) in the LambdaN potential is discussed. For 7LambdaHe and 7LambdaBe, the shifts in binding energies are opposite to those predicted by a recent cluster model calculation, which assumes that the unexplained part of the binding energy difference between 4LambdaH and 4LambdaHe, is due to the CSB of the LambdaN potential. Further examination of CSB in light hypernuclear systems is required both experimentally and theoretically.

  11. Manipulating one-way space wave and its refraction by time-reversal and parity symmetry breaking

    Science.gov (United States)

    Poo, Yin; He, Cheng; Xiao, Chao; Lu, Ming-Hui; Wu, Rui-Xin; Chen, Yan-Feng

    2016-01-01

    One-way transmission and negative refraction are the exotic wave properties founded in photonic crystals which attract a great attention due to their promising applications in photonic devices. How to integrate such two phenomena in one material or device is interesting and valuable. In this work, we theoretically and experimentally demonstrate that one-way electromagnetic space wave can be realized by means of two-dimensional magnetic photonic crystals. Simultaneously breaking the time-reversal and parity symmetries of the magnetic photonic crystals designed, we observe oblique incident space wave propagating one-way in the magnetic photonic crystals with positive or negative refraction occurring at interfaces, which can be manipulated upon the incident angle and operating frequency. Our work may offer a potential platform to realize some exotic photoelectronic and microwave devices such as one-way imaging and one-way cloaking. PMID:27387438

  12. β Decay of Ca38: Sensitive test of Isospin Symmetry-Breaking Corrections from Mirror Superallowed 0+→0+ Transitions

    Science.gov (United States)

    Park, H. I.; Hardy, J. C.; Iacob, V. E.; Bencomo, M.; Chen, L.; Horvat, V.; Nica, N.; Roeder, B. T.; Simmons, E.; Tribble, R. E.; Towner, I. S.

    2014-03-01

    We report the first branching-ratio measurement of the superallowed 0+→0+β transition from Ca38. The result, 0.7728(16), leads to an ft value of 3062.3(68) s with a relative precision of ±0.2%. This makes possible a high-precision comparison of the ft values for the mirror superallowed transitions, Ca38→38mK and K38m→Ar38, which sensitively tests the isospin symmetry-breaking corrections required to extract Vud, the up-down quark-mixing element of the Cabibbo-Kobayashi-Maskawa (CKM) matrix, from superallowed β decay. The result supports the corrections currently used and points the way to even tighter constraints on CKM unitarity.

  13. Follow your gut: relaying information from the site of left-right symmetry breaking in the mouse.

    Science.gov (United States)

    Saijoh, Yukio; Viotti, Manuel; Hadjantonakis, Anna-Katerina

    2014-06-01

    A central unresolved question in the molecular cascade that drives establishment of left-right (LR) asymmetry in vertebrates are the mechanisms deployed to relay information between the midline site of symmetry-breaking and the tissues which will execute a program of asymmetric morphogenesis. The cells located between these two distant locations must provide the medium for signal relay. Of these, the gut endoderm is an attractive candidate tissue for signal transmission since it comprises the epithelium that lies between the node, where asymmetry originates, and the lateral plate, where asymmetry can first be detected. Here, focusing on the mouse as a model, we review our current understanding and entertain open questions concerning the relay of LR information from its origin. © 2014 Wiley Periodicals, Inc.

  14. Symmetry-Breaking Charge Transfer in a Zinc Chlorodipyrrin Acceptor for High Open Circuit Voltage Organic Photovoltaics

    KAUST Repository

    Bartynski, Andrew N.

    2015-04-29

    © 2015 American Chemical Society. Low open-circuit voltages significantly limit the power conversion efficiency of organic photovoltaic devices. Typical strategies to enhance the open-circuit voltage involve tuning the HOMO and LUMO positions of the donor (D) and acceptor (A), respectively, to increase the interfacial energy gap or to tailor the donor or acceptor structure at the D/A interface. Here, we present an alternative approach to improve the open-circuit voltage through the use of a zinc chlorodipyrrin, ZCl [bis(dodecachloro-5-mesityldipyrrinato)zinc], as an acceptor, which undergoes symmetry-breaking charge transfer (CT) at the donor/acceptor interface. DBP/ZCl cells exhibit open-circuit voltages of 1.33 V compared to 0.88 V for analogous tetraphenyldibenzoperyflanthrene (DBP)/C60-based devices. Charge transfer state energies measured by Fourier-transform photocurrent spectroscopy and electroluminescence show that C60 forms a CT state of 1.45 ± 0.05 eV in a DBP/C60-based organic photovoltaic device, while ZCl as acceptor gives a CT state energy of 1.70 ± 0.05 eV in the corresponding device structure. In the ZCl device this results in an energetic loss between ECT and qVOC of 0.37 eV, substantially less than the 0.6 eV typically observed for organic systems and equal to the recombination losses seen in high-efficiency Si and GaAs devices. The substantial increase in open-circuit voltage and reduction in recombination losses for devices utilizing ZCl demonstrate the great promise of symmetry-breaking charge transfer in organic photovoltaic devices.

  15. Experimental verification of orbital engineering at the atomic scale: Charge transfer and symmetry breaking in nickelate heterostructures

    Science.gov (United States)

    Phillips, Patrick J.; Rui, Xue; Georgescu, Alexandru B.; Disa, Ankit S.; Longo, Paolo; Okunishi, Eiji; Walker, Fred; Ahn, Charles H.; Ismail-Beigi, Sohrab; Klie, Robert F.

    2017-05-01

    Epitaxial strain, layer confinement, and inversion symmetry breaking have emerged as powerful new approaches to control the electronic and atomic-scale structural properties of complex metal oxides. Trivalent rare-earth (RE) nickelate R E NiO3 heterostructures have been shown to be exemplars since the orbital occupancy, degeneracy, and, consequently, electronic/magnetic properties can be altered as a function of epitaxial strain, layer thickness, and superlattice structure. One recent example is the tricomponent LaTiO3-LaNiO3-LaAlO3 superlattice which exhibits charge transfer and orbital polarization as the result of its interfacial dipole electric field. A crucial step towards control of these parameters for future electronic and magnetic device applications is to develop an understanding of both the magnitude and range of the octahedral network's response towards interfacial strain and electric fields. An approach that provides atomic-scale resolution and sensitivity towards the local octahedral distortions and orbital occupancy is therefore required. Here, we employ atomic-resolution imaging coupled with electron spectroscopies and first-principles theory to examine the role of interfacial charge transfer and symmetry breaking in a tricomponent nickelate superlattice system. We find that nearly complete charge transfer occurs between the LaTiO3 and LaNiO3 layers, resulting in a mixed Ni2 +/Ni3 + valence state. We further demonstrate that this charge transfer is highly localized with a range of about 1 unit cell within the LaNiO3 layers. We also show how Wannier-function-based electron counting provides a simple physical picture of the electron distribution that connects directly with formal valence charges. The results presented here provide important feedback to synthesis efforts aimed at stabilizing new electronic phases that are not accessible by conventional bulk or epitaxial film approaches.

  16. β decay of 32Cl: Precision γ-ray spectroscopy and a measurement of isospin-symmetry breaking

    Science.gov (United States)

    Melconian, D.; Triambak, S.; Bordeanu, C.; García, A.; Hardy, J. C.; Iacob, V. E.; Nica, N.; Park, H. I.; Tabacaru, G.; Trache, L.; Towner, I. S.; Tribble, R. E.; Zhai, Y.

    2012-02-01

    Background: Models to calculate small isospin-symmetry-breaking effects in superallowed Fermi decays have been placed under scrutiny in recent years. A stringent test of these models is to measure transitions for which the correction is predicted to be large. The decay of 32Cl decay provides such a test case.Purpose: The purpose of this paper is to improve the γ yields following the β decay of 32Cl and to determine the ft values of the the β branches, particularly the one to the isobaric-analog state in 32S.Method: Reaction-produced and recoil-spectrometer-separated 32Cl is collected in a tape and transported to a counting location where β-γ coincidences are measured with a precisely calibrated high-purity germanium detector.Results: The precision on the γ yields for most of the known β branches has been improved by about an order of magnitude, and many new transitions have been observed. We have determined 32Cl-decay transition strengths extending up to Ex˜11 MeV. The ft value for the decay to the isobaric-analog state in 32S has been measured. A comparison to a shell-model calculation shows good agreement.Conclusions: We have experimentally determined the isospin-symmetry-breaking correction to the superallowed transition of this decay to be (δC-δNS)exp=5.4(9)%, significantly larger than for any other known superallowed Fermi transition. This correction agrees with a shell-model calculation, which yields δC-δNS=4.8(5)%. Our results also provide a way to improve the measured ft values for the β decay of 32Ar.

  17. Spectroscopic Visualization of Inversion and Time-Reversal Symmetry Breaking Weyl Semi-metals

    Science.gov (United States)

    Beidenkopf, Haim

    A defining property of a topological material is the existence of surface bands that cannot be realized but as the termination of a topological bulk. In a Weyl semi-metal these surface states are in the form of Fermi-arcs. Their open-contour Fermi-surface curves between pairs of surface projections of bulk Weyl cones. Such Dirac-like bulk bands, as opposed to the gapped bulk of topological insulators, land a unique opportunity to examine the deep notion of bulk to surface correspondence. We study the intricate properties both of inversion symmetry broken and of time-reversal symmetry broken Weyl semimetals using scanning tunneling spectroscopy. We visualize the Fermi arc states on the surface of the non-centrosymmetric Weyl semi-metal TaAs. Using the distinct structure and spatial distribution of the wavefunctions associated with the different topological and trivial bands we detect the scattering processes that involve Fermi arcs. Each of these imaged scattering processes entails information on the unique nature of Fermi arcs and their correspondence to the topological bulk. We further visualize the magnetic response of the candidate magnetic Weyl semimetal GdPtBi in which the magnetic order parameter is coupled to the topological classification. European Research Council (ERC-StG no. 678702, TOPO-NW\\x9D), the Israel Science Foundation (ISF), and the United States-Israel Binational Science Foundation (BSF).

  18. Polar Kerr Effect as Probe for Time-Reversal Symmetry Breaking in Unconventional Superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Kapitulnik, A.

    2010-05-26

    The search for broken time reversal symmetry (TRSB) in unconventional superconductors intensified in the past year as more systems have been predicted to possess such a state. Following our pioneering study of TRSB states in Sr{sub 2}RuO{sub 4} using magneto-optic probes, we embarked on a systematic study of several other of these candidate systems. The primary instrument for our studies is the Sagnac magneto-optic interferometer, which we recently developed. This instrument can measure magneto-optic Faraday or Kerr effects with an unprecedented sensitivity of 10 nanoradians at temperatures as low as 100 mK. In this paper we review our recent studies of TRSB in several systems, emphasizing the study of the pseudogap state of high temperature superconductors and the inverse proximity effect in superconductor/ferromagnet proximity structures.

  19. Breaking inversion symmetry in a state-dependent honeycomb lattice: artificial graphene with tunable band gap

    Science.gov (United States)

    Weinberg, M.; Staarmann, C.; Ölschläger, C.; Simonet, J.; Sengstock, K.

    2016-06-01

    Here, we present the application of a novel method for controlling the geometry of a state-dependent honeycomb lattice: the energy offset between the two sublattices of the honeycomb structure can be adjusted by rotating the atomic quantization axis. This enables us to continuously tune between a homogeneous graphene-like honeycomb lattice and a triangular lattice and to open an energy gap at the characteristic Dirac points. We probe the symmetry of the lattice with microwave spectroscopy techniques and investigate the behavior of atoms excited to the second energy band. We find a striking influence of the energy gap at the Dirac cones onto the lifetimes of bosonic atoms in the excited band.

  20. A symmetry-breaking phase transition in a dynamical decision model

    Science.gov (United States)

    Lambert, Gaultier; Chevereau, Guillaume; Bertin, Eric

    2011-06-01

    We consider a simple decision model in which a set of agents randomly choose one of two competing shops selling the same perishable products (typically food). The satisfaction of agents with respect to a given store is related to the freshness of the previously bought products. Agents select with a higher probability the store that they are most satisfied with. Studying the model from a statistical physics perspective, both through numerical simulations and mean-field analytical methods, we find a rich behaviour with continuous and discontinuous phase transitions between a symmetric phase where both stores maintain the same level of activity, and a phase with broken symmetry where one of the two shops attracts more customers than the other.

  1. Finding symmetry breaking Hartree-Fock solutions: The case of triplet instability

    Science.gov (United States)

    Tóth, Zsuzsanna; Pulay, Peter

    2016-10-01

    Determining the lowest unrestricted Hartree-Fock (UHF) solution is often difficult in even-electron systems. We have developed a deterministic method for locating approximately the UHF minimum using the restricted Hartree-Fock triplet instability matrix. The current method is truncated to fourth order. The minimum energy solution for this model can be determined by solving a small linear system of equations. This solution gives a suitable starting point to determine the exact UHF solution. This should be useful for the black-box determination of active spaces spanned by the fractionally occupied charge natural orbitals of the ground-state UHF wavefunction. The results can be generalized to higher (6th and 8th) degree expansions (odd expansion orders vanish by symmetry), and to other types of instability, including complex instability. The results are illustrated by calculations on ozone, benzene, nitrobenzene, butadiene, hexatriene, octatetraene, dichromium, and nickel porphine. Further examples are given in the supplementary material (ftp://ftp.aip.org/epaps/journ_chem_phys/E-JCPSA6-145-011640).

  2. Emergent dynamics from spiking neuron networks through symmetry breaking of connectivity.

    Directory of Open Access Journals (Sweden)

    M Marmaduke Woodman

    Full Text Available Low-dimensional attractive manifolds with flows prescribing the evolution of state variables are commonly used to capture the lawful behavior of behavioral and cognitive variables. Neural network dynamics underlie many of the mechanistic explanations of function and demonstrate the existence of such low-dimensional attractive manifolds. In this study, we focus on exploring the network mechanisms due to asymmetric couplings giving rise to the emergence of arbitrary flows in low dimensional spaces. Here we use a spiking neural network model, specifically the theta neuron model and simple synaptic dynamics, to show how a qualitatively identical set of basic behaviors arises from different combinations of couplings with broken symmetry, in fluctuations of both firing rate and spike timing. We further demonstrate how such network dynamics can be combined to create more complex processes. These results suggest that 1 asymmetric coupling is not always a variance to be averaged over, 2 different networks may produce the same dynamics by different dynamical routes and 3 complex dynamics may be formed by simpler dynamics through a combination of couplings.

  3. Switching through symmetry breaking for transmission in a T-shaped photonic waveguide coupled with two identical nonlinear micro-cavities.

    Science.gov (United States)

    Bulgakov, Evgeny; Sadreev, Almas

    2011-08-10

    Using coupled mode theory we consider transmission in a T-shaped waveguide coupled with two identical symmetrically positioned nonlinear micro-cavities with mirror symmetry. For input power injected into the central waveguide we show the existence of a symmetry breaking solution which is a result of mixing of the symmetrical input wave with an antisymmetric standing wave in the Fabry-Pérot interferometer. With growth of the input power, a feature in the form of loops arises in the solution which originates from bistability in the transmission in the output left/right waveguide coupled with the first/second nonlinear cavity. The domains of stability of the solution are found. The breaking of mirror symmetry gives rise to nonsymmetrical left and right outputs. We demonstrate that this phenomenon can be explored for all-optical switching of light transmission from the left output waveguide to the right one by application of input pulses.

  4. Production Cross-Section Estimates for Strongly-Interacting Electroweak-Symmetry Breaking Sector Resonances at Particle Colliders

    Science.gov (United States)

    Dobado, Antonio; Guo, Feng-Kun; Llanes-Estrada, Felipe J.

    2015-12-01

    We are exploring a generic strongly-interacting Electroweak Symmetry Breaking Sector (EWSBS) with the low-energy effective field theory for the four experimentally known particles (W±L, ZL, h) and its dispersion-relation based unitary extension. In this contribution we provide simple estimates for the production cross-section of pairs of the EWSBS bosons and their resonances at proton-proton colliders as well as in a future e‑e+ (or potentially a μ‑μ+) collider with a typical few-TeV energy. We examine the simplest production mechanisms, tree-level production through a W (dominant when quantum numbers allow) and the simple effective boson approximation (in which the electroweak bosons are considered as collinear partons of the colliding fermions). We exemplify with custodial isovector and isotensor resonances at 2 TeV, the energy currently being discussed because of a slight excess in the ATLAS 2-jet data. We find it hard, though not unthinkable, to ascribe this excess to one of these WLWL rescattering resonances. An isovector resonance could be produced at a rate smaller than, but close to earlier CMS exclusion bounds, depending on the parameters of the effective theory. The ZZ excess is then problematic and requires additional physics (such as an additional scalar resonance). The isotensor one (that would describe all charge combinations) has smaller cross-section. Supported by the Spanish Excellence Network on Hadronic Physics FIS2014-57026-REDT, by Spanish Grants Universidad Complutense UCM:910309 and Ministerio de Economia y Competitividad MINECO:FPA2011-27853-C02-01, MINECO:FPA2014-53375-C2-1-P, by the Deutsche Forschungsgemeinschaft and National Natural Science Foundation of China through Funds Provided to the Sino-German CRC 110 “Symmetries and the Emergence of Structure in QCD” (NSFC Grant No. 11261130311) and by NSFC (Grant No. 11165005)

  5. A symmetry breaking mechanism by parity assignment in the noncommutative Higgs model

    Science.gov (United States)

    Yang, Masaki J. S.

    2017-12-01

    We apply the orbifold grand unified theory (GUT) mechanism to the noncommutative Higgs model. An assignment of Z2 parity to the “constituent fields” induces parity assignments of both the gauge and Higgs bosons, because these bosons are treated as some kind of composite fields in this formalism.

  6. Spontaneous time reversal symmetry breaking in atomically confined two-dimensional impurity bands in silicon and germanium

    Science.gov (United States)

    Ghosh, Arindam

    Three-dimensional bulk-doped semiconductors, in particular phosphorus (P)-doped silicon (Si) and germanium (Ge), are among the best studied systems for many fundamental concepts in solid state physics, ranging from the Anderson metal-insulator transition to the many-body Coulomb interaction effects on quantum transport. Recent advances in material engineering have led to vertically confined doping of phosphorus (P) atoms inside bulk crystalline silicon and germanium, where the electron transport occurs through one or very few atomic layers, constituting a new and unique platform to investigate many of these phenomena at reduced dimensions. In this talk I shall present results of extensive quantum transport experiments in delta-doped silicon and germanium epilayers, over a wide range of doping density that allow independent tuning of the on-site Coulomb interaction and hopping energy scales. We find that low-frequency flicker noise, or the 1 / f noise, in the electrical conductance of these systems is exceptionally low, and in fact among the lowest when compared with other low-dimensional materials. This is attributed to the physical separation of the conduction electrons, embedded inside the crystalline semiconductor matrix, from the charged fluctuators at the surface. Most importantly, we find a remarkable suppression of weak localization effects, including the quantum correction to conductivity and universal conductance fluctuations, with decreasing doping density or, equivalently, increasing effective on-site Coulomb interaction. In-plane magneto-transport measurements indicate the presence of intrinsic local spin fluctuations at low doping although no signatures of long range magnetic order could be identified. We argue that these results indicate a spontaneous breakdown of time reversal symmetry, which is one of the most fundamental and robust symmetries of nonmagnetic quantum systems. While the microscopic origin of this spontaneous time reversal symmetry

  7. Stability and symmetry of ion-induced surface patterning

    Science.gov (United States)

    Matthes, Christopher S. R.; Ghoniem, Nasr M.; Walgraef, Daniel

    2017-12-01

    We present a continuum model of ion-induced surface patterning. The model incorporates the atomic processes of sputtering, re-deposition and surface diffusion, and is shown to display the generic features of the damped Kuramoto-Sivashinsky (KS) equation of non-linear dynamics. Linear and non-linear stability analyses of the evolution equation give estimates of the emerging pattern wavelength and spatial symmetry. The analytical theory is confirmed by numerical simulations of the evolution equation with the Fast Fourier Transform method, where we show the influence of the incident ion angle, flux, and substrate surface temperature. It is shown that large local geometry variations resulting in quadratic non-linearities in the evolution equation dominate pattern selection and stability at long time scales.

  8. Explaining the symmetry breaking observed in the endofullerenes H2@C60, HF@C60, and H2O@C60.

    Science.gov (United States)

    Felker, Peter M; Vlček, Vojtěch; Hietanen, Isaac; FitzGerald, Stephen; Neuhauser, Daniel; Bačić, Zlatko

    2017-11-29

    Symmetry breaking has been recently observed in the endofullerenes M@C 60 (M = H 2 , HF, H 2 O), manifesting in the splittings of the three-fold degenerate ground states of the endohedral ortho-H 2 , ortho-H 2 O and the j = 1 level of HF. The nature of the interaction causing the symmetry breaking is established in this study. A fragment of the solid C 60 is considered, comprised of the central C 60 molecule surrounded by twelve nearest-neighbor (NN) C 60 molecules. The fullerenes have either P (major) or H (minor) orientational orderings, and are assumed to be rigid with I h symmetry. Only the central C 60 is occupied by the guest molecule M, while the NN fullerenes are all empty. The key proposition of the study is that the electrostatic interactions between the charge densities on the NN C 60 molecules and that on M inside the central C 60 give rise to the symmetry breaking responsible for the measured level splittings. Using this model, the M@C 60 level splittings of interest are calculated variationally and using perturbation theory, for both the P and H orientations. Those obtained for the dominant P orientation are in excellent agreement with the experimental results, with respect to the splitting magnitudes and patterns, for all three M@C 60 systems considered, pointing strongly to the quadrupolar M-NN interactions as the main cause of the symmetry breaking. The level splittings calculated for the H orientation are about 30 times smaller than the ones in the P orientation.

  9. Small-angle light scattering symmetry breaking in polymer-dispersed liquid crystal films with inhomogeneous electrically controlled interface anchoring

    Energy Technology Data Exchange (ETDEWEB)

    Loiko, V. A., E-mail: loiko@ifanbel.bas-net.by; Konkolovich, A. V. [National Academy of Sciences of Belarus, Stepanov Institute of Physics (Belarus); Zyryanov, V. Ya. [Russian Academy of Sciences, Kirensky Institute of Physics, Federal Research Center “Krasnoyarsk Scientific Center,” Siberian Branch (Russian Federation); Miskevich, A. A. [National Academy of Sciences of Belarus, Stepanov Institute of Physics (Belarus)

    2017-03-15

    We have described the method of analyzing and reporting on the results of calculation of the small-angle structure of radiation scattered by a polymer-dispersed liquid crystal film with electrically controlled interfacial anchoring. The method is based on the interference approximation of the wave scattering theory and the hard disk model. Scattering from an individual liquid crystal droplet has been described using the anomalous diffraction approximation extended to the case of droplets with uniform and nonuniform interface anchoring at the droplet–polymer boundary. The director field structure in an individual droplet is determined from the solution of the problem of minimizing the volume density of the free energy. The electrooptical effect of symmetry breaking in the angular distribution of scattered radiation has been analyzed. This effect means that the intensities of radiation scattered within angles +θ{sub s} and–θ{sub s} relative to the direction of illumination in the scattering plane can be different. The effect is of the interference origin and is associated with asymmetry of the phase shift of the wavefront of an incident wave from individual parts of the droplet, which appears due to asymmetry of the director field structure in the droplet, caused by nonuniform anchoring of liquid crystal molecules with the polymer on its surface. This effect is analyzed in the case of normal illumination of the film depending on the interfacial anchoring at the liquid crystal–polymer interface, the orientation of the optical axes of droplets, their concentration, sizes, anisometry, and polydispersity.

  10. On the Unique Identification of the Polar Optical Kerr Effect with Microscopic Time-Reversal Symmetry Breaking

    Science.gov (United States)

    Fried, Alexander

    2014-03-01

    Over the past few decades, there has been an ongoing discussion regarding the choice of electromagnetic constitutive relations which correctly model linear media that exhibit natural optical activity, with most recent debate involving applications to optical phenomena in chiral superconductors and other gyrotropic media. In particular, is the controversy as to whether light incident upon naturally active materials will exhibit non-reciprocal polarization rotation in reflection, also known as the magneto-optical Kerr effect. A variety of constitutive relations have been postulated which describe the Electrodynamics within such materials, but only some of them predict this phenomena, while experimental investigations have similarly yielded mixed results. One such experiment uses a modified Sagnac Interferometer for high resolution and unique measurements of the Kerr effect and also has the property that it inherently tests for ``reciprocity,'' a metrological symmetry wherein the results of a measurement are the same as when an optical source and an optical detector are interchanged. We demonstrate theoretically and experimentally that the Sagnac Interferometer only measures time-reversal symemtry breaking and that gyrotropic materials can not give rise to a Kerr Effect.

  11. The Viedma deracemization of racemic conglomerate mixtures as a paradigm of spontaneous mirror symmetry breaking in aggregation and polymerization.

    Science.gov (United States)

    Blanco, Celia; Crusats, Joaquim; El-Hachemi, Zoubir; Moyano, Albert; Veintemillas-Verdaguer, Sabino; Hochberg, David; Ribó, Josep M

    2013-12-02

    Simulations of a chemical kinetics model, based on the free-energy relationships of classical primary nucleation theory, show that the deracemization phenomenon in systems of achiral or fast racemizing compounds yielding enantiopure crystals as the more stable solid phase is a true spontaneous mirror symmetry breaking process (SMSB). That is, the achievement of a stationary chiral state is more stable than the racemic one. The model translates the free-energy relationships determined by the existence of a critical size cluster to a chemical kinetics model, in which the consideration of forward and backward reaction rate constants avoids the misuse of network parameters that violate thermodynamic constraints (microreversibility principle), which would lead to apparent in silico SMSB. The model provides qualitative agreement for deracemizations by mechanical attrition of visible crystals, as well as for those obtained under temperature gradients. The analysis of the effect of the system parameters to obtain a SMSB scenario shows that the network possesses the principal characteristics of SMSB networks: 1) an enantioselective autocatalytic stage, corresponding to the non-linear kinetics of enantioselective (homochiral) cluster-to-cluster growth, and 2) the mutual inhibition step originating in the backward flow of chiral clusters towards smaller achiral clusters, or even to a racemizing monomer. The application of such a SMSB kinetic model to enantioselective polymerizations and to chiral biopolymers is discussed. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Small-angle light scattering symmetry breaking in polymer-dispersed liquid crystal films with inhomogeneous electrically controlled interface anchoring

    Science.gov (United States)

    Loiko, V. A.; Konkolovich, A. V.; Zyryanov, V. Ya.; Miskevich, A. A.

    2017-03-01

    We have described the method of analyzing and reporting on the results of calculation of the small-angle structure of radiation scattered by a polymer-dispersed liquid crystal film with electrically controlled interfacial anchoring. The method is based on the interference approximation of the wave scattering theory and the hard disk model. Scattering from an individual liquid crystal droplet has been described using the anomalous diffraction approximation extended to the case of droplets with uniform and nonuniform interface anchoring at the droplet-polymer boundary. The director field structure in an individual droplet is determined from the solution of the problem of minimizing the volume density of the free energy. The electrooptical effect of symmetry breaking in the angular distribution of scattered radiation has been analyzed. This effect means that the intensities of radiation scattered within angles +θ s and-θ s relative to the direction of illumination in the scattering plane can be different. The effect is of the interference origin and is associated with asymmetry of the phase shift of the wavefront of an incident wave from individual parts of the droplet, which appears due to asymmetry of the director field structure in the droplet, caused by nonuniform anchoring of liquid crystal molecules with the polymer on its surface. This effect is analyzed in the case of normal illumination of the film depending on the interfacial anchoring at the liquid crystal-polymer interface, the orientation of the optical axes of droplets, their concentration, sizes, anisometry, and polydispersity.

  13. Dynamical instability of white dwarfs and breaking of spherical symmetry under the presence of extreme magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Coelho, J. G.; Cáceres, D. L.; Rueda, J. A.; Ruffini, R. [Dipartimento di Fisica and ICRA, Sapienza Università di Roma, P.le Aldo Moro 5, I-00185 Rome (Italy); Marinho, R. M.; Malheiro, M. [Departamento de Física, Instituto Tecnológico de Aeronáutica, ITA, São José dos Campos, 12228-900 SP (Brazil); Negreiros, R., E-mail: jaziel.coelho@icranet.org, E-mail: jorge.rueda@icra.it, E-mail: m.malheiro@ita.br [Instituto de Física, Universidade Federal Fluminense, UFF, Niterói, 24210-346 RJ (Brazil)

    2014-10-10

    Massive, highly magnetized white dwarfs with fields up to 10{sup 9} G have been observed and theoretically used for the description of a variety of astrophysical phenomena. Ultramagnetized white dwarfs with uniform interior fields up to 10{sup 18} G have been recently purported to obey a new maximum mass limit, M {sub max} ≈ 2.58 M {sub ☉}, which largely overcomes the traditional Chandrasekhar value, M {sub Ch} ≈ 1.44 M {sub ☉}. Such a larger limit would make these astrophysical objects viable candidates for the explanation of the superluminous population of Type Ia supernovae. We show that several macro and micro physical aspects such as gravitational, dynamical stability, breaking of spherical symmetry, general relativity, inverse β decay, and pycnonuclear fusion reactions are of most relevance for the self-consistent description of the structure and assessment of stability of these objects. It is shown in this work that the first family of magnetized white dwarfs indeed satisfy all the criteria of stability, while the ultramagnetized white dwarfs are very unlikely to exist in nature since they violate minimal requests of stability. Therefore, the canonical Chandrasekhar mass limit of white dwarfs still has to be applied.

  14. Magnetic structure and ferroelectric activity in orthorhombic YMnO3: Relative roles of magnetic symmetry breaking and atomic displacements

    Science.gov (United States)

    Solovyev, I. V.; Valentyuk, M. V.; Mazurenko, V. V.

    2012-10-01

    We discuss the relative roles played by the magnetic inversion symmetry breaking and the ferroelectric (FE) atomic displacements in the multiferroic state of YMnO3. For these purposes we derive a realistic low-energy model, using results of first-principles electronic structure calculations and experimental parameters of the crystal structure below and above the FE transition. Then, we solve this model in the mean-field Hartree-Fock approximation. We argue that the multiferroic state in YMnO3 has a magnetic origin, and the centrosymmetric Pbnm structure is formally sufficient for explaining the main details of the noncentrosymmetric magnetic ground state. The relativistic spin-orbit interaction lifts the degeneracy, caused by the frustration of isotropic exchange interactions in the ab plane, and stabilizes a twofold periodic noncollinear magnetic state, which is similar to the E state apart from the spin canting. The noncentrosymmetric atomic displacements in the P21nm phase reduce the spin canting, but do not change the symmetry of the magnetic state. The effect of the P21nm distortion on the FE polarization ΔPa, parallel to the orthorhombic a axis, is twofold: (i) It gives rise to ionic contributions, associated with the oxygen and yttrium sites; (ii) it affects the electronic polarization, mainly through the change of the spin canting. The relatively small value of ΔPa, observed in the experiment, is caused by a partial cancellation of the electronic and ionic contributions, as well as different contributions in the ionic part, which takes place for the experimental P21nm structure. The twofold periodic magnetic state competes with the fourfold periodic one and, even in the displaced P21nm phase, these two states continue to coexist in a narrow energy range. Finally, we theoretically optimize the crystal structure. For these purposes we employ the LSDA+U approach and assume the collinear E-type antiferromagnetic alignment. Then, we use the obtained structural

  15. Consciousness induced restoration of time symmetry (CIRTS): a psychophysical theoretical perspective

    NARCIS (Netherlands)

    Bierman, D.J.

    2010-01-01

    A theoretical framework is proposed that starts from the assumption that information processing by a brain, while it is sustaining consciousness, is restoring the break in time symmetry in physics. No specifics are given with regard to which physical formalism, either quantum or classical, is the

  16. Hecate/Grip2a acts to reorganize the cytoskeleton in the symmetry-breaking event of embryonic axis induction.

    Science.gov (United States)

    Ge, Xiaoyan; Grotjahn, Danielle; Welch, Elaine; Lyman-Gingerich, Jamie; Holguin, Christiana; Dimitrova, Eva; Abrams, Elliot W; Gupta, Tripti; Marlow, Florence L; Yabe, Taijiro; Adler, Anna; Mullins, Mary C; Pelegri, Francisco

    2014-06-01

    Maternal homozygosity for three independent mutant hecate alleles results in embryos with reduced expression of dorsal organizer genes and defects in the formation of dorsoanterior structures. A positional cloning approach identified all hecate mutations as stop codons affecting the same gene, revealing that hecate encodes the Glutamate receptor interacting protein 2a (Grip2a), a protein containing multiple PDZ domains known to interact with membrane-associated factors including components of the Wnt signaling pathway. We find that grip2a mRNA is localized to the vegetal pole of the oocyte and early embryo, and that during egg activation this mRNA shifts to an off-center vegetal position corresponding to the previously proposed teleost cortical rotation. hecate mutants show defects in the alignment and bundling of microtubules at the vegetal cortex, which result in defects in the asymmetric movement of wnt8a mRNA as well as anchoring of the kinesin-associated cargo adaptor Syntabulin. We also find that, although short-range shifts in vegetal signals are affected in hecate mutant embryos, these mutants exhibit normal long-range, animally directed translocation of cortically injected dorsal beads that occurs in lateral regions of the yolk cortex. Furthermore, we show that such animally-directed movement along the lateral cortex is not restricted to a single arc corresponding to the prospective dorsal region, but occur in multiple meridional arcs even in opposite regions of the embryo. Together, our results reveal a role for Grip2a function in the reorganization and bundling of microtubules at the vegetal cortex to mediate a symmetry-breaking short-range shift corresponding to the teleost cortical rotation. The slight asymmetry achieved by this directed process is subsequently amplified by a general cortical animally-directed transport mechanism that is neither dependent on hecate function nor restricted to the prospective dorsal axis.

  17. Planar Cell Polarity Breaks the Symmetry of PAR Protein Distribution prior to Mitosis in Drosophila Sensory Organ Precursor Cells.

    Science.gov (United States)

    Besson, Charlotte; Bernard, Fred; Corson, Francis; Rouault, Hervé; Reynaud, Elodie; Keder, Alyona; Mazouni, Khalil; Schweisguth, François

    2015-04-20

    During development, cell-fate diversity can result from the unequal segregation of fate determinants at mitosis. Polarization of the mother cell is essential for asymmetric cell division (ACD). It often involves the formation of a cortical domain containing the PAR complex proteins Par3, Par6, and atypical protein kinase C (aPKC). In the fly notum, sensory organ precursor cells (SOPs) divide asymmetrically within the plane of the epithelium and along the body axis to generate two distinct cells. Fate asymmetry depends on the asymmetric localization of the PAR complex. In the absence of planar cell polarity (PCP), SOPs divide with a random planar orientation but still asymmetrically, showing that PCP is dispensable for PAR asymmetry at mitosis. To study when and how the PAR complex localizes asymmetrically, we have used a quantitative imaging approach to measure the planar polarization of the proteins Bazooka (Baz, fly Par3), Par6, and aPKC in living pupae. By using imaging of functional GFP-tagged proteins with image processing and computational modeling, we find that Baz, Par6, and aPKC become planar polarized prior to mitosis in a manner independent of the AuroraA kinase and that PCP is required for the planar polarization of Baz, Par6, and aPKC during interphase. This indicates that a "mitosis rescue" mechanism establishes asymmetry at mitosis in PCP mutants. This study therefore identifies PCP as the initial symmetry-breaking signal for the planar polarization of PAR proteins in asymmetrically dividing SOPs. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Stability and Symmetry-Breaking Bifurcation for the Ground States of a NLS with a δ' Interaction

    Science.gov (United States)

    Adami, Riccardo; Noja, Diego

    2013-02-01

    We determine and study the ground states of a focusing Schrödinger equation in dimension one with a power nonlinearity | ψ|2 μ ψ and a strong inhomogeneity represented by a singular point perturbation, the so-called (attractive) δ' interaction, located at the origin. The time-dependent problem turns out to be globally well posed in the subcritical regime, and locally well posed in the supercritical and critical regime in the appropriate energy space. The set of the (nonlinear) ground states is completely determined. For any value of the nonlinearity power, it exhibits a symmetry breaking bifurcation structure as a function of the frequency (i.e., the nonlinear eigenvalue) ω. More precisely, there exists a critical value ω* of the nonlinear eigenvalue ω, such that: if ω0 ground state and it is an odd function; if ω > ω* then there exist two non-symmetric ground states. We prove that before bifurcation (i.e., for ω ground state is orbitally stable. After bifurcation (ω = ω* + 0), ground states are stable if μ does not exceed a value {μ^star} that lies between 2 and 2.5, and become unstable for μ > μ*. Finally, for μ > 2 and {ω ≫ ω^*}, all ground states are unstable. The branch of odd ground states for ω ω*, obtaining a family of orbitally unstable stationary states. Existence of ground states is proved by variational techniques, and the stability properties of stationary states are investigated by means of the Grillakis-Shatah-Strauss framework, where some non-standard techniques have to be used to establish the needed properties of linearization operators.

  19. Hecate/Grip2a acts to reorganize the cytoskeleton in the symmetry-breaking event of embryonic axis induction.

    Directory of Open Access Journals (Sweden)

    Xiaoyan Ge

    2014-06-01

    Full Text Available Maternal homozygosity for three independent mutant hecate alleles results in embryos with reduced expression of dorsal organizer genes and defects in the formation of dorsoanterior structures. A positional cloning approach identified all hecate mutations as stop codons affecting the same gene, revealing that hecate encodes the Glutamate receptor interacting protein 2a (Grip2a, a protein containing multiple PDZ domains known to interact with membrane-associated factors including components of the Wnt signaling pathway. We find that grip2a mRNA is localized to the vegetal pole of the oocyte and early embryo, and that during egg activation this mRNA shifts to an off-center vegetal position corresponding to the previously proposed teleost cortical rotation. hecate mutants show defects in the alignment and bundling of microtubules at the vegetal cortex, which result in defects in the asymmetric movement of wnt8a mRNA as well as anchoring of the kinesin-associated cargo adaptor Syntabulin. We also find that, although short-range shifts in vegetal signals are affected in hecate mutant embryos, these mutants exhibit normal long-range, animally directed translocation of cortically injected dorsal beads that occurs in lateral regions of the yolk cortex. Furthermore, we show that such animally-directed movement along the lateral cortex is not restricted to a single arc corresponding to the prospective dorsal region, but occur in multiple meridional arcs even in opposite regions of the embryo. Together, our results reveal a role for Grip2a function in the reorganization and bundling of microtubules at the vegetal cortex to mediate a symmetry-breaking short-range shift corresponding to the teleost cortical rotation. The slight asymmetry achieved by this directed process is subsequently amplified by a general cortical animally-directed transport mechanism that is neither dependent on hecate function nor restricted to the prospective dorsal axis.

  20. Symmetry breaking by autocatalysis

    Energy Technology Data Exchange (ETDEWEB)

    Lippmann, D. [Department of Chemistry, Southwest Texas State University, San Marcos, Texas 78666 (United States)]|[Center for Studies in Statistical Mechanics and Complex Systems, The University of Texas, Austin, Texas 78712 (United States); Pattanayak, A. [Center for Studies in Statistical Mechanics and Complex Systems, The University of Texas, Austin, Texas 78712 (United States)]|[Department of Chemistry, University of Toronto, Toronto, Ontario, M5S1A1 (CANADA)

    1996-07-01

    The origin of homochirality in biochemical compounds has been a mystery since this homochirality was discovered. In 1953, Frank proposed that a combination of autocatalysis and mutual destruction by a pair of enantiomers will produce an extremely large excess of one enantiomer if there is a small initial excess of that enantiomer. This mechanism is explored further in this article. (AIP)

  1. Break induced replication in eukaryotes: mechanisms, functions, and consequences.

    Science.gov (United States)

    Sakofsky, Cynthia J; Malkova, Anna

    2017-08-01

    Break-induced replication (BIR) is an important pathway specializing in repair of one-ended double-strand DNA breaks (DSBs). This type of DSB break typically arises at collapsed replication forks or at eroded telomeres. BIR initiates by invasion of a broken DNA end into a homologous template followed by initiation of DNA synthesis that can proceed for hundreds of kilobases. This synthesis is drastically different from S-phase replication in that instead of a replication fork, BIR proceeds via a migrating bubble and is associated with conservative inheritance of newly synthesized DNA. This unusual mode of DNA replication is responsible for frequent genetic instabilities associated with BIR, including hyper-mutagenesis, which can lead to the formation of mutation clusters, extensive loss of heterozygosity, chromosomal translocations, copy-number variations and complex genomic rearrangements. In addition to budding yeast experimental systems that were initially employed to investigate eukaryotic BIR, recent studies in different organisms including humans, have provided multiple examples of BIR initiated within different cellular contexts, including collapsed replication fork and telomere maintenance in the absence of telomerase. In addition, significant progress has been made towards understanding microhomology-mediated BIR (MMBIR) that can promote complex chromosomal rearrangements, including those associated with cancer and those leading to a number of neurological disorders in humans.

  2. Avoiding symmetry-breaking spatial non-uniformity in deformable image registration via a quasi-volume-preserving constraint.

    Science.gov (United States)

    Aganj, Iman; Reuter, Martin; Sabuncu, Mert R; Fischl, Bruce

    2015-02-01

    The choice of a reference image typically influences the results of deformable image registration, thereby making it asymmetric. This is a consequence of a spatially non-uniform weighting in the cost function integral that leads to general registration inaccuracy. The inhomogeneous integral measure--which is the local volume change in the transformation, thus varying through the course of the registration--causes image regions to contribute differently to the objective function. More importantly, the optimization algorithm is allowed to minimize the cost function by manipulating the volume change, instead of aligning the images. The approaches that restore symmetry to deformable registration successfully achieve inverse-consistency, but do not eliminate the regional bias that is the source of the error. In this work, we address the root of the problem: the non-uniformity of the cost function integral. We introduce a new quasi-volume-preserving constraint that allows for volume change only in areas with well-matching image intensities, and show that such a constraint puts a bound on the error arising from spatial non-uniformity. We demonstrate the advantages of adding the proposed constraint to standard (asymmetric and symmetrized) demons and diffeomorphic demons algorithms through experiments on synthetic images, and real X-ray and 2D/3D brain MRI data. Specifically, the results show that our approach leads to image alignment with more accurate matching of manually defined neuroanatomical structures, better tradeoff between image intensity matching and registration-induced distortion, improved native symmetry, and lower susceptibility to local optima. In summary, the inclusion of this space- and time-varying constraint leads to better image registration along every dimension that we have measured it. Copyright © 2014 Elsevier Inc. All rights reserved.

  3. Investigation of the charge symmetry breaking reaction dd → {sup 4}Heπ{sup 0} with the WASA-at-COSY facility

    Energy Technology Data Exchange (ETDEWEB)

    Zurek, Maria Katarzyna

    2017-07-01

    Probing elementary symmetries and symmetry breaking tests our understanding of the theory of strong forces, Quantum Chromodynamics. The presented study concentrates on the charge symmetry forbidden reaction dd → {sup 4}Heπ{sup 0}. The aim is to provide experimental results for comparison with predictions from Chiral Perturbation Theory (χ{sub PT}) to study effects induced by quark masses on the hadronic level, e.g., the proton-neutron mass difference. First calculations showed that in addition to the existing high-precision data from TRIUMF and IUCF, more data are required for a precise determination of the parameters of χ{sub PT}. These new data should comprise the measurement of the charge symmetry forbidden dd → {sup 4}Heπ{sup 0} reaction at sufficiently high energy, where the p-wave contribution becomes important. A first measurement with the WASA-at-COSY experiment at an excess energy of ε = 60 MeV was performed, but the results did not allow for a decisive interpretation because of limited statistics. This thesis reports on a second measurement of the dd → {sup 4}Heπ{sup 0} reaction at ε = 60 MeV using an improved WASA detector setup aiming at higher statistics. A sample of 336 ± 43 event candidates have been extracted using a data set from an eight-week long beamtime, and total and differential cross sections have been determined. The angular distribution has been described with a function of the form dσ/dΩ = a + b cos{sup 2}θ*, where θ* is the scattering angle of the pion in the c.m. coordinate system. The obtained parameters a and b and the total cross section are: a = (1.75 ± 0.46(stat.){sup +0.31}{sub -0.8}(syst.)) pb/sr, b = (13.6 ± 2.2(stat.){sup +0.9}{sub -2.7}(syst.)) pb/sr, σ{sub tot} = (79.1 ± 7.3(stat.){sup +1.2}{sub -10.5}(syst.) ± 8.1(norm.) ± 2.0(lumi. syst.)) pb. For this experiment a modified detector setup optimized for a time-of-flight measurement of the forward going particles has been used. After detector

  4. Symmetry breaking and quantum correlations in finite systems: studies of quantum dots and ultracold Bose gases and related nuclear and chemical methods

    Science.gov (United States)

    Yannouleas, Constantine; Landman, Uzi

    2007-12-01

    Investigations of emergent symmetry breaking phenomena occurring in small finite-size systems are reviewed, with a focus on the strongly correlated regime of electrons in two-dimensional semiconductor quantum dots and trapped ultracold bosonic atoms in harmonic traps. Throughout the review we emphasize universal aspects and similarities of symmetry breaking found in these systems, as well as in more traditional fields like nuclear physics and quantum chemistry, which are characterized by very different interparticle forces. A unified description of strongly correlated phenomena in finite systems of repelling particles (whether fermions or bosons) is presented through the development of a two-step method of symmetry breaking at the unrestricted Hartree-Fock level and of subsequent symmetry restoration via post Hartree-Fock projection techniques. Quantitative and qualitative aspects of the two-step method are treated and validated by exact diagonalization calculations. Strongly-correlated phenomena emerging from symmetry breaking include the following. Chemical bonding, dissociation and entanglement (at zero and finite magnetic fields) in quantum dot molecules and in pinned electron molecular dimers formed within a single anisotropic quantum dot, with potential technological applications to solid-state quantum-computing devices. Electron crystallization, with particle localization on the vertices of concentric polygonal rings, and formation of rotating electron molecules (REMs) in circular quantum dots. Such electron molecules exhibit ro-vibrational excitation spectra, in analogy with natural molecules. At high magnetic fields, the REMs are described by parameter-free analytic wave functions, which are an alternative to the Laughlin and composite-fermion approaches, offering a new point of view of the fractional quantum Hall regime in quantum dots (with possible implications for the thermodynamic limit). Crystalline phases of strongly repelling bosons. In rotating

  5. Time-resolved high harmonic spectroscopy of dynamical symmetry breaking in bi-circular laser fields: the role of Rydberg states.

    Science.gov (United States)

    Jiménez-Galán, Álvaro; Zhavoronkov, Nickolai; Schloz, Marcel; Morales, Felipe; Ivanov, Misha

    2017-09-18

    The bi-circular scheme for high harmonic generation, which combines two counter-rotating circular fields with frequency ratio 2:1, has recently permitted to generate high harmonics with essentially circular polarization, opening the way for ultrafast chiral studies. This scheme produces harmonic lines at 3N + 1 and 3N + 2 multiples of the fundamental driving frequency, while the 3N lines are forbidden owing to the three-fold symmetry of the field. It is generally established that the routinely observed signals at these forbidden harmonic lines come from a slight ellipticity in the driving fields, which breaks the three-fold symmetry. We find that this is neither the only nor it is the dominant mechanism responsible. The forbidden lines can be observed even for perfectly circular, long driving pulses. We show that they encode rich information on the sub-cycle electronic dynamics that occur during the generation process. By varying the time delay and relative intensity between the two drivers, we demonstrate that when the second harmonic either precedes or is more intense than the fundamental field, the weak effects of dynamical symmetry breaking caused by finite pulse duration are amplified by electrons trapped in Rydberg orbits (i.e., Freeman resonances), and that the forbidden harmonic lines are a witness of this.

  6. Evidence for Time-Reversal Symmetry Breaking of the Superconducting State near Twin-Boundary Interfaces in FeSe Revealed by Scanning Tunneling Spectroscopy

    Directory of Open Access Journals (Sweden)

    T. Watashige

    2015-08-01

    Full Text Available Junctions and interfaces consisting of unconventional superconductors provide an excellent experimental playground to study exotic phenomena related to the phase of the order parameter. Not only does the complex structure of unconventional order parameters have an impact on the Josephson effects, but it also may profoundly alter the quasiparticle excitation spectrum near a junction. Here, by using spectroscopic-imaging scanning tunneling microscopy, we visualize the spatial evolution of the LDOS near twin boundaries (TBs of the nodal superconductor FeSe. The π/2 rotation of the crystallographic orientation across the TB twists the structure of the unconventional order parameter, which may, in principle, bring about a zero-energy LDOS peak at the TB. The LDOS at the TB observed in our study, in contrast, does not exhibit any signature of a zero-energy peak, and an apparent gap amplitude remains finite all the way across the TB. The low-energy quasiparticle excitations associated with the gap nodes are affected by the TB over a distance more than an order of magnitude larger than the coherence length ξ_{ab}. The modification of the low-energy states is even more prominent in the region between two neighboring TBs separated by a distance ≈7ξ_{ab}. In this region, the spectral weight near the Fermi level (≈±0.2  meV due to the nodal quasiparticle spectrum is almost completely removed. These behaviors suggest that the TB induces a fully gapped state, invoking a possible twist of the order parameter structure, which breaks time-reversal symmetry.

  7. Unconventional Superconductivity in La(7)Ir(3) Revealed by Muon Spin Relaxation: Introducing a New Family of Noncentrosymmetric Superconductor That Breaks Time-Reversal Symmetry.

    Science.gov (United States)

    Barker, J A T; Singh, D; Thamizhavel, A; Hillier, A D; Lees, M R; Balakrishnan, G; Paul, D McK; Singh, R P

    2015-12-31

    The superconductivity of the noncentrosymmetric compound La(7)Ir(3) is investigated using muon spin rotation and relaxation. Zero-field measurements reveal the presence of spontaneous static or quasistatic magnetic fields below the superconducting transition temperature T(c)=2.25  K-a clear indication that the superconducting state breaks time-reversal symmetry. Furthermore, transverse-field rotation measurements suggest that the superconducting gap is isotropic and that the pairing symmetry of the superconducting electrons is predominantly s wave with an enhanced binding strength. The results indicate that the superconductivity in La(7)Ir(3) may be unconventional and paves the way for further studies of this family of materials.

  8. Spontaneous symmetry breaking of fundamental states, vortices, and dipoles in two- and one-dimensional linearly coupled traps with cubic self-attraction

    Science.gov (United States)

    Chen, Zhaopin; Li, Yongyao; Malomed, Boris A.; Salasnich, Luca

    2017-09-01

    We introduce two- and one-dimensional (2D and 1D) systems of two linearly coupled Gross-Pitaevskii equations (GPEs) with the cubic self-attraction and harmonic-oscillator (HO) trapping potential in each GPE. The system models a Bose-Einstein condensate with a negative scattering length, loaded in a double-pancake trap, combined with the in-plane HO potential. In addition to that, the 1D version applies to the light transmission in a dual-core waveguide with the Kerr nonlinearity and in-core confinement represented by the HO potential. The subject of the analysis is spontaneous symmetry breaking in 2D and 1D ground-state (GS, alias fundamental) modes, as well as in 2D vortices and 1D dipole modes. (The latter ones do not exist without the HO potential.) By means of the variational approximation and numerical analysis, it is found that both the 2D and 1D systems give rise to a symmetry-breaking bifurcation (SBB) of the supercritical type. The stability of symmetric and asymmetric states, produced by the SBB, is analyzed through the computation of eigenvalues for perturbation modes and verified by direct simulations. The asymmetric GSs are always stable, while the stability region for vortices shrinks and eventually disappears with the increase of the linear-coupling constant, κ . The SBB in the 2D system does not occur if κ is too large (at κ >κmax ); in that case, the two-component system behaves, essentially, as its single-component counterpart. In the 1D system, both asymmetric and symmetric dipole modes feature an additional oscillatory instability, unrelated to the symmetry breaking. This instability occurs in several regions which expand with the increase of κ .

  9. Morphological composition of web-break inducing shives in ...

    African Journals Online (AJOL)

    Web-breaks during paper production cause a serious inconvenience in production process and increase cost of production. Earlier studies indicate that web breaks occur at tensions far below the ultimate tensile strength values determined by tensile testing in the laboratory. It was also reported that most of the web-breaks ...

  10. Time-reversal symmetry breaking in the noncentrosymmetric superconductor Re6Hf : Further evidence for unconventional behavior in the α -Mn family of materials

    Science.gov (United States)

    Singh, D.; Barker, J. A. T.; Thamizhavel, A.; Paul, D. McK.; Hillier, A. D.; Singh, R. P.

    2017-11-01

    The discovery of new families of unconventional superconductors is important both experimentally and theoretically, especially if it challenges current models and thinking. By using muon spin relaxation in zero field, time-reversal symmetry breaking has been observed in Re6Hf . Moreover, the temperature dependence of the superfluid density exhibits s -wave superconductivity with an enhanced electron-phonon coupling. This, coupled with the results from isostructural Re6Zr , shows that the Re6X family is indeed a new and important group of unconventional superconductors.

  11. Time reversal symmetry breaking in superconducting(Pr,La)Os{sub 4}Sb{sub 12} and Pr(Os,Ru){sub 4}Sb{sub 12}

    Energy Technology Data Exchange (ETDEWEB)

    Shu, L. [Department of Physics, University of California, Riverside, CA 92521 (United States)]. E-mail: lei.shu@email.ucr.edu; Higemoto, W. [Japan Atomic Energy Agency, Tokai-Mura, Ibaraki 319-1195 (Japan); Aoki, Y. [Department of Physics, Tokyo Metropolitan University, Tokyo 192-0397 (Japan); Frederick, N.A. [Department of Physics, University of California, San Diego, La Jolla, CA 92093 (United States); Yuhasz, W.M. [Materials Science and Engineering Program, University of California, San Diego, La Jolla, CA 92093 (United States); Heffner, R.H. [Japan Atomic Energy Agency, Tokai-Mura, Ibaraki 319-1195 (Japan); Ohishi, K. [Japan Atomic Energy Agency, Tokai-Mura, Ibaraki 319-1195 (Japan); Ishida, K. [Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502 (Japan); Kadono, R. [Meson Science Laboratory, KEK, Tsukuba, Ibaraki 305-0801 (Japan); Koda, A. [Meson Science Laboratory, KEK, Tsukuba, Ibaraki 305-0801 (Japan); Kikuchi, D. [Department of Physics, Tokyo Metropolitan University, Tokyo 192-0397 (Japan); Sato, H. [Department of Physics, Tokyo Metropolitan University, Tokyo 192-0397 (Japan); Sugawara, H. [Faculty of the Integrated Arts and Sciences, University of Tokushima, Minami-jousanjima-machi 1-1, Tokushima 770-8502 (Japan); Ito, T.U. [Japan Atomic Energy Agency, Tokai-Mura, Ibaraki 319-1195 (Japan); Sanada, S. [Department of Physics, Tokyo Metropolitan University, Tokyo 192-0397 (Japan); Tunashima, Y. [Department of Physics, Tokyo Metropolitan University, Tokyo 192-0397 (Japan); Yonezawa, Y. [Department of Physics, Tokyo Metropolitan University, Tokyo 192-0397 (Japan); Maple, M.B. [Department of Physics, University of California, San Diego, La Jolla, CA 92093 (United States); MacLaughlin, D.E. [Department of Physics, University of California, Riverside, CA 92521 (United States)

    2007-03-15

    Zero-field muon spin relaxation ({mu}SR) experiments have been carried out in the Pr(Os{sub 1-x}Ru{sub x}){sub 4}Sb{sub 12} and Pr{sub 1-y}La{sub y}Os{sub 4}Sb{sub 12} alloy systems to investigate the time-reversal symmetry (TRS) breaking found in an earlier ZF-{mu}SR study of the end compound PrOs{sub 4}Sb{sub 12}. Our results suggest that Ru doping is considerably more efficient than La doping in suppressing TRS-breaking superconducting pairing in PrOs{sub 4}Sb{sub 12}.

  12. Sulforaphane induces DNA single strand breaks in cultured human cells

    Energy Technology Data Exchange (ETDEWEB)

    Sestili, Piero, E-mail: piero.sestili@uniurb.it [Dipartimento di Scienze Biomolecolari, Via Maggetti, 21, Universita degli Studi di Urbino ' Carlo Bo' , 61029 Urbino, PU (Italy); Paolillo, Marco [Dipartimento di Scienze Biomolecolari, Via Maggetti, 21, Universita degli Studi di Urbino ' Carlo Bo' , 61029 Urbino, PU (Italy); Lenzi, Monia [Dipartimento di Farmacologia, Universita degli Studi di Bologna, Via Irnerio 48, 40126 Bologna (Italy); Colombo, Evelin; Vallorani, Luciana; Casadei, Lucia; Martinelli, Chiara [Dipartimento di Scienze Biomolecolari, Via Maggetti, 21, Universita degli Studi di Urbino ' Carlo Bo' , 61029 Urbino, PU (Italy); Fimognari, Carmela [Dipartimento di Farmacologia, Universita degli Studi di Bologna, Via Irnerio 48, 40126 Bologna (Italy)

    2010-07-07

    Sulforaphane (SFR), an isothiocyanate from cruciferous vegetables, possesses growth-inhibiting and apoptosis-inducing activities in cancer cell lines. Recently, SFR has been shown to promote the mitochondrial formation of reactive oxygen species (ROS) in human cancer cell lines. The present study was undertaken to see whether SFR-derived ROS might cause DNA damage in cultured human cells, namely T limphoblastoid Jurkat and human umbilical vein endothelial cells (HUVEC). 1-3 h treatments with 10-30 {mu}M SFR elicited intracellular ROS formation (as assayed with dihydrorhodamine, DHR, oxidation) as well as DNA breakage (as assessed with fast halo assay, FHA). These effects lacked cell-type specificity, since could be observed in both Jurkat and HUVEC. Differential-pH FHA analysis of damaged DNA showed that SFR causes frank DNA single strand breaks (SSBs); no DNA double strand breaks (DSBs) were found within the considered treatment times (up to 3 h). SFR-derived ROS were formed at the mitochondrial respiratory chain (MRC) level: indeed rotenone or myxothiazol (MRC Complex I and III inhibitors, respectively) abrogated ROS formation. Furthermore ROS were not formed in Jurkat cells pharmacologically depleted of respiring mitochondria (MRC-/Jurkat). Formation of ROS was causally linked to the induction of SSBs: indeed all the experimental conditions capable of preventing ROS formation also prevented the damage of nuclear DNA from SFR-intoxicated cells. As to the toxicological relevance of SSBs, we found that their prevention slightly but significantly attenuated SFR cytotoxicity, suggesting that high-dose SFR toxicity is the result of a complex series of events among which GSH depletion seems to play a pivotal role. In conclusion, the present study identifies a novel mechanism contributing to SFR toxicity which - since DNA damage is a prominent mechanism underlying the cytotoxic activity of established antineoplastic agents - might help to exploit the therapeutic value

  13. Lorentz-like force emerging from kinematic interactions between electrons and nuclei in molecules: A quantum mechanical origin of symmetry breaking that can trigger molecular chirality

    Science.gov (United States)

    Takatsuka, Kazuo

    2017-02-01

    The Longuet-Higgins (Berry) phase arising from nonadiabatic dynamics and the Aharonov-Bohm phase associated with the dynamics of a charged particle in the electromagnetic vector potential are well known to be individually a manifestation of a class of the so-called geometrical phase. We herein discuss another similarity between the force working on a charged particle moving in a magnetic field, the Lorentz force, and a force working on nuclei while passing across a region where they have a strong quantum mechanical kinematic (nonadiabatic) coupling with electrons in a molecule. This kinematic force is indeed akin to the Lorentz force in that its magnitude is proportional to the velocity of the relevant nuclei and works in the direction perpendicular to its translational motion. Therefore this Lorentz-like nonadiabatic force is realized only in space of more or equal to three dimensions, thereby highlighting a truly multi-dimensional effect of nonadiabatic interaction. We investigate its physical significance qualitatively in the context of breaking of molecular spatial symmetry, which is not seen otherwise without this force. This particular symmetry breaking is demonstrated in application to a coplanar collision between a planar molecule and an atom sharing the same plane. We show that the atom is guided by this force to the direction out from the plane, resulting in a configuration that distinguishes one side of the mirror plane from the other. This can serve as a trigger for the dynamics towards molecular chirality.

  14. Scaling and renormalization group in replica-symmetry-breaking space: evidence for a simple analytical solution of the Sherrington-Kirkpatrick model at zero temperature.

    Science.gov (United States)

    Oppermann, R; Sherrington, D

    2005-11-04

    Using numerical self-consistent solutions of a sequence of finite replica symmetry breakings (RSB) and Wilson's renormalization group but with the number of RSB steps playing a role of decimation scales, we report evidence for a nontrivial T-->0 limit of the Parisi order function q(x) for the Sherrington-Kirkpatrick spin glass. Supported by scaling in RSB space, the fixed point order function is conjectured to be q*(a)=sqrt[pi]/2 a/xi erf(xi/a) on 0infinity, where x/T --> a at T =0 and xi approximately 1.13+/-0.01. Xi plays the role of a correlation length in a-space. q*(a) may be viewed as the solution of an effective 1D field theory.

  15. Weak ferromagnetic order breaking the threefold rotational symmetry of the underlying kagome lattice in CdC u3(OH) 6(NO3)2.H2O

    Science.gov (United States)

    Okuma, Ryutaro; Yajima, Takeshi; Nishio-Hamane, Daisuke; Okubo, Tsuyoshi; Hiroi, Zenji

    2017-03-01

    Novel magnetic phases are expected to occur in highly frustrated spin systems. Here, we study the structurally perfect kagome antiferromagnet CdC u3(OH) 6(NO3)2.H2O by magnetization, magnetic torque, and heat capacity measurements using single crystals. An antiferromagnetic order accompanied by a small spontaneous magnetization that surprisingly is confined in the kagome plane sets in at TN˜4 K , well below the nearest-neighbor exchange interaction J /kB=45 K . This suggests that a unique "q =0 " type 120∘ spin structure with "negative" (downward) vector chirality, which breaks the underlying threefold rotational symmetry of the kagome lattice and thus allows a spin canting within the plane, is exceptionally realized in this compound rather than a common one with "positive" (upward) vector chirality. The origin is discussed in terms of the Dzyaloshinskii-Moriya interaction.

  16. Symmetry-induced quantum interference effects in metalloporphyrin wires.

    Science.gov (United States)

    Ferradás, R; García-Suárez, V M; Ferrer, J

    2013-08-14

    We calculate the electronic and transport properties of a series of metalloporphyrin molecules sandwiched between gold electrodes using a combination of density functional theory and scattering theory. The impact of strong correlations at the central metallic atom is gauged by comparing our results obtained using conventional DFT and DFT + U approaches. The zero- and finite-bias transport properties may or may not show spin-filtering behavior, depending on the nature of the d state closest to the Fermi energy. The type of d state depends on the metallic atom and gives rise to interference effects that produce different Fano features. The inclusion of the U term opens a gap between the d states and changes the conductance and spin-filtering behavior qualitatively in some of the molecules. We explain the origin of the quantum interference effects found as due to the symmetry-dependent coupling between the d states and other molecular orbitals and propose the use of these systems as nanoscale chemical sensors. We also demonstrate that an adequate treatment of strong correlations is really necessary to correctly describe the transport properties of metalloporphyrins and similar molecular magnets.

  17. Stem Cell Differentiation Stage Factors and Their Role in Triggering Symmetry Breaking Processes during Cancer Development: A Quantum Field Theory Model for Reprogramming Cancer Cells to Healthy Phenotypes.

    Science.gov (United States)

    Biava, Pier Mario; Burigana, Fabio; Germano, Roberto; Kurian, Philip; Verzegnassi, Claudio; Vitiello, Giuseppe

    2017-09-20

    A long history of research has pursued the use of embryonic factors isolated during cell differentiation processes for the express purpose of transforming cancer cells back to healthy phenotypes. Recent results have clarified that the substances present at different stages of cell differentiation-which we call stem cell differentiation stage factors (SCDSFs)-are proteins with low molecular weight and nucleic acids that regulate genomic expression. The present review summarizes how these substances, taken at different stages of cellular maturation, are able to retard proliferation of many human tumor cell lines and thereby reprogram cancer cells to healthy phenotypes. The model presented here is a quantum field theory (QFT) model in which SCDSFs are able to trigger symmetry breaking processes during cancer development. These symmetry breaking processes, which lie at the root of many phenomena in elementary particle physics and condensed matter physics, govern the phase transitions of totipotent cells to higher degrees of diversity and order, resulting in cell differentiation. In cancers, which share many genomic and metabolic similarities with embryonic stem cells, stimulated re-differentiation often signifies the phenotypic reversion back to health and non-proliferation. In addition to acting on key components of the cellular cycle, SCDSFs are able to reprogram cancer cells by delicately influencing the cancer microenvironment, modulating the electrochemistry and thus the collective electrodynamic behaviors between dipole networks in biomacromolecules and the interstitial water field. Coherent effects in biological water, which are derived from a dissipative QFT framework, may offer new diagnostic and therapeutic targets at a systemic level, before tumor instantiation occurs in specific tissues or organs. Thus, by including the environment as an essential component of our model, we may push the prevailing paradigm of mutation-driven oncogenesis toward a closer

  18. Symmetry-Breaking Transitions in RECuAs2-xPx (RE=Sm, Gd, Ho, and Er)

    Energy Technology Data Exchange (ETDEWEB)

    Mozharivskyj, Yurij [Iowa State Univ., Ames, IA (United States)

    2002-01-01

    Structural changes resulting in lower symmetries can be understood in terms of electronic instabilities and Coulomb interactions. The interplay of these two interrelated factors is complicated and difficult to analyze. The RECuAs2-xP x phases, because of the variation in the chemical content (As/P substitution), allow, with the aid of band structures, Madelung energies and Landau theory, a partial unraveling of the forces important in the symmetry-breaking transitions in RECuAs2-xP x (RE = Sm, Gd, Ho and Er). Distortions of the P layers in SmCu1.15P2, GdCuP2.20 and ErCuP2 are usefully thought of as generalized Peierls distortions, i.e., they lower the electronic (and total) energy and lead to more stable structures. On the other hand, the P4/nmm → Pmmn transitions, which are observed in all studied arsenophosphide series and occur upon substitution of P for As, originate from the B1g vibrational mode and are structural adaptations to smaller P atoms. These transitions provide tighter atomic packing and better Coulomb interactions. Configurational contribution to the entropy becomes important in stabilizing the mixed occupancy in the RECuAs 2-xP x arsenophosphides. While geometric and electronic factors favor separation of the As and P atoms over two different crystallographic sites, configurational entropy stabilizes the As/P mixing on these two sites.;Progress in the research on RECuAs2-xP x was dependent upon the ability of Landau theory to predict, explain and dismiss structural models and transitions. The space group Pmmn (arising from the B 1g vibrational mode) in all mixed arsenophosphides and the existence of these mixed arsenophosphides followed from the analysis of GdCuAs 2 and GdCuP2, using Landau theory. The impossibility of obtaining the high-symmetry structure (P4/nmm) and the low symmetry structure

  19. Hartee Fock Symmetry Breaking Effects in La2CuO4: Hints for connecting the Mott and Slater Pictures and Pseudogap Prediction

    Directory of Open Access Journals (Sweden)

    Alejandro Cabo Montes de Oca

    2010-03-01

    Full Text Available This work expands the results and derivations presented in a recent letter. It is argued that symmetry breaking Hartree-Fock (HF solutions of a simple model of the Cu-O planes in La2CuO4, are able to describe the insulator and antiferromagnetic characters of this material. Then, this classical primer of a Mott insulator is alternatively obtained here as an exact Slater insulator within the simplest of the first principles schemes. Moreover, pseudogap HF states are also predicted. The maximal energy gap of 100 meV over the Fermi surface of this wavefunction, reasonably well matches the ARPES upper pseudogap measurements for La2CuO4 in the zero doping limit. These surprising results followed after eliminating spin and crystal symmetry constraints usually imposed on the HF orbitals. The discussion helps to clarify the role of the antiferromagnetism and pseudogaps in the physics of the HTSC materials and indicates a promising way to start conciliating the Mott and Slater pictures for the description of the transition metal oxides.

  20. Partial chiral symmetry-breaking as a route to spectrally isolated topological defect states in two-dimensional artificial materials

    Science.gov (United States)

    Poli, Charles; Schomerus, Henning; Bellec, Matthieu; Kuhl, Ulrich; Mortessagne, Fabrice

    2017-06-01

    Bipartite quantum systems from the chiral universality classes admit topologically protected zero modes at point defects. However, in two-dimensional systems these states can be difficult to separate from compacton-like localized states that arise from flat bands, formed if the two sublattices support a different number of sites within a unit cell. Here we identify a natural reduction of chiral symmetry, obtained by coupling sites on the majority sublattice, which gives rise to spectrally isolated point-defect states, topologically characterized as zero modes supported by the complementary minority sublattice. We observe these states in a microwave realization of a dimerized Lieb lattice with next-nearest neighbour coupling, and also demonstrate topological mode selection via sublattice-staggered absorption.

  1. Homology Requirements and Competition between Gene Conversion and Break-Induced Replication during Double-Strand Break Repair.

    Science.gov (United States)

    Mehta, Anuja; Beach, Annette; Haber, James E

    2017-02-02

    Saccharomyces cerevisiae mating-type switching is initiated by a double-strand break (DSB) at MATa, leaving one cut end perfectly homologous to the HMLα donor, while the second end must be processed to remove a non-homologous tail before completing repair by gene conversion (GC). When homology at the matched end is ≤150 bp, efficient repair depends on the recombination enhancer, which tethers HMLα near the DSB. Thus, homology shorter than an apparent minimum efficient processing segment can be rescued by tethering the donor near the break. When homology at the second end is ≤150 bp, second-end capture becomes inefficient and repair shifts from GC to break-induced replication (BIR). But when pol32 or pif1 mutants block BIR, GC increases 3-fold, indicating that the steps blocked by these mutations are reversible. With short second-end homology, absence of the RecQ helicase Sgs1 promotes gene conversion, whereas deletion of the FANCM-related Mph1 helicase promotes BIR. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Born-Oppenheimer symmetry breaking in the C state of NO2: importance of static and dynamic correlation effects.

    Science.gov (United States)

    Bera, Partha P; Yamaguchi, Yukio; Schaefer, Henry F; Crawford, T Daniel

    2008-03-27

    A systematic theoretical treatment is performed with highly correlated ab initio theoretical methods to establish the structural nature of the C state of NO2. We predict the C state to have an asymmetric structure (point group C(s)). Spin-restricted and spin-unrestricted configuration interaction (CISD), coupled cluster [CCSD and CCSD(T)], multireference complete active space self-consistent field (CASSCF), and internally contracted multireference configuration interaction (ICMRCI) methods were used in conjunction with very large correlation-consistent polarized valence zeta cc-pVXZ and aug-cc-pVXZ [X = T, Q, 5] basis sets. The asymmetric C 2A'' state is predicted to lie T(e) = 47.5 kcal/mol (2.06 eV, 16,600 cm(-1)) above the X 2A1 state at the aug-cc-pV5Z/UCCSD(T) level of theory, with T0 = 46.0 kcal/mol (2.00 eV, 16,100 cm(-1)), in good agreement with the experimental values of 46.77 kcal/mol (2.028 eV, 16,360 cm(-1)) by Weaver and 46.42 kcal/mol (2.013 eV, 16,234 cm(-1)) by Aoki. The symmetric structure (in C(2v) symmetry) with re(NO) = 1.274 A and theta(e) (ONO) = 109.9 degrees is a transition state between the two equivalent asymmetric (in C(s) symmetry) structures and is located only 1.53 kcal/mol (0.066 eV, 540 cm(-1)) above the asymmetric structure. The asymmetric structure is predicted to have structural parameters r(e)(NOl) = 1.489 A, r(e)(NOs) = 1.169 A, and theta(e)(ONO) = 109.7 degrees with the same method, aug-cc-pV5Z/UCCSD(T). The averaged NO bond distance is 1.329 A, and the difference between the two NO bond distances is 0.320 A. The three harmonic vibrational frequencies for the C 2A'' state are 1656 (in-phase stretch), 759 (bend), and 378 (out- of-phase stretch) cm(-1). While these theoretical results further corroborate the previous predictions concerning the asymmetric nature of the C state, there remains discrepancy between the theoretical and experimental symmetric stretching mode omega1 (1656 and 923 cm(-1), respectively). It is possible

  3. The arrow of time in open quantum systems and dynamical breaking of the resonance-anti-resonance symmetry

    Science.gov (United States)

    Ordonez, Gonzalo; Hatano, Naomichi

    2017-10-01

    Open quantum systems are often represented by non-Hermitian effective Hamiltonians that have complex eigenvalues associated with resonances. In previous work we showed that the evolution of tight-binding open systems can be represented by an explicitly time-reversal symmetric expansion involving all the discrete eigenstates of the effective Hamiltonian. These eigenstates include complex-conjugate pairs of resonant and anti-resonant states. An initially time-reversal-symmetric state contains equal contributions from the resonant and anti-resonant states. Here we show that as the state evolves in time, the symmetry between the resonant and anti-resonant states is automatically broken, with resonant states becoming dominant for t>0 and anti-resonant states becoming dominant for tassociate with the ‘Zeno time’. We also compare the time-reversal symmetric expansion with an asymmetric expansion used previously by several researchers. We show how the present time-reversal symmetric expansion bypasses the non-Hilbert nature of the resonant and anti-resonant states, which previously introduced exponential divergences into the asymmetric expansion.

  4. Modelling wave-induced sea ice break-up in the marginal ice zone

    Science.gov (United States)

    Montiel, F.; Squire, V. A.

    2017-10-01

    A model of ice floe break-up under ocean wave forcing in the marginal ice zone (MIZ) is proposed to investigate how floe size distribution (FSD) evolves under repeated wave break-up events. A three-dimensional linear model of ocean wave scattering by a finite array of compliant circular ice floes is coupled to a flexural failure model, which breaks a floe into two floes provided the two-dimensional stress field satisfies a break-up criterion. A closed-feedback loop algorithm is devised, which (i) solves the wave-scattering problem for a given FSD under time-harmonic plane wave forcing, (ii) computes the stress field in all the floes, (iii) fractures the floes satisfying the break-up criterion, and (iv) generates an updated FSD, initializing the geometry for the next iteration of the loop. The FSD after 50 break-up events is unimodal and near normal, or bimodal, suggesting waves alone do not govern the power law observed in some field studies. Multiple scattering is found to enhance break-up for long waves and thin ice, but to reduce break-up for short waves and thick ice. A break-up front marches forward in the latter regime, as wave-induced fracture weakens the ice cover, allowing waves to travel deeper into the MIZ.

  5. Modelling wave-induced sea ice break-up in the marginal ice zone.

    Science.gov (United States)

    Montiel, F; Squire, V A

    2017-10-01

    A model of ice floe break-up under ocean wave forcing in the marginal ice zone (MIZ) is proposed to investigate how floe size distribution (FSD) evolves under repeated wave break-up events. A three-dimensional linear model of ocean wave scattering by a finite array of compliant circular ice floes is coupled to a flexural failure model, which breaks a floe into two floes provided the two-dimensional stress field satisfies a break-up criterion. A closed-feedback loop algorithm is devised, which (i) solves the wave-scattering problem for a given FSD under time-harmonic plane wave forcing, (ii) computes the stress field in all the floes, (iii) fractures the floes satisfying the break-up criterion, and (iv) generates an updated FSD, initializing the geometry for the next iteration of the loop. The FSD after 50 break-up events is unimodal and near normal, or bimodal, suggesting waves alone do not govern the power law observed in some field studies. Multiple scattering is found to enhance break-up for long waves and thin ice, but to reduce break-up for short waves and thick ice. A break-up front marches forward in the latter regime, as wave-induced fracture weakens the ice cover, allowing waves to travel deeper into the MIZ.

  6. Brane induced supersymmetry breaking and de Sitter supergravity

    Science.gov (United States)

    Bandos, Igor; Martucci, Luca; Sorokin, Dmitri; Tonin, Mario

    2016-02-01

    We obtain a four-dimensional supergravity with spontaneously broken super-symmetry allowing for de Sitter vacua by coupling a superspace action of minimal N = 1, D = 4 supergravity to a locally supersymmetric generalization of the Volkov-Akulov goldstino action describing the dynamics of a space-filling non-BPS 3-brane in N = 1, D = 4 superspace. To the quadratic order in the goldstino field the obtained action coincides with earlier constructions of supergravities with nilpotent superfields, while matching the higher-order contributions will require a non-linear redefinition of fields. In the unitary gauge, in which the goldstino field is set to zero, the action coincides with that of Volkov and Soroka. We also show how a nilpotency constraint on a chiral curvature superfield emerges in this formulation.

  7. Guanidinium-induced denaturation by breaking of salt bridges

    NARCIS (Netherlands)

    Meuzelaar, H.; Panman, M.R.; Woutersen, S.

    2015-01-01

    Despite its wide use as a denaturant, the mechanism by which guanidinium (Gdm+) induces protein unfolding remains largely unclear. Herein, we show evidence that Gdm+ can induce denaturation by disrupting salt bridges that stabilize the folded conformation. We study the Gdm+-​induced denaturation of

  8. Adriamycin does not affect the repair of X-ray induced DNA single strand breaks

    Energy Technology Data Exchange (ETDEWEB)

    Cantoni, O.; Sestili, P.; Cattabeni, F.

    1985-06-01

    The ability of the antitumor antibiotic adriamycin (Ad) to inhibit the rejoining of DNA single strand breaks produced by X-rays was investigated in cultured cells. Chinese hamster ovary cells were given 400 rad and were allowed to repair in the presence or absence of Ad for 60 min at 37degC. The drug did not affect the ability of cells to repair DNA breaks and residual breaks found after the repair period were attributed to those induced by Ad alone. (author). 16 refs.

  9. Inducing Chaos by Breaking Axial Symmetry in a Black Hole Magnetosphere

    Czech Academy of Sciences Publication Activity Database

    Kopáček, Ondřej; Karas, Vladimír

    2014-01-01

    Roč. 787, č. 2 (2014), A117/1-A117/12 ISSN 0004-637X R&D Projects: GA ČR(CZ) GC13-00070J Grant - others:GA ČR(CZ) GA202/09/0772; GA ČR(CZ) GA202/09/0772 Program:GA; GA Institutional support: RVO:67985815 Keywords : black hole s * chaos Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 5.993, year: 2014

  10. Symmetry-Breaking-Induced Enhancement of Visible Light Absorption in Delafossite Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Huda, M. N.; Yan, Y.; Walsh, A.; Wei, S. H.; Al-Jassim, M. M.

    2009-06-01

    Through density functional theory calculations, we demonstrate that enhancement of optical absorption and optimization of the fundamental band gap for Cu delafossites can be achieved through alloying group IIIA and IIIB delafossites. These alloys significantly improved the flexibility in designing delafossite-based photoelectrodes for application in photoelectrochemical decomposition of water by visible spectra of solar light.

  11. Translational Symmetry and Microscopic Constraints on Symmetry-Enriched Topological Phases: A View from the Surface

    Directory of Open Access Journals (Sweden)

    Meng Cheng

    2016-12-01

    Full Text Available The Lieb-Schultz-Mattis theorem and its higher-dimensional generalizations by Oshikawa and Hastings require that translationally invariant 2D spin systems with a half-integer spin per unit cell must either have a continuum of low energy excitations, spontaneously break some symmetries, or exhibit topological order with anyonic excitations. We establish a connection between these constraints and a remarkably similar set of constraints at the surface of a 3D interacting topological insulator. This, combined with recent work on symmetry-enriched topological phases with on-site unitary symmetries, enables us to develop a framework for understanding the structure of symmetry-enriched topological phases with both translational and on-site unitary symmetries, including the effective theory of symmetry defects. This framework places stringent constraints on the possible types of symmetry fractionalization that can occur in 2D systems whose unit cell contains fractional spin, fractional charge, or a projective representation of the symmetry group. As a concrete application, we determine when a topological phase must possess a “spinon” excitation, even in cases when spin rotational invariance is broken down to a discrete subgroup by the crystal structure. We also describe the phenomena of “anyonic spin-orbit coupling,” which may arise from the interplay of translational and on-site symmetries. These include the possibility of on-site symmetry defect branch lines carrying topological charge per unit length and lattice dislocations inducing degeneracies protected by on-site symmetry.

  12. Chiral symmetry breaking, duality in the $\\overline{Q}q$ channel and $b \\to \\overline{c}cs$ decays

    CERN Document Server

    Blok, B Yu; Uraltsev, N

    1997-01-01

    We address the issue of the quark-hadron duality in the spectral densities induced by the heavy-light quark currents anti-Q q. In the limit m_Q ->oo, m_q ->0 we observe an enhancement of the physical spectral density compared to the quark one in the scalar and axial channels, due to the Goldstone meson contributions. This may imply that the scale where duality sets in in these channels is higher than in the vector (pseudoscalar) case. Implications for the nonleptonic decays of B mesons (the b -> anti-c cs transition) are considered.

  13. Sensitivity of ATLAS to alternative mechanisms of electroweak symmetry breaking in vector boson scattering qq{yields}qql{nu}l{nu}

    Energy Technology Data Exchange (ETDEWEB)

    Schumacher, Jan W.

    2010-10-15

    An analysis of the expected sensitivity of the ATLAS experiment at the Large Hadron Collider at CERN to alternative mechanisms of electroweak symmetry breaking in the dileptonic vector boson scattering channel is presented. With the generalized K-Matrix model of vector boson scattering recently implemented in the event generator Whizard, several additional resonances are investigated. Whizard is validated for ATLAS use and an interface for the Les Houches event format is adapted for the ATLAS software Athena. Systematic model and statistical Monte Carlo uncertainties are reduced with a signal definition using events reweighted in the couplings g of the new resonances. Angular correlations conserved by Whizard are used in the event selection. A multivariate analyzer is trained to take into account correlations between the selection variables and thereby to improve the sensitivity compared to cut analyses. The statistical analysis is implemented with a profile likelihood method taking into account systematic uncertainties and statistical uncertainties from Monte Carlo. Ensemble tests are performed to assure the applicability of the method. Expected discovery significances and coupling limits for new additional resonances in vector boson scattering are determined. (orig.)

  14. Electroweak breaking and supersymmetry breaking

    Indian Academy of Sciences (India)

    We discuss the clash between the absence of fine tuning in the Higgs potential and a sufficient suppression of flavour changing neutral current transitions in supersymmetric extensions of the standard model. It is pointed out that horizontal U ( 1 ) symmetry combined with the D -term supersymmetry breaking provides a ...

  15. Supramolecular recognition influences magnetism in [X@HV(IV) 8 V(V) 14 O54 ](6-) self-assemblies with symmetry-breaking guest anions.

    Science.gov (United States)

    Monakhov, Kirill Yu; Linnenberg, Oliver; Kozłowski, Piotr; van Leusen, Jan; Besson, Claire; Secker, Tim; Ellern, Arkady; López, Xavier; Poblet, Josep M; Kögerler, Paul

    2015-02-02

    Mixed-valence polyoxovanadates(IV/V) have emerged as one of the most intricate class of supramolecular all-inorganic host species, able to encapsulate a wide variety of smaller guest templates during their self-assembly formation process. As showcased herein, the incorporation of guests, though governed solely by ultra-weak electrostatic and van der Waals interactions, can cause drastic effects on the electronic and magnetic characteristics of the shell complex of the polyoxovanadate. We address the question of methodology for the magnetochemical analysis of virtually isostructural {V(IV/V) 22 O54 }-type polyoxoanions of D2d symmetry enclosing diamagnetic VO2 F2 (-) (C2v ), SCN(-) (C∞v ), or ClO4 (-) (Td ) template anions. These induce different polarization effects related to differences in their geometric structures, symmetry, ion radii, and valence shells, eventually resulting in a supramolecular modulation of magnetic exchange between the V(3d) electrons that are partly delocalized over the {V22 O54 } shells. We also include the synthesis and characterization of the novel [V(V) O2 F2 @HV(IV) 8 V(V) 14 O54 ](6-) system that comprises the rarely encountered discrete difluorovanadate anion as a quasi-isolated guest species. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Induced and natural break sites in the chromosomes of Hawaiian Drosophila

    Energy Technology Data Exchange (ETDEWEB)

    Tonzetich, J.; Lyttle, T.W.; Carson, H.L.

    1988-03-01

    Gamma-irradiation of a laboratory strain of the Hawaiian species of Drosophila heteroneura yielded 310 breaks in the five major acrocentric polytene chromosomes. Their map positions conform to the Poisson distribution, unlike most of the 436 natural breaks mapped in 105 closely related species endemic to Hawaii. Genome element E is longer and has more induced breaks than the others. Both in Hawaiian and related species groups, this element shows increased polymorphism and fixation of naturally occurring inversions. The X chromosome (element A) also accumulates many natural breaks; the majority of the resulting aberrations become fixed rather than remain as polymorphisms. Although size may play a small role in initial break distribution, the major effects relative to the establishment of a rearrangement in natural populations are ascribed to the interaction of selection and drift. Nonconformance of the natural breaks to the Poisson distribution appears to be due to the tendency for breaks to accumulate both in the proximal euchromatic portion of each arm and in heterochromatic regions that are not replicated in the polytene chromosomes.

  17. Genetics of x-ray induced double strand break repair in saccharomyces cerevisiae

    Energy Technology Data Exchange (ETDEWEB)

    Budd, M.E.

    1982-07-01

    The possible fates of x-ray-induced double-strand breaks in Saccharomyces cerevisiae were examined. One possible pathway which breaks can follow, the repair pathway, was studied by assaying strains with mutations in the RAD51, RAD54, and RAD57 loci for double-strand break repair. In order of increasing radiation sensitivity one finds: rad57-1(23/sup 0/)> rad51-1(30/sup 0/)> rad54-3(36/sup 0/). At 36/sup 0/, rad54-3 cells cannot repair double-strand breaks, while 23/sup 0/, they can. Strains with the rad57-1 mutation can rejoin broken chromosomes at both temperatures. However, the low survival at 36/sup 0/ shows that the assay is not distinguishing large DNA fragments which allow cell survival from those which cause cell death. A rad51-1 strain could also rejoin broken chromosomes, and was thus capable of incomplete repair. The data can be explained with the hypothesis that rad54-3 cells are blocked in an early step of repair, while rad51-1 and rad57-1 strains are blocked in a later step of repair. The fate of double-strand breaks when they are left unrepaired was investigated with the rad54-3 mutation. If breaks are prevented from entering the RAD54 repair pathway they become uncommitted lesions. These lesions are repaired slower than the original breaks. One possible fate for an uncommitted lesion is conversion into a fixed lesion, which is likely to be an unrepairable or misrepaired double-strand break. The presence of protein synthesis after irradiation increases the probability that a break will enter the repair pathway. Evidence shows that increased probability of repair results from enhanced synthesis of repair proteins shortly after radiation. (ERB)

  18. Guanidinium-Induced Denaturation by Breaking of Salt Bridges.

    Science.gov (United States)

    Meuzelaar, Heleen; Panman, Matthijs R; Woutersen, Sander

    2015-12-07

    Despite its wide use as a denaturant, the mechanism by which guanidinium (Gdm(+) ) induces protein unfolding remains largely unclear. Herein, we show evidence that Gdm(+) can induce denaturation by disrupting salt bridges that stabilize the folded conformation. We study the Gdm(+) -induced denaturation of a series of peptides containing Arg/Glu and Lys/Glu salt bridges that either stabilize or destabilize the folded conformation. The peptides containing stabilizing salt bridges are found to be denatured much more efficiently by Gdm(+) than the peptides containing destabilizing salt bridges. Complementary 2D-infrared measurements suggest a denaturation mechanism in which Gdm(+) binds to side-chain carboxylate groups involved in salt bridges. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Inducible Defenses with a "Twist": Daphnia barbata Abandons Bilateral Symmetry in Response to an Ancient Predator.

    Directory of Open Access Journals (Sweden)

    Quirin Herzog

    Full Text Available Predation is one of the most important drivers of natural selection. In consequence a huge variety of anti-predator defenses have evolved in prey species. Under unpredictable and temporally variable predation pressure, the evolution of phenotypically plastic defensive traits is favored. These "inducible defenses", range from changes in behavior, life history, physiology to morphology and can be found in almost all taxa from bacteria to vertebrates. An important group of model organisms in ecological, evolutionary and environmental research, water fleas of the genus Daphnia (Crustacea: Cladocera, are well known for their ability to respond to predators with an enormous variety of inducible morphological defenses. Here we report on the "twist", a body torsion, as a so far unrecognized inducible morphological defense in Daphnia, expressed by Daphnia barbata exposed to the predatory tadpole shrimp Triops cancriformis. This defense is realized by a twisted carapace with the helmet and the tail spine deviating from the body axis into opposing directions, resulting in a complete abolishment of bilateral symmetry. The twisted morphotype should considerably interfere with the feeding apparatus of the predator, contributing to the effectiveness of the array of defensive traits in D. barbata. As such this study does not only describe a completely novel inducible defense in the genus Daphnia but also presents the first report of a free living Bilateria to flexibly respond to predation risk by abandoning bilateral symmetry.

  20. Effective inhibition by beta-carotene of cellular DNA breaking induced by peroxynitrous acid.

    Science.gov (United States)

    Hiramoto, K; Tomiyama, S; Kikugawa, K

    1999-01-01

    Peroxynitrous acid synthesized by reaction of hydrogen peroxide and nitrite and generated from 3-morpholinosydononimine (SIN-1) induced cellular DNA breaking of human promyelocytic leukemia HL-60 cells in phosphate buffer (pH 7.5) as assessed by alkaline single cell gel electrophoresis (comet) assay and quantification of comet types. Ascorbate and Trolox inhibited cellular DNA breaking induced by peroxynitrous acid, but the concentrations of these antioxidants required for effective inhibition was about 50-fold higher than that of peroxynitrous acid. beta-Carotene protected DNA breaking by peroxynitrous acid in 20% tetrahydrofuran-phosphate buffer (pH 7.5) much more effectively than ascorbate and Trolox. The concentrations of beta-carotene required for effective inhibition was lower than the concentration of peroxynitrous acid.

  1. THE SYMMETRY BREAKING PHENOMENON IN 1,2,3-TRIOXOLENE AND C2Y3Z2 (Z= O, S, Se, Te, Z= H, F COMPOUNDS: A PSEUDO JAHN-TELLER ORIGIN STUDY

    Directory of Open Access Journals (Sweden)

    Ali Reza Ilkhani

    Full Text Available 1,2,3-Trioxolene (C2O3H2 is an intermediate in the acetylene ozonolysis reaction which is called primary ozonide intermediate. The symmetry breaking phenomenon were studied in C2O3H2 and six its derivatives then oxygen atoms of the molecule are substituted by sulphur, selenium, tellurium (C2Y3H2 and hydrogen ligands are replaced with fluorine atoms (C2Y3F2. Based on calculation results, all seven C2Y3Z2 considered in the series were puckered from unstable planar configuration with C2v symmetry to a Cs symmetry stable geometry. The vibronic coupling interaction between the 1A1 ground state and the first excited state 1B1 via the (1A1+1B1 ⊗b1 pseudo Jahn-Teller effect problem is the reason of the breaking symmetry phenomenon and un-planarity of the C2Y3 ring in the C2Y3Z2 series.

  2. Symmetry Breaking in Pedestrian Dynamics

    CERN Document Server

    Morton, Nickolas A

    2016-01-01

    When two pedestrians travelling in opposite directions approach one another, each must decide on which side (the left or the right) they will attempt to pass. If both make the same choice then passing can be completed with ease, while if they make opposite choices an embarrassing stand-off or collision can occur. Pedestrians who encounter each other frequently can establish "social norms" that bias this decision. In this study we investigate the effect of binary decision-making by pedestrians when passing on the dynamics of pedestrian flows in order to study the emergence of a social norm in crowds with a mixture of individual biases. Such a situation may arise, for instance, when individuals from different communities mix at a large sporting event or at transport hubs. We construct a phase diagram that shows that a social norm can still emerge provided pedestrians are sufficiently attentive to the choices of others in the crowd. We show that this collective behaviour has the potential to greatly influence th...

  3. TALEN-Induced Double-Strand Break Repair of CTG Trinucleotide Repeats

    Directory of Open Access Journals (Sweden)

    Valentine Mosbach

    2018-02-01

    Full Text Available Trinucleotide repeat expansions involving CTG/CAG triplets are responsible for several neurodegenerative disorders, including myotonic dystrophy and Huntington’s disease. Because expansions trigger the disease, contracting repeat length could be a possible approach to gene therapy for these disorders. Here, we show that a TALEN-induced double-strand break was very efficient at contracting expanded CTG repeats in yeast. We show that RAD51, POL32, and DNL4 are dispensable for double-strand break repair within CTG repeats, the only required genes being RAD50, SAE2, and RAD52. Resection was totally abolished in the absence of RAD50 on both sides of the break, whereas it was reduced in a sae2Δ mutant on the side of the break containing the longest repeat tract, suggesting that secondary structures at double-strand break ends must be removed by the Mre11-Rad50 complex and Sae2. Following the TALEN double-strand break, single-strand annealing occurred between both sides of the repeat tract, leading to repeat contraction.

  4. Experimental evidence of symmetry breaking in the multiferroic Ba3NbFe3Si2O14 using sound velocity measurements

    Science.gov (United States)

    Quirion, G.; Bidaud, C.; Quilliam, J. A.; Lejay, P.; Simonet, V.; Ballou, R.

    2017-10-01

    Using high-resolution sound velocity measurements, we determined the temperature dependence of the principal elastic constants of the multiferroic compound Ba3NbFe3Si2O14 at different magnetic fields. All four elastic constants revealed an anomaly at TN=27.1 (1 ) K, which coincides very well with the emergence of the magnetic chiral state. More importantly, we carried out velocity measurements as a function of a field rotating in the basal trigonal plane at different fields and temperatures. In particular, in the magnetically ordered state, we observed an angular hysteresis of Δ C11/C11 , which might be associated with the field-induced ferroelectric polarization suddenly switching from the b* axis to the a direction, due to the magnetoelectric effect previously observed in Ba3NbFe3Si2O14 . The data analysis also leads to an estimate for the lattice distortion (e1-e2≤10-5 ) accounting for a symmetry reduction in the magnetic chiral state possibly associated with the induced polarization along the a axis in zero field.

  5. Double-strand break repair-adox: Restoration of suppressed double-strand break repair during mitosis induces genomic instability.

    Science.gov (United States)

    Terasawa, Masahiro; Shinohara, Akira; Shinohara, Miki

    2014-12-01

    Double-strand breaks (DSBs) are one of the severest types of DNA damage. Unrepaired DSBs easily induce cell death and chromosome aberrations. To maintain genomic stability, cells have checkpoint and DSB repair systems to respond to DNA damage throughout most of the cell cycle. The failure of this process often results in apoptosis or genomic instability, such as aneuploidy, deletion, or translocation. Therefore, DSB repair is essential for maintenance of genomic stability. During mitosis, however, cells seem to suppress the DNA damage response and proceed to the next G1 phase, even if there are unrepaired DSBs. The biological significance of this suppression is not known. In this review, we summarize recent studies of mitotic DSB repair and discuss the mechanisms of suppression of DSB repair during mitosis. DSB repair, which maintains genomic integrity in other phases of the cell cycle, is rather toxic to cells during mitosis, often resulting in chromosome missegregation and aberration. Cells have multiple safeguards to prevent genomic instability during mitosis: inhibition of 53BP1 or BRCA1 localization to DSB sites, which is important to promote non-homologous end joining or homologous recombination, respectively, and also modulation of the non-homologous end joining core complex to inhibit DSB repair. We discuss how DSBs during mitosis are toxic and the multiple safeguard systems that suppress genomic instability. © 2014 The Authors. Cancer Science published by Wiley Publishing Asia Pty Ltd on behalf of Japanese Cancer Association.

  6. Distinct genetic control of homologous recombination repair of Cas9-induced double-strand breaks, nicks and paired nicks

    NARCIS (Netherlands)

    Vriend, Lianne E. M.; Prakash, Rohit; Chen, Chun-Chin; Vanoli, Fabio; Cavallo, Francesca; Zhang, Yu; Jasin, Maria; Krawczyk, Przemek M.

    2016-01-01

    DNA double-strand breaks (DSBs) are known to be powerful inducers of homologous recombination (HR), but single-strand breaks (nicks) have also been shown to trigger HR. Both DSB- and nick-induced HR ((nick)HR) are exploited in advanced genome-engineering approaches based on the bacterial RNA-guided

  7. Inhomogeneous diffusion and ergodicity breaking induced by global memory effects.

    Science.gov (United States)

    Budini, Adrián A

    2016-11-01

    We introduce a class of discrete random-walk model driven by global memory effects. At any time, the right-left transitions depend on the whole previous history of the walker, being defined by an urnlike memory mechanism. The characteristic function is calculated in an exact way, which allows us to demonstrate that the ensemble of realizations is ballistic. Asymptotically, each realization is equivalent to that of a biased Markovian diffusion process with transition rates that strongly differs from one trajectory to another. Using this "inhomogeneous diffusion" feature, the ergodic properties of the dynamics are analytically studied through the time-averaged moments. Even in the long-time regime, they remain random objects. While their average over realizations recovers the corresponding ensemble averages, departure between time and ensemble averages is explicitly shown through their probability densities. For the density of the second time-averaged moment, an ergodic limit and the limit of infinite lag times do not commutate. All these effects are induced by the memory effects. A generalized Einstein fluctuation-dissipation relation is also obtained for the time-averaged moments.

  8. Distribution of X-ray induced chromosome rearrangement breaks along the polytene chromosomes of Anopheles messeae

    Energy Technology Data Exchange (ETDEWEB)

    Pleshkova, G.N. (Tomskij Gosudarstvennyj Univ. (USSR). Nauchno-Issledovatel' skij Inst. Biologii i Biofiziki)

    1983-09-01

    Distribution of chromosomal aberrations localization along polytene chromosomes (aoutosomes) of salivary glands of malarial mosquito. Anopheles messeae is presented. Induced aberrations in F/sub 1/ posterity from X-ray irradiated fecundated females are studied. Points of breaks of inversions and translocations are localized separately. There are no considerable differences in the distribution character of two types of aberrations. Over the length of autosomes the breaks are more frequent in distal halves, their frequency in proximal parts anally in near centromeric regions of chromosomes is reduced. Concentration of breaks in certain ''hot points'' of the chromosomes is pointed out. Comparison of distribution of actual and expected frequencies of break points according to chi/sup 2/ criterion revealed highly fiducial discrepancies, testifying to uneven participation of different regions of chromosomes in aberration formation. Similarities and differences of the data obtained from analogous ones, demonstrated in Drosophila, as well as possible reasons for the distribution unevennes are discussed. On the basis of analysis of intrinsic and literature data a supposition is made that the ''hot points'' (break concentrations) can be considered as localizaion markers of intercalary heterochromatin.

  9. Crystalline arrays of pairs of molecular rotors: correlated motion, rotational barriers, and space-inversion symmetry breaking due to conformational mutations.

    Science.gov (United States)

    Lemouchi, Cyprien; Iliopoulos, Konstantinos; Zorina, Leokadiya; Simonov, Sergey; Wzietek, Pawel; Cauchy, Thomas; Rodríguez-Fortea, Antonio; Canadell, Enric; Kaleta, Jiří; Michl, Josef; Gindre, Denis; Chrysos, Michael; Batail, Patrick

    2013-06-26

    The rod-like molecule bis((4-(4-pyridyl)ethynyl)bicyclo[2.2.2]oct-1-yl)buta-1,3-diyne, 1, contains two 1,4-bis(ethynyl)bicyclo[2.2.2]octane (BCO) chiral rotators linked by a diyne fragment and self-assembles in a one-dimensional, monoclinic C2/c centrosymmetric structure where two equilibrium positions with large occupancy imbalance (88% versus 12%) are identified on a single rotor site. Combining variable-temperature (70-300 K) proton spin-lattice relaxation, (1)H T1(-1), at two different (1)H Larmor frequencies (55 and 210 MHz) and DFT calculations of rotational barriers, we were able to assign two types of Brownian rotators with different activation energies, 1.85 and 6.1 kcal mol(-1), to the two (1)H spin-lattice relaxation processes on the single rotor site. On the basis of DFT calculations, the low-energy process has been assigned to adjacent rotors in a well-correlated synchronous motion, whereas the high-energy process is the manifestation of an abrupt change in their kinematics once two blades of adjacent rotors are seen to rub together. Although crystals of 1 should be second harmonic inactive, a large second-order optical response is recorded when the electric field oscillates in a direction parallel to the unique rotor axle director. We conclude that conformational mutations by torsional interconversion of the three blades of the BCO units break space-inversion symmetry in sequences of mutamers in dynamic equilibrium in the crystal in domains at a mesoscopic scale comparable with the wavelength of light used. A control experiment was performed with a crystalline film of a similar tetrayne molecule, 1,4-bis(3-((trimethylsilyl)ethynyl)bicyclo[1.1.1]pent-1-yl)buta-1,3-diyne, whose bicyclopentane units can rotate but are achiral and produce no second-order optical response.

  10. Uncovering symmetry-breaking vector and reliability order for assigning secondary structures of proteins from atomic NMR chemical shifts in amino acids.

    Science.gov (United States)

    Yu, Wookyung; Lee, Woonghee; Lee, Weontae; Kim, Suhkmann; Chang, Iksoo

    2011-12-01

    Unravelling the complex correlation between chemical shifts of (13) C (α), (13) C (β), (13) C', (1) H (α), (15) N, (1) H ( N ) atoms in amino acids of proteins from NMR experiment and local structural environments of amino acids facilitates the assignment of secondary structures of proteins. This is an important impetus for both determining the three-dimensional structure and understanding the biological function of proteins. The previous empirical correlation scores which relate chemical shifts of (13) C (α), (13) C (β), (13) C', (1) H (α), (15) N, (1) H ( N ) atoms to secondary structures resulted in progresses toward assigning secondary structures of proteins. However, the physical-mathematical framework for these was elusive partly due to both the limited and orthogonal exploration of higher-dimensional chemical shifts of hetero-nucleus and the lack of physical-mathematical understanding underlying those correlation scores. Here we present a simple multi-dimensional hetero-nuclear chemical shift score function (MDHN-CSSF) which captures systematically the salient feature of such complex correlations without any references to a random coil state of proteins. We uncover the symmetry-breaking vector and its reliability order not only for distinguishing different secondary structures of proteins but also for capturing the delicate sensitivity interplayed among chemical shifts of (13) C (α), (13) C (β), (13) C', (1) H (α), (15) N, (1) H ( N ) atoms simultaneously, which then provides a straightforward framework toward assigning secondary structures of proteins. MDHN-CSSF could correctly assign secondary structures of training (validating) proteins with the favourable (comparable) Q3 scores in comparison with those from the previous correlation scores. MDHN-CSSF provides a simple and robust strategy for the systematic assignment of secondary structures of proteins and would facilitate the de novo determination of three-dimensional structures

  11. Universality class of replica symmetry breaking, scaling behavior, and the low-temperature fixed-point order function of the Sherrington-Kirkpatrick model.

    Science.gov (United States)

    Oppermann, R; Schmidt, M J

    2008-12-01

    A scaling theory of replica symmetry breaking (RSB) in the Sherrington-Kirkpatrick (SK) model is presented in the framework of critical phenomena for the scaling regime of large RSB orders kappa , small temperatures T , and small (homogeneous) magnetic fields H . We employ the pseudodynamical picture [R. Oppermann, M. J. Schmidt, and D. Sherrington, Phys. Rev. Lett. 98, 127201 (2007)], where two critical points CP1 and CP2 are associated with the order function's pseudodynamical limits lim_{a-->infinity}q(a)=1 and lim_{a-->0}q(a)=0 at (T=0 , H=0 , 1kappa=0) . CP1 - and CP2 -dominated contributions to the free energy functional F[q(a)] require an unconventional scaling hypothesis. We determine the scaling contributions in accordance with detailed numerical self-consistent solutions for up to 200 orders of RSB. Power laws, scaling functions, and crossover lines are obtained. CP1 -dominated behavior is found for the nonequilibrium susceptibility, which decays like chi_{1}=kappa;{-53}f_{1}(Tkappa;{-53}) , for the entropy, which obeys S(T=0) approximately chi_{1};{2} , and for the subclass of diverging parameters a_{i}=kappa;{53}f_{a_{i}}(Tkappa;{-53}) [describing Parisi box sizes m_{i}(T) identical witha_{i}(T)T ], with f_{1}(zeta) approximately zeta and f_{a_{i}}(zeta) approximately 1zeta for zeta-->infinity , while f(0) is finite. CP2 -dominated behavior, controlled by the magnetic field H while temperature is irrelevant, is retrieved in the plateau height (or width) of the order function q(a) according to q_{pl}(H)=kappa;{-1}f_{pl}(H;{23}kappa;{-1}) with f_{pl}mid R:(zeta)mid R:_{zeta-->infinity} approximately zeta and f_{pl}(0) finite. Divergent characteristic RSB orders kappa_{CP1}(T) approximately T;{-35} and kappa_{CP2}(H) approximately H;{-23} , respectively, describe the crossover from mean field SK- to RSB-critical behavior with rational-valued exponents extracted with high precision from our RSB data. The order function q(a) is obtained as a fixed

  12. Bidomain Predictions of Virtual Electrode-Induced Make and Break Excitations around Blood Vessels.

    Science.gov (United States)

    Connolly, Adam J; Vigmond, Edward; Bishop, Martin J

    2017-01-01

    Virtual electrodes formed by field stimulation during defibrillation of cardiac tissue play an important role in eliciting activations. It has been suggested that the coronary vasculature is an important source of virtual electrodes, especially during low-energy defibrillation. This work aims to further the understanding of how virtual electrodes from the coronary vasculature influence defibrillation outcomes. Using the bidomain model, we investigated how field stimulation elicited activations from virtual electrodes around idealized intramural blood vessels. Strength-interval curves, which quantify the stimulus strength required to elicit wavefront propagation from the vessels at different states of tissue refractoriness, were computed for each idealized geometry. Make excitations occurred at late diastolic intervals, originating from regions of depolarization around the vessel. Break excitations occurred at early diastolic intervals, whereby the vessels were able to excite surrounding refractory tissue due to the local restoration of excitability by virtual electrode-induced hyperpolarizations. Overall, strength-interval curves had similar morphologies and underlying excitation mechanisms compared with previous experimental and numerical unipolar stimulation studies of cardiac tissue. Including the presence of the vessel wall increased the field strength required for make excitations but decreased the field strength required for break excitations, and the field strength at which break excitations occurred was generally greater than 5 V/cm. Finally, in a more realistic ventricular slice geometry, the proximity of virtual electrodes around subepicardial vessels was seen to cause break excitations in the form of propagating unstable wavelets to the subepicardial layer. Representing the blood vessel wall microstructure in computational bidomain models of defibrillation is recommended as it significantly alters the electrophysiological response of the vessel to

  13. Zebularine induces replication-dependent double-strand breaks which are preferentially repaired by homologous recombination.

    Science.gov (United States)

    Orta, Manuel Luis; Pastor, Nuria; Burgos-Morón, Estefanía; Domínguez, Inmaculada; Calderón-Montaño, José Manuel; Huertas Castaño, Carlos; López-Lázaro, Miguel; Helleday, Thomas; Mateos, Santiago

    2017-09-01

    Zebularine is a second-generation, highly stable hydrophilic inhibitor of DNA methylation with oral bioavailability that preferentially target cancer cells. It acts primarily as a trap for DNA methyl transferases (DNMTs) protein by forming covalent complexes between DNMT protein and zebularine-substrate DNA. It's well documented that replication-blocking DNA lesions can cause replication fork collapse and thereby to the formation of DNA double-strand breaks (DSB). DSB are dangerous lesions that can lead to potentially oncogenic genomic rearrangements or cell death. The two major pathways for repair of DSB are non-homologous end joining (NHEJ) and homologous recombination (HR). Recently, multiple functions for the HR machinery have been identified at arrested forks. Here we investigate in more detail the importance of the lesions induced by zebularine in terms of DNA damage and cytotoxicity as well as the role of HR in the repair of these lesions. When we examined the contribution of NHEJ and HR in the repair of DSB induced by zebularine we found that these breaks were preferentially repaired by HR. Also we show that the production of DSB is dependent on active replication. To test this, we determined chromosome damage by zebularine while transiently inhibiting DNA synthesis. Here we report that cells deficient in single-strand break (SSB) repair are hypersensitive to zebularine. We have observed more DSB induced by zebularine in XRCC1 deficient cells, likely to be the result of conversion of SSB into toxic DSB when encountered by a replication fork. Furthermore we demonstrate that HR is required for the repair of these breaks. Overall, our data suggest that zebularine induces replication-dependent DSB which are preferentially repaired by HR. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Formulation of the low-energy effective theory of electroweak symmetry-breaking without a Higgs particle; Formulation de la theorie effective a basse energie du secteur electrofaible sans particule de Higgs

    Energy Technology Data Exchange (ETDEWEB)

    Hirn, J

    2004-07-01

    The low-energy effective theory of electroweak symmetry-breaking without a Higgs particle is constructed using the methods of Chiral Perturbation Theory. Weinberg's power-counting formula demonstrates the consistency of the loop expansion, with the corresponding renormalization. We find that the suppression of effective operators by a mass scale, which was automatic in the case of the Standard Model, no longer holds in the Higgs-less case. Moreover, the incriminated operators appear at leading order in the chiral expansion, at variance with experiments. To account for their suppression, invariance under a larger symmetry is required, corresponding to the composite sector (which produces the three Goldstone modes) being decoupled from the elementary sector (quarks, leptons and Yang-Mills fields). The couplings are introduced via spurions: this reduces the symmetry to SU(2) x U(1). In the simultaneous expansion in powers of momenta and spurions, the aforementioned operators are relegated to higher orders. In addition, the method allows for a systematic treatment of weak isospin breaking. The Weinberg power-counting formula can be recovered, and small neutrino masses accounted for. The three right-handed neutrinos (lighter than the TeV), which are introduced in connection with the custodial symmetry, are quasi-sterile and stable. A constraint on the underlying theory is obtained by studying the anomaly-matching in the composite sector and generalizing the Wess-Zumino construction. The spurion formalism is also applied to open linear moose models, for which generalized Weinberg sum rules are derived. (author)

  15. Mammalian RAD52 Functions in Break-Induced Replication Repair of Collapsed DNA Replication Forks

    DEFF Research Database (Denmark)

    Sotiriou, Sotirios K; Kamileri, Irene; Lugli, Natalia

    2016-01-01

    RNA or knockout of the gene by CRISPR/Cas9 compromised restart of collapsed forks and led to DNA damage in cells experiencing DRS. Furthermore, in cancer-prone, heterozygous APC mutant mice, homozygous deletion of the Rad52 gene suppressed tumor growth and prolonged lifespan. We therefore propose that mammalian......Human cancers are characterized by the presence of oncogene-induced DNA replication stress (DRS), making them dependent on repair pathways such as break-induced replication (BIR) for damaged DNA replication forks. To better understand BIR, we performed a targeted siRNA screen for genes whose...... RAD52 facilitates repair of collapsed DNA replication forks in cancer cells....

  16. Acoustic radiation- and streaming-induced microparticle velocities determined by microparticle image velocimetry in an ultrasound symmetry plane

    DEFF Research Database (Denmark)

    Barnkob, Rune; Augustsson, Per; Laurell, Thomas

    2012-01-01

    We present microparticle image velocimetry measurements of suspended microparticles of diameters from 0.6 to 10μm undergoing acoustophoresis in an ultrasound symmetry plane in a microchannel. The motion of the smallest particles is dominated by the Stokes drag from the induced acoustic streaming...

  17. Symmetry breaking in a nutshell: the odyssey of a pseudo problem in molecular physics. The X̃(2)Σ(u)(+) BNB case revisited.

    Science.gov (United States)

    Kalemos, Apostolos

    2013-06-14

    The X̃(2)Σu (+) BNB state considered to be of symmetry broken (SB) character has been studied by high level multireference variational and full configuration interaction methods. We discuss in great detail the roots of the so-called SB problem and we offer an in depth analysis of the unsuspected reasons behind the double minimum topology found in practically all previous theoretical investigations. We argue that the true reason of failure to recover a D∞h equilibrium geometry lies in the lack of the correct permutational symmetry of the wavefunctions employed and is by no means a real effect.

  18. Loop induced type-II seesaw model and GeV dark matter with U(1)B - L gauge symmetry

    Science.gov (United States)

    Nomura, Takaaki; Okada, Hiroshi

    2017-11-01

    We propose a model with U(1) B - L gauge symmetry and several new fermions in no conflict with anomaly cancellation where the neutrino masses are given by the vacuum expectation value of Higgs triplet induced at the one-loop level. The new fermions are odd under discrete Z2 symmetry and the lightest one becomes dark matter candidate. We find that the mass of dark matter is typically O (1)- O (10) GeV. Then relic density of the dark matter is discussed.

  19. Anomalous U(1) as a mediator of Supersymmetry Breaking

    CERN Document Server

    Dvali, Gia; Dvali, Gia; Pomarol, Alex

    1996-01-01

    We point out that an anomalous gauge U(1) symmetry is a natural candida= te for being the mediator and messenger of supersymmetry breaking. It facilitate= s dynamical supersymmetry breaking even in the flat limit. Soft masses are induced by both gravity and the U(1) gauge interactions giving an unusual= mass hierarchy in the sparticle spectrum which suppresses flavor violations. T= his scenario does not suffer from the Polonyi problem.

  20. Electronic cigarettes induce DNA strand breaks and cell death independently of nicotine in cell lines.

    Science.gov (United States)

    Yu, Vicky; Rahimy, Mehran; Korrapati, Avinaash; Xuan, Yinan; Zou, Angela E; Krishnan, Aswini R; Tsui, Tzuhan; Aguilera, Joseph A; Advani, Sunil; Crotty Alexander, Laura E; Brumund, Kevin T; Wang-Rodriguez, Jessica; Ongkeko, Weg M

    2016-01-01

    Evaluate the cytotoxicity and genotoxicity of short- and long-term e-cigarette vapor exposure on a panel of normal epithelial and head and neck squamous cell carcinoma (HNSCC) cell lines. HaCaT, UMSCC10B, and HN30 were treated with nicotine-containing and nicotine-free vapor extract from two popular e-cigarette brands for periods ranging from 48 h to 8 weeks. Cytotoxicity was assessed using Annexin V flow cytometric analysis, trypan blue exclusion, and clonogenic assays. Genotoxicity in the form of DNA strand breaks was quantified using the neutral comet assay and γ-H2AX immunostaining. E-cigarette-exposed cells showed significantly reduced cell viability and clonogenic survival, along with increased rates of apoptosis and necrosis, regardless of e-cigarette vapor nicotine content. They also exhibited significantly increased comet tail length and accumulation of γ-H2AX foci, demonstrating increased DNA strand breaks. E-cigarette vapor, both with and without nicotine, is cytotoxic to epithelial cell lines and is a DNA strand break-inducing agent. Further assessment of the potential carcinogenic effects of e-cigarette vapor is urgently needed. Copyright © 2015 Elsevier Ltd. All rights reserved.

  1. Distributions of Low- and High-LET Radiation-Induced Breaks in Chromosomes are Associated with Inter- and Intrachromosome Exchanges

    Science.gov (United States)

    Hada, Megumi; Zhang, Ye; Feiveson, Alan; Cucinotta, Francis A.; Wu, Honglu

    2010-01-01

    To study the breakpoint along the length of the chromosome induced by low- and high-LET radiations, we exposed human epithelial cells in vitro to Cs-137 rays at both low and high dose rates, secondary neutrons at a low dose rate, and 600 MeV/u Fe ions at a high dose rate. The location of the breaks was identified using the multicolor banding in situ hybridization (mBAND) that paints Chromosome 3 in 23 different colored bands. The breakpoint distributions were found to be similar between rays of low and high dose rates and between the two high-LET radiation types. Detailed analysis of the chromosome break ends involved in inter- and intrachromosome exchanges revealed that only the break ends participating in interchromosome exchanges contributed to the hot spots found for low-LET. For break ends participating in intrachromosome exchanges, the distributions for all four radiation scenarios were similar with clusters of breaks found in three regions. Analysis of the locations of the two break ends in Chromosome 3 that joined to form an intrachromosome exchange demonstrated that two breaks with a greater genomic separation may be more likely to rejoin than two closer breaks, indicating that chromatin folding can play an important role in the rejoining of chromosome breaks. Our study demonstrated that the gene-rich regions do not necessarily contain more breaks. The breakpoint distribution depends more on the likelihood that a break will join with another break in the same chromosome or in a different chromosome.

  2. Protection against {sup 131}I-induced Double Strand DNA Breaks in Thyroid Cells

    Energy Technology Data Exchange (ETDEWEB)

    Hershman, J.M.; Okunyan, A.; Cannon, S.; Hogen, V. [Endocrinology, UCLA-VA, Los Angeles (United States); Rivina, Y. [Radiation Biology, UCLA, Los Angeles (United States)

    2012-07-01

    Radioiodine-131 (I{sup 131}) released from nuclear reactor accidents has dramatically increased the incidence of papillary thyroid cancer in exposed individuals, especially young children. The accepted measure for prevention of radiation-induced thyroid cancer is potassium iodide tablets that contain 100 mg iodide taken daily to block thyroid uptake of I{sup 131}. The deposition of ionizing radiation in cells results in double-strand DNA breaks (DSB) at fragile sites, and this early event can generate oncogenic rearrangements that eventually cause the cancer. We have developed a thyroid cell model to quantify the mitogenic effect of I{sup 131}. I{sup 131} causes double strand DNA breaks in FRTL-5 cells detected by 53BP1 or gamma H2AX and had no effect on cells that do not transport iodide. Perchlorate, iodide, and thiocyanate protect against DSB induced by I{sup 131}. Preincubation with the anion or radioprotective compounds prevents DSB; delayed addition of the anion is much less effective. These data provide a basis for studies of radioprotection against DSB induced by I{sup 131} in animals in order to refine the prevention of thyroid cancer resulting from nuclear fallout

  3. Supersymmetric model with an extra U(1) gauge symmetry forbidding proton decay

    Science.gov (United States)

    Aoki; Oshimo

    2000-06-05

    In the standard model the proton is protected from decay naturally by gauge symmetries, whereas in the ordinary minimal supersymmetric standard model an ad hoc discrete symmetry is imposed for the proton stability. We present a new supersymmetric model in which the proton decay is forbidden by an extra U(1) gauge symmetry. Particle contents are necessarily increased to be free from anomalies, incorporating right-handed neutrinos. Both Dirac and Majorana masses are generated for neutrinos, yielding nonvanishing but small masses. The superpotential consists only of trilinear couplings and the mass parameter &mgr; of the minimal model is induced by spontaneous breaking of the U(1) symmetry.

  4. The Effects of Akaloid Fraction of Korean Ginseng on the Radiation-Induced DNA Strand Breaks

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Chul Koo; Kim, Tae Hwan; Yoo, Seong Yul [Seoul National University College of Medicine, Seoul (Korea, Republic of)] (and others)

    1995-06-15

    Purpose : To investigate the effect of alkaloid fraction from Korean ginseng on radiation-induced DNA double strand breaks(dsb) formation and repair in murine lymphocytes. Materials and Methods : We used the neutral filter elution technique to assay {sup 60}Co {gamma} ray-induced DNA double strand breaks formation and repair in C57BL/6 mouse spleen lymphocytes for evaluation the dose-response relationship in the presence of alkaloid fraction as a radioprotective agent. The lymphocytes were stimulated with phytohemagglutinin (PHA, 2 {mu} g/ml) to label {sup 3} [H]-thymidine. Isotope-labelled lymphocytes in suspension were exposed to 100 Gy at 0 .deg. C in the alkaloid fraction-treated group and elution procedure was performed at pH 9.6. The extents of formation of radiation-induced DNA double strand breaks and repair were compared respectively via strand scission factor (SSF) and relative strand scission factor (RSSF). Results : Alkaloid fraction reduced the formation of double strand breaks with dose modification factor of 2.15, compared to control group. Rejoining of DNA dsb appeared to take place via two components. The first fast component was completed within 20.4 minutes, but the second slow component was not completed until 220.2 minutes after irradiation. About 30% of dsb formed by irradiation was ultimately unrejoined despite the administration of alkaloid fraction. The administration of alkaloid fraction had a great effect on the second slow component of repair ; the half-time of fast component repair was not changed, but that of slow component was 621.8 minutes. Conclusion : Neutral filter elution assay proved to be a very effective method to quantitate the extents of DNA dsb formation and its repair. By using this technique, we were able to evaluate the efficiency of alkaloid fraction from Korean ginseng as a valuable radioprotector. Alkaloid fraction can be used prophylactically to prevent or ameliorate the severe radiation damages in workers and

  5. Correlation analysis of symmetry breaking in the surface nanostructure ordering: case study of the ventral scale of the snake Morelia viridis

    Science.gov (United States)

    Kovalev, A.; Filippov, A.; Gorb, S. N.

    2016-03-01

    In contrast to the majority of inorganic or artificial materials, there is no ideal long-range ordering of structures on the surface in biological systems. Local symmetry of the ordering on biological surfaces is also often broken. In the present paper, the particular symmetry violation was analyzed for dimple-like nano-pattern on the belly scales of the skin of the pythonid snake Morelia viridis using correlation analysis and statistics of the distances between individual nanostructures. The results of the analysis performed on M. viridis were compared with a well-studied nano-nipple pattern on the eye of the sphingid moth Manduca sexta, used as a reference. The analysis revealed non-random, but very specific symmetry violation. In the case of the moth eye, the nano-nipple arrangement forms a set of domains, while in the case of the snake skin, the nano-dimples arrangement resembles an ordering of particles (molecules) in amorphous (glass) state. The function of the nano-dimples arrangement may be to provide both friction and strength isotropy of the skin. A simple model is suggested, which provides the results almost perfectly coinciding with the experimental ones. Possible mechanisms of the appearance of the above nano-formations are discussed.

  6. D-foam-induced flavor condensates and breaking of supersymmetry in free Wess-Zumino fluids

    CERN Document Server

    Mavromatos, Nick E; Tarantino, Walter; 10.1103/PhysRevD.84.044050

    2011-01-01

    Recently {[}N. E. Mavromatos and S. Sarkar, New J. Phys. 10, 073009 (2008); N. E. Mavromatos, S. Sarkar, and W. Tarantino, Phys. Rev. D 80, 084046 (2009)], we argued that a particular model of string-inspired quantum space-time foam (D-foam) may induce oscillations and mixing among flavored particles. As a result, rather than the mass-eigenstate vacuum, the correct ground state to describe the underlying dynamics is the flavor vacuum, proposed some time ago by Blasone and Vitiello as a description of quantum field theories with mixing. At the microscopic level, the breaking of target-space supersymmetry is induced in our space-time foam model by the relative transverse motion of brane defects. Motivated by these results, we show that the flavor vacuum, introduced through an inequivalent representation of the canonical (anti-) commutation relations, provides a vehicle for the breaking of supersymmetry at a low-energy effective field-theory level; on considering the flavor-vacuum expectation value of the energy...

  7. Radiation induced DNA double-strand breaks in radiology; Strahleninduzierte DNA-Doppelstrangbrueche in der Radiologie

    Energy Technology Data Exchange (ETDEWEB)

    Kuefner, M.A. [Dornbirn Hospital (Austria). Dept. of Radiology; Brand, M.; Engert, C.; Uder, M. [Erlangen University Hospital (Germany). Dept. of Radiology; Schwab, S.A. [Radiologis, Oberasbach (Germany)

    2015-10-15

    Shortly after the discovery of X-rays, their damaging effect on biological tissues was observed. The determination of radiation exposure in diagnostic and interventional radiology is usually based on physical measurements or mathematical algorithms with standardized dose simulations. γ-H2AX immunofluorescence microscopy is a reliable and sensitive method for the quantification of radiation induced DNA double-strand breaks (DSB) in blood lymphocytes. The detectable amount of these DNA damages correlates well with the dose received. However, the biological radiation damage depends not only on dose but also on other individual factors like radiation sensitivity and DNA repair capacity. Iodinated contrast agents can enhance the x-ray induced DNA damage level. After their induction DSB are quickly repaired. A protective effect of antioxidants has been postulated in experimental studies. This review explains the principle of the γ-H2AX technique and provides an overview on studies evaluating DSB in radiologic examinations.

  8. Carbon ion induced DNA double-strand breaks in melanophore B{sub 16}

    Energy Technology Data Exchange (ETDEWEB)

    Wei Zengquan; Zhou Guangming; Wang Jufang; He Jing; Li Qiang; Li Wenjian; Xie Hongmei; Cai Xichen; Tao Huang; Dang Bingrong; Han Guangwu [Chinese Academy of Sciences, Lanzhou (China). Inst. of Modern Physics; Gao Qingxiang [Lanzhou Univ. (China)

    1997-09-01

    DNA double-strand breaks (DSBs) in melanophore B{sub 16} induced by plateau and extended Bragg peak of 75 MeV/u {sup 12}C{sup 6+} ions were studied by using a technique of inverse pulsed-field gel electrophoresis (PIGE). DNA fragment lengths were distributed in two ranges: the larger in 1.4 Mbp-3.2 Mbp and the smaller in less than 1.2 Mbp. It indicates that distribution of DNA fragments induced by heavy ion irradiation is not stochastic and there probably are sensitive sites to heavy ions in DNA molecules of B{sub 16}. Percentage of DNA released from plug (PR) increased and trended towards a quasi-plateau {proportional_to}85% as dose increased. Content of the larger fragments decreased and flattened with increasing dose while content of the smaller ones increased and trended towards saturation. (orig.)

  9. In search of symmetry lost

    CERN Multimedia

    Wilczek, Frank

    2004-01-01

    Powerful symmetry principles have guided physicists in their quest for nature's fundamental laws. The successful gauge theory of electroweak interactions postulates a more extensive symmetry for its equations than are manifest in the world (8 pages) Powerful symmetry principles have guided physicists in their quest for nature's fundamental laws. The successful gauge theory of electroweak interactions postulates a more extensive symmetry for its equations than are manifest in the world. The discrepancy is ascribed to a pervasive symmetry-breaking field, which fills all space uniformly, rendering the Universe a sort of exotic superconductor. So far, the evidence for these bold ideas is indirect. But soon the theory will undergo a critical test depending on whether the quanta of this symmetry-breaking field, the so-called Higgs particles, are produced at the Large Hadron Collider (due to begin operation in 2007).

  10. Broken symmetry makes helium

    CERN Multimedia

    Gray, P L

    2003-01-01

    "The subatomic pion particle breaks the charge symmetry rule that governs both fusion and decay. In experiments performed at the Indiana University Cyclotron Laboratory, physicists forced heavy hydrogen (1 proton + 1 neutron) to fuse into helium in a controlled, measurable environment" (1 paragraph).

  11. DNA strand breaks in human nasal respiratory epithelium are induced upon exposure to urban pollution

    Energy Technology Data Exchange (ETDEWEB)

    Calderon-Garciduenas, L.; Osnaya-Brizuela, N.; Ramirez-Martinez, L. [Instituto Nacional de Pediatria, Mexico City (Mexico)] [and others

    1996-02-01

    All organisms have the ability to respond and adapt to a myriad of environmental insults. The human respiratory epithelium, when exposed to oxidant gases in photochemical smog, is at risk of DNA damage and requires efficient cellular adaptative responses to resist the environmentally induced cell damage. Ozone and its reaction products induce in vitro and in vivo DNA single strand breaks (SSBs) in respiratory epithelial cells and alveolar macrophages. To determine if exposure to a polluted atmosphere with ozone as the main criteria pollutant of 19 children and 13 adult males who lived in a low-polluted Pacific port, 69 males and 16 children who were permanent residents of Southwest Metropolitan Mexico City (SWMMC), and 22 young males newly arrived to SWMMC and followed for 12 weeks. Respiratory symptoms, nasal cytology and histopathology, cell viabilities, and single-cell gel electrophoresis were investigated. Atmospheric pollutant data were obtained from a fixed-site monitoring station. SWMMC volunteers spent >7 hr/day outdoors and all had upper respiratory symptoms. A significant difference in the numbers of DNA-damaged nasal cells was observed between control and chronically exposed subjects, both in children (p<0.00001) and in adults (p>0.01). SSBs in newly arrived subjects quickly increased upon arrival to the city, from 39.8 {+-}8.34% in the first week to 67.29 {+-}2.35 by week 2. Thereafter, the number of cells with SSBs remained stable in spite of the continuous increase in cumulative ozone, suggesting a threshold for cumulative DNA nasal damage. Exposure to a polluted urban atmosphere induces SSBs in human nasal respiratory epithelium, and nasal SSBs could serve as a biomarker of ozone exposure. Further, because DNA strand breaks are a threat to cell viability and genome integrity and appear to be a critical lesion responsible for p53 induction, nasal SSBs should be evaluated in ozone-exposed individuals. 43 refs., 5 figs., 4 tabs.

  12. Mirror-Symmetry-Breaking in Poly[(9,9-di-n-octylfluorenyl-2,7-diyl-alt-biphenyl] (PF8P2 is Susceptible to Terpene Chirality, Achiral Solvents, and Mechanical Stirring

    Directory of Open Access Journals (Sweden)

    Ayako Nakao

    2013-06-01

    Full Text Available Solvent chirality transfer of (S-/(R-limonenes allows the instant generation of optically active PF8P2 aggregates with distinct circular dichroism (CD/circularly polarized luminescence (CPL amplitudes with a high quantum yield of 16–20%. The present paper also reports subtle mirror-symmetry-breaking effects in CD-/CPL-amplitude and sign, CD/UV-vis spectral wavelengths, and photodynamics of the aggregates, though the reasons for the anomaly are unsolved. However, these photophysical properties depend on (i the chemical natures of chiral and achiral molecules when used in solvent quantity, (ii clockwise and counterclockwise stirring operations, and (iii the order of addition of limonene and methanol to the chloroform solution.

  13. The nematicity induced d-symmetry charge density wave in electron-doped iron-pnictide superconductors

    Science.gov (United States)

    Chou, Chung-Pin; Chen, Hong-Yi; Ting, C. S.

    2018-03-01

    The interplay among the nematicity, the stripe spin-density-wave (SDW) order and superconductivity in iron-pnictides is studied in a self-consistent Bogoliubov-de Gennes equations. Our calculations have shown that the nematic-order breaks the degeneracy of dxz and dyz orbitals and causes the elliptic Fermi surface near the Γ point in the normal state. In addition, the appearance of the orthorhombic magnetic fluctuations generates two uneven pairs of peaks at ( ± π, 0) and (0, ± π) in its Fourier transformation. All these are comparing favorably with experimental measurements. In the nematic phase, our results indicate that the charge density and its spatial image in the local density of states exhibit a dx2 -y2-like symmetry. Finally, the complete phase diagram is obtained and the nematic phase is found to be in a narrow region close to the SDW transition in the electron-doped iron-pnictide superconductors.

  14. Break-Induced Replication Is a Source of Mutation Clusters Underlying Kataegis

    Directory of Open Access Journals (Sweden)

    Cynthia J. Sakofsky

    2014-06-01

    Full Text Available Clusters of simultaneous multiple mutations can be a source of rapid change during carcinogenesis and evolution. Such mutation clusters have been recently shown to originate from DNA damage within long single-stranded DNA (ssDNA formed at resected double-strand breaks and dysfunctional replication forks. Here, we identify double-strand break (DSB-induced replication (BIR as another powerful source of mutation clusters that formed in nearly half of wild-type yeast cells undergoing BIR in the presence of alkylating damage. Clustered mutations were primarily formed along the track of DNA synthesis and were frequently associated with additional breakage and rearrangements. Moreover, the base specificity, strand coordination, and strand bias of the mutation spectrum were consistent with mutations arising from damage in persistent ssDNA stretches within unconventional replication intermediates. Altogether, these features closely resemble kataegic events in cancers, suggesting that replication intermediates during BIR may be the most prominent source of mutation clusters across species.

  15. Expansions and contractions in a tandem repeat induced by double-strand break repair.

    Science.gov (United States)

    Pâques, F; Leung, W Y; Haber, J E

    1998-04-01

    Repair of a double-strand break (DSB) in yeast can induce very frequent expansions and contractions in a tandem array of 375-bp repeats. These results strongly suggest that DSB repair can be a major source of amplification of tandemly repeated sequences. Most of the DSB repair events are not associated with crossover. Rearrangements appear in 50% of these repaired recipient molecules. In contrast, the donor template nearly always remains unchanged. Among the rare crossover events, similar rearrangements are found. These results cannot readily be explained by the gap repair model of Szostak et al. (J. W. Szostak, T. L. Orr-Weaver, R. J. Rothstein, and F. W. Stahl, Cell 33:25-35, 1983) but can be explained by synthesis-dependent strand annealing (SDSA) models that allow for crossover. Support for SDSA models is provided by a demonstration that a single DSB repair event can use two donor templates located on two different chromosomes.

  16. On The Double-Vacua Duality of Multi-Scalar Higgs and NGB-Dual Higgses in Scherk-Schwarz Breaking of 5-dimensional SU(6 Symmetry

    Directory of Open Access Journals (Sweden)

    Jusak Sali Kosasih

    2014-07-01

    Full Text Available A special condition of Scherk-Schwarz and S^1/Z2 orbifold breaking brings about both a weakly-coupled SU(6 baby Higgs and a strongly-coupled will-be simplest little Higgs scalar in the near-brane of SU(3 x SU(3x U(1. The latter produces SU(3 VEVs and simplest little-like Higgs after triplet-triplet splitting and, under quadratic-based and non-quadratic-based Coleman-Weinberg potential, the simplest little-like Higgs yields exotic Higgses, scalar-pair and 3-scalar Higgses in the so-called one-by-one and collective breakings. A generalized non-quadratic-based Coleman-Weinberg potential utilizing a NGB-like scalar produces NGB-dual Higgses with a squared mass relevant to the components of a 3-scalar Higgs that further create a duality of 3-scalar Higgs and NGB-dual Higgses. This is due to a double-vacua property such that each vacuum responds equally to the shifts happening at either non-zero or zero-VEV vacuum.

  17. Mammalian RAD52 Functions in Break-Induced Replication Repair of Collapsed DNA Replication Forks.

    Science.gov (United States)

    Sotiriou, Sotirios K; Kamileri, Irene; Lugli, Natalia; Evangelou, Konstantinos; Da-Ré, Caterina; Huber, Florian; Padayachy, Laura; Tardy, Sebastien; Nicati, Noemie L; Barriot, Samia; Ochs, Fena; Lukas, Claudia; Lukas, Jiri; Gorgoulis, Vassilis G; Scapozza, Leonardo; Halazonetis, Thanos D

    2016-12-15

    Human cancers are characterized by the presence of oncogene-induced DNA replication stress (DRS), making them dependent on repair pathways such as break-induced replication (BIR) for damaged DNA replication forks. To better understand BIR, we performed a targeted siRNA screen for genes whose depletion inhibited G1 to S phase progression when oncogenic cyclin E was overexpressed. RAD52, a gene dispensable for normal development in mice, was among the top hits. In cells in which fork collapse was induced by oncogenes or chemicals, the Rad52 protein localized to DRS foci. Depletion of Rad52 by siRNA or knockout of the gene by CRISPR/Cas9 compromised restart of collapsed forks and led to DNA damage in cells experiencing DRS. Furthermore, in cancer-prone, heterozygous APC mutant mice, homozygous deletion of the Rad52 gene suppressed tumor growth and prolonged lifespan. We therefore propose that mammalian RAD52 facilitates repair of collapsed DNA replication forks in cancer cells. Copyright © 2016 The Author(s). Published by Elsevier Inc. All rights reserved.

  18. Computation of hyperfine tensors for dinuclear Mn(III) Mn(IV) complexes by broken-symmetry approaches: anisotropy transfer induced by local zero-field splitting.

    Science.gov (United States)

    Schraut, Johannes; Arbuznikov, Alexei V; Schinzel, Sandra; Kaupp, Martin

    2011-12-09

    Based on broken-symmetry density functional calculations, the (55)Mn hyperfine tensors of a series of exchange-coupled, mixed-valence, dinuclear Mn(III) Mn(IV) complexes have been computed. We go beyond previous quantum chemical work by fully including the effects of local zero-field splitting (ZFS) interactions in the spin projection, following the first-order perturbation formalism of Sage et al. [J. Am. Chem. Soc. 1989, 111, 7239]. This allows the ZFS-induced transfer of hyperfine anisotropy from the Mn(III) site to the Mn(IV) site to be described with full consideration of the orientations of local hyperfine and ZFS tensors. After scaling to correct for systematic deficiencies in the quantum chemically computed local ZFS tensors, good agreement with experimental (55)Mn anisotropies at the Mn(IV) site is obtained. The hyperfine coupling anisotropies on the Mn(III) site depend sensitively on structural distortions for a d(4) ion. The latter are neither fully reproduced by using a DFT-optimized coordination environment nor by using experimental structures. For very small exchange-coupling constants, the perturbation treatment breaks down and a dramatic sensitivity to the scaling of the local ZFS tensors is observed. These results are discussed with respect to ongoing work to elucidate the structure of the oxygen-evolving complex of photosystem II by analysis of the EPR spectra. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. A unique $Z_4^R$ symmetry for the MSSM

    CERN Document Server

    Lee, Hyun Min; Ratz, Michael; Ross, Graham G; Schieren, Roland; Schmidt-Hoberg, Kai; Vaudrevange, Patrick K S

    2011-01-01

    We consider the possible anomaly free Abelian discrete symmetries of the MSSM that forbid the mu-term at perturbative order. Allowing for anomaly cancellation via the Green-Schwarz mechanism we identify discrete R-symmetries as the only possibility and prove that there is a unique Z_4^R symmetry that commutes with SO(10). We argue that non-perturbative effects will generate a mu-term of electroweak order thus solving the mu-problem. The non-perturbative effects break the Z_4^R symmetry leaving an exact Z_2 matter parity. As a result dimension four baryon- and lepton-number violating operators are absent while, at the non-perturbative level, dimension five baryon- and lepton-number violating operators get induced but are highly suppressed so that the nucleon decay rate is well within present bounds.

  20. Postincubation with aclarubicin reverses topoisomerase II mediated DNA cleavage, strand breaks, and cytotoxicity induced by VP-16

    DEFF Research Database (Denmark)

    Petersen, L N; Jensen, P B; Sørensen, B S

    1994-01-01

    In previous studies, we found that VP-16 (etoposide) induced cytotoxicity and protein-concealed strand break formation was prevented in a small cell lung cancer (SCLC) cell line, when the cells were incubated with aclarubicin prior to treatment with VP-16. In the present work, we studied the effect...... of adding aclarubicin to the cell suspension after VP-16. In a clonogenic assay, we found that the cytotoxicity induced by VP-16 in SCLC cells was inhibited when cells were postincubated with aclarubicin. The addition of aclarubicin at any time in relation to VP-16 was able to stop further cytotoxicity...... induced by the topoisomerase II (topo-II) targeting drug. Aclarubicin was also found to antagonize the cytotoxicity induced by VM-26 (teniposide), and m-AMSA. With the alkaline elution technique we found that postincubating the cells with aclarubicin inhibited VP-16-induced DNA strand break formation...

  1. Electroweak breaking in supersymmetric models

    CERN Document Server

    Ibáñez, L E

    1992-01-01

    We discuss the mechanism for electroweak symmetry breaking in supersymmetric versions of the standard model. After briefly reviewing the possible sources of supersymmetry breaking, we show how the required pattern of symmetry breaking can automatically result from the structure of quantum corrections in the theory. We demonstrate that this radiative breaking mechanism works well for a heavy top quark and can be combined in unified versions of the theory with excellent predictions for the running couplings of the model. (To be published in ``Perspectives in Higgs Physics'', G. Kane editor.)

  2. Quantitative measurement of hydroxyl radical induced DNA double-strand breaks and the effect of N-acetyl-L-cysteine.

    Science.gov (United States)

    Su, Meihong; Yang, Yao; Yang, Guoliang

    2006-07-24

    Reactive oxygen species, such as hydroxyl or superoxide radicals, can be generated by exogenous agents as well as from normal cellular metabolism. Those radicals are known to induce various lesions in DNA, including strand breaks and base modifications. These lesions have been implicated in a variety of diseases such as cancer, arteriosclerosis, arthritis, neurodegenerative disorders and others. To assess these oxidative DNA damages and to evaluate the effects of the antioxidant N-acetyl-L-cysteine (NAC), atomic force microscopy (AFM) was used to image DNA molecules exposed to hydroxyl radicals generated via Fenton chemistry. AFM images showed that the circular DNA molecules became linear after incubation with hydroxyl radicals, indicating the development of double-strand breaks. The occurrence of the double-strand breaks was found to depend on the concentration of the hydroxyl radicals and the duration of the reaction. Under the conditions of the experiments, NAC was found to exacerbate the free radical-induced DNA damage.

  3. Formation and rejoining of deoxyribonucleic acid double-strand breaks induced in isolated cell nuclei by antineoplastic intercalating agents.

    Science.gov (United States)

    Pommier, Y; Schwartz, R E; Kohn, K W; Zwelling, L A

    1984-07-03

    The biochemical characteristics of the formation and disappearance of intercalator-induced DNA double-strand breaks (DSB) were studied in nuclei from mouse leukemia L1210 cells by using filter elution methodology [Bradley, M. O., & Kohn, K.W. (1979) Nucleic Acids Res. 7, 793-804]. The three intercalators used were 4'-(9-acridinylamino)-methanesulfon-m-anisidide (m-AMSA), 5-iminodaunorubicin (5-ID), and ellipticine. These compounds differ in that they produced predominantly DNA single-strand breaks (SSB) (m-AMSA) or predominantly DNA double-strand breaks (ellipticine) or a mixture of both SSB and DSB (5-ID) in whole cells. In isolated nuclei, each intercalator produced DSB at a frequency comparable to that which is produced in whole cells. Moreover, these DNA breaks reversed within 30 min after drug removal. It thus appeared that neither ATP nor other nucleotides were necessary for intercalator-dependent DNA nicking-closing reactions. The formation of the intercalator-induced DSB was reduced at ice temperature. Break formation was also reduced in the absence of magnesium, at a pH above 6.4 and at NaCl concentrations above 200 mM. In the presence of ATP and ATP analogues, the intercalator-induced cleavage was enhanced. These results suggest that the intercalator-induced DSB are enzymatically mediated and that the enzymes involved in these reactions can catalyze DNA double-strand cleavage and rejoining in the absence of ATP, although the occupancy of an ATP binding site might convert the enzyme to a form more reactive to intercalators. Three inhibitors of DNA topoisomerase II--novobiocin, nalidixic acid, and norfloxacin--reduced the formation of DNA strand breaks.(ABSTRACT TRUNCATED AT 250 WORDS)

  4. Local breaking of fourfold rotational symmetry by short-range magnetic order in heavily overdoped Ba (Fe1 -xCux)2As2

    Science.gov (United States)

    Wang, Weiyi; Song, Yu; Hu, Ding; Li, Yu; Zhang, Rui; Harriger, L. W.; Tian, Wei; Cao, Huibo; Dai, Pengcheng

    2017-10-01

    We investigate Cu-doped Ba (Fe1-xCux) 2As2 with transport, magnetic susceptibility, and elastic neutron scattering measurements. In the heavily Cu-doped regime where long-range stripe-type antiferromagnetic order in BaFe2As2 is suppressed, Ba (Fe1-xCux) 2As2 (0.145 ≤x ≤0.553 ) samples exhibit spin-glass-like behavior in magnetic susceptibility and insulating-like temperature dependence in electrical transport. Using elastic neutron scattering, we find stripe-type short-range magnetic order in the spin-glass region identified by susceptibility measurements. The persistence of short-range magnetic order over a large doping range in Ba (Fe1-xCux) 2As2 likely arises from local arrangements of Fe and Cu that favor magnetic order, with Cu acting as vacancies relieving magnetic frustration and degeneracy. These results indicate locally broken fourfold rotational symmetry, suggesting that stripe-type magnetism is ubiquitous in iron pnictides.

  5. Spontaneous symmetry breaking approach to La{sub 2}CuO{sub 4} properties: Hints for matching the Mott and Slater pictures

    Energy Technology Data Exchange (ETDEWEB)

    Cabo-Bizet, Alejandro [Departamento de Fisica, Centro de Aplicaciones Tecnologicas y Desarrollo, Nuclear (CEADEN), Calle 30, esq. a 5ta, La Habana (Cuba); Cabo Montes de Oca, Alejandro [Grupo de Fisica Teorica, Instituto de Cibernetica Matematematica y Fisica (ICIMAF), Calle E, No. 309, entre 13 y 15, Vedado, La Habana (Cuba)], E-mail: cabo@icmf.inf.cu

    2009-05-04

    Special solutions of the Hartree-Fock (HF) problem for Coulomb interacting electrons described by a simple model of the Cu-O planes in La{sub 2}CuO{sub 4} are presented. One of the mean field states obtained, is able to predict some of the most interesting properties of this material, such as its insulator character and the antiferromagnetic order. The natural appearance of pseudogaps in some states of this material is also indicated by another of the HF states obtained. These surprising results follow after eliminating spin and crystal symmetry restrictions usually imposed on the single particle HF orbitals, by employing the rotational invariant formulation of the HF scheme originally introduced by Dirac. Therefore, it is exemplified here, how up to know considered strong correlation effects, can be described by improving the HF solution of the considered system. In other words, it has been argued, that defining correlation effects as the ones shown by the system and not predicted by the HF best (lowest energy) solution, allows to explain important, up to know considered as strong correlation properties, as simple mean field ones. The discussion also helps to clarify the role of the antiferromagnetism and pseudogaps in the physical properties of the HTSC materials and indicates a promising way to start conciliating the Mott and Slater pictures in the physics of the transition metal oxides and other strongly correlated electron systems.

  6. DNA strand breaks induced by electrons simulated with Nanodosimetry Monte Carlo Simulation Code: NASIC.

    Science.gov (United States)

    Li, Junli; Li, Chunyan; Qiu, Rui; Yan, Congchong; Xie, Wenzhang; Wu, Zhen; Zeng, Zhi; Tung, Chuanjong

    2015-09-01

    The method of Monte Carlo simulation is a powerful tool to investigate the details of radiation biological damage at the molecular level. In this paper, a Monte Carlo code called NASIC (Nanodosimetry Monte Carlo Simulation Code) was developed. It includes physical module, pre-chemical module, chemical module, geometric module and DNA damage module. The physical module can simulate physical tracks of low-energy electrons in the liquid water event-by-event. More than one set of inelastic cross sections were calculated by applying the dielectric function method of Emfietzoglou's optical-data treatments, with different optical data sets and dispersion models. In the pre-chemical module, the ionised and excited water molecules undergo dissociation processes. In the chemical module, the produced radiolytic chemical species diffuse and react. In the geometric module, an atomic model of 46 chromatin fibres in a spherical nucleus of human lymphocyte was established. In the DNA damage module, the direct damages induced by the energy depositions of the electrons and the indirect damages induced by the radiolytic chemical species were calculated. The parameters should be adjusted to make the simulation results be agreed with the experimental results. In this paper, the influence study of the inelastic cross sections and vibrational excitation reaction on the parameters and the DNA strand break yields were studied. Further work of NASIC is underway. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  7. Evidence for non-conservative current-induced forces in the breaking of Au and Pt atomic chains

    Directory of Open Access Journals (Sweden)

    Carlos Sabater

    2015-12-01

    Full Text Available This experimental work aims at probing current-induced forces at the atomic scale. Specifically it addresses predictions in recent work regarding the appearance of run-away modes as a result of a combined effect of the non-conservative wind force and a ‘Berry force’. The systems we consider here are atomic chains of Au and Pt atoms, for which we investigate the distribution of break down voltage values. We observe two distinct modes of breaking for Au atomic chains. The breaking at high voltage appears to behave as expected for regular break down by thermal excitation due to Joule heating. However, there is a low-voltage breaking mode that has characteristics expected for the mechanism of current-induced forces. Although a full comparison would require more detailed information on the individual atomic configurations, the systems we consider are very similar to those considered in recent model calculations and the comparison between experiment and theory is very encouraging for the interpretation we propose.

  8. Two-Photon Spectroscopy of a Series of Platinum Acetylides: Conformation-Induced Ground-State Symmetry Breaking (Postprint)

    Science.gov (United States)

    2017-05-01

    Dayton, Ohio 45433, United States ‡General Dynamics Information Technology, Dayton, Ohio 45431, United States §Slagle Photonics, Dayton, Ohio 45433...photon spectra result from nonplanar ground- state conformations. Previously studied related chromophores having extended conjugation (Rebane, A...left vertical axis) of the 11 Pt-(R-X)2 compounds in THF studied by the NLT method (left vertical axis). The ground- state extinction spectrum (blue line

  9. Heat generation above break-even from laser-induced fusion in ultra-dense deuterium

    Science.gov (United States)

    Holmlid, Leif

    2015-08-01

    Previous results from laser-induced processes in ultra-dense deuterium D(0) give conclusive evidence for ejection of neutral massive particles with energy >10 MeV u-1. Such particles can only be formed from nuclear processes like nuclear fusion at the low laser intensity used. Heat generation is of interest for future fusion energy applications and has now been measured by a small copper (Cu) cylinder surrounding the laser target. The temperature rise of the Cu cylinder is measured with an NTC resistor during around 5000 laser shots per measured point. No heating in the apparatus or the gas feed is normally used. The fusion process is suboptimal relative to previously published studies by a factor of around 10. The small neutral particles HN(0) of ultra-dense hydrogen (size of a few pm) escape with a substantial fraction of the energy. Heat loss to the D2 gas (at deuterium as fusion fuel. With a slightly different setup, a thermal gain of 2 is reached, thus clearly above break-even for all neutronicity values possible. Also including the large kinetic energy which is directly measured for MeV particles leaving through a small opening gives a gain of 2.3. Taking into account the lower efficiency now due to the suboptimal fusion process, previous studies indicate a gain of at least 20 during long periods.

  10. Telmisartan induces growth inhibition, DNA double-strand breaks and apoptosis in human endometrial cancer cells.

    Directory of Open Access Journals (Sweden)

    Naoko Koyama

    Full Text Available Telmisartan, an angiotensin II receptor type 1 blocker, is often used as an antihypertension drug, and it has also been characterized as a peroxisome proliferator-activated receptor-gamma (PPARγ ligand. The purpose of this study was to elucidate the antitumor effects of telmisartan on endometrial cancer cells. We treated three endometrial cancer cell lines with various concentrations of telmisartan, and we investigated the effects of the telmisartan on the cell proliferation, apoptosis, and their related measurements in vitro. We also administered telmisartan to nude mice with experimental tumors to determine its in vivo effects and toxicity. All three endometrial cancer cell lines were sensitive to the growth-inhibitory effect of telmisartan. The induction of apoptosis was confirmed in concert with the altered expression of genes and proteins related to the apoptosis. We also observed that DNA double-strand breaks (DSBs were induced in HHUA (human endometrial cancer cells by telmisartan treatment. In addition, experiments in nude mice showed that telmisartan significantly inhibited human endometrial tumor growth, without toxic side effects. Our results suggest that telmisartan might be a new therapeutic option for the treatment of endometrial cancers.

  11. SU(3) breaking in hyperon beta decays

    Energy Technology Data Exchange (ETDEWEB)

    Roos, M. (Helsinki Univ. (Finland). Dept. of High Energy Physics)

    1990-08-23

    The symmetry breaking in the hyperon semi-leptonic decays is analyzed with the constraint that vertical strokeV{sub us}vertical stroke is given by K{sub e3}. The mechanism of symmetry breaking of Donoghue, Holstein and Klimt and the one-loop corrected vector form factors of Krause are compared with data. (orig.).

  12. SU(3) breaking in hyperon beta decays

    Science.gov (United States)

    Roos, M.

    1990-08-01

    The symmetry breaking in the hyperon semi-leptonic decays is analyzed with the constraint the | us| is given by K e3. The mechanisms of symmetry breaking of Donoghue, Holstein and Klimt and the one-loop corrected vector form factors of Krause are compared with data.

  13. Induced-charge electrokinetics in a conducting nanochannel with broken geometric symmetry: Towards a flexible control of ionic transport

    Science.gov (United States)

    Zhao, Cunlu; Song, Yongxin; Yang, Chun

    2015-01-01

    In the literature, conventional electrokinetics is widely used as a principle of operating nanofluidic devices. Different from the conventional electrokinetics involving nonpolarizable solid surfaces with fixed surface charge, induced-charge electrokinetic (ICEK) phenomena deal with polarizable surfaces with the ability of surface charge modulation through electric polarization under external electric fields. Because of several advantages, ICEK phenomena have drawn a great deal of attention in microfluidic community. Herein, we propose the first effort of extending the ICEK phenomena from microfluidics to nanofluidics. In particular, we report a numerical model for the ICEK phenomena in a tapered nanochannel with conducting (ideally polarizable) walls. It is shown that due to the broken geometric symmetry of the nanochannel, induced-charge electroosmotic flow inside the nanochannel exhibits a flow rectification such that electrolyte solution always flows from the narrow end of the nanochannel to the wide end for either a forward electric bias (electric field from the narrow to wide ends) or a reverse electric bias (electric field from the wide to narrow ends). In addition, we demonstrate that the ion selectivity of such tapered conducting nanochannel can be actively tuned to be cation-selective with a forward bias and anion-selective with a reverse bias. Promisingly, conducting nanochannels with broken geometric symmetry could be potentially used for constructing nanofluidic pumps with the unidirectional pumping capacity and ion selectors with the tuneable ionic selection.

  14. Spin and electric currents induced by a spin-motive force in two-dimensional Dirac semimetals protected by nonsymmorphic symmetries

    Science.gov (United States)

    Habe, Tetsuro

    2017-08-01

    We theoretically study the spin and charge currents induced by a spin-motive force in a two-dimensional Dirac semimetal protected by nonsymmorphic symmetries. Glide mirror plane symmetry, a nonsymmorphic symmetry, leads to a constraint to the induced current; the spin-motive force acting on out-of-plane spin (in-plane spin) induces the pure spin (charge) current. We calculate the response function to the spin-motive force in linear-response theory and find that the conductivity for the pure spin current remains nonzero even if the Fermi energy is crossing the node of linear dispersion. We also find that the conserved spin current is induced at the charge neutral point.

  15. Wave-induced stress and breaking of sea ice in a coupled hydrodynamic discrete-element wave-ice model

    Science.gov (United States)

    Herman, Agnieszka

    2017-11-01

    In this paper, a coupled sea ice-wave model is developed and used to analyze wave-induced stress and breaking in sea ice for a range of wave and ice conditions. The sea ice module is a discrete-element bonded-particle model, in which ice is represented as cuboid grains floating on the water surface that can be connected to their neighbors by elastic joints. The joints may break if instantaneous stresses acting on them exceed their strength. The wave module is based on an open-source version of the Non-Hydrostatic WAVE model (NHWAVE). The two modules are coupled with proper boundary conditions for pressure and velocity, exchanged at every wave model time step. In the present version, the model operates in two dimensions (one vertical and one horizontal) and is suitable for simulating compact ice in which heave and pitch motion dominates over surge. In a series of simulations with varying sea ice properties and incoming wavelength it is shown that wave-induced stress reaches maximum values at a certain distance from the ice edge. The value of maximum stress depends on both ice properties and characteristics of incoming waves, but, crucially for ice breaking, the location at which the maximum occurs does not change with the incoming wavelength. Consequently, both regular and random (Jonswap spectrum) waves break the ice into floes with almost identical sizes. The width of the zone of broken ice depends on ice strength and wave attenuation rates in the ice.

  16. Top-antitop production from W{sup +}{sub L}W{sup -}{sub L} and Z{sub L}Z{sub L} scattering under a strongly interacting symmetry-breaking sector

    Energy Technology Data Exchange (ETDEWEB)

    Castillo, Andres [Universidad Nacional de Colombia, Sede Bogota, Departamento de Fisica, Facultad de Ciencias, Bogota (Colombia); Delgado, Rafael L.; Dobado, Antonio; Llanes-Estrada, Felipe J. [Universidad Complutense de Madrid, Departamento de Fisica Teorica I, Madrid (Spain)

    2017-07-15

    By considering a non-linear electroweak chiral Lagrangian, including the Higgs, coupled to heavy quarks, and the equivalence theorem, we compute the one-loop scattering amplitudes W{sup +}W{sup -} → t anti t, ZZ → t anti t and hh → t anti t (in the regime M{sub t}{sup 2}/v{sup 2} << √(s)M{sub t}/v{sup 2} << s/v{sup 2} and to NLO in the effective theory). We calculate the scalar partial-wave helicity amplitudes which allow us to check unitarity at the perturbative level in both M{sub t}/v and s/v. As with growing energy perturbative unitarity deteriorates, we also introduce a new unitarization method with the right analytical behavior on the complex s-plane and that can support poles on the second Riemann sheet to describe resonances in terms of the Lagrangian couplings. Thus we have achieved a consistent phenomenological description of any resonant t anti t production that may be enhanced by a possible strongly interacting electroweak symmetry breaking sector. (orig.)

  17. Protamine-induced DNA compaction but not aggregation shows effective radioprotection against double-strand breaks

    Science.gov (United States)

    Suzuki, Mari; Crozatier, Cecile; Yoshikawa, Kenichi; Mori, Toshiaki; Yoshikawa, Yuko

    2009-09-01

    Protamine, an arginine-rich protein, is essential for the compaction of sperm DNA. We performed single-molecule observations of DNA double-strand breaks caused by 60Co γ-ray irradiation and quantitatively evaluated the protective effect of protamine. It was shown that double-strand breaks were significantly protected for the tightly compact DNA, whereas there is no apparent decrease on the damage for loosely aggregated DNA molecules. Our findings suggest that the densely packed structure of DNA reduces the ability of radiolytic reactive oxygen species to access DNA and thus protects DNA from double-strand breaks.

  18. Optically isotropic responses induced by discrete rotational symmetry of nanoparticle clusters

    Science.gov (United States)

    Hopkins, Ben; Liu, Wei; Miroshnichenko, Andrey E.; Kivshar, Yuri S.

    2013-06-01

    Fostered by the recent progress of the fields of plasmonics and metamaterials, the seminal topic of light scattering by clusters of nanoparticles is attracting enormous renewed interest gaining more attention than ever before. Related studies have not only found various new applications in different branches of physics and chemistry, but also spread rapidly into other fields such as biology and medicine. Despite the significant achievements, there still exists unsolved but vitally important challenges of how to obtain robust polarisation-invariant responses of different types of scattering systems. In this paper, we demonstrate polarisation-independent responses of any scattering system with a rotational symmetry with respect to an axis parallel to the propagation direction of the incident wave. We demonstrate that the optical responses such as extinction, scattering, and absorption, can be made independent of the polarisation of the incident wave for all wavelengths. Such polarisation-independent responses are proven to be a robust and generic feature that is purely due to the rotational symmetry of the whole structure. We anticipate our finding will play a significant role in various applications involving light scattering such as sensing, nanoantennas, optical switches, and photovoltaic devices.

  19. Heat generation above break-even from laser-induced fusion in ultra-dense deuterium

    Directory of Open Access Journals (Sweden)

    Leif Holmlid

    2015-08-01

    Full Text Available Previous results from laser-induced processes in ultra-dense deuterium D(0 give conclusive evidence for ejection of neutral massive particles with energy >10 MeV u−1. Such particles can only be formed from nuclear processes like nuclear fusion at the low laser intensity used. Heat generation is of interest for future fusion energy applications and has now been measured by a small copper (Cu cylinder surrounding the laser target. The temperature rise of the Cu cylinder is measured with an NTC resistor during around 5000 laser shots per measured point. No heating in the apparatus or the gas feed is normally used. The fusion process is suboptimal relative to previously published studies by a factor of around 10. The small neutral particles HN(0 of ultra-dense hydrogen (size of a few pm escape with a substantial fraction of the energy. Heat loss to the D2 gas (at <1 mbar pressure is measured and compensated for under various conditions. Heat release of a few W is observed, at up to 50% higher energy than the total laser input thus a gain of 1.5. This is uniquely high for the use of deuterium as fusion fuel. With a slightly different setup, a thermal gain of 2 is reached, thus clearly above break-even for all neutronicity values possible. Also including the large kinetic energy which is directly measured for MeV particles leaving through a small opening gives a gain of 2.3. Taking into account the lower efficiency now due to the suboptimal fusion process, previous studies indicate a gain of at least 20 during long periods.

  20. Localisation of aphidicolin-induced break points in Holstein-Friesian cattle (Bos taurus using RBG-banding

    Directory of Open Access Journals (Sweden)

    Mernies Beatriz

    2002-11-01

    Full Text Available Abstract Fragile sites (FS seem to play a role in genome instability and may be involved in karyotype evolution and chromosome aberrations. The majority of common fragile sites are induced by aphidicolin. Aphidicolin was used at two different concentrations (0.15 and 0.30 μM to study the occurrence of FS in the cattle karyotype. In this paper, a map of aphidicolin induced break points and fragile sites in cattle chromosomes was constructed. The statistical analysis indicated that any band with three or more breaks was significantly damaged (P r = 0.54. On the contrary, 21 FS were identified on negative R bands while 9 FS were located on positive R bands.

  1. Analysis of restriction enzyme-induced DNA double-strand breaks in Chinese hamster ovary cells by pulsed-field gel electrophoresis: implications for chromosome damage.

    Science.gov (United States)

    Ager, D D; Phillips, J W; Columna, E A; Winegar, R A; Morgan, W F

    1991-11-01

    Restriction enzymes can be electroporated into mammalian cells, and the induced DNA double-strand breaks can lead to aberrations in metaphase chromosomes. Chinese hamster ovary cells were electroporated with PstI, which generates 3' cohesive-end breaks, PvuII, which generates blunt-end breaks, or XbaI, which generates 5' cohesive-end breaks. Although all three restriction enzymes induced similar numbers of aberrant metaphase cells, PvuII was dramatically more effective at inducing both exchange-type and deletion-type chromosome aberrations. Our cytogenetic studies also indicated that enzymes are active within cells for only a short time. We used pulsed-field gel electrophoresis to investigate (i) how long it takes for enzymes to cleave DNA after electroporation into cells, (ii) how long enzymes are active in the cells, and (iii) how the DNA double-strand breaks induced are related to the aberrations observed in metaphase chromosomes. At the same concentrations used in the cytogenetic studies, all enzymes were active within 10 min of electroporation. PstI and PvuII showed a distinct peak in break formation at 20 min, whereas XbaI showed a gradual increase in break frequency over time. Another increase in the number of breaks observed with all three enzymes at 2 and 3 h after electroporation was probably due to nonspecific DNA degradation in a subpopulation of enzyme-damaged cells that lysed after enzyme exposure. Break frequency and chromosome aberration frequency were inversely related: The blunt-end cutter PvuII gave rise to the most aberrations but the fewest breaks, suggesting that it is the type of break rather than the break frequency that is important for chromosome aberration formation.

  2. Translation-symmetry protected topological orders on lattice

    OpenAIRE

    Kou, Su-Peng; Wen, Xiao-Gang

    2009-01-01

    In this paper we systematically study a simple class of translation-symmetry protected topological orders in quantum spin systems using slave-particle approach. The spin systems on square lattice are translation invariant, but may break any other symmetries. We consider topologically ordered ground states that do not spontaneously break any symmetry. Those states can be described by Z2A or Z2B projective symmetry group. We find that the Z2A translation symmetric topological orders can still b...

  3. Cosmological Reflection of Particle Symmetry

    Directory of Open Access Journals (Sweden)

    Maxim Khlopov

    2016-08-01

    Full Text Available The standard model involves particle symmetry and the mechanism of its breaking. Modern cosmology is based on inflationary models with baryosynthesis and dark matter/energy, which involves physics beyond the standard model. Studies of the physical basis of modern cosmology combine direct searches for new physics at accelerators with its indirect non-accelerator probes, in which cosmological consequences of particle models play an important role. The cosmological reflection of particle symmetry and the mechanisms of its breaking are the subject of the present review.

  4. Explaining B →K(*)ℓ+ℓ- anomaly by radiatively induced coupling in U (1 )μ -τ gauge symmetry

    Science.gov (United States)

    Ko, P.; Nomura, Takaaki; Okada, Hiroshi

    2017-06-01

    We propose a scenario to generate flavor violating Z' interactions at one-loop level by introducing U (1 )μ -τ gauge symmetry, extra vectorlike quark doublets Qa', and a singlet scalar χ . Both Qa' and χ are charged under U (1 )μ-τ and carry odd dark Z2 parity. Assuming that χ is the dark matter (DM) of the Universe and imposing various constraints from a dark matter search, flavor physics, and a collider search for Qa', one can show that radiative corrections to b →s Z'*→s l+l- involving Qa' and χ can induce Δ C9˜-1 , which can resolve the LHCb anomalies related with B →K(*)ℓ+ℓ-. Therefore, both DM and B physics anomalies can be accommodated in the model.

  5. Observations on the Partial Breaking of $N=2$ Rigid Supersymmetry

    CERN Document Server

    Andrianopoli, Laura; Ferrara, Sergio; Trigiante, Mario

    2015-01-01

    We study the partial breaking of $N=2$ rigid supersymmetry for a generic rigid special geometry of $n$ abelian vector multiplets in the presence of Fayet-Iliopoulos terms induced by the Hyper-K\\"ahler momentum map. By exhibiting the symplectic structure of the problem we give invariant conditions for the breaking to occur, which rely on a quartic invariant of the Fayet-Iliopoulos charges as well as on a modification of the $N=2$ rigid symmetry algebra by a vector central charge.

  6. Observations on the partial breaking of N=2 rigid supersymmetry

    Directory of Open Access Journals (Sweden)

    Laura Andrianopoli

    2015-05-01

    Full Text Available We study the partial breaking of N=2 rigid supersymmetry for a generic rigid special geometry of n abelian vector multiplets in the presence of Fayet–Iliopoulos terms induced by the hyper-Kähler momentum map. By exhibiting the symplectic structure of the problem we give invariant conditions for the breaking to occur, which rely on a quartic invariant of the Fayet–Iliopoulos charges as well as on a modification of the N=2 rigid symmetry algebra by a vector central charge.

  7. Discrete symmetries in the MSSM

    Energy Technology Data Exchange (ETDEWEB)

    Schieren, Roland

    2010-12-02

    The use of discrete symmetries, especially abelian ones, in physics beyond the standard model of particle physics is discussed. A method is developed how a general, abelian, discrete symmetry can be obtained via spontaneous symmetry breaking. In addition, anomalies are treated in the path integral approach with special attention to anomaly cancellation via the Green-Schwarz mechanism. All this is applied to the minimal supersymmetric standard model. A unique Z{sup R}{sub 4} symmetry is discovered which solves the {mu}-problem as well as problems with proton decay and allows to embed the standard model gauge group into a simple group, i.e. the Z{sup R}{sub 4} is compatible with grand unification. Also the flavor problem in the context of minimal flavor violation is addressed. Finally, a string theory model is presented which exhibits the mentioned Z{sup R}{sub 4} symmetry and other desirable features. (orig.)

  8. Adsorption-induced symmetry reduction of metal-phthalocyanines studied by vibrational spectroscopy

    Science.gov (United States)

    Sforzini, J.; Bocquet, F. C.; Tautz, F. S.

    2017-10-01

    We investigate the vibrational properties of Pt- and Pd-phthalocyanine (PtPc and PdPc) molecules on Ag(111) with high-resolution electron energy loss spectroscopy (HREELS). In the monolayer regime, both molecules exhibit long-range order. The vibrational spectra prove a flat adsorption geometry. The redshift of specific vibrational modes suggests a moderate interaction of the molecules with the substrate. The presence of asymmetric vibrational peaks indicates an interfacial dynamical charge transfer (IDCT). The molecular orbital that is involved in IDCT is the former Eg lowest unoccupied molecular orbital (LUMO) of the molecules that becomes partially occupied upon adsorption. A group-theoretical analysis of the IDCT modes, based on calculated vibrational frequencies and line shape fits, provides proof for the reduction of the symmetry of the molecule-substrate complex from fourfold D4 h to C2 v(σv) , Cs(σv) , or C2 and the ensuing lifting of the degeneracy of the former LUMO of the molecule. The vibration-based analysis of orbital degeneracies, as carried out here for PtPc/Ag(111) and PdPc/Ag(111), is particularly useful whenever the presence of multiple molecular in-plane orientations at the interface makes the analysis of orbital degeneracies with angle-resolved photoemission spectroscopy difficult.

  9. Spontaneous symmetry breaking in magnetized dust flows

    Energy Technology Data Exchange (ETDEWEB)

    Reichstein, Torben, E-mail: reichstein@physik.uni-kiel.de; Wilms, Jochen; Piel, Alexander [IEAP, Christian-Albrechts-Universität, D-24098 Kiel (Germany)

    2014-02-15

    Toroidal dust flows in magnetized anodic plasmas are driven by an azimuthal Hall component of the ion drag. By means of Langmuir probe measurements, it was found that the ion drag has a strong radial gradient. This finding is supported by the rotation velocities obtained by particle tracking analysis. The topology of shear flows is also attributed to the radial gradient of the ion drag. Furthermore, from a critical comparison of particle image velocimetry and particle tracking, a much better agreement between the measured rotation velocity and simulations could be achieved.

  10. Electroweak symmetry breaking beyond the Standard Model

    Indian Academy of Sciences (India)

    reduced gauge coupling which helps it to evade the LEP-2 limit. This again implies that we can employ a lighter stop in the loop, ..... It is also called a holographic Higgs [29]. The holographic 5D-to-4D translation involves the presence of ... rial representation 4 of SO(5). The spectrum of new particles can therefore reveal the.

  11. When and Why Did Brains Break Symmetry?

    Directory of Open Access Journals (Sweden)

    Lesley J. Rogers

    2015-12-01

    Full Text Available Asymmetry of brain function is known to be widespread amongst vertebrates, and it seems to have appeared very early in their evolution. In fact, recent evidence of functional asymmetry in invertebrates suggests that even small brains benefit from the allocation of different functions to the left and right sides. This paper discusses the differing functions of the left and right sides of the brain, including the roles of the left and right antennae of bees (several species in both short- and long-term recall of olfactory memories and in social behaviour. It considers the likely advantages of functional asymmetry in small and large brains and whether functional asymmetry in vertebrates and invertebrates is analogous or homologous. Neural or cognitive capacity can be enhanced both by the evolution of a larger brain and by lateralization of brain function: a possible reason why both processes occur side-by-side is offered.

  12. Discrete symmetry breaking beyond the standard model

    NARCIS (Netherlands)

    Dekens, Wouter Gerard

    2015-01-01

    The current knowledge of elementary particles and their interactions is summarized in the Standard Model of particle physics. Practically all the predictions of this model, that have been tested, were confirmed experimentally. Nonetheless, there are phenomena which the model cannot explain. For

  13. Spontaneous mirror symmetry breaking via enantioselective autocatalysis

    Energy Technology Data Exchange (ETDEWEB)

    Avetisov, V.A. [N. N. Semenov Institute of Chemical Physics of the Russian Academy of Sciences, ul.Kossvgina 4, 11-7977 Moscow (Russia)

    1996-07-01

    The conditions for spontaneous generation of optically active product under autocatalytic type reactions is considered on the base of the general kinetic model of enantioselective autocatalytic stages. It is shown that the spontaneous generation of optical activity mostly depends on the enantioselectivity of catalytic transformations. The properties of autocatalytic reactions, which are needed for an experiment, as well as the necessary chemical conditions, are discussed. {copyright} {ital 1996 American Institute of Physics.}

  14. Cracking up: symmetry breaking in cellular systems

    NARCIS (Netherlands)

    Paluch, E.; Gucht, van der J.; Sykes, C.

    2006-01-01

    The shape of animal cells is, to a large extent, determined by the cortical actin network that underlies the cell membrane. Because of the presence of myosin motors, the actin cortex is under tension, and local relaxation of this tension can result in cortical flows that lead to deformation and

  15. Elucidaton of DNA methylation changes in response to ionizng radiation induced double strand breaks

    Energy Technology Data Exchange (ETDEWEB)

    Herrlitz, Maren Linda

    2014-07-04

    would be an effect of overexpression or be indicative of a possible function in these nuclear subcompartments is yet to be elucidated. Additionally, by using flow cytometry analysis, exposure to IR and concomitant overexpression of TET2CD-GFP strongly induced 5hmC formation, therefore suggesting a function of TET2 in response to irradiation. Recruitment analysis showed that the TET2 catalytic domain was recruited to UV laser-induced but not X-rays- or heavy ion-induced damage sites. Endogenous TET2, which was analyzed in high TET2 expressing human fibroblasts, was recruited to damage sites after irradiation with heavy ions or X-rays. As 5hmC is the direct product of the catalytic activity of TET enzymes, local 5hmC formation and abundance at damage sites was investigated. It was observed that 5hmC accumulated at heavy ion- as well as X-ray-induced DNA double strand breaks (DSBs). In addition, investigating 5hmC foci over time after irradiation with X-rays revealed that 5hmC formation and kinetics is similar to that of γH2AX foci, whereby every 5hmC focus co-localized with γH2AX. However, this did not hold true for all γH2AX foci, whose total number was always higher than that of 5hmC. Furthermore, 5hmC (and γH2AX) foci formation was almost unaffected by the inhibition of DNA-PKcs' enzymatic activity. Conversely, 5hmC and γH2AX foci persistence was significantly delayed after DNA-PKcs inhibition. Results obtained in this thesis show that DNA methylation changes (5hmC formation) take place within the time frame of one replication cycle after exposure to IR and that these changes can be observed at sites of DSBs. 5hmC at DSBs might be formed by the oxidative function of TET2, which was shown to be recruited to DSBs. However, involvement of the other TET enzymes in 5hmC production cannot be excluded. Therefore, these results suggest a role of 5hmC in the response to IR induced DSBs, whereby the here presented data suggest that the fast, radiation induced

  16. Acute hypoxia and hypoxic exercise induce DNA strand breaks and oxidative DNA damage in humans

    DEFF Research Database (Denmark)

    Møller, P; Loft, S; Lundby, C

    2001-01-01

    The present study investigated the effect of a single bout of exhaustive exercise on the generation of DNA strand breaks and oxidative DNA damage under normal conditions and at high-altitude hypoxia (4559 meters for 3 days). Twelve healthy subjects performed a maximal bicycle exercise test; lymph...

  17. Ethylene Is Not Involved in Hormone- and Bromoethane-Induced Dormancy Break in Russet Burbank Minitubers

    Science.gov (United States)

    The involvement of ethylene in the dormancy breaking actions of cytokinins, GA, and BE was investigated using Russet Burbank minitubers. Injection of 10µg tuber-1 BA, CP, GA, NG, or ZEA or 24 hour exposure to BE effectively broke dormancy and stimulated sprout growth over a two-week period. Althou...

  18. Symmetry of Charge Partitioning in Collisional and UV Photon-Induced Dissociation of Protein Assemblies

    NARCIS (Netherlands)

    Tamara, Sem|info:eu-repo/dai/nl/411923110; Dyachenko, Andrey|info:eu-repo/dai/nl/371569583; Fort, Kyle L|info:eu-repo/dai/nl/412516489; Makarov, Alexander A; Scheltema, Richard A|info:eu-repo/dai/nl/328673056; Heck, Albert J R|info:eu-repo/dai/nl/105189332

    2016-01-01

    Tandem mass spectrometry can provide structural information on intact protein assemblies, generating mass fingerprints indicative of the stoichiometry and quaternary arrangement of the subunits. However, in such experiments, collision-induced dissociation yields restricted information due to

  19. Classically conformal radiative neutrino model with gauged B−L symmetry

    Directory of Open Access Journals (Sweden)

    Hiroshi Okada

    2016-09-01

    Full Text Available We propose a classically conformal model in a minimal radiative seesaw, in which we employ a gauged B−L symmetry in the standard model that is essential in order to work the Coleman–Weinberg mechanism well that induces the B−L symmetry breaking. As a result, nonzero Majorana mass term and electroweak symmetry breaking simultaneously occur. In this framework, we show a benchmark point to satisfy several theoretical and experimental constraints. Here theoretical constraints represent inert conditions and Coleman–Weinberg condition. Experimental bounds come from lepton flavor violations (especially μ→eγ, the current bound on the Z′ mass at the CERN Large Hadron Collider, and neutrino oscillations.

  20. Mirror symmetry

    CERN Document Server

    Voisin, Claire

    1999-01-01

    This is the English translation of Professor Voisin's book reflecting the discovery of the mirror symmetry phenomenon. The first chapter is devoted to the geometry of Calabi-Yau manifolds, and the second describes, as motivation, the ideas from quantum field theory that led to the discovery of mirror symmetry. The other chapters deal with more specialized aspects of the subject: the work of Candelas, de la Ossa, Greene, and Parkes, based on the fact that under the mirror symmetry hypothesis, the variation of Hodge structure of a Calabi-Yau threefold determines the Gromov-Witten invariants of its mirror; Batyrev's construction, which exhibits the mirror symmetry phenomenon between hypersurfaces of toric Fano varieties, after a combinatorial classification of the latter; the mathematical construction of the Gromov-Witten potential, and the proof of its crucial property (that it satisfies the WDVV equation), which makes it possible to construct a flat connection underlying a variation of Hodge structure in the ...