Symmetry and symmetry breaking
International Nuclear Information System (INIS)
Balian, R.; Lambert, D.; Brack, A.; Lachieze-Rey, M.; Emery, E.; Cohen-Tannoudji, G.; Sacquin, Y.
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.)
International Nuclear Information System (INIS)
Weinberg, S.
1976-01-01
The problem of how gauge symmetries of the weak interactions get broken is discussed. Some reasons why such a heirarchy of gauge symmetry breaking is needed, the reason gauge heirarchies do not seem to arise in theories of a given and related type, and the implications of theories with dynamical symmetry breaking, which can exhibit a gauge hierarchy
Radiative symmetry breaking from interacting UV fixed points
DEFF Research Database (Denmark)
Abel, Steven; Sannino, Francesco
2017-01-01
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...
Chiral symmetry and chiral-symmetry breaking
International Nuclear Information System (INIS)
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
Strong Electroweak Symmetry Breaking
Grinstein, Benjamin
2011-01-01
Models of spontaneous breaking of electroweak symmetry by a strong interaction do not have fine tuning/hierarchy problem. They are conceptually elegant and use the only mechanism of spontaneous breaking of a gauge symmetry that is known to occur in nature. The simplest model, minimal technicolor with extended technicolor interactions, is appealing because one can calculate by scaling up from QCD. But it is ruled out on many counts: inappropriately low quark and lepton masses (or excessive FCNC), bad electroweak data fits, light scalar and vector states, etc. However, nature may not choose the minimal model and then we are stuck: except possibly through lattice simulations, we are unable to compute and test the models. In the LHC era it therefore makes sense to abandon specific models (of strong EW breaking) and concentrate on generic features that may indicate discovery. The Technicolor Straw Man is not a model but a parametrized search strategy inspired by a remarkable generic feature of walking technicolor,...
International Nuclear Information System (INIS)
Lim, S C; Teo, L P
2008-01-01
Quartic self-interacting fractional Klein-Gordon scalar massive and massless field theories on toroidal spacetime are studied. The effective potential and topologically generated mass are determined using zeta-function regularization technique. Renormalization of these quantities are derived. Conditions for symmetry breaking are obtained analytically. Simulations are carried out to illustrate regions or values of compactified dimensions where symmetry-breaking mechanisms appear
Natural cold baryogenesis from strongly interacting electroweak symmetry breaking
Energy Technology Data Exchange (ETDEWEB)
Konstandin, Thomas; Servant, Géraldine, E-mail: tkonstan@cern.ch, E-mail: geraldine.servant@cern.ch [CERN Physics Department, Theory Division, CH-1211 Geneva 23 (Switzerland)
2011-07-01
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 any particular UV completion but only on a stage of supercooling ended by a first-order phase transition in the evolution of the universe, which can be natural if there is nearly conformal dynamics at the TeV scale. Besides, baryon-number violation originates from the Standard Model only.
Natural Cold Baryogenesis from Strongly Interacting Electroweak Symmetry Breaking
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...
Natural cold baryogenesis from strongly interacting electroweak symmetry breaking
International Nuclear Information System (INIS)
Konstandin, Thomas; Servant, Géraldine
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 any particular UV completion but only on a stage of supercooling ended by a first-order phase transition in the evolution of the universe, which can be natural if there is nearly conformal dynamics at the TeV scale. Besides, baryon-number violation originates from the Standard Model only
BOOK REVIEW: Symmetry Breaking
Ryder, L. H.
2005-11-01
One of the most fruitful and enduring advances in theoretical physics during the last half century has been the development of the role played by symmetries. One needs only to consider SU(3) and the classification of elementary particles, the Yang Mills enlargement of Maxwell's electrodynamics to the symmetry group SU(2), and indeed the tremendous activity surrounding the discovery of parity violation in the weak interactions in the late 1950s. This last example is one of a broken symmetry, though the symmetry in question is a discrete one. It was clear to Gell-Mann, who first clarified the role of SU(3) in particle physics, that this symmetry was not exact. If it had been, it would have been much easier to discover; for example, the proton, neutron, Σ, Λ and Ξ particles would all have had the same mass. For many years the SU(3) symmetry breaking was assigned a mathematical form, but the importance of this formulation fell away when the quark model began to be taken seriously; the reason the SU(3) symmetry was not exact was simply that the (three, in those days) quarks had different masses. At the same time, and in a different context, symmetry breaking of a different type was being investigated. This went by the name of `spontaneous symmetry breaking' and its characteristic was that the ground state of a given system was not invariant under the symmetry transformation, though the interactions (the Hamiltonian, in effect) was. A classic example is ferromagnetism. In a ferromagnet the atomic spins are aligned in one direction only—this is the ground state of the system. It is clearly not invariant under a rotation, for that would change the ground state into a (similar but) different one, with the spins aligned in a different direction; this is the phenomenon of a degenerate vacuum. The contribution of the spin interaction, s1.s2, to the Hamiltonian, however, is actually invariant under rotations. As Coleman remarked, a little man living in a ferromagnet would
International Nuclear Information System (INIS)
Suzuki, Toshio; Sagawa, H.; Giai, N. van.
1992-01-01
Effects of CIB (charge independence breaking) and CSB (charge symmetry breaking) interactions on the Coulomb displacement energies of isobaric analog states are investigated for 48 Ca, 90 Zr and 208 Pb. Mass number dependence of the Coulomb energy anomalies is well explained when CIB and CSB interactions are used which reproduce the differences of the scattering lengths as well as those of the effective ranges of low energy nucleon-nucleon scattering. (author) 17 refs., 3 figs., 3 tabs
Contribution of charge symmetry breaking interactions in binding energy difference of mirror nuclei
International Nuclear Information System (INIS)
Asghari, M.
2006-01-01
Nolen-Schiffer Anomaly in mirror nuclei due to the NN interactions with isospin mixing between T=0 and T=1 mesons of the same spin and parity are investigated. With the computation of coulomb energy along with the charge symmetry breaking effects provide a reasonably accurate description of binding energy differences between 39 Ca- 39 K , 41 Sc- 41 Ca mirror nuclei
Inhomogeneous chiral symmetry breaking in isospin-asymmetric strong-interaction matter
Energy Technology Data Exchange (ETDEWEB)
Nowakowski, Daniel
2017-07-01
In this thesis we investigate the effects of an isospin asymmetry on inhomogeneous chiral symmetry breaking phases, which are characterized by spatially modulated quarkantiquark condensates. In order to determine the relevance of such phases for the phase diagram of strong-interaction matter, a two-flavor Nambu-Jona-Lasinio model is used to study the properties of the ground state of the system. Confirming the presence of inhomogeneous chiral symmetry breaking in isospin-asymmetric matter for a simple Chiral Density Wave, we generalize the modulation of the quark-antiquark pairs to more complicated shapes and study the effects of different degrees of flavor-mixing on the inhomogeneous phase at non-zero isospin asymmetry. Then, we investigate the occurrence of crystalline chiral symmetry breaking phases in charge-neutral matter, from which we determine the influence of crystalline phases on a quark star by calculating mass-radius sequences. Finally, our model is extended through color-superconducting phases and we study the interplay of these phases with inhomogeneous chiral-symmetry breaking at non-vanishing isospin asymmetry, before we discuss our findings.
Strong coupling electroweak symmetry breaking
International Nuclear Information System (INIS)
Barklow, T.L.; Burdman, G.; Chivukula, R.S.
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
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.
Dynamical symmetry breaking of the electroweak interactions and the renormalization group
International Nuclear Information System (INIS)
Hill, C.T.
1990-08-01
We discuss dynamical symmetry breaking with an emphasis on the renormalization group as the key tool to obtaining reliable predictions. In particular we discuss the mechanism for breaking the electroweak interactions which relies upon the formation of condensates involving the conventional quarks and leptons. Such a scheme indicates that the top quark is heavy, greater than or of order 200 GeV, and gives further predictions for the Higgs boson mass. We also briefly describe recent attempts to incorporate a 4th generation in a more natural scheme. 13 refs., 3 figs., 1 tab
Energy Technology Data Exchange (ETDEWEB)
Hill, Christopher T.
2018-03-19
We review and expand upon recent work demonstrating that Weyl invariant theories can be broken "inertially," which does not depend upon a potential. This can be understood in a general way by the "current algebra" of these theories, independently of specific Lagrangians. Maintaining the exact Weyl invariance in a renormalized quantum theory can be accomplished by renormalization conditions that refer back to the VEV's of fields in the action. We illustrate the computation of a Weyl invariant Coleman-Weinberg potential that breaks a U(1) symmetry together,with scale invariance.
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.
Models of electroweak symmetry breaking
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.
Symmetry, Symmetry Breaking and Topology
Directory of Open Access Journals (Sweden)
Siddhartha Sen
2010-07-01
Full Text Available The ground state of a system with symmetry can be described by a group G. This symmetry group G can be discrete or continuous. Thus for a crystal G is a finite group while for the vacuum state of a grand unified theory G is a continuous Lie group. The ground state symmetry described by G can change spontaneously from G to one of its subgroups H as the external parameters of the system are modified. Such a macroscopic change of the ground state symmetry of a system from G to H correspond to a “phase transition”. Such phase transitions have been extensively studied within a framework due to Landau. A vast range of systems can be described using Landau’s approach, however there are also systems where the framework does not work. Recently there has been growing interest in looking at such non-Landau type of phase transitions. For instance there are several “quantum phase transitions” that are not of the Landau type. In this short review we first describe a refined version of Landau’s approach in which topological ideas are used together with group theory. The combined use of group theory and topological arguments allows us to determine selection rule which forbid transitions from G to certain of its subgroups. We end by making a few brief remarks about non-Landau type of phase transition.
Physics of chiral symmetry breaking
International Nuclear Information System (INIS)
Shuryak, E.V.
1991-01-01
This subsection of the 'Modeling QCD' Workshop has included five talks. E. Shuryak spoke on 'Recent Progress in Understanding Chiral Symmetry Breaking'; below it is split into two parts: (i) a mini-review of the field and (ii) a brief presentation of the status of the theory of interacting instantons. The next sections correspond to the following talks: (iii) K. Goeke et al., 'Chiral Restoration and Medium Corrections to Nucleon in the NJL Model'; (iv) M. Takizawa and K. Kubodera, 'Study of Meson Properties and Quark Condensates in the NJL Model with Instanton Effects'; (v) G. Klein and A. G. Williams, 'Dynamical Chiral Symmetry Breaking in Dual QCD'; and (vi) R. D. Ball, 'Skyrmions and Baryons.' (orig.)
Spontaneous symmetry breaking and its cosmological consequences
International Nuclear Information System (INIS)
Kobzarev, I.Yu.
1975-01-01
The concept of symmetry and of the spontaneous symmetry breaking are presented in popular form as applied to quantum physics. Though the presence of the spontaneous symmetry breaking is not proved directly for interactions of elementary particles, on considering the hypothesis of its presence as applied to the hot Universe theory a possibility of obtaining rather uncommon cosmological consequences is discussed. In particular, spontaneous symmetry breaking of vacuum and the rather hot Universe lead necessarily to the presence of the domain structure of the Universe with the surfase energy at the domain interface in the form of a real physical object
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 ...
Current-current interactions, dynamical symmetry-breaking, and quantum chromodynamics
International Nuclear Information System (INIS)
Neuenschwander, D.E. Jr.
1983-01-01
Quantum Chromodynamics with massive gluons (gluon mass triple bond xm/sub p/) in a contact-interaction limit called CQCD (strong coupling g→infinity; x→infinity), despite its non-renormalizability and lack of hope of confinement, is nevertheless interesting for at least two reasons. Some authors have suggested a relation between 4-Fermi and Yang-Mills theories. If g/x 2 much less than 1, then CQCD is not merely a 4-Fermi interaction, but includes 4,6,8 etc-Fermi non-Abelian contact interactions. With possibility of infrared slavery, perturbative evaluation of QCD in the infrared is a dubious practice. However, if g 2 /x 2 much less than 1 in CQCD, then the simplest 4-Fermi interaction is dominant, and CQCD admits perturbative treatment, but only in the infrared. With the dominant interaction, a dynamical Nambu-Goldstone realization of chiral symmetry-breaking (XSB) is found. Although in QCD the relation between confinement and XSB is controversial, XSB occurs in CQCD provided confinement is sacrificed
Current-current interactions, dynamical symmetry-breaking, and quantum chromodynamics
Energy Technology Data Exchange (ETDEWEB)
Neuenschwander, D.E. Jr.
1983-01-01
Quantum Chromodynamics with massive gluons (gluon mass triple bond xm/sub p/) in a contact-interaction limit called CQCD (strong coupling g..-->..infinity; x..-->..infinity), despite its non-renormalizability and lack of hope of confinement, is nevertheless interesting for at least two reasons. Some authors have suggested a relation between 4-Fermi and Yang-Mills theories. If g/x/sup 2/ much less than 1, then CQCD is not merely a 4-Fermi interaction, but includes 4,6,8 etc-Fermi non-Abelian contact interactions. With possibility of infrared slavery, perturbative evaluation of QCD in the infrared is a dubious practice. However, if g/sup 2//x/sup 2/ much less than 1 in CQCD, then the simplest 4-Fermi interaction is dominant, and CQCD admits perturbative treatment, but only in the infrared. With the dominant interaction, a dynamical Nambu-Goldstone realization of chiral symmetry-breaking (XSB) is found. Although in QCD the relation between confinement and XSB is controversial, XSB occurs in CQCD provided confinement is sacrificed.
Lie-algebra approach to symmetry breaking
International Nuclear Information System (INIS)
Anderson, J.T.
1981-01-01
A formal Lie-algebra approach to symmetry breaking is studied in an attempt to reduce the arbitrariness of Lagrangian (Hamiltonian) models which include several free parameters and/or ad hoc symmetry groups. From Lie algebra it is shown that the unbroken Lagrangian vacuum symmetry can be identified from a linear function of integers which are Cartan matrix elements. In broken symmetry if the breaking operators form an algebra then the breaking symmetry (or symmetries) can be identified from linear functions of integers characteristic of the breaking symmetries. The results are applied to the Dirac Hamiltonian of a sum of flavored fermions and colored bosons in the absence of dynamical symmetry breaking. In the partially reduced quadratic Hamiltonian the breaking-operator functions are shown to consist of terms of order g 2 , g, and g 0 in the color coupling constants and identified with strong (boson-boson), medium strong (boson-fermion), and fine-structure (fermion-fermion) interactions. The breaking operators include a boson helicity operator in addition to the familiar fermion helicity and ''spin-orbit'' terms. Within the broken vacuum defined by the conventional formalism, the field divergence yields a gauge which is a linear function of Cartan matrix integers and which specifies the vacuum symmetry. We find that the vacuum symmetry is chiral SU(3) x SU(3) and the axial-vector-current divergence gives a PCAC -like function of the Cartan matrix integers which reduces to PCAC for SU(2) x SU(2) breaking. For the mass spectra of the nonets J/sup P/ = 0 - ,1/2 + ,1 - the integer runs through the sequence 3,0,-1,-2, which indicates that the breaking subgroups are the simple Lie groups. Exact axial-vector-current conservation indicates a breaking sum rule which generates octet enhancement. Finally, the second-order breaking terms are obtained from the second-order spin tensor sum of the completely reduced quartic Hamiltonian
International Nuclear Information System (INIS)
Tornow, W.; Howell, C.R.; Walter, R.L.; Slaus, I.
1992-01-01
Comparison of data for neutron-deuteron and proton-deuteron analyzing power A y for elastic scattering has become crucial for investigating charge-symmetry breaking in the 3 P nucleon-nucleon interactions. We extended this comparison down to 5 MeV and find that the relative difference between n-d and p-d scattering at the A y maximum near 120 degree increases with decreasing energy. By applying a straightforward Coulomb ''correction'' to the p-d data, we account for most of the difference, suggesting that the Coulomb force, rather than charge-symmetry breaking, is responsible for most of the observed difference
The problem of symmetry breaking hierarchy
International Nuclear Information System (INIS)
Natale, A.A.
1983-01-01
The problem of symmetry breaking hierarchy in grand unified theories is discussed, proving the impossibility to get a big hierarchy of interactions, in a natural way within the framework of perturbation theory. (L.C.) [pt
Symmetry breaking by bifundamentals
Schellekens, A. N.
2018-03-01
We derive all possible symmetry breaking patterns for all possible Higgs fields that can occur in intersecting brane models: bifundamentals and rank-2 tensors. This is a field-theoretic problem that was already partially solved in 1973 by Ling-Fong Li [1]. In that paper the solution was given for rank-2 tensors of orthogonal and unitary group, and U (N )×U (M ) and O (N )×O (M ) bifundamentals. We extend this first of all to symplectic groups. When formulated correctly, this turns out to be straightforward generalization of the previous results from real and complex numbers to quaternions. The extension to mixed bifundamentals is more challenging and interesting. The scalar potential has up to six real parameters. Its minima or saddle points are described by block-diagonal matrices built out of K blocks of size p ×q . Here p =q =1 for the solutions of Ling-Fong Li, and the number of possibilities for p ×q is equal to the number of real parameters in the potential, minus 1. The maximum block size is p ×q =2 ×4 . Different blocks cannot be combined, and the true minimum occurs for one choice of basic block, and for either K =1 or K maximal, depending on the parameter values.
History of electroweak symmetry breaking
International Nuclear Information System (INIS)
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. (paper)
Quark diquark symmetry breaking
International Nuclear Information System (INIS)
Souza, M.M. de
1980-01-01
Assuming the baryons are made of quark-diquark pairs, the wave functions for the 126 allowed ground states are written. The quark creation and annihilations operators are generalized to describe the quark-diquark structure in terms of a parameter σ. Assuming that all quark-quark interactions are mediated by gluons transforming like an octet of vector mesons, the effective Hamiltonian and the baryon masses as constraint equations for the elements of the mass matrix is written. The symmetry is the SU(6) sub(quark)x SU(21) sub(diquark) broken by quark-quark interactions respectively invariant under U(6), U(2) sub(spin), U(3) and also interactions transforming like the eighth and the third components of SU(3). In the limit of no quark-diquark structure (σ = 0), the ground state masses is titted to within 1% of the experimental data, except for the Δ(1232), where the error is almost 2%. Expanding the decuplet mass equations in terms of σ and keeping terms only up to the second order, this error is reduced to 67%. (Author) [pt
Stochastic mechanism of symmetry breaking
International Nuclear Information System (INIS)
Baseyan, H.Z.
1983-01-01
A new symmetry breaking mechanism conditioned by presence of random fields in vacuum is proposed. Massive Yang-Mills fields finally arise, that may be interpreted as ''macroscopic'' manifestation of the ''microscopic'' Yang-Mills massless theory
Energy Technology Data Exchange (ETDEWEB)
Miller, G.A. [Department of Physics, University of Washington, Seattle (United States); Kolck, U. van [Department of Physics, University of Arizona, Tucson (United States)
2003-06-01
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 the down quark has a negative charge of -1/3. If charge symmetry was exact, the proton and the neutron would have the same mass and they would both be electrically neutral. This is because the proton is made of two up quarks and a down quark, while the neutron comprises two downs and an up. Replacing up quarks with down quarks, and vice versa, therefore transforms a proton into a neutron. Charge-symmetry breaking causes the neutron to be about 0.1% heavier than the proton because the down quark is slightly heavier than the up quark. Physicists had already elucidated certain aspects of charge-symmetry breaking, but our spirits were raised greatly when we heard of the recent work of Allena Opper of Ohio University in the US and co-workers at the TRIUMF laboratory in British Columbia, Canada. Her team has been trying to observe a small charge-symmetry-breaking effect for several years, using neutron beams at the TRIUMF accelerator. The researchers studied the
Sequential flavor symmetry breaking
International Nuclear Information System (INIS)
Feldmann, Thorsten; Jung, Martin; Mannel, Thomas
2009-01-01
The gauge sector of the standard model exhibits a flavor symmetry that allows for independent unitary transformations of the fermion multiplets. In the standard model the flavor symmetry is broken by the Yukawa couplings to the Higgs boson, and the resulting fermion masses and mixing angles show a pronounced hierarchy. In this work we connect the observed hierarchy to a sequence of intermediate effective theories, where the flavor symmetries are broken in a stepwise fashion by vacuum expectation values of suitably constructed spurion fields. We identify the possible scenarios in the quark sector and discuss some implications of this approach.
Sequential flavor symmetry breaking
Feldmann, Thorsten; Jung, Martin; Mannel, Thomas
2009-08-01
The gauge sector of the standard model exhibits a flavor symmetry that allows for independent unitary transformations of the fermion multiplets. In the standard model the flavor symmetry is broken by the Yukawa couplings to the Higgs boson, and the resulting fermion masses and mixing angles show a pronounced hierarchy. In this work we connect the observed hierarchy to a sequence of intermediate effective theories, where the flavor symmetries are broken in a stepwise fashion by vacuum expectation values of suitably constructed spurion fields. We identify the possible scenarios in the quark sector and discuss some implications of this approach.
International Nuclear Information System (INIS)
Bunakov, V.E.; Ivanov, I.B.
1999-01-01
Connections between the symmetries of Hamiltonian systems in classical and quantum mechanics, on one hand, and their regularity or chaoticity, on the other hand, are considered. The quantum-chaoticity criterion that was proposed previously and which was borrowed from the theory of compound-nucleus resonances is used to analyze the quantum diamagnetic Kepler problem - that is, the motion of a spinless charged particle in a Coulomb and a uniform magnetic field
Parity Symmetry and Parity Breaking in the Quantum Rabi Model with Addition of Ising Interaction
International Nuclear Information System (INIS)
Wang Qiong; He Zhi; Yao Chun-Mei
2015-01-01
We explore the possibility to generate new parity symmetry in the quantum Rabi model after a bias is introduced. In contrast to a mathematical treatment in a previous publication [J. Phys. A 46 (2013) 265302], we consider a physically realistic method by involving an additional spin into the quantum Rabi model to couple with the original spin by an Ising interaction, and then the parity symmetry is broken as well as the scaling behavior of the ground state by introducing a bias. The rule can be found that the parity symmetry is broken by introducing a bias and then restored by adding new degrees of freedom. Experimental feasibility of realizing the models under discussion is investigated. (paper)
Unified gauge theories with spontaneous symmetry breaking
International Nuclear Information System (INIS)
MacDowell, S.W.
1975-01-01
Unified gauge theories with spontaneous symmetry breaking are studied with a view to renormalize quantum field theory. Georgi-Glashow and Weinberg-Salam models to unify weak and electromagnetic interactions are discussed in detail. Gauge theories of strong interactions are also considered [pt
Instantons and chiral symmetry breaking
International Nuclear Information System (INIS)
Carneiro, C.E.I.; McDougall, N.A.
1984-01-01
A detailed investigation of chiral symmetry breaking due to instanton dynamics is carried out, within the framework of the dilute gas approximation, for quarks in both the fundamental and adjoint representations of SU(2). The momentum dependence of the dynamical mass is found to be very similar in each representation. (orig.)
Instantons and chiral symmetry breaking
Energy Technology Data Exchange (ETDEWEB)
Carneiro, C.E.I.; McDougall, N.A. (Oxford Univ. (UK). Dept. of Theoretical Physics)
1984-10-22
A detailed investigation of chiral symmetry breaking due to instanton dynamics is carried out, within the framework of the dilute gas approximation, for quarks in both the fundamental and adjoint representations of SU(2). The momentum dependence of the dynamical mass is found to be very similar in each representation.
A model of intrinsic symmetry breaking
International Nuclear Information System (INIS)
Ge, Li; Li, Sheng; George, Thomas F.; Sun, Xin
2013-01-01
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
Gauge principle, vector-meson dominance, and spontaneous symmetry breaking
International Nuclear Information System (INIS)
Nambu, Yoichiro
1989-01-01
The author concentrates on certain theoretical developments of the late 1950s which are concerned with the meaning and role of symmetries and symmetry breaking, and especially work done in Chicago, and notes his own involvement in this debate. He worked on symmetry-breaking in superconductivity, using a four-fermion interaction model. (UK)
Shamim, S; Mahapatra, S; Scappucci, G; Klesse, W M; Simmons, M Y; Ghosh, A
2014-06-13
We report experimental evidence of a remarkable spontaneous time-reversal symmetry breaking in two-dimensional electron systems formed by atomically confined doping of phosphorus (P) atoms inside bulk crystalline silicon (Si) and germanium (Ge). Weak localization corrections to the conductivity and the universal conductance fluctuations were both found to decrease rapidly with decreasing doping in the Si:P and Ge:P delta layers, suggesting an effect driven by Coulomb interactions. In-plane magnetotransport measurements indicate the presence of intrinsic local spin fluctuations at low doping, providing a microscopic mechanism for spontaneous lifting of the time-reversal symmetry. Our experiments suggest the emergence of a new many-body quantum state when two-dimensional electrons are confined to narrow half-filled impurity bands.
International Nuclear Information System (INIS)
Cheng Yongshan; Adhikari, S. K.
2010-01-01
By direct numerical simulation of the time-dependent Gross-Pitaevskii equation using the split-step Fourier spectral method, we study different aspects of the localization of a cigar-shaped interacting binary (two-component) Bose-Einstein condensate (BEC) in a one-dimensional bichromatic quasiperiodic optical-lattice potential, as used in a recent experiment on the localization of a BEC [Roati et al., Nature 453, 895 (2008)]. We consider two types of localized states: (i) when both localized components have a maximum of density at the origin x=0, and (ii) when the first component has a maximum of density and the second a minimum of density at x=0. In the noninteracting case, the density profiles are symmetric around x=0. We numerically study the breakdown of this symmetry due to interspecies and intraspecies interactions acting on the two components. Where possible, we have compared the numerical results with a time-dependent variational analysis. We also demonstrate the stability of the localized symmetry-broken BEC states under small perturbation.
Dynamical study of symmetries: breaking and restauration
International Nuclear Information System (INIS)
Schuck, P.
1986-09-01
First symmetry breaking (spontaneous) is explained and the physical implication discussed for infinite systems. The relation with phase transitions is indicated. Then the specific aspects of symmetry breaking in finite systems is treated and illustrated in detail for the case of translational invariance with the help of an oversimplified but exactly solvable model. The method of projection (restauration of symmetry) is explained for the static case and also applied to the model. Symmetry breaking in the dynamical case and for instance the notion of a soft mode responsible for the symmetry breaking is discussed in the case of superfluidity and another exactly solvable model is introduced. The Goldstone mode is treated in detail. Some remarks on analogies with the breaking of chiral symmetry are made. Some recent developments in the theory of symmetry restauration are briefly outlined [fr
Rotational Symmetry Breaking in Baby Skyrme Models
Karliner, Marek; Hen, Itay
We discuss one of the most interesting phenomena exhibited by baby skyrmions - breaking of rotational symmetry. The topics we will deal with here include the appearance of rotational symmetry breaking in the static solutions of baby Skyrme models, both in flat as well as in curved spaces, the zero-temperature crystalline structure of baby skyrmions, and finally, the appearance of spontaneous breaking of rotational symmetry in rotating baby skyrmions.
Symmetry breaking in gauge glasses
International Nuclear Information System (INIS)
Hansen, K.
1988-09-01
In order to explain why nature selects the gauge groups of the Standard Model, Brene and Nielsen have proposed a way to break gauge symmetry which does not rely on the existence of a Higgs field. The observed gauge groups will in this scheme appear as the only surviving ones when this mechanism is applied to a random selection of gauge groups. The essential assumption is a discrete space-time with random couplings. Some working assumptions were made for computational reasons of which the most important is that quantum fluctuations were neclected. This work presents an example which under the same conditions show that a much wider class of groups than predicted by Brene and Nielsen will be broken. In particular no possible Standard Model Group survives unbroken. Numerical calculations support the analytical result. (orig.)
Steering particles by breaking symmetries
Bet, Bram; Samin, Sela; Georgiev, Rumen; Burak Eral, Huseyin; van Roij, René
2018-06-01
We derive general equations of motions for highly-confined particles that perform quasi-two-dimensional motion in Hele-Shaw channels, which we solve analytically, aiming to derive design principles for self-steering particles. Based on symmetry properties of a particle, its equations of motion can be simplified, where we retrieve an earlier-known equation of motion for the orientation of dimer particles consisting of disks (Uspal et al 2013 Nat. Commun. 4), but now in full generality. Subsequently, these solutions are compared with particle trajectories that are obtained numerically. For mirror-symmetric particles, excellent agreement between the analytical and numerical solutions is found. For particles lacking mirror symmetry, the analytic solutions provide means to classify the motion based on particle geometry, while we find that taking the side-wall interactions into account is important to accurately describe the trajectories.
Symmetry and symmetry breaking in quantum mechanics
International Nuclear Information System (INIS)
Chomaz, Philippe
1998-01-01
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
Charge-symmetry-breaking nucleon form factors
Energy Technology Data Exchange (ETDEWEB)
Kubis, Bastian, E-mail: kubis@hiskp.uni-bonn.de [Universitaet Bonn, Helmholtz-Institut fuer Strahlen- und Kernphysik (Theorie) and Bethe Center for Theoretical Physics (Germany)
2011-11-15
A quantitative understanding of charge-symmetry breaking is an increasingly important ingredient for the extraction of the nucleon's strange vector form factors. We review the theoretical understanding of the charge-symmetry-breaking form factors, both for single nucleons and for {sup 4}He.
Charge-symmetry-breaking nucleon form factors
International Nuclear Information System (INIS)
Kubis, Bastian
2011-01-01
A quantitative understanding of charge-symmetry breaking is an increasingly important ingredient for the extraction of the nucleon’s strange vector form factors. We review the theoretical understanding of the charge-symmetry-breaking form factors, both for single nucleons and for 4 He.
Dynamical Symmetry Breaking of Extended Gauge Symmetries
Appelquist, Thomas; Shrock, Robert
2003-01-01
We construct asymptotically free gauge theories exhibiting dynamical breaking of the left-right, strong-electroweak gauge group $G_{LR} = {\\rm SU}(3)_c \\times {\\rm SU}(2)_L \\times {\\rm SU}(2)_R \\times {\\rm U}(1)_{B-L}$, and its extension to the Pati-Salam gauge group $G_{422}={\\rm SU}(4)_{PS} \\times {\\rm SU}(2)_L \\times {\\rm SU}(2)_R$. The models incorporate technicolor for electroweak breaking, and extended technicolor for the breaking of $G_{LR}$ and $G_{422}$ and the generation of fermion ...
RG analysis of magnetic catalysis in dynamical symmetry breaking
International Nuclear Information System (INIS)
Hong, Deog Ki; Kim, Youngman
1996-01-01
We perform the renormalization group analysis on the dynamical symmetry breaking under strong external magnetic field, studied recently by Gusynin, Miransky and Shovkovy. We find that any attractive four-Fermi interaction becomes strong in the low energy, thus leading to dynamical symmetry breaking. When the four-Fermi interaction is absent, the β-function for the electromagnetic coupling vanishes in the leading order in 1/N. By solving the Schwinger-Dyson equation for the fermion propagator, we show that in 1/N expansion, for any electromagnetic coupling, dynamical symmetry breaking occurs due to the presence of Landau energy gap by the external magnetic field. 5 refs
Dynamical symmetry breaking in barium isotopes
International Nuclear Information System (INIS)
Rawat, Bir Singh; Chattopadhyay, P.K.
1997-01-01
The isotopes of Xe with mass numbers 124, 126, 128, 130 and the isotopes of barium with mass numbers 128, 130, 132, 134 were shown to correspond to the O(6) dynamical symmetry of IBM. In the investigation of the dynamical symmetry breaking in this region, the barium isotopes for departures from O(6) symmetry have been studied
Density-dependent coupling constants and charge symmetry breaking
International Nuclear Information System (INIS)
Barreiro, L.A.
2001-01-01
The effect of the medium in the coupling constants implicate in a charge symmetry breaking on nuclear interactions. The amount of energy due to this modification can explain the Nolen-Schiffer anomaly. (author)
Symmetry breaking and scalar bosons
International Nuclear Information System (INIS)
Gildener, E.; Weinberg, S.
1976-01-01
There are reasons to suspect that the spontaneous breakdown of the gauge symmetries of the observed weak and electromagnetic interactions may be produced by the vacuum expectation values of massless weakly coupled elementary scalar fields. A method is described for finding the broken-symmetry solutions of such theories even when they contain arbitrary numbers of scalar fields with unconstrained couplings. In any such theory, there should exist a number of heavy Higgs bosons, with masses comparable to the intermediate vector bosons, plus one light Higgs boson, or ''scalon'' with mass of order αG/sub F/sub 1/2/. The mass and couplings of the scalon are calculable in terms of other masses, even without knowing all the details of the theory. For an SU(2) direct-product U(1) model with arbitrary numbers of scalar isodoublets, the scalon mass is greater than 5.26 GeV; a likely value is 7--10 GeV. The production and decay of the scalon are briefly considered. Some comments are offered on the relation between the mass scales associated with the weak and strong interactions
Symmetry and symmetry breaking in modern physics
International Nuclear Information System (INIS)
Barone, M; Theophilou, A K
2008-01-01
In modern physics, the theory of symmetry, i.e. group theory, is a basic tool for understanding and formulating the fundamental principles of Physics, like Relativity, Quantum Mechanics and Particle Physics. In this work we focus on the relation between Mathematics, Physics and objective reality
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)
Coulomb-like elastic interaction induced by symmetry breaking in nematic liquid crystal colloids.
Lee, Beom-Kyu; Kim, Sung-Jo; Kim, Jong-Hyun; Lev, Bohdan
2017-11-21
It is generally thought that colloidal particles in a nematic liquid crystal do not generate the first multipole term called deformation elastic charge as it violates the mechanical equilibrium. Here, we demonstrate theoretically and experimentally that this is not the case, and deformation elastic charges, as well as dipoles and quadrupoles, can be induced through anisotropic boundary conditions. We report the first direct observation of Coulomb-like elastic interactions between colloidal particles in a nematic liquid crystal. The behaviour of two spherical colloidal particles with asymmetric anchoring conditions induced by asymmetric alignment is investigated experimentally; the interaction of two particles located at the boundary of twist and parallel aligned regions is observed. We demonstrate that such particles produce deformation elastic charges and interact by Coulomb-like interactions.
Flavor universal dynamical electroweak symmetry breaking
International Nuclear Information System (INIS)
Burdman, G.; Evans, N.
1999-01-01
The top condensate seesaw mechanism of Dobrescu and Hill allows electroweak symmetry to be broken while deferring the problem of flavor to an electroweak singlet, massive sector. We provide an extended version of the singlet sector that naturally accommodates realistic masses for all the standard model fermions, which play an equal role in breaking electroweak symmetry. The models result in a relatively light composite Higgs sector with masses typically in the range of (400 - 700) GeV. In more complete models the dynamics will presumably be driven by a broken gauged family or flavor symmetry group. As an example of the higher scale dynamics a fully dynamical model of the quark sector with a GIM mechanism is presented, based on an earlier top condensation model of King using broken family gauge symmetry interactions (that model was itself based on a technicolor model of Georgi). The crucial extra ingredient is a reinterpretation of the condensates that form when several gauge groups become strong close to the same scale. A related technicolor model of Randall which naturally includes the leptons too may also be adapted to this scenario. We discuss the low energy constraints on the massive gauge bosons and scalars of these models as well as their phenomenology at the TeV scale. copyright 1999 The American Physical Society
Dynamical effects of exchange symmetry breaking in mixtures of interacting bosons
DEFF Research Database (Denmark)
Tichy, Malte C.; Sherson, Jacob; Mølmer, Klaus
2012-01-01
of two distinguishable species with identical physical properties, that is, which are governed by an isospecific interaction and external potential. In the mean-field limit, the spatial population imbalance of the mixture can be described by the dynamics of a single species in an effective potential...... approximates the full counting statistics well also outside the realm of spin-coherent states. The method is extended to general Bose-Hubbard systems and to their classical mean-field limits, which suggests an effective single-species description of multicomponent Bose gases with weakly an...... with modified properties or, equivalently, with an effective total particle number. The oscillation behavior can be tuned by populating the second species while maintaining the spatial population imbalance and all other parameters constant. In the corresponding many-body approach, the single-species description...
Group theory of spontaneous symmetry breaking
International Nuclear Information System (INIS)
Ghaboussi, F.
1987-01-01
The connection between the minimality of the Higgs field potential and the maximal little groups of its representation obtained by spontaneous symmetry breaking is analyzed. It is shown that for several representations the lowest minimum of the potential is related to the maximal little group of those representations. Furthermore, a practical necessity criterion is given for the representation of the Higgs field needed for spontaneous symmetry breaking
Symmetry breaking and restoration in gauge theories
International Nuclear Information System (INIS)
Natale, A.A.
A review is made of the utilization of the Higgs mechanism in spontaneous symmetry breaking. It is shown that such as ideas came from an analogy with the superconductivity phenomenological theory based on a Ginzburg-Landau lagrangean. The symmetry restoration through the temperature influence is studied. (L.C.) [pt
Symmetry breaking patterns for inflation
Klein, Remko; Roest, Diederik; Stefanyszyn, David
2018-06-01
We study inflationary models where the kinetic sector of the theory has a non-linearly realised symmetry which is broken by the inflationary potential. We distinguish between kinetic symmetries which non-linearly realise an internal or space-time group, and which yield a flat or curved scalar manifold. This classification leads to well-known inflationary models such as monomial inflation and α-attractors, as well as a new model based on fixed couplings between a dilaton and many axions which non-linearly realises higher-dimensional conformal symmetries. In this model, inflation can be realised along the dilatonic direction, leading to a tensor-to-scalar ratio r ˜ 0 .01 and a spectral index n s ˜ 0 .975. We refer to the new model as ambient inflation since inflation proceeds along an isometry of an anti-de Sitter ambient space-time, which fully determines the kinetic sector.
International Nuclear Information System (INIS)
Suzuki, T.; Sagawa, H.; Arima, A.
1992-01-01
Coulomb energy differences (Nolen-Schiffer anomalies) of mirror nuclei 17 O- 17 F and 41 Ca- 41 Sc are studied by using realistic Hartree-Fock and Woods-Saxon single-particle wave functions which are determined precisely through the analysis of the magnetic form factors of electron scattering. These single-particle wave functions are used to evaluate the Coulomb energy differences due to charge symmetry breaking forces, with new coupling constants determined by the analysis of the scattering lengths of pp and nn system which have been successfully applied to the Coulomb energy difference of 3 He- 3 H. We also evaluated the effects of the charge symmetry breaking forces using Hartree-Fock wave functions. Together with various other contributions, our calculated values of the Coulomb energy differences, which showed deviations of 3-9% from the experimental values in the previous analysis of Nolen and Schiffer, agree with the experimental values within 1% (2%) accuracy for A=17 (41). (orig.)
Symmetry breaking in string theory
International Nuclear Information System (INIS)
Potting, R.
1998-01-01
A mechanism for a spontaneous breakdown of CPT symmetry appears in string theory, with possible implications for particle models. A realistic string theory might exhibit CPT violation at levels detectable in current or future experiments. A possible new mechanism for baryogenesis in the early Universe is also discussed
'Oblique corrections' and symmetry breaking
International Nuclear Information System (INIS)
Ramirez, C.A.
1991-11-01
Low Energy Parameters (Peskin-Takeuchi) are computed for two Symmetry Braking Schemes (heavy Higgs and techni-ρ). The differences between them are found comparable to the experimental uncertainties (in agreement with previous calculations for the Technicolor Models). Some constraints are obtained for the techni-ρ case. (author). 22 refs, 11 figs
Isospin symmetry breaking in sd shell nuclei
International Nuclear Information System (INIS)
Lam, Y.W.
2011-12-01
In the thesis, we develop a microscopic approach to describe the isospin-symmetry breaking effects in sd-shell nuclei. The work is performed within the nuclear shell model. A realistic isospin-conserving Hamiltonian is perfected by a charge-dependent part consisting of the Coulomb interaction and Yukawa-type meson exchange potentials to model charge-dependent forces of nuclear origin. The extended database of the experimental isobaric mass multiplet equation coefficients was compiled during the thesis work and has been used in a fit of the Hamiltonian parameters. The constructed Hamiltonian provides an accurate theoretical description of the isospin mixing nuclear states. A specific behaviour of the IMME (Isobaric Multiplet Mass Equation) coefficients have been revealed. We present two important applications: (i) calculations of isospin-forbidden proton emission amplitudes, which is often of interest for nuclear astrophysics, and (ii) calculation on corrections to nuclear Fermi beta decay, which is crucial for the tests of fundamental symmetries of the weak interaction. (author)
Electroweak symmetry breaking: Higgs/whatever
International Nuclear Information System (INIS)
Chanowitz, M.S.
1990-01-01
In these two lectures the author discusses electroweak symmetry breaking from a general perspective, stressing properties that are model independent and follow just from the assumption that the electroweak interactions are described by a spontaneously broken gauge theory. This means he assumes the Higgs mechanism though not necessarily the existence of Higgs bosons. The first lecture presents the general framework of a spontaneously broken gauge theory: (1) the Higgs mechanism sui generis, with or without Higgs boson(s) and (2) the implications of symmetry and unitarity for the mass scale and interaction strength of the new physics that the Higgs mechanism requires. In addition he reviews a softer theoretical argument based on the naturalness problem which leads to a prejudice against Higgs bosons unless they are supersymmetric. This is a prejudice, not a theorem, and it could be overturned in the future by a clever new idea. In the second lecture he illustrates the general framework by reviewing some specific models: (1) the Weinberg-Salam model of the Higgs sector; (2) the minimal supersymmetric extension of the Weinberg-Salam model; and (3) technicolor as an example of the Higgs mechanism without Higgs bosons. He concludes the second lecture with a discussion of strong WW scattering that must occur if L SB lives above 1 TeV. In particular he describes some of the experimental signals and backgrounds at the SSC. 57 refs., 12 figs
Passive appendages generate drift through symmetry breaking
Lācis, U.; Brosse, N.; Ingremeau, F.; Mazzino, A.; Lundell, F.; Kellay, H.; Bagheri, S.
2014-10-01
Plants and animals use plumes, barbs, tails, feathers, hairs and fins to aid locomotion. Many of these appendages are not actively controlled, instead they have to interact passively with the surrounding fluid to generate motion. Here, we use theory, experiments and numerical simulations to show that an object with a protrusion in a separated flow drifts sideways by exploiting a symmetry-breaking instability similar to the instability of an inverted pendulum. Our model explains why the straight position of an appendage in a fluid flow is unstable and how it stabilizes either to the left or right of the incoming flow direction. It is plausible that organisms with appendages in a separated flow use this newly discovered mechanism for locomotion; examples include the drift of plumed seeds without wind and the passive reorientation of motile animals.
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.
Workshop on electroweak symmetry breaking: proceedings
International Nuclear Information System (INIS)
Hinchliffe, I.
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
Spontaneous symmetry breaking in N=3 supergravity
International Nuclear Information System (INIS)
Zinov'ev, Yu.M.
1986-01-01
The possibility of the spontaneous symmetry breaking without a cosmological term in N=3 supergravity is investigated. A new, dual version of N=3 supergravity - U(3)-supergravity is constructed. Such a theory is shown to admit a spontaneous supersymmetry breaking without a cosmological term and with three arbitrary scales, including partial super-Higgs effect N=3 → N=2 and N=3 → N=1
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.
Dynamical symmetry breaking with hypercolour and high colour representations
International Nuclear Information System (INIS)
Zoupanos, G.
1985-01-01
A model is presented in which the electroweak gauge group is spontaneously broken according to a dynamical scenario based on the existence of high colour representations. An unattractive feature of this scenario was the necessity to introduce elementary Higgs fields in order to obtain the spontaneous symmetry breaking of part of the theory. In the present model, this breaking can also be understood dynamically with the introduction of hypercolour interactions. (author)
Radiatively induced breaking of conformal symmetry in a superpotential
International Nuclear Information System (INIS)
Arbuzov, A.B.; Cirilo-Lombardo, D.J.
2016-01-01
Radiatively induced symmetry breaking is considered for a toy model with one scalar and one fermion field unified in a superfield. It is shown that the classical quartic self-interaction of the superfield possesses a quantum infrared singularity. Application of the Coleman–Weinberg mechanism for effective potential leads to the appearance of condensates and masses for both scalar and fermion components. That induces a spontaneous breaking of the initial classical symmetries: the supersymmetry and the conformal one. The energy scales for the scalar and fermion condensates appear to be of the same order, while the renormalization scale is many orders of magnitude higher. A possibility to relate the considered toy model to conformal symmetry breaking in the Standard Model is discussed.
Charge symmetry breaking in the A=4 hypernuclei
Czech Academy of Sciences Publication Activity Database
Gazda, Daniel; Gal, A.
2016-01-01
Roč. 954, OCT (2016), s. 161-175 ISSN 0375-9474 R&D Projects: GA ČR(CZ) GA15-04301S Institutional support: RVO:61389005 Keywords : hypernuclei * hyperon-nucleon interactions * charge symmetry breaking Subject RIV: BE - Theoretical Physics Impact factor: 1.916, year: 2016
Cosmoparticle physics of family symmetry breaking
International Nuclear Information System (INIS)
Khlopov, M.Yu.
1993-07-01
The foundations of both particle theory and cosmology are hidden at super energy scale and can not be tested by direct laboratory means. Cosmoparticle physics is developed to probe these foundations by the proper combination of their indirect effects, thus providing definite conclusions on their reliability. Cosmological and astrophysical tests turn to be complementary to laboratory searches of rare processes, induced by new physics, as it can be seen in the case of gauge theory of broken symmetry of quark and lepton families, ascribing to the hierarchy of the horizontal symmetry breaking the observed hierarchy of masses and the mixing between quark and lepton families. 36 refs
On the character of scale symmetry breaking in gauge theories
International Nuclear Information System (INIS)
Gusijnin, V.P.; Kushnir, V.A.; Miransky, V.A.
1988-01-01
The problem of scale symmetry breaking in gauge theories is discussed. It is shown that the phenomenon of spontaneous breaking of scale symmetry in gauge theories is incompatible with the PCAAC dynamics. 12 refs
Dual realizations of dynamical symmetry breaking
International Nuclear Information System (INIS)
Dudas, Emilian; Papineau, Chloe
2006-01-01
We show the infrared equivalence between a recently proposed model containing a six dimensional scalar field with a four-dimensional localized Higgs type potential and the four-dimensional Nambu-Jona-Lasinio (NJL) model. In the dual NJL description, the fermions are localized at the origin of a large two-dimensional compact space. Due to a classical running effect above the compactification scale, the four-fermion coupling of the NJL model increases from the cutoff scale down to the compactification scale, providing the large Fermi coupling needed for the dynamical symmetry breaking. We also present a string theory embedding of our field-theory construction. On more general grounds, our results suggest that 4d models with dynamical symmetry breaking can be given a higher dimensional description in terms of field theories with nontrivial boundary conditions in the internal space
Analysis of chiral symmetry breaking mechanism
International Nuclear Information System (INIS)
Guo, X. H.; Academia Sinica, Beijing; Huang, T.; CCAST
1997-01-01
The renormalization group invariant quark condensate μ is determined both from the consistent equation for quark condensate in the chiral limit and from the Schwinger-Dyson (SD) equation improved by the intermediate range QCD force singular like δ (q) which is associated with the gluon condensate. The solutions of μ in these two equations are consistent. The authors also obtain the critical strong coupling constant α c above which chiral symmetry breaks in these two approaches. The nonperturbative kernel of the SD equation makes α c smaller and μ bigger. An intuitive picture of the condensation above α c is discussed. In addition, with the help of the Slavnov-Taylor-Ward (STW) identity they derive the equations for the nonperturbative quark propagator from the SD equation in the presence of the intermediate range force and find that the intermediate-range force is also responsible for dynamical chiral symmetry breaking
Electroweak symmetry breaking: Higgs/whatever
International Nuclear Information System (INIS)
Chanowitz, M.S.
1989-01-01
In the first of these two lectures the Higgs mechanism is reviewed in its most general form, which does not necessarily require the existence of Higgs bosons. The general consequences of the hypothesis that electroweak symmetry breaking is due to the Higgs mechanism are deduced just from gauge invariance and unitarity. In the second lecture the general properties are illustrated with three specific models: the Weinberg-Salam model, its minimal supersymmetric extension, and technicolor. The second lecture concludes with a discussion of the experiment signals for strong WW scattering, whose presence or absence will allow us to determine whether the symmetry breaking sector lies above or below 1 TeV. 57 refs
Dynamics of Symmetry Breaking and Tachyonic Preheating
Felder, G; Greene, P B; Kofman, L A; Linde, Andrei D; Tkachev, Igor I; Felder, Gary; Garcia-Bellido, Juan; Greene, Patrick B.; Kofman, Lev; Linde, Andrei; Tkachev, Igor
2001-01-01
We reconsider the old problem of the dynamics of spontaneous symmetry breaking using 3d lattice simulations, and develop a theory of tachyonic preheating, which occurs due to the spinodal instability of the scalar field. Tachyonic preheating is so efficient that symmetry breaking typically completes within a single oscillation of the field distribution as it rolls towards the minimum of its effective potential. As an application of this theory we consider preheating in the hybrid inflation scenario, including SUSY-motivated F-term and D-term inflationary models. We show that preheating in hybrid inflation is typically tachyonic and the stage of oscillations of a homogeneous component of the scalar fields driving inflation ends after a single oscillation. Our results may also be relevant for the theory of the formation of disoriented chiral condensates in heavy ion collisions.
Chiral symmetry breaking and the pion quark structure
International Nuclear Information System (INIS)
Bernard, V.
1986-01-01
The mechanism of dynamical breaking of chiral symmetry in hadronic matter is first studied in the framework of the Nambu and Jona-Lasinio model on one hand and its generalisation to finite hadron size on the other hand. The analysis uses a variational procedure modelled after the BCS superconductor. Our study indicates for example, a great sensitivity of various quantities characterizing the breaking of symmetry to the shape of the interaction. Also the mechanism of breaking of chiral symmetry is essentially related to the mechanism of confinement. When a symmetry is spontaneously broken, there exists a Goldstone particle of zero mass. This is true in our model. This particle, the pion, is obtained as solution of a Bethe Salpeter equation for a qantiq bound state. This enables us to establish a connection between the pion as a Goldstone boson related to spontaneous symmetry breaking and the quark-antiquark structure of the pion. The finite mass of the physical pion is obtained with non zero current quark mass. Various properties of this particle are then studied in the RPA formalism. One important point of our model is the highly collective character of the pion. 85 refs [fr
Effective potential and chiral symmetry breaking
International Nuclear Information System (INIS)
Hochberg, David
2010-01-01
The nonequilibrium effective potential is calculated for the Frank model of spontaneous mirror-symmetry breaking in chemistry in which external noise is introduced to account for random environmental effects. The well-mixed limit, corresponding to negligible diffusion, and the case of diffusion in two space dimensions are studied in detail. White noise has a disordering effect in the former case, whereas in the latter case a phase transition occurs for external noise exceeding a critical intensity which racemizes the system.
Enhanced breaking of heavy quark spin symmetry
Energy Technology Data Exchange (ETDEWEB)
Guo, Feng-Kun, E-mail: fkguo@hiskp.uni-bonn.de [Helmholtz-Institut für Strahlen- und Kernphysik and Bethe Center for Theoretical Physics, Universität Bonn, D-53115 Bonn (Germany); Meißner, Ulf-G., E-mail: meissner@hiskp.uni-bonn.de [Helmholtz-Institut für Strahlen- und Kernphysik and Bethe Center for Theoretical Physics, Universität Bonn, D-53115 Bonn (Germany); Institute for Advanced Simulation, Institut für Kernphysik and Jülich Center for Hadron Physics, Forschungszentrum Jülich, D-52425 Jülich (Germany); Shen, Cheng-Ping, E-mail: shencp@ihep.ac.cn [School of Physics and Nuclear Energy Engineering, Beihang University, Beijing 100191 (China)
2014-11-10
Heavy quark spin symmetry is useful to make predictions on ratios of decay or production rates of systems involving heavy quarks. The breaking of spin symmetry is generally of the order of O(Λ{sub QCD}/m{sub Q}), with Λ{sub QCD} the scale of QCD and m{sub Q} the heavy quark mass. In this paper, we will show that a small S- and D-wave mixing in the wave function of the heavy quarkonium could induce a large breaking in the ratios of partial decay widths. As an example, we consider the decays of the ϒ(10860) into the χ{sub bJ}ω(J=0,1,2), which were recently measured by the Belle Collaboration. These decays exhibit a huge breaking of the spin symmetry relation were the ϒ(10860) a pure 5S bottomonium state. We propose that this could be a consequence of a mixing of the S-wave and D-wave components in the ϒ(10860). Prediction on the ratio Γ(ϒ(10860)→χ{sub b0}ω)/Γ(ϒ(10860)→χ{sub b2}ω) is presented assuming that the decay of the D-wave component is dominated by the coupled-channel effects.
Symmetry Breaking in MILP Formulations for Unit Commitment Problems
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.
Symmetry Breaking in MILP Formulations for Unit Commitment Problems
Lima, Ricardo; Novais, Augusto Q.
2015-01-01
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.
New particles and breaking the colour symmetry
International Nuclear Information System (INIS)
Krolikowski, W.
1975-01-01
In the framework of one-gluon-exchange static forces mediated by a colour octet or nonet of vector gluons, we discuss quark binding in coloured-meson states and its connection with breaking the colour symmetry. A possible identification of psi (3.1), psi(3.7) and the broad bump at 4.1 GeV with some coloured bound states of quarks and antiquarks is pointed out. This identification implies the existence of a second bump in the region of 5 GeV. The general conclusion of the paper is that the colour interpretation of the new particles may be true only if the colour symmetry is badly broken (provided the considered forces are relevant). (author)
Symmetry breaking during seeded growth of nanocrystals.
Xia, Xiaohu; Xia, Younan
2012-11-14
Currently, most of the reported noble-metal nanocrystals are limited to a high level of symmetry, as constrained by the inherent, face-centered cubic (fcc) lattice of these metals. In this paper, we report, for the first time, a facile and versatile approach (backed up by a clear mechanistic understanding) for breaking the symmetry of an fcc lattice and thus obtaining nanocrystals with highly unsymmetrical shapes. The key strategy is to induce and direct the growth of nanocrystal seeds into unsymmetrical modes by manipulating the reduction kinetics. With silver as an example, we demonstrated that the diversity of possible shapes taken by noble-metal nanocrystals could be greatly expanded by incorporating a series of new shapes drastically deviated from the fcc lattice. This work provides a new method to investigate shape-controlled synthesis of metal nanocrystal.
Electroweak Symmetry Breaking (3/3)
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.
Electroweak Symmetry Breaking (2/3)
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.
Electroweak Symmetry Breaking (1/3)
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.
Electroweak symmetry breaking beyond the Standard Model
International Nuclear Information System (INIS)
Bhattacharyya, Gautam
2012-01-01
In this paper, two key issues related to electroweak symmetry breaking are addressed. First, how fine-tuned different models are that trigger this phenomenon? Second, even if a light Higgs boson exists, does it have to be necessarily elementary? After a brief introduction, the fine-tuning aspects of the MSSM, NMSSM, generalized NMSSM and GMSB scenarios shall be reviewed, then the little Higgs, composite Higgs and the Higgsless models shall be compared. Finally, a broad overview will be given on where we stand at the end of 2011. (author)
Several ways of breaking the colour symmetry
International Nuclear Information System (INIS)
Krolikowski, W.
1975-01-01
We discuss some cases of colour-symmetry breaking and its implications for quark binding by one-gluon-exchange forces. We pay special attention to the case, where colour-isospin and colour-hypercharge subsymmetries are preserved. Then, the ω-PHI-like mixing of colour-nonet components 0 and 8 leads to a Zweig-type approximate selection rule for decays of PHI-like meson = antiqsub(B)qsub(B)(qsub(B) is the '' blue'' quark) into ordinary mesons (and photons). (author)
Dynamics of symmetry breaking in strongly coupled QED
International Nuclear Information System (INIS)
Bardeen, W.A.
1988-10-01
I review the dynamical structure of strong coupled QED in the quenched planar limit. The symmetry structure of this theory is examined with reference to the nature of both chiral and scale symmetry breaking. The renormalization structure of the strong coupled phase is analysed. The compatibility of spontaneous scale and chiral symmetry breaking is studied using effective lagrangian methods. 14 refs., 3 figs
Hyperscaling violation and electroweak symmetry breaking
Energy Technology Data Exchange (ETDEWEB)
Elander, Daniel, E-mail: pelander@purdue.edu [Department of Physics, Purdue University, 525 Northwestern Avenue, West Lafayette, IN 47907-2036 (United States); Lawrance, Robert; Piai, Maurizio [Department of Physics, College of Science, Swansea University, Singleton Park, Swansea, Wales (United Kingdom)
2015-08-15
We consider a class of simplified models of dynamical electroweak symmetry breaking built in terms of their five-dimensional weakly-coupled gravity duals, in the spirit of bottom-up holography. The sigma-model consists of two abelian gauge bosons and one real, non-charged scalar field coupled to gravity in five dimensions. The scalar potential is a simple exponential function of the scalar field. The background metric resulting from solving the classical equations of motion exhibits hyperscaling violation, at least at asymptotically large values of the radial direction. We study the spectrum of scalar composite states of the putative dual field theory by fluctuating the sigma-model scalars and gravity, and discuss in which cases we find a parametrically light scalar state in the spectrum. We model the spontaneous breaking of the (weakly coupled) gauge symmetry to the diagonal subgroup by the choice of IR boundary conditions. We compute the mass spectrum of spin-1 states, and the precision electroweak parameter S as a function of the hyperscaling coefficient. We find a general bound on the mass of the lightest spin-1 resonance, by requiring that the indirect bounds on the precision parameters be satisfied, that implies that precision electroweak physics excludes the possibility of a techni-rho meson with mass lighter than several TeV.
Flavor symmetry breaking and meson masses
International Nuclear Information System (INIS)
Bhagwat, Mandar S.; Roberts, Craig D.; Chang Lei; Liu Yuxin; Tandy, Peter C.
2007-01-01
The axial-vector Ward-Takahashi identity is used to derive mass formulas for neutral pseudoscalar mesons. Flavor symmetry breaking entails nonideal flavor content for these states. Adding that the η ' is not a Goldstone mode, exact chiral-limit relations are developed from the identity. They connect the dressed-quark propagator to the topological susceptibility. It is confirmed that in the chiral limit the η ' mass is proportional to the matrix element which connects this state to the vacuum via the topological susceptibility. The implications of the mass formulas are illustrated using an elementary dynamical model, which includes an Ansatz for that part of the Bethe-Salpeter kernel related to the non-Abelian anomaly. In addition to the current-quark masses, the model involves two parameters, one of which is a mass-scale. It is employed in an analysis of pseudoscalar- and vector-meson bound-states. While the effects of SU(N f =2) and SU(N f =3) flavor symmetry breaking are emphasized, the five-flavor spectra are described. Despite its simplicity, the model is elucidative and phenomenologically efficacious; e.g., it predicts η-η ' mixing angles of ∼-15 deg. and π 0 -η angles of ∼1 deg
Fermion masses in potential models of chiral symmetry breaking
International Nuclear Information System (INIS)
Jaroszewicz, T.
1983-01-01
A class of models of spontaneous chiral symmetry breaking is considered, based on the Hamiltonian with an instantaneous potential interaction of fermions. An explicit mass term mΨ-barΨ is included and the physical meaning of the mass parameter is discussed. It is shown that if the Hamiltonian is normal-ordered (i.e. self-energy omitted), then the mass m introduced in the Hamiltonian is not the current mass appearing in the current algebra relations. (author)
Chiral symmetry breaking and confinement - solutions of relativistic wave equations
International Nuclear Information System (INIS)
Murugesan, P.
1983-01-01
In this thesis, an attempt is made to explore the question whether confinement automatically leads to chiral symmetry breaking. While it should be accepted that chiral symmetry breaking manifests in nature in the absence of scalar partners of pseudoscalar mesons, it does not necessarily follow that confinement should lead to chiral symmetry breaking. If chiral conserving forces give rise to observed spectrum of hadrons, then the conjuncture that confinement is responsible for chiral symmetry breaking is not valid. The method employed to answer the question whether confinement leads to chiral symmetry breaking or not is to solve relativistic wave equations by introducing chiral conserving as well as chiral breaking confining potentials and compare the results with experimental observations. It is concluded that even though chiral symmetry is broken in nature, confinement of quarks need not be the cause of it
Spontaneous symmetry breaking in N = 2 supergravity
International Nuclear Information System (INIS)
Zinov'ev, Y.M.
1987-01-01
A model describing the interaction of N = 2 supergravity with a vector and a linear multiplet is constructed. The model admits the introduction of spontaneous supersymmetry breaking with two arbitrary scales, one of which can be equal to zero, corresponding to the partial super-Higgs effect (N = 2→N = 1). The cosmological term is automatically equal to zero
Quark confinement through hidden breaking of colour symmetry
International Nuclear Information System (INIS)
Werle, J.
1993-01-01
The aim of this paper is to study of a non-linear mechanism of quark confinement. The sets of coupled equation for Dirac fields carrying colours and flavours are discussed. They contain non-linear self-interaction and mutual interaction terms of the same fractional form that was studied before for single Dirac fields (Phys.Lett. 71B, 357 (1977); Phys.Lett. 76B, 391 (1980); Acta Phys.Pol. B12, 601 (1981)). It turns out that the only way of preventing creation of isolated coloured objects consists in breaking global colour symmetry. An explicit form of the symmetry breaking term is proposed (different from that used in Acta Phys.Pol. B19, 203 (1988)), which implies that only white currents are conserved and the three colours are truly inseparable. Moreover, the new equations have the advantage of having strictly colour symmetric (white) solution that correspond to an absolute minimum of the symmetry breaking term of energy. (author). 4 refs
Passive appendages aid locomotion through symmetry breaking
Bagheri, Shervin; Lacis, Ugis; Mazzino, Andrea; Kellay, Hamid; Brosse, Nicolas; Lundell, Fredrik; Ingremeau, Francois
2014-11-01
Plants and animals use plumes, barbs, tails, feathers, hairs, fins, and other types of appendages to aid locomotion. Despite their enormous variation, passive appendages may contribute to locomotion by exploiting the same physical mechanism. We present a new mechanism that applies to body appendages surrounded by a separated flow, which often develops behind moving bodies larger than a few millimeters. We use theory, experiments, and numerical simulations to show that bodies with protrusions turn and drift by exploiting a symmetry-breaking instability similar to the instability of an inverted pendulum. Our model explains why the straight position of an appendage in flowing fluid is unstable and how it stabilizes either to the left or right of the incoming fluid flow direction. The discovery suggests a new mechanism of locomotion that may be relevant for certain organisms; for example, how plumed seeds may drift without wind and how motile animals may passively reorient themselves.
A (critical) overview of electroweak symmetry breaking
International Nuclear Information System (INIS)
Csaki, Csaba
2010-01-01
This presentation discusses the following points: The standard Higgs, big vs. little hierarchy; Electroweak Symmetry Breaking in supersymmetry and little hierarchy of Minimal Supersymmetric Standard Model (MSSM): Buried Higgs, Bigger quartic (D-terms, Next-to-Minimal Supersymmetric Standard Model (NMSSM), fat Higgs,..); Strong dynamics and related models: Technicolor, Monopole condensate, Warped extra dimensions, Realistic RS, Higgs-less, Composite Higgs, Little Higgs. In summary, we do not understand how Higgs is light and still no trace of new physics. In Supersymmetry (SUSY) it calls for extension of MSSM. In strong dynamics models: electroweak penguin (EWP) usually issue (Warped extra dimension - composite Higgs, Higgs-less, Little Higgs, Technicolor, monopole condensation,..). None of them is fully convincing but LHC should settle these
Symmetry breaking bifurcations of a current sheet
International Nuclear Information System (INIS)
Parker, R.D.; Dewar, R.L.; Johnson, J.L.
1990-01-01
Using a time evolution code with periodic boundary conditions, the viscoresistive hydromagnetic equations describing an initially static, planar current sheet with large Lundquist number have been evolved for times long enough to reach a steady state. A cosh 2 x resistivity model was used. For long periodicity lengths L p , the resistivity gradient drives flows that cause forced reconnection at X point current sheets. Using L p as a bifurcation parameter, two new symmetry breaking bifurcations were found: a transition to an asymmetric island chain with nonzero, positive, or negative phase velocity, and a transition to a static state with alternating large and small islands. These states are reached after a complex transient behavior, which involves a competition between secondary current sheet instability and coalescence
Instantons, monopoles and chiral symmetry breaking
International Nuclear Information System (INIS)
Feurstein, M.; Markum, H.; Thurner, S.
1996-01-01
We analyze the interplay of topological objects in four dimensional QCD. The distributions of color magnetic monopoles obtained in the maximum abelian gauge are computed around instantons in both pure and full QCD. We find an enhanced probability of encountering monopoles inside the core of an instanton. We show this by means of local correlation functions of the topological variables. For specific gauge field configurations we visualize the situation graphically. Motivated by the fact that a fermion in the field of a static monopole has an energy zero mode we investigate how monopole loops and instantons are locally correlated with the chiral condensate. The observed correlations suggest that monopoles are involved in the mechanism of breaking of chiral symmetry. (orig.)
Symmetry breaking: The standard model and superstrings
International Nuclear Information System (INIS)
Gaillard, M.K.
1988-01-01
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 2 = (√2G/sub F/)/sup /minus/1/ ≅ 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 3 )GeV. The second approach involves theoretical speculations, such as technicolor and supersymmetry, that attempt to explain the TeV scale. 23 refs., 5 figs
Symmetry breaking bifurcations of a current sheet
International Nuclear Information System (INIS)
Parker, R.D.; Dewar, R.L.; Johnson, J.L.
1988-08-01
Using a time evolution code with periodic boundary conditions, the viscoresistive hydromagnetic equations describing an initially static, planar current sheet with large Lundquist number have been evolved for times long enough to reach a steady state. A cosh 2 x resistivity model was used. For long periodicity lengths, L p , the resistivity gradient drives flows which cause forced reconnection at X point current sheets. Using L p as a bifurcation parameter, two new symmetry breaking bifurcations were found - a transition to an asymmetric island chain with nonzero, positive or negative phase velocity, and a transition to a static state with alternating large and small islands. These states are reached after a complex transient behavior which involves a competition between secondary current sheet instability and coalescence. 31 refs., 6 figs
Effects of rotational symmetry breaking in polymer-coated nanopores
Osmanović, D.; Kerr-Winter, M.; Eccleston, R. C.; Hoogenboom, B. W.; Ford, I. J.
2015-01-01
The statistical theory of polymers tethered around the inner surface of a cylindrical channel has traditionally employed the assumption that the equilibrium density of the polymers is independent of the azimuthal coordinate. However, simulations have shown that this rotational symmetry can be broken when there are attractive interactions between the polymers. We investigate the phases that emerge in these circumstances, and we quantify the effect of the symmetry assumption on the phase behavior of the system. In the absence of this assumption, one can observe large differences in the equilibrium densities between the rotationally symmetric case and the non-rotationally symmetric case. A simple analytical model is developed that illustrates the driving thermodynamic forces responsible for this symmetry breaking. Our results have implications for the current understanding of the behavior of polymers in cylindrical nanopores.
Effects of rotational symmetry breaking in polymer-coated nanopores
Energy Technology Data Exchange (ETDEWEB)
Osmanović, D.; Hoogenboom, B. W.; Ford, I. J. [London Centre for Nanotechnology (LCN) and Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom); Kerr-Winter, M.; Eccleston, R. C. [Centre for Mathematics, Physics and Engineering in the Life Sciences and Experimental Biology, University College London, Gower Street, London WC1E 6BT (United Kingdom)
2015-01-21
The statistical theory of polymers tethered around the inner surface of a cylindrical channel has traditionally employed the assumption that the equilibrium density of the polymers is independent of the azimuthal coordinate. However, simulations have shown that this rotational symmetry can be broken when there are attractive interactions between the polymers. We investigate the phases that emerge in these circumstances, and we quantify the effect of the symmetry assumption on the phase behavior of the system. In the absence of this assumption, one can observe large differences in the equilibrium densities between the rotationally symmetric case and the non-rotationally symmetric case. A simple analytical model is developed that illustrates the driving thermodynamic forces responsible for this symmetry breaking. Our results have implications for the current understanding of the behavior of polymers in cylindrical nanopores.
Phenomenology of induced electroweak symmetry breaking
International Nuclear Information System (INIS)
Chang, Spencer; Galloway, Jamison; Luty, Markus A.; Salvioni, Ennio; Tsai, Yuhsin
2015-01-01
We study the phenomenology of models of electroweak symmetry breaking where the Higgs potential is destabilized by a tadpole arising from the coupling to an “auxiliary” Higgs sector. The auxiliary Higgs sector can be either perturbative or strongly coupled, similar to technicolor models. Since electroweak symmetry breaking is driven by a tadpole, the cubic and quartic Higgs couplings can naturally be significantly smaller than their values in the standard model. The theoretical motivation for these models is that they can explain the 125 GeV Higgs mass in supersymmetry without fine-tuning. The auxiliary Higgs sector contains additional Higgs states that cannot decouple from standard model particles, so these models predict a rich phenomenology of Higgs physics beyond the standard model. In this paper we analyze a large number of direct and indirect constraints on these models. We present the current constraints after the 8 TeV run of the LHC, and give projections for the sensitivity of the upcoming 14 TeV run. We find that the strongest constraints come from the direct searches A 0 →Zh, A 0 →tt-bar, with weaker constraints from Higgs coupling fits. For strongly-coupled models, additional constraints come from ρ + →WZ where ρ + is a vector resonance. Our overall conclusion is that a significant parameter space for such models is currently open, allowing values of the Higgs cubic coupling down to 0.4 times the standard model value for weakly coupled models and vanishing cubic coupling for strongly coupled models. The upcoming 14 TeV run of the LHC will stringently test this scenario and we identify several new searches with discovery potential for this class of models.
Breaking of electroweak symmetry: origin and effects
International Nuclear Information System (INIS)
Delaunay, C.
2008-10-01
The Higgs boson appears as the corner stone of high energy physics, it might be the cause of the excess of matter that led to the formation of the structures of the universe and it seems that it drives the breaking of the electroweak symmetry. Moreover, when the stability at low energies of the Higgs boson is assured by an extra space dimension, it appears that this extra dimension can explain most issues in the flavor physics that are not understood by the standard model. The first chapter presents the main tools of effective field theories, the role of experimental data in the construction of theories valid beyond the standard model is discussed. The second chapter focuses on the electroweak baryogenesis that allows the testing of new physics via the electroweak phase transition. We detail the calculation of a Higgs potential at finite temperature. We follow the dynamics of the phase transition including nucleation an supercooling. Finally we investigate the prospects of gravity wave detection to see the effects of a strong electroweak phase transition. The 2 last chapters are dedicated to the physics of extra-dimension. The properties of the dynamics of scalar, vector fields with a 1/2 spin plunged in a 5 d. Anti de Sitter geometry are reviewed. We present a model of lepton masses and mixings based on the A 4 non-Abelian discrete symmetry. It is shown that this model does not contradict the tests of electroweak precision. (A.C.)
Golden Probe of Electroweak Symmetry Breaking
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...
Symmetries and symmetry breaking beyond the electroweak theory
International Nuclear Information System (INIS)
Grojean, Ch.
1999-01-01
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)
Chiral symmetry breaking in QED for weak coupling
Energy Technology Data Exchange (ETDEWEB)
Huang, J.C. (Missouri Univ., Columbia, MO (USA). Dept. of Physics and Astronomy); Shen, T.C. (Illinois Univ., Urbana, IL (USA). Beckman Inst.)
1991-05-01
We examine the procedure for studying chiral symmetry breaking for weak coupling in QED. We note that while the lowest non-trivial order calculations using numerical solutions to the Schwinger-Dyson equation indicate a breaking of chiral symmetry, the neglected higher-order contributions to the effective potential have imaginary values which can indicate possible instabilities in the theory. (author).
Chiral symmetry breaking in QED for weak coupling
International Nuclear Information System (INIS)
Huang, J.C.; Shen, T.C.
1991-01-01
We examine the procedure for studying chiral symmetry breaking for weak coupling in QED. We note that while the lowest non-trivial order calculations using numerical solutions to the Schwinger-Dyson equation indicate a breaking of chiral symmetry, the neglected higher-order contributions to the effective potential have imaginary values which can indicate possible instabilities in the theory. (author)
Physical pictures of symmetry breaking in quenched QED4
International Nuclear Information System (INIS)
Kogut, J.B.; Argonne National Lab., IL
1989-01-01
We discuss 'collapse of the wavefunction' as the phenomenon underlying chiral symmetry breaking in quenched QED4. The 1/r singularity in the 'collapsed' qanti q wavefunction causes 'catalyzed symmetry breaking' which is the field theoretic analog of 'monopole induced proton decay'. The evasion of mean field exponents by the quenched theory's chiral phase transition is emphasized. (orig.)
Chiral symmetry breaking and cooling in lattice QCD
International Nuclear Information System (INIS)
Woloshyn, R.M.; Lee, F.X.
1995-08-01
Chiral symmetry breaking is calculated as a function of cooling in quenched lattice QCD. A non-zero signal is found for the chiral condensate beyond one hundred cooling steps, suggesting that there is chiral symmetry breaking associated with instantons. Quantitatively, the chiral condensate in cooled gauge field configurations is small compared to the value without cooling. (author) 7 refs., 1 tab., 3 figs
Salam-Weinberg symmetry breaking with superheavy Higgs particles
International Nuclear Information System (INIS)
Misra, S.P.
1986-09-01
We discuss here the possibility of the breaking of the Salam-Weinberg symmetry by Higgs particles which are superheavy. The symmetry-breaking is associated with a nonzero vacuum expectation value of fermion condensates. This mechanism, if operative in nature, will imply the absence of Higgs particles at the weak scale. (author)
Optimal Spatial Harvesting Strategy and Symmetry-Breaking
International Nuclear Information System (INIS)
Kurata, Kazuhiro; Shi Junping
2008-01-01
A reaction-diffusion model with logistic growth and constant effort harvesting is considered. By minimizing an intrinsic biological energy function, we obtain an optimal spatial harvesting strategy which will benefit the population the most. The symmetry properties of the optimal strategy are also discussed, and related symmetry preserving and symmetry breaking phenomena are shown with several typical examples of habitats
Coupling of tt̄ and γγ with a strongly interacting Electroweak Symmetry Breaking Sector
Directory of Open Access Journals (Sweden)
Delgado Rafael L.
2017-01-01
Full Text Available We report the coupling of an external γγ or tt̄ state to a strongly interacting EWSBS satisfying unitarity. We exploit perturbation theory for those coupling of the external state, whereas the EWSBS is taken as strongly interacting. We use a modified version of the IAM unitarization procedure to model such a strongly interacting regime. The matrix elements VLVL → VLVL, VLVL ↔ hh, hh → hh, VLVL ↔ {γγ, tt̄}, hh ↔ {γγ, tt̄} are all computed to NLO in perturbation theory with the Nonlinear Effective Field Theory of the EWSBS, within the Equivalence Theorem. This allows us to describe resonances of the electroweak sector that may be found at the LHC and their effect on other channels such as γγ or tt̄ where they may be discovered.
Brane Lorentz symmetry from Lorentz breaking in the bulk
Energy Technology Data Exchange (ETDEWEB)
Bertolami, O [Departamento de Fisica, Instituto Superior Tecnico, Avenida Rovisco Pais 1, 1049-001 Lisbon (Portugal); Carvalho, C [Departamento de Fisica, Instituto Superior Tecnico, Avenida Rovisco Pais 1, 1049-001 Lisbon (Portugal)
2007-05-15
We propose the mechanism of spontaneous symmetry breaking of a bulk vector field as a way to generate the selection of bulk dimensions invisible to the standard model confined to the brane. By assigning a nonvanishing vacuum value to the vector field, a direction is singled out in the bulk vacuum, thus breaking the bulk Lorentz symmetry. We present the condition for induced Lorentz symmetry on the brane, as phenomenologically required.
Temperature renormalization group approach to spontaneous symmetry breaking
International Nuclear Information System (INIS)
Manesis, E.; Sakakibara, S.
1985-01-01
We apply renormalization group equations that describe the finite-temperature behavior of Green's functions to investigate thermal properties of spontaneous symmetry breaking. Specifically, in the O(N).O(N) symmetric model we study the change of symmetry breaking patterns with temperature, and show that there always exists the unbroken symmetry phase at high temperature, modifying the naive result of leading order in finite-temperature perturbation theory. (orig.)
Snezhkova, Olesia; Bischoff, Felix; He, Yuanqin; Wiengarten, Alissa; Chaudhary, Shilpi; Johansson, Niclas; Schulte, Karina; Knudsen, Jan; Barth, Johannes V; Seufert, Knud; Auwärter, Willi; Schnadt, Joachim
2016-03-07
We have examined the geometric and electronic structures of iron phthalocyanine assemblies on a Cu(111) surface at different sub- to mono-layer coverages and the changes induced by thermal annealing at temperatures between 250 and 320 °C by scanning tunneling microscopy, x-ray photoelectron spectroscopy, and x-ray absorption spectroscopy. The symmetry breaking observed in scanning tunneling microscopy images is found to be coverage dependent and to persist upon annealing. Further, we find that annealing to temperatures between 300 and 320 °C leads to both desorption of iron phthalocyanine molecules from the surface and their agglomeration. We see clear evidence of temperature-induced homocoupling reactions of the iron phthalocyanine molecules following dehydrogenation of their isoindole rings, similar to what has been observed for related tetrapyrroles on transition metal surfaces. Finally, spectroscopy indicates a modified substrate-adsorbate interaction upon annealing with a shortened bond distance. This finding could potentially explain a changed reactivity of Cu-supported iron phthalocyanine in comparison to that of the pristine compound.
Radiative Symmetry Breaking in Brane Models
Antoniadis, Ignatios; Quirós, Mariano
2000-01-01
We propose a way to generate the electroweak symmetry breaking radiatively in non-supersymmetric type I models with string scale in the TeV region. By identifying the Higgs field with a tree-level massless open string state, we find that a negative squared mass term can be generated at one loop. It is finite, computable and typically a loop factor smaller than the string scale, that acts as an ultraviolet cutoff in the effective field theory. When the Higgs open string has both ends confined on our world brane, its mass is predicted to be around 120 GeV, i.e. that of the lightest Higgs in the minimal supersymmetric model for large $\\tan\\beta$ and $m_A$. Moreover, the string scale turns out to be one to two orders of magnitude higher than the weak scale. We also discuss possible effects of higher order string threshold corrections that might increase the string scale and the Higgs mass.
Explicit symmetry breaking in electrodynamic systems and electromagnetic radiation
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.
Holographic theories of electroweak symmetry breaking without a Higgs Boson
International Nuclear Information System (INIS)
Burdman, Gustavo; Nomura, Yasunori
2003-01-01
Recently, realistic theories of electroweak symmetry breaking have been constructed in which the electroweak symmetry is broken by boundary conditions imposed at a boundary of higher dimensional spacetime. These theories have equivalent 4D dual descriptions, in which the electroweak symmetry is dynamically broken by non-trivial infrared dynamics of some gauge interaction, whose gauge coupling (tilde g) and size N satisfy (tilde g) 2 N ∼> 16π 2 . Such theories allow one to calculate electroweak radiative corrections, including the oblique parameters S, T and U, as long as (tilde g) 2 N/16π 2 and N are sufficiently larger than unity. We study how the duality between the 4D and 5D theories manifests itself in the computation of various physical quantities. In particular, we calculate the electroweak oblique parameters in a warped 5D theory where the electroweak symmetry is broken by boundary conditions at the infrared brane. We show that the value of S obtained in the minimal theory exceeds the experimental bound if the theory is in a weakly coupled regime. This requires either an extension of the minimal model or departure from weak coupling. A particularly interesting scenario is obtained if the gauge couplings in the 5D theory take the largest possible values--the value suggested by naive dimensional analysis. We argue that such a theory can provide a potentially consistent picture for dynamical electroweak symmetry breaking: corrections to the electroweak observables are sufficiently small while realistic fermion masses are obtained without conflicting with bounds from flavor violation. The theory contains only the standard model quarks, leptons and gauge bosons below ≅2 TeV, except for a possible light scalar associated with the radius of the extra dimension. At ≅2 TeV increasingly broad string resonances appear. An analysis of top-quark phenomenology and flavor violation is also presented, which is applicable to both the weakly-coupled and strongly
Conformal dynamics for electroweak symmetry breaking, from LHC to cosmology
International Nuclear Information System (INIS)
Sannino, Francesco
2009-01-01
Full text. I will first introduce dynamical electroweak symmetry breaking and then present how to resolve some of the long-standing problems using (near) conformal dynamics. In order to construct sensible extension of DEWSB I will then review the state-of-the-art of the phase diagram of gauge theories of fundamental interactions as function of the number of colors, flavors and matter representation. Finally I will introduce recent models known as minimal walking models and show how they lead to natural candidates of dark matter. (author)
Spontaneous symmetry breaking and response functions
International Nuclear Information System (INIS)
Beraudo, A.; De Pace, A.; Martini, M.; Molinari, A.
2005-01-01
We study the quantum phase transition occurring in an infinite homogeneous system of spin 1/2 fermions in a non-relativistic context. As an example we consider neutrons interacting through a simple spin-spin Heisenberg force. The two critical values of the coupling strength-signaling the onset into the system of a finite magnetization and of the total magnetization, respectively-are found and their dependence upon the range of the interaction is explored. The spin response function of the system in the region where the spin-rotational symmetry is spontaneously broken is also studied. For a ferromagnetic interaction the spin response along the direction of the spontaneous magnetization occurs in the particle-hole continuum and displays, for not too large momentum transfers, two distinct peaks. The response along the direction orthogonal to the spontaneous magnetization displays instead, beyond a softened and depleted particle-hole continuum, a collective mode to be identified with a Goldstone boson of type II. Notably, the random phase approximation on a Hartree-Fock basis accounts for it, in particular for its quadratic-close to the origin-dispersion relation. It is shown that the Goldstone boson contributes to the saturation of the energy-weighted sum rule for ∼25% when the system becomes fully magnetized (that is in correspondence of the upper critical value of the interaction strength) and continues to grow as the interaction strength increases
Quantum symmetries in particle interactions
International Nuclear Information System (INIS)
Shirkov, D.V.
1983-01-01
The concept of a quantum symmetry is introduced as a symmetry in the formulation of which quantum representations and specific quantum notions are used essentially. Three quantum symmetry principles are discussed: the principle of renormalizability (possibly super-renormalizability), the principle of local gauge symmetry, and the principle of supersymmetry. It is shown that these principles play a deterministic role in the development of quantum field theory. Historically their use has led to ever stronger restrictions on the interaction mechanism of quantum fields
Introduction to symmetry-breaking phenomena in physics
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 ...
Phenomenology of symmetry breaking from extra dimensions
International Nuclear Information System (INIS)
Alfaro, Jorge; Broncano, Alicia; Belen Gavela, Maria; Rigolin, Stefano; Salvatori, Matteo
2007-01-01
Motivated by the electroweak hierarchy problem, we consider theories with two extra dimensions in which the four-dimensional scalar fields are components of gauge boson in full space. We explore the Nielsen-Olesen instability for SU(N) on a torus, in the presence of a magnetic background. A field theory approach is developed, computing explicitly the minimum of the complete effective potential, including tri-linear and quartic couplings and determining the symmetries of the stable vacua. We also develop appropriate gauge-fixing terms when both Kaluza-Klein and Landau levels are present and interacting, discussing the interplay between the possible six and four dimensional choices. The equivalence between coordinate dependent and constant Scherk-Schwarz boundary conditions - associated to either continuous or discrete Wilson lines - is analyzed
Spontaneous symmetry breaking, self-trapping, and Josephson oscillations
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.
Spontaneous breaking of the BRST symmetry in the ABJM theory
International Nuclear Information System (INIS)
Faizal, Mir; Upadhyay, Sudhaker
2014-01-01
In this paper, we will analyze the ghost condensation in the ABJM theory. We will perform our analysis in N=1 superspace. We show that in the Delbourgo–Jarvis–Baulieu–Thierry–Mieg gauge the spontaneous breaking of BRST symmetry can occur in the ABJM theory. This spontaneous breaking of BRST symmetry is caused by ghost–anti-ghost condensation. We will also show that in the ABJM theory, the ghost–anti-ghost condensates remain present in the modified abelian gauge. Thus, the spontaneous breaking of BRST symmetry in ABJM theory can even occur in the modified abelian gauge
Evidence for SU(3) symmetry breaking from hyperon production
International Nuclear Information System (INIS)
Yang Jianjun
2002-01-01
We examine the SU(3) symmetry breaking in hyperon semileptonic decays (HSD) by considering two typical sets of quark contributions to the spin content of the octet baryons: set 1 with SU(3) flavor symmetry and set 2 with SU(3) flavor symmetry breaking in the HSD. The quark distributions of the octet baryons are calculated with a successful statistical model. Using an approximate relation between the quark fragmentation functions and the quark distributions, we predict the polarizations of the octet baryons produced in e + e - annihilation and semi-inclusive deep lepton-nucleon scattering in order to reveal the SU(3) symmetry breaking effect on the spin structure of the octet baryons. We find that the SU(3) symmetry breaking significantly affects the hyperon polarization. The available experimental data on the Λ polarization seem to favor the theoretical predictions with SU(3) symmetry breaking. We conclude that there is a possibility to get collateral evidence for SU(3) symmetry breaking from hyperon production. The theoretical errors for our predictions are discussed
Spontaneous symmetry breaking as a basis of particle mass
International Nuclear Information System (INIS)
Quigg, Chris
2007-01-01
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 and Englert and by Guralnik, Hagen, and 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 ± 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
Spontaneous Symmetry Breaking as a Basis of Particle Mass
International Nuclear Information System (INIS)
Quigg, Chris
2007-01-01
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 and Englert, and by Guralnik, Hagen, and 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 ± 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
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.
Hybrid local-order mechanism for inversion symmetry breaking
Wolpert, Emma H.; Overy, Alistair R.; Thygesen, Peter M. M.; Simonov, Arkadiy; Senn, Mark S.; Goodwin, Andrew L.
2018-04-01
Using classical Monte Carlo simulations, we study a simple statistical mechanical model of relevance to the emergence of polarization from local displacements on the square and cubic lattices. Our model contains two key ingredients: a Kitaev-like orientation-dependent interaction between nearest neighbors and a steric term that acts between next-nearest neighbors. Taken by themselves, each of these two ingredients is incapable of driving long-range symmetry breaking, despite the presence of a broad feature in the corresponding heat-capacity functions. Instead, each component results in a "hidden" transition on cooling to a manifold of degenerate states; the two manifolds are different in the sense that they reflect distinct types of local order. Remarkably, their intersection, i.e., the ground state when both interaction terms are included in the Hamiltonian, supports a spontaneous polarization. In this way, our study demonstrates how local-order mechanisms might be combined to break global inversion symmetry in a manner conceptually similar to that operating in the "hybrid" improper ferroelectrics. We discuss the relevance of our analysis to the emergence of spontaneous polarization in well-studied ferroelectrics such as BaTiO3 and KNbO3.
Positive Disintegration as a Process of Symmetry Breaking.
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.
Dynamical symmetry breaking as an alternative for Higg's mechanics
International Nuclear Information System (INIS)
Shellard, R.C.
1979-01-01
The effective action of a theory where dynamical symmetry breaking occurs is expanded in terms of loops, producing a Ginzburg-Landau-like Lagrangian reproducing fenomenologically the Higg's potencial. (L.C.) [pt
Dynamical chiral-symmetry breaking in dual QCD
International Nuclear Information System (INIS)
Krein, G.; Williams, A.G.
1991-01-01
We have extended recent studies by Baker, Ball, and Zachariasen (BBZ) of dynamical chiral-symmetry breaking in dual QCD. Specifically, we have taken dual QCD to specify the nonperturbative infrared nature of the quark-quark interaction and then we have smoothly connected onto this the known leading-log perturbative QCD interaction in the ultraviolet region. In addition, we have solved for a momentum-dependent self-energy and have used the complete lowest-order dual QCD quark-quark interaction. We calculate the quark condensate left-angle bar qq right-angle and the pion decay constant f π within this model. We find that the dual QCD parameters needed to give acceptable results are reasonably consistent with those extracted from independent physical considerations by BBZ
Spontaneous symmetry breaking in vortex systems with two repulsive lengthscales.
Curran, P J; Desoky, W M; Milosević, M V; Chaves, A; Laloë, J-B; Moodera, J S; Bending, S J
2015-10-23
Scanning Hall probe microscopy (SHPM) has been used to study vortex structures in thin epitaxial films of the superconductor MgB2. Unusual vortex patterns observed in MgB2 single crystals have previously been attributed to a competition between short-range repulsive and long-range attractive vortex-vortex interactions in this two band superconductor; the type 1.5 superconductivity scenario. Our films have much higher levels of disorder than bulk single crystals and therefore both superconducting condensates are expected to be pushed deep into the type 2 regime with purely repulsive vortex interactions. We observe broken symmetry vortex patterns at low fields in all samples after field-cooling from above Tc. These are consistent with those seen in systems with competing repulsions on disparate length scales, and remarkably similar structures are reproduced in dirty two band Ginzburg-Landau calculations, where the simulation parameters have been defined by experimental observations. This suggests that in our dirty MgB2 films, the symmetry of the vortex structures is broken by the presence of vortex repulsions with two different lengthscales, originating from the two distinct superconducting condensates. This represents an entirely new mechanism for spontaneous symmetry breaking in systems of superconducting vortices, with important implications for pinning phenomena and high current density applications.
Concepts of electroweak symmetry breaking and Higgs physics
International Nuclear Information System (INIS)
Gomez-Bock, M.; Zerwas, P.M.; RWTH Aachen; Univ. Paris- Sud, Orsay
2007-12-01
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. (orig.)
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.)
Anomalous U(1)A and electroweak symmetry breaking
International Nuclear Information System (INIS)
Gogoladze, I.; Tsulaya, M.
2000-01-01
A new mechanism for electroweak symmetry breaking in the supersymmetric Standard Model is suggested. Our suggestion is based on the presence of an anomalous U(1) A gauge symmetry, which naturally arises in the four-dimensional superstring theory, and heavily relies on the corresponding Fayet-Illiopoulos ξ-term
Anomalous U(1)A and electroweak symmetry breaking
International Nuclear Information System (INIS)
Gogoladze, Ilia
2000-10-01
We suggest a mechanism for electroweak symmetry breaking in the Supersymmetric Standard Model. Our suggestion is based on the presence of an anomalous U(1) A gauge symmetry, which naturally arises in the four dimensional superstring theory, and heavily relies on the value of the corresponding Fayet-Illiopoulos ξ-term. (author)
Gauge symmetry breaking in gauge theories -- in search of clarification
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
Electroweak symmetry breaking: Unitarity, dynamics, and experimental prospects
International Nuclear Information System (INIS)
Chanowitz, M.S.
1988-01-01
A review of what is known about the unexplained mechanism that breaks the electroweak symmetry and thereby gives mass to the W and Z gauge bosons while leaving the photon massless is given. Symmetry, unitarity, technicolor, supersymmetry, higgs sector dynamics, and experimental status and prospects are discussed
Electroweak symmetry breaking in supersymmetric gauge-Higgs unification models
International Nuclear Information System (INIS)
Choi, Kiwoon; Jeong, Kwang-Sik; Okumura, Ken-ichi; Haba, Naoyuki; Shimizu, Yasuhiro; Yamaguchi, Masahiro
2004-01-01
We examine the Higgs mass parameters and electroweak symmetry breaking in supersymmetric orbifold field theories in which the 4-dimensional Higgs fields originate from higher-dimensional gauge supermultiplets. It is noted that such gauge-Higgs unification leads to a specific boundary condition on the Higgs mass parameters at the compactification scale, which is independent of the details of supersymmetry breaking mechanism. With this boundary condition, phenomenologically viable parameter space of the model is severely constrained by the condition of electroweak symmetry breaking for supersymmetry breaking scenarios which can be realized naturally in orbifold field theories. For instance, if it is assumed that the 4-dimensional effective theory is the minimal supersymmetric standard model with supersymmetry breaking parameters induced by the Scherk-Schwarz mechanism, a correct electroweak symmetry breaking can not be achieved for reasonable range of parameters of the model, even when one includes additional contributions to the Higgs mass parameters from the auxiliary component of 4-dimensional conformal compensator. However if there exists a supersymmetry breaking mediated by brane superfields, sizable portion of the parameter space can give a correct electroweak symmetry breaking. (author)
Constraints of dynamical symmetry breaking mechanisms from electroweak data
International Nuclear Information System (INIS)
Ali, A.; Degrassi, G.
1991-04-01
Consistency of the Salam-Weinberg theory, including quantum corrections, with high precision data from LEP and elsewhere imposes non-trivial bounds on the parameters of this theory, in particular the top quark mass. We take stock of the available experimental information in the electroweak sector with the view of constraining possible additional interactions, such as present in dynamical symmetry breaking scenarios. Using the Peskin-Takeuchi isospin conserving, S and -violating, T, parametrization of new physics contribution to vacuum polarization corrections, we show here that the full one family technicolor models are ruled out at the 95% C.L. from the LEP data and m W -measurements alone. We stress the role of improved precision measurements of the W-boson mass and the decay width Γ(Z→banti b) in the enhanced sensitivity gained on such interactions. (orig.)
Effect of symmetry breaking on transition strength distributions
International Nuclear Information System (INIS)
Mitchell, G.E.; Shriner, J.F. Jr.
2001-01-01
The quantum numbers of over 100 states in 30 P have been determined from the ground state to 8 MeV. Previous measurements had provided complete spectroscopy in 26 Al. For these N=Z=odd nuclei, states of isospin T=0 and T=1 coexist at all energies. These spectra provide a unique opportunity to test the effect of symmetry breaking (of the approximate symmetry isospin) on the level statistics and on the transition strength distributions. The level statistics are strongly affected by the small symmetry breaking and the transition strength distributions differ from the Porter-Thomas distribution
The geometric role of symmetry breaking in gravity
International Nuclear Information System (INIS)
Wise, Derek K
2012-01-01
In gravity, breaking symmetry from a group G to a group H plays the role of describing geometry in relation to the geometry of the homogeneous space G/H. The deep reason for this is Cartan's 'method of equivalence,' giving, in particular, an exact correspondence between metrics and Cartan connections. I argue that broken symmetry is thus implicit in any gravity theory, for purely geometric reasons. As an application, I explain how this kind of thinking gives a new approach to Hamiltonian gravity in which an observer field spontaneously breaks Lorentz symmetry and gives a Cartan connection on space.
Spontaneous symmetry breaking in 4-dimensional heterotic string
International Nuclear Information System (INIS)
Maharana, J.
1989-07-01
The evolution of a 4-dimensional heterotic string is considered in the background of its massless excitations such as graviton, antisymmetric tensor, gauge fields and scalar bosons. The compactified bosonic coordinates are fermionized. The world-sheet supersymmetry requirement enforces Thirring-like four fermion coupling to the background scalar fields. The non-abelian gauge symmetry is exhibited through the Ward identities of the S-matrix elements. The spontaneous symmetry breaking mechanism is exhibited through the broken Ward identities. An effective 4-dimensional action is constructed and the consequence of spontaneous symmetry breaking is envisaged for the effective action. 19 refs
Emergent Electroweak Symmetry Breaking with Composite W, Z Bosons
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.
Patterns of symmetry breaking in chiral QCD
Bolognesi, Stefano; Konishi, Kenichi; Shifman, Mikhail
2018-05-01
We consider S U (N ) Yang-Mills theory with massless chiral fermions in a complex representation of the gauge group. The main emphasis is on the so-called hybrid ψ χ η model. The possible patterns of realization of the continuous chiral flavor symmetry are discussed. We argue that the chiral symmetry is broken in conjunction with a dynamical Higgsing of the gauge group (complete or partial) by bifermion condensates. As a result a color-flavor locked symmetry is preserved. The 't Hooft anomaly matching proceeds via saturation of triangles by massless composite fermions or, in a mixed mode, i.e. also by the "weakly" coupled fermions associated with dynamical Abelianization, supplemented by a number of Nambu-Goldstone mesons. Gauge-singlet condensates are of the multifermion type and, though it cannot be excluded, the chiral symmetry realization via such gauge invariant condensates is more contrived (requires a number of four-fermion condensates simultaneously and, even so, problems remain) and less plausible. We conclude that in the model at hand, chiral flavor symmetry implies dynamical Higgsing by bifermion condensates.
Roca-Maza, X; Colò, G; Sagawa, H
2018-05-18
We analyze and propose a solution to the apparent inconsistency between our current knowledge of the equation of state of asymmetric nuclear matter, the energy of the isobaric analog state (IAS) in a heavy nucleus such as ^{208}Pb, and the isospin symmetry breaking forces in the nuclear medium. This is achieved by performing state-of-the-art Hartree-Fock plus random phase approximation calculations of the IAS that include all isospin symmetry breaking contributions. To this aim, we propose a new effective interaction that is successful in reproducing the IAS excitation energy without compromising other properties of finite nuclei.
Electroweak symmetry breaking beyond the Standard Model
Indian Academy of Sciences (India)
words, now that the gauge symmetry is established with a significant ..... picture, the Higgs is some kind of a composite bound state emerging from a strongly .... (i) Little Higgs vs. composite: Little Higgs models were introduced to solve the little ...
Chiral symmetry breaking in finite quantum electrodynamics
International Nuclear Information System (INIS)
Montero, J.C.; Pleitez, V.
1987-01-01
The dynamical breakdown of chiral symmetry in a finite Abelian gauge theory using a variational approach for the effective potential for composite operators is discussed. It is shown that, at least in a variational approach, the fermion either remains massless or gets a dynamical mass for every non-zero coupling constant. (Author) [pt
A perfectly conducting surface in electrodynamics with Lorentz symmetry breaking
Borges, L. H. C.; Barone, F. A.
2017-10-01
In this paper we consider a model which exhibits explicit Lorentz symmetry breaking due to the presence of a single background vector v^{μ } coupled to the gauge field. We investigate such a theory in the vicinity of a perfectly conducting plate for different configurations of v^{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^{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.
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.)
Electroweak symmetry breaking from a holographic fourth generation
International Nuclear Information System (INIS)
Burdman, Gustavo; Rold, Leandro Da
2007-01-01
We consider a model with four generations of standard model fermions propagating in an extra dimension with an AdS background metric. We show that if the zero modes of the fourth generation are highly localized towards the infrared brane, it is possible to break the electroweak symmetry via their condensation, partly driven by their interactions with the Kaluza-Klein excitations of the gauge bosons, as well as by the presence of bulk higher-dimensional operators. This dynamical mechanism results in a composite Higgs, which is highly localized and generally heavy. The localization of fermions in the five-dimensional bulk naturally leads to the standard model Yukawa couplings via the action of the bulk higher-dimensional operators, which are suppressed by the Planck scale. We obtain the spectrum of the model and explore some of its phenomenological consequences, both for electroweak precision constraints as well as at the Large Hadron Collider
Dynamics of the universe and spontaneous symmetry breaking
Kazanas, D.
1980-01-01
It is shown that the presence of a phase transition early in the history of the universe, associated with spontaneous symmetry breaking (believed to take place at very high temperatures at which the various fundamental interactions unify), significantly modifies its dynamics and evolution. This is due to the energy 'pumping' during the phase transition from the vacuum to the substance, rather than the gravitating effects of the vacuum. The expansion law of the universe then differs substantially from the relation considered so far for the very early time expansion. In particular it is shown that under certain conditions this expansion law is exponential. It is further argued that under reasonable assumptions for the mass of the associated Higgs boson this expansion stage could last long enough to potentially account for the observed isotropy of the universe.
Symmetry Breaking in a random passive scalar
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.
Electroweak symmetry breaking in supersymmetric models with heavy scalar superpartners
International Nuclear Information System (INIS)
Chankowski, Piotr H.; Falkowski, Adam; Pokorski, Stefan; Wagner, Jakub
2004-01-01
We propose a novel mechanism of electroweak symmetry breaking in supersymmetric models, as the one recently discussed by Birkedal, Chacko and Gaillard, in which the Standard Model Higgs doublet is a pseudo-Goldstone boson of some global symmetry. The Higgs mass parameter is generated at one-loop level by two different, moderately fine-tuned sources of the global symmetry breaking. The mechanism works for scalar superpartner masses of order 10 TeV, but gauginos can be light. The scale at which supersymmetry breaking is mediated to the visible sector has to be low, of order 100 TeV. Fine-tuning in the scalar potential is at least two orders of magnitude smaller than in the MSSM with similar soft scalar masses. The physical Higgs boson mass is (for tanβ >> 1) in the range 120-135 GeV
Maximal Rashba-like spin splitting via kinetic-energy-coupled inversion-symmetry breaking
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.
Minimally doubled fermions and spontaneous chiral symmetry breaking
Directory of Open Access Journals (Sweden)
Osmanaj (Zeqirllari Rudina
2018-01-01
Full Text Available Chiral symmetry breaking in massless QCD is a very important feature in the current understanding of low energy physics. Low - lying Dirac modes are suitable to help us understand the spontaneous chiral symmetry breaking, since the formation of a non zero chiral condensate is an effect of their accumulation near zero. The Banks – Casher relation links the spectral density of the Dirac operator to the condensate with an identity that can be read in both directions. In this work we propose a spectral method to achieve a reliable determination of the density of eigenvalues of Dirac operator near zero using the Gauss – Lanczos quadrature. In order to understand better the dynamical chiral symmetry breaking and use the method we propose, we have chosen to work with minimally doubled fermions. These kind of fermions have been proposed as a strictly local discretization of the QCD fermions action, which preserves chiral symmetry at finite cut-off. Being chiral fermions, is easier to work with them and their low - lying Dirac modes and to understand the dynamical spontaneous chiral symmetry breaking.
Minimally doubled fermions and spontaneous chiral symmetry breaking
Osmanaj (Zeqirllari), Rudina; Hyka (Xhako), Dafina
2018-03-01
Chiral symmetry breaking in massless QCD is a very important feature in the current understanding of low energy physics. Low - lying Dirac modes are suitable to help us understand the spontaneous chiral symmetry breaking, since the formation of a non zero chiral condensate is an effect of their accumulation near zero. The Banks - Casher relation links the spectral density of the Dirac operator to the condensate with an identity that can be read in both directions. In this work we propose a spectral method to achieve a reliable determination of the density of eigenvalues of Dirac operator near zero using the Gauss - Lanczos quadrature. In order to understand better the dynamical chiral symmetry breaking and use the method we propose, we have chosen to work with minimally doubled fermions. These kind of fermions have been proposed as a strictly local discretization of the QCD fermions action, which preserves chiral symmetry at finite cut-off. Being chiral fermions, is easier to work with them and their low - lying Dirac modes and to understand the dynamical spontaneous chiral symmetry breaking.
Constraints on GUTS with Coleman-Weinberg symmetry breaking
International Nuclear Information System (INIS)
Sher, M.A.
1981-01-01
A popular assumption introduced by Coleman and Weinberg is that the elementary Higgs scalars of a gauge theory are massless at the tree level; the symmetry breakdown is then entirely due to quantum radiative corrections. In grand unified theories (GUTS), this assumption becomes particularly attractive. Many GUTS have intermediate mass scales [scales of symmetry breaking between baryon number generation and SU(2) x U(1) breaking], and it is attractive to apply the Coleman-Weinberg assumption to all stages of symmetry breaking after baryon number generation. In this paper, it is shown that most such GUTS are phenomenologically unacceptable. The reason is that as the universe cools, at each scale of symmetry breaking there will be a phase transition; if the symmetry is broken a la Coleman-Weinberg, this transition is strongly first order and thus generates entropy, decreasing the previously generated baryon number to entropy ratio by a large, and perhaps unacceptable amount. The entropy generated in a general intermediate mass scale transition is calculated, and the severe constraints that any Coleman-Weinberg-type GUT with intermediate mass scales must satisfy (in order to avoid excessive entropy generation) are found. Turning to specific models, it is shown that all intermediate mass scale transitions associated with SO(10) do not satisfy these constraints; the Coleman-Weinberg form of these transitions is inconsistent with cosmological observations and is thus phenomenologically unacceptable. (orig.)
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.
Strong evidence for spontaneous chiral symmetry breaking in (quenched) QCD
International Nuclear Information System (INIS)
Barbour, I.M.; Gibbs, P.; Schierholz, G.; Teper, M.; Gilchrist, J.P.; Schneider, H.
1983-09-01
We calculate the chiral condensate for all quark masses using Kogut-Susskind fermions in lattice-regularized quenched QCD. The large volume behaviour of at small quark masses demonstrates that the explicit U(1) chiral symmetry is spontaneously broken. We perform the calculation for β = 5.1 to 5.9 and find very good continuum renormalization group behaviour. We infer that the spontaneous breaking we observe belongs to continuum QCD. This constitutes the first unambiguous demonstration of spontaneous chiral symmetry breaking in continuum quenched QCD. (orig.)
Symmetry breaking in a five-dimensional SU(5) model
International Nuclear Information System (INIS)
Svetovoi, V.B.; Khariton, N.G.
1986-01-01
Two-state symmetry breaking in a SU(5) model in a space with M 4 x S 1 topology is discussed. The scalar 24-plet is a component of a five-vector and acquires a nonzero vacuum expectation value at the quantum level. The vacuum differs substantially from that of the standard SU(5) model. Its orientation in the SU(5) space and absolute magnitude are fixed uniquely. The second stage of the symmetry breaking occurs on account of a five-scalar in the fundamental representation of SU(5) by means of the Weinberg mechanism. The small mass of the scalar SU(2) doublet is not explained
Chiral symmetry breaking in a semilocalized magnetic field
Cao, Gaoqing
2018-03-01
In this work, we explore the pattern of chiral symmetry breaking and restoration in a solvable magnetic field configuration within the Nambu-Jona-Lasinio model. The special semilocalized static magnetic field can roughly mimic the realistic situation in peripheral heavy ion collisions; thus, the study is important for the dynamical evolution of quark matter. We find that the magnetic-field-dependent contribution from discrete spectra usually dominates over the contribution from continuum spectra and chiral symmetry breaking is locally catalyzed by both the magnitude and scale of the magnetic field. The study is finally extended to the case with finite temperature or chemical potential.
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.
Evidence for dynamic SU(5) symmetry breaking in meson mass multiplets
International Nuclear Information System (INIS)
Frikkee, E.
1994-07-01
It is shown that the mass differences and multiplet pattern for pseudoscalar and vector mesons correspond to a chain of dynamic symmetry reductions SU(n) contains SU(n-1)xU(1). In this symmetry-reduction model, the differences between the masses of the quark flavours are the result of intra-hadronic interactions. Quark confinement is explained as a consequence of the fact that this symmetry breaking chain only occurs in hadrons. The results of a quantitative analysis of mass splittings in meson multiplets indicate that SU(5) is probably the highest symmetry for hadron states. In the proposed dynamic symmetry breaking scheme with five quark flavours there is no one-to-one correspondence between lepton and quark generations. (orig.)
Mass generation and chiral symmetry breaking by pseudoparticles
International Nuclear Information System (INIS)
Hietarinta, J.; Palmer, W.F.; Pinsky, S.S.
1978-01-01
Massless QCD is studied with regard to mass generation and chiral SU(N/sub f/) symmetry breaking from pseudoparticle effects. While mass is generated when there is only one massless quark, and chiral U(1) is always broken, no rigorous indication of the breaking of chiral SU(N/sub f/) and mass generation is seen when there are more than one massless quarks in the original theory
Chiral symmetry-breaking and the quark mass
International Nuclear Information System (INIS)
Gautam, V.P.; Kar, S.C.
1988-01-01
The generation of mass for light and heavy-quark sectors in the case of chiral symmetry-breaking is studied and an attempt is made to find the origin of quark mass and renormalization point corresponding to current-quark mass. (M.G.B.). 12 refs
Simple mathematical models of symmetry breaking. Application to particle physics
International Nuclear Information System (INIS)
Michel, L.
1976-01-01
Some mathematical facts relevant to symmetry breaking are presented. A first mathematical model deals with the smooth action of compact Lie groups on real manifolds, a second model considers linear action of any group on real or complex finite dimensional vector spaces. Application of the mathematical models to particle physics is considered. (B.R.H.)
Nonextensive Entropy, Prior PDFs and Spontaneous Symmetry Breaking
Shafee, Fariel
2008-01-01
We show that using nonextensive entropy can lead to spontaneous symmetry breaking when a parameter changes its value from that applicable for a symmetric domain, as in field theory. We give the physical reasons and also show that even for symmetric Dirichlet priors, such a defnition of the entropy and the parameter value can lead to asymmetry when entropy is maximized.
Coupling-constant flows and dynamical symmetry breaking
International Nuclear Information System (INIS)
Yamagishi, H.
1981-01-01
The Coleman-Weinberg theory is reformulated in terms of flows in coupling-constant space. It is shown that the existence of dynamical symmetry breaking is governed essentially by the b functions. An application is made to the massless Weinberg-Salam model
Model for dynamical chiral symmetry breaking and quark condensate
International Nuclear Information System (INIS)
Nekrasov, M.L.; Rochev, V.E.
1986-01-01
In the framework of the model, proposed earlier to describe nonperturbative QCD, the singularity of the type 1/k 4 in the gluon propagator is shown to result in dynamical chiral symmetry breaking and appearance of quark condensate. The value, obtained for quark condensate, is close to the phenomenological one
Symmetry-breaking and high-spin states
Energy Technology Data Exchange (ETDEWEB)
Khanna, F C [Alberta Univ., Edmonton, AB (Canada). Dept. of Physics; [TRIUMF, Vancouver, BC (Canada)
1992-08-01
Spontaneous symmetry breaking in nuclear matter would require Nambu-Goldstone bosons in the system. A model calculation gives the nature of these excitations. In finite nuclei the excitations will be a mixture of rotational, surface vibrations and pseudo-Goldstone bosons. A search for such excitations would be fruitful. (author). 5 refs.
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...
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...
Symmetry breaking by Wilson loops in gauge field theory
International Nuclear Information System (INIS)
Dowker, J.S.; Jadhav, S.P.
1989-01-01
An analysis is presented of the gauge symmetry breaking caused by Wilson loops on a space-time whose spatial section is openR/sup d/ x S 3 /Γ, for all those fundamental groups Γ that give a homogeneous space. We concentrate on pure SU(3) and SU(5) gauge field theories and find that symmetry breaking can occur when d = 0, for all Γ. If d = 3, the extra minimal scalars prevent any breaking and one must include other fields to achieve this. Explicit forms for the vacuum energies are exhibited in the case of lens and prism spaces, the former for SU(n). For Γ = Z/sub m/, when m and the radius of the sphere become infinite, we recover the results on the space-time openR/sup d//sup +3/ x S 1
Strong Electroweak Symmetry Breaking and Spin-0 Resonances
International Nuclear Information System (INIS)
Evans, Jared; Luty, Markus A.
2009-01-01
We argue that theories of the strong electroweak symmetry breaking sector necessarily contain new spin 0 states at the TeV scale in the tt and tb/bt channels, even if the third generation quarks are not composite at the TeV scale. These states couple sufficiently strongly to third generation quarks to have significant production at LHC via gg→φ 0 or gb→tφ - . The existence of narrow resonances in QCD suggests that the strong electroweak breaking sector contains narrow resonances that decay to tt or tb/bt, with potentially significant branching fractions to 3 or more longitudinal W and Z bosons. These may give new 'smoking gun' signals of strong electroweak symmetry breaking.
Symmetries and symmetry-breaking in oscillator ensembles
International Nuclear Information System (INIS)
Ujjwal, Sangeeta R.; Ramaswamy, Ram
2017-01-01
The behaviour of collections of oscillators has also been of interest for at least a few centuries as well. As it happens, Huygens described the interaction of two pendulums that resulted in their synchrony, namely the entrainment of one oscillator by the other. He gave a fairly accurate physical explanation for the process, namely that the pendulums oscillated in 'sympathy', adjusting their rhythms as a consequence of the weak coupling between them. The study of synchrony has thus been of interest since long, given the wide variety of systems that show 'sync'. These range from simple mechanical oscillators such as pendulums, to chemical and biological oscillators, coupled Josephson junctions and so on. In short, any system that is capable of showing sustained oscillations is also potentially able to synchronise
Discrete symmetry breaking beyond the standard model
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
Time-reversal symmetry breaking in quantum billiards
Energy Technology Data Exchange (ETDEWEB)
Schaefer, Florian
2009-01-26
The present doctoral thesis describes experimentally measured properties of the resonance spectra of flat microwave billiards with partially broken timereversal invariance induced by an embedded magnetized ferrite. A vector network analyzer determines the complex scattering matrix elements. The data is interpreted in terms of the scattering formalism developed in nuclear physics. At low excitation frequencies the scattering matrix displays isolated resonances. At these the effect of the ferrite on isolated resonances (singlets) and pairs of nearly degenerate resonances (doublets) is investigated. The hallmark of time-reversal symmetry breaking is the violation of reciprocity, i.e. of the symmetry of the scattering matrix. One finds that reciprocity holds in singlets; it is violated in doublets. This is modeled by an effective Hamiltonian of the resonator. A comparison of the model to the data yields time-reversal symmetry breaking matrix elements in the order of the level spacing. Their dependence on the magnetization of the ferrite is understood in terms of its magnetic properties. At higher excitation frequencies the resonances overlap and the scattering matrix elements fluctuate irregularly (Ericson fluctuations). They are analyzed in terms of correlation functions. The data are compared to three models based on random matrix theory. The model by Verbaarschot, Weidenmueller and Zirnbauer describes time-reversal invariant scattering processes. The one by Fyodorov, Savin and Sommers achieves the same for systems with complete time-reversal symmetry breaking. An extended model has been developed that accounts for partial breaking of time-reversal invariance. This extended model is in general agreement with the data, while the applicability of the other two models is limited. The cross-correlation function between forward and backward reactions determines the time-reversal symmetry breaking matrix elements of the Hamiltonian to up to 0.3 mean level spacings. Finally
Time-reversal symmetry breaking in quantum billiards
International Nuclear Information System (INIS)
Schaefer, Florian
2009-01-01
The present doctoral thesis describes experimentally measured properties of the resonance spectra of flat microwave billiards with partially broken timereversal invariance induced by an embedded magnetized ferrite. A vector network analyzer determines the complex scattering matrix elements. The data is interpreted in terms of the scattering formalism developed in nuclear physics. At low excitation frequencies the scattering matrix displays isolated resonances. At these the effect of the ferrite on isolated resonances (singlets) and pairs of nearly degenerate resonances (doublets) is investigated. The hallmark of time-reversal symmetry breaking is the violation of reciprocity, i.e. of the symmetry of the scattering matrix. One finds that reciprocity holds in singlets; it is violated in doublets. This is modeled by an effective Hamiltonian of the resonator. A comparison of the model to the data yields time-reversal symmetry breaking matrix elements in the order of the level spacing. Their dependence on the magnetization of the ferrite is understood in terms of its magnetic properties. At higher excitation frequencies the resonances overlap and the scattering matrix elements fluctuate irregularly (Ericson fluctuations). They are analyzed in terms of correlation functions. The data are compared to three models based on random matrix theory. The model by Verbaarschot, Weidenmueller and Zirnbauer describes time-reversal invariant scattering processes. The one by Fyodorov, Savin and Sommers achieves the same for systems with complete time-reversal symmetry breaking. An extended model has been developed that accounts for partial breaking of time-reversal invariance. This extended model is in general agreement with the data, while the applicability of the other two models is limited. The cross-correlation function between forward and backward reactions determines the time-reversal symmetry breaking matrix elements of the Hamiltonian to up to 0.3 mean level spacings. Finally
Nambu mechanism of dynamical symmetry breaking by the top quark
Pham, Xuan-Yem
1990-05-01
It may be possible that the gauge symmetry breaking of the standard electroweak interactions is not due to the elementary scalar Higgs fields but has a dynamic origin intimately involving the top quark. A prototype of this dynamical scenario is the Nambu and Jona-Lasinio model in which both the top quark and the gauge bosons become massive by some strong attractive nonlinear interactions similar to the gap energy produced in BCS superconductivity. Self-consistent equations for the charged Goldstone boson and for the vector meson are used to get an upper bound for the top quark mass. In the bubble approximation of keeping only fermion loops, we obtain an equation relating the top quark mass to the W boson one; from the top mass is found to be around 84 GeV. Its typical dominant decay mode t→W+s then follows. Also discussed are distinctive signatures of the scalar overlinett bound state identified as the physical Higgs particle whose mass is twice that of the top quark.
B-L mediated SUSY breaking with radiative B-L symmetry breaking
International Nuclear Information System (INIS)
Kikuchi, Tatsuru; Kubo, Takayuki
2008-01-01
We explore a mechanism of radiative B-L symmetry breaking in analogous to the radiative electroweak symmetry breaking. The breaking scale of B-L symmetry is related to the neutrino masses through the see-saw mechanism. Once we incorporate the U(1) B-L gauge symmetry in SUSY models, the U(1) B-L gaugino, Z-tilde B-L appears, and it can mediate the SUSY breaking (Z-prime mediated SUSY breaking) at around the scale of 10 6 GeV. Then we find a links between the neutrino mass (more precisly the see-saw or B-L scale of order 10 6 GeV) and the Z-prime mediated SUSY breaking scale. It is also very interesting that the gluino at the weak scale becomes relatively light, and almost compressed mass spectra for the gaugino sector can be realized in this scenario, which is very interesting in scope of the LHC.
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.
Spontaneous SUSY breaking without R symmetry in supergravity
Maekawa, Nobuhiro; Omura, Yuji; Shigekami, Yoshihiro; Yoshida, Manabu
2018-03-01
We discuss spontaneous supersymmetry (SUSY) breaking in a model with an anomalous U (1 )A symmetry. In this model, the size of the each term in the superpotential is controlled by the U (1 )A charge assignment and SUSY is spontaneously broken via the Fayet-Iliopoulos of U (1 )A at the metastable vacuum. In the global SUSY analysis, the gaugino masses become much smaller than the sfermion masses, because an approximate R symmetry appears at the SUSY breaking vacuum. In this paper, we show that gaugino masses can be as large as gravitino mass, taking the supergravity effect into consideration. This is because the R symmetry is not imposed so that the constant term in the superpotential, which is irrelevant to the global SUSY analysis, largely contributes to the soft SUSY breaking terms in the supergravity. As the mediation mechanism, we introduce the contributions of the field not charged under U (1 )A and the moduli field to cancel the anomaly of U (1 )A. We comment on the application of our SUSY breaking scenario to the grand unified theory.
Steyn-Ross, Moira L.; Steyn-Ross, D. A.; Sleigh, J. W.
2013-04-01
Electrical recordings of brain activity during the transition from wake to anesthetic coma show temporal and spectral alterations that are correlated with gross changes in the underlying brain state. Entry into anesthetic unconsciousness is signposted by the emergence of large, slow oscillations of electrical activity (≲1Hz) similar to the slow waves observed in natural sleep. Here we present a two-dimensional mean-field model of the cortex in which slow spatiotemporal oscillations arise spontaneously through a Turing (spatial) symmetry-breaking bifurcation that is modulated by a Hopf (temporal) instability. In our model, populations of neurons are densely interlinked by chemical synapses, and by interneuronal gap junctions represented as an inhibitory diffusive coupling. To demonstrate cortical behavior over a wide range of distinct brain states, we explore model dynamics in the vicinity of a general-anesthetic-induced transition from “wake” to “coma.” In this region, the system is poised at a codimension-2 point where competing Turing and Hopf instabilities coexist. We model anesthesia as a moderate reduction in inhibitory diffusion, paired with an increase in inhibitory postsynaptic response, producing a coma state that is characterized by emergent low-frequency oscillations whose dynamics is chaotic in time and space. The effect of long-range axonal white-matter connectivity is probed with the inclusion of a single idealized point-to-point connection. We find that the additional excitation from the long-range connection can provoke seizurelike bursts of cortical activity when inhibitory diffusion is weak, but has little impact on an active cortex. Our proposed dynamic mechanism for the origin of anesthetic slow waves complements—and contrasts with—conventional explanations that require cyclic modulation of ion-channel conductances. We postulate that a similar bifurcation mechanism might underpin the slow waves of natural sleep and comment on the
Directory of Open Access Journals (Sweden)
Moira L. Steyn-Ross
2013-05-01
Full Text Available Electrical recordings of brain activity during the transition from wake to anesthetic coma show temporal and spectral alterations that are correlated with gross changes in the underlying brain state. Entry into anesthetic unconsciousness is signposted by the emergence of large, slow oscillations of electrical activity (≲1 Hz similar to the slow waves observed in natural sleep. Here we present a two-dimensional mean-field model of the cortex in which slow spatiotemporal oscillations arise spontaneously through a Turing (spatial symmetry-breaking bifurcation that is modulated by a Hopf (temporal instability. In our model, populations of neurons are densely interlinked by chemical synapses, and by interneuronal gap junctions represented as an inhibitory diffusive coupling. To demonstrate cortical behavior over a wide range of distinct brain states, we explore model dynamics in the vicinity of a general-anesthetic-induced transition from “wake” to “coma.” In this region, the system is poised at a codimension-2 point where competing Turing and Hopf instabilities coexist. We model anesthesia as a moderate reduction in inhibitory diffusion, paired with an increase in inhibitory postsynaptic response, producing a coma state that is characterized by emergent low-frequency oscillations whose dynamics is chaotic in time and space. The effect of long-range axonal white-matter connectivity is probed with the inclusion of a single idealized point-to-point connection. We find that the additional excitation from the long-range connection can provoke seizurelike bursts of cortical activity when inhibitory diffusion is weak, but has little impact on an active cortex. Our proposed dynamic mechanism for the origin of anesthetic slow waves complements—and contrasts with—conventional explanations that require cyclic modulation of ion-channel conductances. We postulate that a similar bifurcation mechanism might underpin the slow waves of natural
Chiral symmetry breaking parameters from QCD sum rules
Energy Technology Data Exchange (ETDEWEB)
Mallik, S [Karlsruhe Univ. (T.H.) (Germany, F.R.). Inst. fuer Theoretische Kernphysik; Bern Univ. (Switzerland). Inst. fuer Theoretische Physik)
1982-10-04
We obtain new QCD sum rules by considering vacuum expectation values of two-point functions, taking all the five quark bilinears into account. These sum rules are employed to extract values of different chiral symmetry breaking parameters in QCD theory. We find masses of light quarks, m=1/2msub(u)+msub(d)=8.4+-1.2 MeV, msub(s)=205+-65 MeV. Further, we obtain corrections to certain soft pion (kaon) PCAC relations and the violation of SU(3) flavour symmetry by the non-strange and strange quark-antiquark vacuum condensate.
Coleman-Weinberg symmetry breaking in an anisotropic spacetime
International Nuclear Information System (INIS)
Futamase, T.
1984-01-01
The Coleman-Weinberg mechanism of symmetry breaking in a Bianchi type-I universe is investigated. The one-loop effective potential for a phi 4 theory and for scalar electrodynamics is calculated by the zeta-function method. The result indicates that the symmetry of the theory will be restored in the highly anisotropic, cold, early universe, irrespective of the coupling between the scalar field and the spacetime curvature scalar. This mechanism of the phase transition explains the isotropy of our universe
Macroscopic influence on the spontaneous symmetry breaking in quantum field
International Nuclear Information System (INIS)
Kirzhnitz, D.A.
1977-01-01
Major results of investigations concerning macroscopic influence (heating, compression, external field and current) on elementary particle systems with spontaneous symmetry breaking are briefly reviewed. The study of this problem has been stimulated by recent progress in the unified renormalizable theory of elementary particles. Typically it appears that at some values of external parameters a phase transition with symmetry restoration takes place. There exists a profound and far going analogy with phase transition in many-body physics especially with superconductivity phenomenon. Some applications to cosmology are also considered
Facets of confinement and dynamical chiral symmetry breaking
International Nuclear Information System (INIS)
Maris, P.; Raya, A.; Roberts, C.D.; Schmidt, S.M.
2003-01-01
The gap equation is a cornerstone in understanding dynamical chiral symmetry breaking and may also provide clues to confinement. A symmetry-preserving truncation of its kernel enables proofs of important results and the development of an efficacious phenomenology. We describe a model of the kernel that yields: a momentum-dependent dressed-quark propagator in fair agreement with quenched lattice-QCD results; and chiral limit values, f π 0 =68 MeV and left angle anti q q right angle =-(190 MeV) 3 . It is compared with models inferred from studies of the gauge sector. (orig.)
On radiative gauge symmetry breaking in the minimal supersymmetric model
International Nuclear Information System (INIS)
Gamberini, G.; Ridolfi, G.; Zwirner, F.
1990-01-01
We present a critical reappraisal of radiative gauge symmetry breaking in the minimal supersymmetric standard model. We show that a naive use of the renormalization group improved tree-level potential can lead to incorrect conclusions. We specify the conditions under which the above method gives reliable results, by performing a comparison with the results obtained from the full one-loop potential. We also point out how the stability constraint and the conditions for the absence of charge- and colour-breaking minima should be applied. Finally, we comment on the uncertainties affecting the model predictions for physical observables, in particular for the top quark mass. (orig.)
SU(3) flavour symmetry breaking and charmed states
Energy Technology Data Exchange (ETDEWEB)
Horsley, R. [Edinburgh Univ. (United Kingdom). School of Physics and Astronomy; Najjar, J. [Regensburg Univ. (Germany). Institut fuer Theoretische Physik; Nakamura, Y. [RIKEN Advanced Institute for Computational Science, Hyogo (Japan); Perlt, H.; Schiller, A. [Leipzig Univ. (Germany). Inst. fuer Theoretische Physik; Pleiter, D. [Forschungszentrum Juelich GmbH (Germany). Juelich Supercomputing Centre (JSC); Regensburg Univ. (Germany). Institut fuer Theoretische Physik; Rakow, P.E.L. [Liverpool Univ. (United Kingdom). Theoretical Physics Div.; Schierholz, G. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Stueben, H. [Hamburg Univ. (Germany). Regionales Rechenzentrum; Zanotti, J.M. [Adelaide Univ. (Australia). CSSM, School of Chemistry and Physics; Collaboration: QCDSF-UKQCD Collaborations
2013-11-15
By extending the SU(3) flavour symmetry breaking expansion from up, down and strange sea quark masses to partially quenched valence quark masses we propose a method to determine charmed quark hadron masses including possible QCD isospin breaking effects. Initial results for some open charmed pseudoscalar meson states and singly and doubly charmed baryon states are encouraging and demonstrate the potential of the procedure. Essential for the method is the determination of the scale using singlet quantities, and to this end we also give here a preliminary estimation of the recently introduced Wilson flow scales.
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.
Chiral symmetry breaking is permitted in supersymmetric QED
International Nuclear Information System (INIS)
Walker, M.
2000-01-01
Full text: A chirally symmetric theory will generally have a chirally symmetric and a chirally asymmetric solution for the dressed fermionic propagator. It has been claimed that no chirally asymmetric solution for the fermionic propagator exists in supersymmetric QED. This result in the superfield formalism uses a gauge dependent argument whose validity has since been questioned. We present an analogous analysis using the component formalism which demonstrates that chiral symmetry breaking is permitted in this theory. We open the presentation with a brief introduction to supersymmetry, supersymmetric QED, and the superfield formalism. We describe chiral symmetry breaking and the Dyson-Schwinger equation used to analyse it. The derivation of the erroneous theorem claiming the lack of an a chiral propagator is outlined and its flaws discussed. We finish with the equivalent derivation in component fields and our contradictory result
Radiative breaking scenario for the GUT gauge symmetry
International Nuclear Information System (INIS)
Fukuyama, T.; Kikuchi, T.
2006-01-01
The origin of the grand unified theory (GUT) scale from the top-down perspective is explored. The GUT gauge symmetry is broken by the renormalization group effects, which is an extension of the radiative electroweak symmetry breaking scenario to the GUT models. That is, in the same way as the origin of the electroweak scale, the GUT scale is generated from the Planck scale through the radiative corrections to the soft supersymmetry breaking mass parameters. This mechanism is applied to a perturbative SO(10) GUT model, recently proposed by us. In the SO(10) model, the relation between the GUT scale and the Planck scale can naturally be realized by using order-one coupling constants. (orig.)
Stochastic recruitment leads to symmetry breaking in foraging populations
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.
Probing electroweak symmetry breaking at multi-TeV colliders
International Nuclear Information System (INIS)
Chanowitz, M.S.
1987-01-01
Low energy theorems are derived for scattering of longitudinally polarized W and Z's, providing the basis for an estimate of the observable signal if electroweak symmetry breaking is due to new physics at the TeV scale. A pp collider with L, √s = 40 TeV, 10 33 cm. -2 s -1 is just sufficient to observe the signal while pp colliders with 40, 10 32 or 20, 10 33 are not. A collider that is sensitive to the TeV-scale signal provides valuable information about symmetry breaking whether the masses of the associated new particles are below, within, or above the 1-2 TeV region. 6 refs., 6 figs., 2 tabs
Inflation and cosmic strings in models with dynamical symmetry breaking
International Nuclear Information System (INIS)
Matheson, A.M.; Brandenberger, R.H.
1989-01-01
We derive the effective action for the composite field which in dynamical symmetry breaking plays the role of the Higgs field. We show that this effective action does not give rise to inflation. It is, however, possible to obtain topological defects such as cosmic strings. There will be fermionic zero modes trapped on the strings, and the strings will therefore be superconducting in a generalized sense. (orig.)
Chiral symmetry breaking in gauge theories from Reggeon diagram analysis
International Nuclear Information System (INIS)
White, A.R.
1991-01-01
It is argued that reggeon diagrams can be used to study dynamical properties of gauge theories containing a large number of massless fermions. SU(2) gauge theory is studied in detail and it is argued that there is a high energy solution which is analogous to the solution of the massless Schwinger model. A generalized winding-number condensate produces the massless pseudoscalar spectrum associated with chiral symmetry breaking and a ''trivial'' S-Matrix
On the large-N dynamics of gauge symmetry breaking
International Nuclear Information System (INIS)
Karchev, N.I.
1983-07-01
We consider a Gsub(W)xUsub(TC)(N) gauge theory. A method of colour singlet bilocal collective coordinates is proposed to show, large-N colour dynamics is responsible for the Gsub(W) gauge symmetry breaking if the large-N Schwinger-Dyson equation admits anomalous solutions. The dynamically generated mass matrix is computed through these solutions. The technicolour model is discussed. (author)
Noncritical quadrature squeezing through spontaneous polarization symmetry breaking
Garcia-Ferrer, Ferran V.; Navarrete-Benlloch, Carlos; de Valcárcel, Germán J.; Roldán, Eugenio
2010-01-01
We discuss the possibility of generating noncritical quadrature squeezing by spontaneous polarization symmetry breaking. We consider first type-II frequency-degenerate optical parametric oscillators, but discard them for a number of reasons. Then we propose a four-wave mixing cavity in which the polarization of the output mode is always linear but has an arbitrary orientation. We show that in such a cavity complete noise suppression in a quadrature of the output field occurs, irrespective of ...
Noncritical quadrature squeezing through spontaneous polarization symmetry breaking.
Garcia-Ferrer, Ferran V; Navarrete-Benlloch, Carlos; de Valcárcel, Germán J; Roldán, Eugenio
2010-07-01
We discuss the possibility of generating noncritical quadrature squeezing by spontaneous polarization symmetry breaking. We first consider Type II frequency-degenerate optical parametric oscillators but discard them for a number of reasons. Then we propose a four-wave-mixing cavity, in which the polarization of the output mode is always linear but has an arbitrary orientation. We show that in such a cavity, complete noise suppression in a quadrature of the output field occurs, irrespective of the parameter values.
Canonical forms of tensor representations and spontaneous symmetry breaking
International Nuclear Information System (INIS)
Cummins, C.J.
1986-01-01
An algorithm for constructing canonical forms for any tensor representation of the classical compact Lie groups is given. This method is used to find a complete list of the symmetry breaking patterns produced by Higgs fields in the third-rank antisymmetric representations of U(n), SU(n) and SO(n) for n<=7. A simple canonical form is also given for kth-rank symmetric tensor representations. (author)
e +e- modes and U(1) spontaneous chiral symmetry breaking
International Nuclear Information System (INIS)
Steininger, K.
1992-01-01
In this paper, motivated by evidence for a chiral phase transition in strong coupling lattice QED, the authors calculate the two-particle spectrum of the broken QED phase. This is done in the framework of a Nambu and Jona-Lasinio model with U(1) symmetry including chiral symmetry and symmetry breaking properties of QED. The second order chiral phase transition behavior in our model and in lattice QED are in excellent agreement. The authors then present a detailed analysis of the spectra of the e + e - modes in the broken phase. The authors examine whether these modes have any possible relationship to the narrow e + e - resonances found in soft heavy ion collisions at GSL. The authors' answer is negative
Quasiaverages, symmetry breaking and irreducible Green functions method
Directory of Open Access Journals (Sweden)
A.L.Kuzemsky
2010-01-01
Full Text Available The development and applications of the method of quasiaverages to quantum statistical physics and to quantum solid state theory and, in particular, to quantum theory of magnetism, were considered. It was shown that the role of symmetry (and the breaking of symmetries in combination with the degeneracy of the system was reanalyzed and essentially clarified within the framework of the method of quasiaverages. The problem of finding the ferromagnetic, antiferromagnetic and superconducting "symmetry broken" solutions of the correlated lattice fermion models was discussed within the irreducible Green functions method. A unified scheme for the construction of generalized mean fields (elastic scattering corrections and self-energy (inelastic scattering in terms of the equations of motion and Dyson equation was generalized in order to include the "source fields". This approach complements previous studies of microscopic theory of antiferromagnetism and clarifies the concepts of Neel sublattices for localized and itinerant antiferromagnetism and "spin-aligning fields" of correlated lattice fermions.
Radiative gauge symmetry breaking in supersymmetric flipped SU(5)
Energy Technology Data Exchange (ETDEWEB)
Drees, M.
1988-05-19
The radiative breaking of the SU(5)xU(1) symmetry in the flipped SU(5) model recently proposed by Antoniadis et al. is studied using renormalization group techniques. It is shown that gaugino masses can only be the dominant source of supersymmetry breaking at the Planck scale if the U(1) gaugino mass M/sub 1/ is at least 10 times larger than the SU(5) gaugino mass M/sub 5/. If M/sub 1/ approx. = M/sub 5/ at the Planck scale, non-vanishing trilinear soft breaking terms ('A-terms') are needed already at the Planck scale. In both cases consequences for the sparticle spectrum at the weak scale are discussed.
EXECUTIVE SUMMARY OF THE SNOWMASS 2001 WORKING GROUP : ELECTROWEAK SYMMETRY BREAKING
International Nuclear Information System (INIS)
CARENA, M.; GERDES, D.W.; HABER, H.E.; TURCOT, A.S.; ZERWAS, P.M.
2001-01-01
In this summary report of the 2001 Snowmass Electroweak Symmetry Breaking Working Group, the main candidates for theories of electroweak symmetry breaking are surveyed, and the criteria for distinguishing among the different approaches are discussed. The potential for observing electroweak symmetry breaking phenomena at the upgraded Tevatron and the LHC is described. We emphasize the importance of a high-luminosity e + e - linear collider for precision measurements to clarify the underlying electroweak symmetry breaking dynamics. Finally, we note the possible roles of the μ + μ - collider and VLHC for further elucidating the physics of electroweak symmetry breaking
Nonperturbative calculation of symmetry breaking in quantum field theory
Bender, Carl M.; Milton, Kimball A.
1996-01-01
A new version of the delta expansion is presented, which, unlike the conventional delta expansion, can be used to do nonperturbative calculations in a self-interacting scalar quantum field theory having broken symmetry. We calculate the expectation value of the scalar field to first order in delta, where delta is a measure of the degree of nonlinearity in the interaction term.
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.
Symmetry breaking and generational mixing in top-color-assisted technicolor
International Nuclear Information System (INIS)
Lane, K.
1996-01-01
Top-color-assisted technicolor provides a dynanamical explanation for electroweak and flavor symmetry breaking and for the large mass of the top quark without unnatural fine-tuning. A major challenge is to generate the observed mixing between heavy and light generations while breaking the strong top-color interactions near 1 TeV. I argue that these phenomena, as well as electroweak symmetry breaking, are intimately connected and I present a scenario for them based on nontrivial patterns of technifermion condensation. I also exhibit a class of models realizing this scenario. This picture leads to a rich phenomenology, especially in hadron and lepton collider experiments in the few hundred GeV to few TeV region and in precision electroweak tests at the Z 0 , atomic parity violation, and polarized Mo/ller scattering. copyright 1996 The American Physical Society
Spontaneous symmetry breaking in curved space-time
International Nuclear Information System (INIS)
Toms, D.J.
1982-01-01
An approach dealing with some of the complications which arise when studying spontaneous symmetry breaking beyond the tree-graph level in situations where the effective potential may not be used is discussed. These situations include quantum field theory on general curved backgrounds or in flat space-times with non-trivial topologies. Examples discussed are a twisted scalar field in S 1 xR 3 and instabilities in an expanding universe. From these it is seen that the topology and curvature of a space-time may affect the stability of the vacuum state. There can be critical length scales or times beyond which symmetries may be broken or restored in certain cases. These features are not present in Minkowski space-time and so would not show up in the usual types of early universe calculations. (U.K.)
Symmetry breaking in the double-well hermitian matrix models
International Nuclear Information System (INIS)
Brower, R.C.; Deo, N.; Jain, S.; Tan, C.I.
1993-01-01
We study symmetry breaking in Z 2 symmetric large N matrix models. In the planar approximation for both the symmetric double-well φ 4 model and the symmetric Penner model, we find there is an infinite family of broken symmetry solutions characterized by different sets of recursion coefficients R n and S n that all lead to identical free energies and eigenvalue densities. These solutions can be parameterized by an arbitrary angle θ(x), for each value of x=n/N 4 theory the double scaling string equations are parameterized by a conserved angular momentum parameter in the range 0≤l<∞ and a single arbitrary U(1) phase angle. (orig.)
Symmetry breaking in the double-well hermitian matrix models
Brower, R C; Jain, S; Tan, C I; Brower, Richard C.; Deo, Nevidita; Jain, Sanjay; Tan, Chung-I
1993-01-01
We study symmetry breaking in $Z_2$ symmetric large $N$ matrix models. In the planar approximation for both the symmetric double-well $\\phi^4$ model and the symmetric Penner model, we find there is an infinite family of broken symmetry solutions characterized by different sets of recursion coefficients $R_n$ and $S_n$ that all lead to identical free energies and eigenvalue densities. These solutions can be parameterized by an arbitrary angle $\\theta(x)$, for each value of $x = n/N < 1$. In the double scaling limit, this class reduces to a smaller family of solutions with distinct free energies already at the torus level. For the double-well $\\phi^4$ theory the double scaling string equations are parameterized by a conserved angular momentum parameter in the range $0 \\le l < \\infty$ and a single arbitrary $U(1)$ phase angle.
Confinement and dynamical chiral symmetry breaking in QED3
International Nuclear Information System (INIS)
Bashir, A.; Raya, A.; Cloeet, I. C.; Roberts, C. D.
2008-01-01
We establish that QED3 can possess a critical number of flavors, N f c , associated with dynamical chiral symmetry breaking if, and only if, the fermion wave function renormalization and photon vacuum polarization are homogeneous functions at infrared momenta when the fermion mass function vanishes. The Ward identity entails that the fermion-photon vertex possesses the same property and ensures a simple relationship between the homogeneity degrees of each of these functions. Simple models for the photon vacuum polarization and fermion-photon vertex are used to illustrate these observations. The existence and value of N f c are contingent upon the precise form of the vertex but any discussion of gauge dependence is moot. We introduce an order parameter for confinement. Chiral symmetry restoration and deconfinement are coincident owing to an abrupt change in the analytic properties of the fermion propagator when a nonzero scalar self-energy becomes insupportable
Neutrino mass ordering and μ-τ reflection symmetry breaking
Xing, Zhi-zhong; Zhu, Jing-yu
2017-12-01
If the neutrino mass spectrum turns out to be m 3case the columns of the 3×3 lepton flavor mixing matrix U should be reordered accordingly, and the resulting pattern U‧ may involve one or two large mixing angles in the standard parametrization or its variations. Since the Majorana neutrino mass matrix remains unchanged in such a mass relabeling, a possible μ-τ reflection symmetry is respected in this connection and its breaking effects are model-independently constrained at the 3σ level by using current experimental data. Supported by National Natural Science Foundation of China (11135009, 11375207)
Analytical Formulae linking Quark Confinement and Chiral Symmetry Breaking
International Nuclear Information System (INIS)
Doi, Takahiro M.; Redlich, Krzysztof; Sasaki, Chihiro; Suganuma, Hideo
2016-01-01
Dirac spectrum representations of the Polyakov loop fluctuations are derived on the temporally odd-number lattice, where the temporal length is odd with the periodic boundary condition. We investigate the Polyakov loop fluctuations based on these analytical relations. It is semi-analytically and numerically found that the low-lying Dirac eigenmodes have little contribution to the Polyakov loop fluctuations, which are sensitive probe for the quark deconfinement. Our results suggest no direct one-to-one corresponding between quark confinement and chiral symmetry breaking in QCD
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.
Single-mode Laser by Parity-time Symmetry Breaking
2014-11-21
solenoid -like Pds5B that reside in direct proximity to Wapl and the Smc3-Scc1 in- teraction interface (fig. S13), implying that Wapl and Pds5 control the...accepted 26 September 2014 10.1126/science.1256904 REPORTS ◥ OPTICS Single-mode laser by parity-time symmetry breaking Liang Feng,1* Zi Jing Wong,1...Ren-Min Ma,1* Yuan Wang,1,2 Xiang Zhang1,2† Effective manipulation of cavity resonant modes is crucial for emission control in laser physics and
Colour-symmetry-breaking effects in hard processes
International Nuclear Information System (INIS)
Efremov, A.V.
1982-01-01
A possibility of colour symmetry U(1)xSU(3)sub(C) spontaneous breaking and integer-charged quarks is considered. It is argued that one-photon processes are sensitive only to the colour-averaged charges of quarks and gluons. The true charges can be observed in rigid processes involving at least two real photons. The available now experimental data on processes #betta#p → #betta#X, #betta##betta# → jet+jet are in better agreement with the integer-charges than with the standard QCD
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.
Schwinger Dyson equations: Dynamical chiral symmetry breaking and confinement
International Nuclear Information System (INIS)
Roberts, C.D.
1992-01-01
A representative but not exhaustive review of the Schwinger-Dyson equation (SDE) approach to the nonperturbative study of QCD is presented. The main focus is the SDE for the quark self energy but studies of the gluon propagator and quark-gluon vertex are also discussed insofar as they are important to the quark SDE. The scope of this article is the application of these equations to the study of dynamical chiral symmetry breaking, quark confinement and the phenomenology of the spectrum and dynamics of QCD
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.
Light-front realization of chiral symmetry breaking
International Nuclear Information System (INIS)
Itakura, Kazunori; Maedan, Shinji
2001-01-01
We discuss a description of chiral symmetry breaking in the light-front (LF) formalism. Based on careful analyses of several modes, we give clear answers to the following three fundamental questions: (i) What is the difference between the LF chiral transformation and the ordinary chiral transformation? (ii) How does a gap equation for the chiral condensate emerge? (iii) What is the consequence of the coexistence of a nonzero chiral condensate and the trivial Fock vacuum? The answer to Question (i) is given through a classical analysis of each model. Question (ii) is answered based on our recognition of the importance of characteristic constraints, such as the zero-mode and fermionic constraints. Question (iii) is intimately related to another important problem, reconciliation of the nonzero chiral condensate ≠ 0 and the invariance of the vacuum under the LF chiral transformation Q 5 LF | 0> = 0. This and Question (iii) are understood in terms of the modified chiral transformation laws of the dependent variables. The characteristic ways in which the chiral symmetry breaking is realized are that the chiral charge Q 5 LF is no longer conserved and that the transformation of the scalar and pseudoscalar fields is modified. We also discuss other outcomes, such as the light-cone wave function of the pseudoscalar meson in the Nambu-Jona-Lasinio model. (author)
Sakai-Sugimoto model, tachyon condensation and chiral symmetry breaking
International Nuclear Information System (INIS)
Dhar, Avinash; Nag, Partha
2008-01-01
We modify the Sakai-Sugimoto model of chiral symmetry breaking to take into account the open string tachyon which stretches between the flavour D8-branes and D8-bar-branes. There are several reasons of consistency for doing this: (i) Even if it might be reasonable to ignore the tachyon in the ultraviolet where the flavour branes and antibranes are well separated and the tachyon is small, it is likely to condense and acquire large values in the infrared where the branes meet. This takes the system far away from the perturbatively stable minimum of the Sakai-Sugimoto model; (ii) The bifundamental coupling of the tachyon to fermions of opposite chirality makes it a suitable candidate for the quark mass and chiral condensate parameters. We show that the modified Sakai-Sugimoto model with the tachyon present has a classical solution satisfying all the desired consistency properties. In this solution chiral symmetry breaking coincides with tachyon condensation. We identify the parameters corresponding to the quark mass and the chiral condensate and also briefly discuss the mesonic spectra
Higgsless theory of electroweak symmetry breaking from warped space
International Nuclear Information System (INIS)
Nomura, Yasunori
2003-01-01
We study a theory of electroweak symmetry breaking without a Higgs boson, recently suggested by Csaki et al. The theory is formulated in 5D warped space with the gauge bosons and matter fields propagating in the bulk. In the 4D dual picture, the theory appears as the standard model without a Higgs field, but with an extra gauge group G which becomes strong at the TeV scale. The strong dynamics of G breaks the electroweak symmetry, giving the masses for the W and Z bosons and the quarks and leptons. We study corrections in 5D which are logarithmically enhanced by the large mass ratio between the Planck and weak scales, and show that they do not destroy the structure of the electroweak gauge sector at the leading order. We introduce a new parameter, the ratio between the two bulk gauge couplings, into the theory and find that it allows us to control the scale of new physics. We also present a potentially realistic theory accommodating quarks and leptons and discuss its implications, including the violation of universality in the W and Z boson couplings to matter and the spectrum of the Kaluza-Klein excitations of the gauge bosons. The theory reproduces many successful features of the standard model, although some cancellations may still be needed to satisfy constraints from the precision electroweak data. (author)
International Nuclear Information System (INIS)
Oppermann, R.; Rosenow, B.
1997-10-01
We report large effects of Parisi replica permutation symmetry breaking (RPSB) on elementary excitations of fermionic systems with frustrated magnetic interactions. The electronic density of states is obtained exactly in the zero temperature limit for (K = 1)- step RPSB together with relations for arbitrary breaking K, which lead to a new fermionic and dynamical Parisi solution at K = ∞. The Ward identity for charge conservation indicates RPSB-effects on the conductivity in metallic quantum spin glasses. This implies that RPSB is essential for any fermionic system showing spin glass sections within its phase diagram. An astonishing similarity with a neural network problem is also observed. (author)
Stock market speculation: Spontaneous symmetry breaking of economic valuation
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.
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
Supersymmetry in a sector of Higgsless electroweak symmetry breaking
International Nuclear Information System (INIS)
Knochel, Alexander Karl
2009-01-01
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 χ + ∼100.. 110 GeV, the dark matter relic density points to LSP masses of around m χ ∼90 GeV. At the LHC, the standard particle content of our
Instabilities of the chiral-symmetry-breaking ground state in a truncation-free expansion
International Nuclear Information System (INIS)
Rembiesa, P.
1988-01-01
We use the composite-field effective-action method to examine the stability of the chiral-symmetry-breaking vacua in a QED-like model of interacting fermion fields. Unlike most of the existing approaches, ours does not rely on the truncated Baker-Johnson-Willey expansion. Instead, we break the hierarchy of the Dyson-Schwinger equations by the requirement that the vertex function is dominated by the contributions from the vicinity of the mass shell of the exchanged gluon and that it explicitly satisfies the Ward identity. The composite-field effective potential is then expanded in terms of the eigenfunctions of the Bethe-Salpeter equation. The signature of the second derivatives of the effective potential shows that the broken-symmetry vacua are unstable
A Clifford algebra approach to chiral symmetry breaking and fermion mass hierarchies
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.
Charged tensor matter fields and Lorentz symmetry violation via spontaneous symmetry breaking
International Nuclear Information System (INIS)
Colatto, L.P.; Penna, A.L.A.; Santos, W.C.
2003-10-01
We consider a model with a charged vector field along with a Cremmer-Scherk-Kalb-Ramond (CSKR) matter field coupled to a U(1) gauge potential. We obtain a natural Lorentz symmetry violation due to the local U(1) spontaneous symmetry breaking mechanism triggered by the imaginary part of the vector matter. The choice of the unitary gauge leads to the decoupling of the gauge-Kr sector from the Higgs-Kr sector. The excitation spectrum is carefully analyzed and the physical modes are identified. We propose an identification of the neutral massive spin-1 Higgs-like field with the massive Z' boson of the so-called mirror matter models. (author)
International Nuclear Information System (INIS)
Capri, Marcio; Justo, Igor; Guimaraes, Marcelo; Sorella, Silvio; Dudal, David; Palhares, Leticia
2013-01-01
Full text: In recent years much attention has been devoted to the study of the issue of the Gribov copies and of its relevance for confinement in Yang-Mills theories. The existence of the Gribov copies is a general feature of the gauge-fixing quantization procedure, being related to the impossibility of finding a local gauge condition which picks up only one gauge configuration for each gauge orbit. As it has been shown by Gribov and Zwanziger, a partial solution of the Gribov problem in the Landau gauge can be achieved by restricting the domain of integration in the functional Euclidean integral to the first Gribov horizon. Among the various open aspects of the Gribov-Zwanziger framework, the issue of the BRST symmetry is a source of continuous investigations. In a recent work, we have been able to obtain an equivalent formulation of the Gribov-Zwanziger action which displays an exact BRST symmetry which turns out to be spontaneously broken by the restriction of the domain of integration to the Gribov horizon. In particular, the BRST operator retains the important property of being nilpotent. Moreover, it has also been shown that the Goldstone mode associated to the spontaneous breaking of the BRST symmetry is completely decoupled. The aim of the present work is that of fills up a gap not addressed in the previous work, namely, the renormalizability to all orders of the spontaneous symmetry breaking formulation of the Gribov-Zwanziger theory. As we shall see, the action obtained enjoys a large set of Ward identities which enables to prove that it is, in fact, multiplicatively renormalizable to all orders. (author)
Magnetic Catalysis of Chiral Symmetry Breaking: A Holographic Prospective
International Nuclear Information System (INIS)
Filev, V.; Rashkov, R.; Rashkov, R.
2010-01-01
We review a recent investigation of the effect of magnetic catalysis of mass generation in holographic Yang-Mills theories. We aim at a self-contained and pedagogical form of the review. We provide a brief field theory background and review the basics of holographic flavordynamics. The main part of the paper investigates the influence of external magnetic field to holographic gauge theories dual to the D3/D5- and D3/D7-brane intersections. Among the observed phenomena are the spontaneous breaking of a global internal symmetry, Zeeman splitting of the energy levels, and the existence of pseudo, Goldstone modes. An analytic derivation of the Gell-Mann-Oaks-Renner relation for the D3/D7 set up is reviewed. In the D3/D5 case, the pseudo-Goldstone modes satisfy nonrelativistic dispersion relation. The studies reviewed confirm the universal nature of the magnetic catalysis of mass generation.
Dynamical chiral symmetry breaking and pion decay constant
International Nuclear Information System (INIS)
Gogohia, V.Sh.; Kluge, Gy.
1991-08-01
Flavour non-singlet, chiral axial-vector Ward-Takahashi identity is investigated in the framework of dynamical chiral symmetry breaking. The use of the condition of stationarity for the bound-state amplitude is proposed in order to fully determine this quantity and the regular piece of the corresponding axial vertex. This makes it possible to express the pion decay constant in terms of the quark propagator variables only. An exact expression was found for the pion decay constant in current algebra and in Jackiw-Johnson representation as well. We also find a new expression for the pion decay constant in the Pagels-Stokar-Cornwall variables within the framework of Jackiw-Johnson representation. (author) 22 refs.; 2 figs
Where to Go: Breaking the Symmetry in Cell Motility
2016-01-01
Cell migration in the “correct” direction is pivotal for many biological processes. Although most work is devoted to its molecular mechanisms, the cell’s preference for one direction over others, thus overcoming intrinsic random motility, epitomizes a profound principle that underlies all complex systems: the choice of one axis, in structure or motion, from a uniform or symmetric set of options. Explaining directional motility by an external chemo-attractant gradient does not solve but only shifts the problem of causation: whence the gradient? A new study in PLOS Biology shows cell migration in a self-generated gradient, offering an opportunity to take a broader look at the old dualism of extrinsic instruction versus intrinsic symmetry-breaking in cell biology. PMID:27196433
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.
Second order optical nonlinearity in silicon by symmetry breaking
Energy Technology Data Exchange (ETDEWEB)
Cazzanelli, Massimo, E-mail: massimo.cazzanelli@unitn.it [Laboratorio IdEA, Dipartimento di Fisica, Università di Trento, via Sommarive, 14 Povo (Trento) (Italy); Schilling, Joerg, E-mail: joerg.schilling@physik.uni-halle.de [Centre for Innovation Competence SiLi-nano, Martin-Luther-University Halle-Wittenberg, Karl-Freiherr-von-Fritsch Str. 3, 06120 Halle (Germany)
2016-03-15
Although silicon does not possess a dipolar bulk second order nonlinear susceptibility due to its centro-symmetric crystal structure, in recent years several attempts were undertaken to create such a property in silicon. This review presents the different sources of a second order susceptibility (χ{sup (2)}) in silicon and the connected second order nonlinear effects which were investigated up to now. After an introduction, a theoretical overview discusses the second order nonlinearity in general and distinguishes between the dipolar contribution—which is usually dominating in non-centrosymmetric structures—and the quadrupolar contribution, which even exists in centro-symmetric materials. Afterwards, the classic work on second harmonic generation from silicon surfaces in reflection measurements is reviewed. Due to the abrupt symmetry breaking at surfaces and interfaces locally a dipolar second order susceptibility appears, resulting in, e.g., second harmonic generation. Since the bulk contribution is usually small, the study of this second harmonic signal allows a sensitive observation of the surface/interface conditions. The impact of covering films, strain, electric fields, and defect states at the interfaces was already investigated in this way. With the advent of silicon photonics and the search for ever faster electrooptic modulators, the interest turned to the creation of a dipolar bulk χ{sup (2)} in silicon. These efforts have been focussing on several experiments applying an inhomogeneous strain to the silicon lattice to break its centro-symmetry. Recent results suggesting the impact of electric fields which are exerted from fixed charges in adjacent covering layers are also included. After a subsequent summary on “competing” concepts using not Si but Si-related materials, the paper will end with some final conclusions, suggesting possible future research direction in this dynamically developing field.
Noncommutative gauge theory and symmetry breaking in matrix models
International Nuclear Information System (INIS)
Grosse, Harald; Steinacker, Harold; Lizzi, Fedele
2010-01-01
We show how the fields and particles of the standard model can be naturally realized in noncommutative gauge theory. Starting with a Yang-Mills matrix model in more than four dimensions, an SU(n) gauge theory on a Moyal-Weyl space arises with all matter and fields in the adjoint of the gauge group. We show how this gauge symmetry can be broken spontaneously down to SU(3) c xSU(2) L xU(1) Q [resp. SU(3) c xU(1) Q ], which couples appropriately to all fields in the standard model. An additional U(1) B gauge group arises which is anomalous at low energies, while the trace-U(1) sector is understood in terms of emergent gravity. A number of additional fields arise, which we assume to be massive, in a pattern that is reminiscent of supersymmetry. The symmetry breaking might arise via spontaneously generated fuzzy spheres, in which case the mechanism is similar to brane constructions in string theory.
Probing the two-scale-factor universality hypothesis by exact rotation symmetry-breaking mechanism
Energy Technology Data Exchange (ETDEWEB)
Neto, J.F.S.; Lima, K.A.L.; Carvalho, P.R.S. [Universidade Federal do Piaui, Departamento de Fisica, Teresina, PI (Brazil); Sena-Junior, M.I. [Universidade de Pernambuco, Escola Politecnica de Pernambuco, Recife, PE (Brazil); Universidade Federal de Alagoas, Instituto de Fisica, Maceio, AL (Brazil)
2017-12-15
We probe the two-scale-factor universality hypothesis by evaluating, firstly explicitly and analytically at the one-loop order, the loop quantum corrections to the amplitude ratios for O(N)λφ{sup 4} scalar field theories with rotation symmetry breaking in three distinct and independent methods in which the rotation symmetry-breaking mechanism is treated exactly. We show that the rotation symmetry-breaking amplitude ratios turn out to be identical in the three methods and equal to their respective rotation symmetry-breaking ones, although the amplitudes themselves, in general, depend on the method employed and on the rotation symmetry-breaking parameter. At the end, we show that all these results can be generalized, through an inductive process based on a general theorem emerging from the exact calculation, to any loop level and physically interpreted based on symmetry ideas. (orig.)
AdS Branes from Partial Breaking of Superconformal Symmetries
International Nuclear Information System (INIS)
Ivanov, E.A.
2005-01-01
It is shown how the static-gauge world-volume superfield actions of diverse superbranes on the AdS d+1 superbackgrounds can be systematically derived from nonlinear realizations of the appropriate AdS supersymmetries. The latter are treated as superconformal symmetries of flat Minkowski superspaces of the bosonic dimension d. Examples include the N = 1 AdS 4 supermembrane, which is associated with the 1/2 partial breaking of the OSp(1|4) supersymmetry down to the N = 1, d = 3 Poincare supersymmetry, and the T-duality related L3-brane on AdS 5 and scalar 3-brane on AdS 5 x S 1 , which are associated with two different patterns of 1/2 breaking of the SU(2, 2|1) supersymmetry. Another (closely related) topic is the AdS/CFT equivalence transformation. It maps the world-volume actions of the codimension-one AdS d+1 (super)branes onto the actions of the appropriate Minkowski (super)conformal field theories in the dimension d
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.)
On the Possible Links Between Electroweak Symmetry Breaking and Dark Matter
International Nuclear Information System (INIS)
Hambye, Thomas; Tytgat, Michel H. G.
2009-01-01
The mechanism behind electroweak symmetry breaking (EWSB) and the nature of dark matter (DM) are currently very important issues in particle physics. Usually, in most models, these two issues are not or poorly connected. However, since a natural dark matter candidate is a weakly interacting massive particle or WIMP, with mass around the electroweak scale, it is clearly of interest to investigate the possibility that DM and EWSB are closely related. In the context of a very simple extension of the Standard Model, the Inert Doublet Model, we show that dark matter could play a crucial role in the breaking of the electroweak symmetry. In this model, dark matter is the lightest component of an inert scalar doublet which can induce dynamically electroweak symmetry breaking at one loop level. Moreover, in a large fraction of the parameter space of this model, the mass of the dark matter particle is essentially determined by the electroweak scale, so that the fact that the WIMP DM mass is around the electroweak scale is not a coincidence.
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.
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.
WHY COLOR-FLAVOR LOCKING IS JUST LIKE CHIRAL SYMMETRY BREAKING
International Nuclear Information System (INIS)
PISARSKI, R.D.; RISCHKE, D.H.
2000-01-01
The authors review how a classification into representations of color and flavor can be used to understand the possible patterns of symmetry breaking for color superconductivity in dense quark matter. In particular, the authors show how for three flavors, color-flavor locking is precisely analogous to the usual pattern of chiral symmetry breaking in the QCD vacuum
No-go for tree-level R-symmetry breaking
Energy Technology Data Exchange (ETDEWEB)
Liu, Feihu [University of Electronic Science and Technology of China, School of Physical Electronics, Chengdu (China); Liu, Muyang [Sichuan University, Center for Theoretical Physics, College of Physical Science and Technology, Chengdu (China); Sun, Zheng [Sichuan University, Center for Theoretical Physics, College of Physical Science and Technology, Chengdu (China); Chinese Academy of Sciences, CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Beijing (China)
2017-11-15
We show that in gauge mediation models with tree-level R-symmetry breaking where supersymmetry and R-symmetries are broken by different fields, the gaugino mass either vanishes at one loop or finds a contribution from loop-level R-symmetry breaking. Thus tree-level R-symmetry breaking for phenomenology is either no-go or redundant in the simplest type of models. Including explicit messenger mass terms in the superpotential with a particular R-charge arrangement is helpful to bypass the no-go theorem, and the resulting gaugino mass is suppressed by the messenger mass scale. (orig.)
Symmetry breaking in small rotating clouds of trapped ultracold Bose atoms
International Nuclear Information System (INIS)
Dagnino, D.; Barberan, N.; Riera, A.; Osterloh, K.; Lewenstein, M.
2007-01-01
We study the signatures of rotational and phase symmetry breaking in small rotating clouds of trapped ultracold Bose atoms by looking at rigorously defined condensate wave function. Rotational symmetry breaking occurs in narrow frequency windows, where energy degeneracy between the lowest energy states of different total angular momentum takes place. This leads to a complex condensate wave function that exhibits vortices clearly seen as holes in the density, as well as characteristic local phase patterns, reflecting the appearance of vorticities. Phase symmetry (or gauge symmetry) breaking, on the other hand, is clearly manifested in the interference of two independent rotating clouds
Interplay between chiral symmetry breaking and color superconductivity in dense quark matter
International Nuclear Information System (INIS)
Kitazawa, Masakiyo
2003-01-01
We investigate the QCD phase diagram in finite temperature and density in a simple Nambu-Jona-Lasinio model with the vector interaction. It is shown that the repulsive density-density interaction coming from the vector term enhances competition between the chiral symmetry breaking (χSB) and color superconducting (CSC) phase transition: When the vector coupling is increased, the first order transition between the χSB and CSC phase becomes weaker, and the coexisting phase in which both the chiral and color-gauge symmetries are dynamically broken comes to exist in a wider region in the T-μ plane. We find that the critical line of the first order transition can have two endpoints for an intermediate range of the vector coupling. (author)
International Nuclear Information System (INIS)
Wang Dianfu
2008-01-01
In terms of the Nambu-Jona-Lasinio mechanism, dynamical breaking of gauge symmetry for the maximally generalized Yang-Mills model is investigated. The gauge symmetry behavior at finite temperature is also investigated and it is shown that the gauge symmetry broken dynamically at zero temperature can be restored at finite temperatures
Symmetry breaking in nematic liquid crystals: analogy with cosmology and magnetism.
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.
Vacuum solutions of a gravity model with vector-induced spontaneous Lorentz symmetry breaking
International Nuclear Information System (INIS)
Bertolami, O.; Paramos, J.
2005-01-01
We study the vacuum solutions of a gravity model where Lorentz symmetry is spontaneously broken once a vector field acquires a vacuum expectation value. Results are presented for the purely radial Lorentz symmetry breaking (LSB), radial/temporal LSB and axial/temporal LSB. The purely radial LSB result corresponds to new black hole solutions. When possible, parametrized post-Newtonian parameters are computed and observational boundaries used to constrain the Lorentz symmetry breaking scale
Supplies in gravitational dynamics and electroweak symmetry breaking
International Nuclear Information System (INIS)
Soldate, M.
1988-01-01
During the past few years, my research interests have centered on physics associated with the Planck and electroweak scales. In each instance there is a physical issue which has motivated my work. The first is the dynamical determination of the observed geometry of spacetime. Typically, in a theory of quantum gravity, the topology and long-distance geometry of spacetime are not fixed uniquely by the field equations. One would like to be able to determine them through a dynamical principle for predictive power. The matter is of particular relevance to superstring theories, as they are most simply formulated in 10-dimensional Minkowski space. The second topic is the origin of electroweak symmetry breaking (EWSB). My work here has tended to be more phenomenological; it appears unlikely that a complete understanding of the gauge hierarchy problem can be obtained without some experimental knowledge of particles rather directly related to EWSB. I feel that both of these issues are of broad interest. In this paper, I will describe my future research plans in these areas after motivating and summarizing my previous work on them. 22 refs
Symmetry breaking in SNS junctions: edge transport and field asymmetries
Suominen, Henri; Nichele, Fabrizio; Kjaergaard, Morten; Rasmussen, Asbjorn; Danon, Jeroen; Flensberg, Karsten; Levitov, Leonid; Shabani, Javad; Palmstrom, Chris; Marcus, Charles
We study magnetic diffraction patterns in a tunable superconductor-semiconductor-superconductor junction. By utilizing epitaxial growth of aluminum on InAs/InGaAs we obtain transparent junctions which display a conventional Fraunhofer pattern of the critical current as a function of applied perpendicular magnetic field, B⊥. By studying the angular dependence of the critical current with applied magnetic fields in the plane of the junction we find a striking anisotropy. We attribute this effect to dephasing of Andreev states in the bulk of the junction, leading to SQUID like behavior when the magnetic field is applied parallel to current flow. Furthermore, in the presence of both in-plane and perpendicular fields, asymmetries in +/-B⊥ are observed. We suggest possible origins and discuss the role of spin-orbit and Zeeman physics together with a background disorder potential breaking spatial symmetries of the junction. Research supported by Microsoft Project Q, the Danish National Research Foundation and the NSF through the National Nanotechnology Infrastructure Network.
Vacuum decay in theories with symmetry breaking by radiative corrections
International Nuclear Information System (INIS)
Weinberg, E.J.
1993-01-01
The standard bounce formalism for calculating the decay rate of a metastable vacuum cannot be applied to theories in which the symmetry breaking is due to radiative corrections, because in such theories the tree-level action has no bounce solutions. In this paper I derive a modified formalism to deal with such cases. As in the usual case, the bubble nucleation rate may be written in the form Ae -B . To leading approximation, B is the bounce action obtained by replacing the tree-level potential by the leading one-loop approximation to the effective potential, in agreement with the generally adopted ad hoc remedy. The next correction to B (which is proportional to an inverse power of a small coupling) is given in terms of the next-to-leading term in the effective potential and the leading correction to the two-derivative term in the effective action. The corrections beyond these (which may be included in the prefactor) do not have simple expressions in terms of the effective potential and the other functions in the effective action. In particular, the scalar-loop terms which give an imaginary part to the effective potential do not explicitly appear; the corresponding effects are included in a functional determinant which gives a manifestly real result for the nucleation rate
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 Ãvora, 7000-671 Ãvora, 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.
Chiral-symmetry breaking and confinement in Minkowski space
International Nuclear Information System (INIS)
Biernat, Elmar P.; Peña, M. T.; Ribeiro, J. E.; Stadler, Alfred; Gross, Franz
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
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.
Graphene symmetry-breaking with molecular adsorbates: modeling and experiment
Groce, M. A.; Hawkins, M. K.; Wang, Y. L.; Cullen, W. G.; Einstein, T. L.
2012-02-01
Graphene's structure and electronic properties provide a framework for understanding molecule-substrate interactions and developing techniques for band gap engineering. Controlled deposition of molecular adsorbates can create superlattices which break the degeneracy of graphene's two-atom unit cell, opening a band gap. We simulate scanning tunneling microscopy and spectroscopy measurements for a variety of organic molecule/graphene systems, including pyridine, trimesic acid, and isonicotinic acid, based on density functional theory calculations using VASP. We also compare our simulations to ultra-high vacuum STM and STS results.
Contact interactions, stress and material symmetry
Directory of Open Access Journals (Sweden)
Podio-Guidugli P.
2002-01-01
Full Text Available An argument is given intimating that, for nonsimple materials, the concepts of contact interaction and material symmetry, as well as the bridging concept of stress, should be carefully revised and generalized. .
Recent progress in understanding gauge topology, confinement and chiral symmetry breaking
Energy Technology Data Exchange (ETDEWEB)
Larsen, Rasmus, E-mail: rasmus.n.larsen@stonybrook.edu; Shuryak, Edward
2016-12-15
A model of interacting instanton-dyons as the dominant degrees of freedom was used to discuss confinement and chiral symmetry breaking in SU(2). The case without fermions and with two flavors of fermions was discussed. Numerical results show that within this model, both with and without fermions, confinement is induced by the repulsion between dyons of same type, as the density of dyons increase at lower temperature. With fermions, the result of confinement at lower temperature, combined with the increased density made the effective distance between fermionic zero-modes smaller, thus inducing a non-zero chiral condensate, obtained by fitting to a eigenvalue density formula from random matrix theory.
Charge symmetry breaking nuclear forces and the properties of nuclear matter
International Nuclear Information System (INIS)
Haensel, P.
1977-01-01
The charge symmetry breaking (CSB) component of the nuclear forces yields the charge asymmetric term Esub(a)(N-Z)/A in the nuclear binding energy of nuclear matter. Calculation performed with several models of the CSB nuclear forces, and accounting for the strong short-range two-body correlations, gives Esub(a) approximately -0.2 MeV at the normal nuclear density. The charge asymmetry of the effective nucleon-nucleon interaction is determined primarily by the CSB nuclear forces at the neutron excess, observed in finite nuclei. The exclusion principle and dispersion (self-consistency) effects of the nuclear medium decrease this charge asymmetry. (author)
Reformulation od spontaneous symmetry breaking and the Weinberg-Salam model
International Nuclear Information System (INIS)
Rawat, A.S.; Rawat, S.; Negi, O.P.S.
1999-01-01
Spontaneous symmetry breaking and the Weinberg-Salam model have been reformulated in terms of quaternion-valued field variables. The quaternion-valued scalar Lagrangian reduces to four different field equations associated with the scalar quartet of a quaternion field φ φ 0 +e 1φ1 +e 2φ2 +e 3φ3 . It has been shown that the quaternion gauge group SO(4) is spontaneously broken to two gauge groups of SU(2) non Abelian gauge fields. The Weinberg-Salam model of electroweak interaction has been extensively studied to enlarge the gauge group structure SU(2) L xSU(2) R xU(1)
Symmetry-breaking solutions of the Hubbard model
International Nuclear Information System (INIS)
Kuzemsky, A.L.; )
1998-10-01
The problem of finding the ferromagnetic and antiferromagnetic ''broken symmetry'' solutions of the correlated lattice fermion models beyond the mean-field approximation has been investigated. The calculation of the quasiparticle excitation spectrum with damping for the single- and multi-orbital Hubbard model has been performed in the framework of the equation-of-motion method for two-time temperature Green's Functions within a non-perturbative approach. A unified scheme for the construction of Generalised Mean Fields (elastic scattering corrections) and self-energy (inelastic scattering) in terms of Dyson equation has been generalised in order to include the presence of the ''source fields''. The damping of quasiparticles, which reflects the interaction of the single-particle and collective degrees of freedom has been calculated. The ''broken symmetry'' dynamical solutions of the Hubbard model, which correspond to various types of itinerant antiferromagnetism have been discussed. This approach complements previous studies and clarifies the nature of the concepts of itinerant antiferromagnetism and ''spin-aligning field'' of correlated lattice fermions. (author)
Particle-Hole Symmetry Breaking in the Pseudogap State of Bi2201
Energy Technology Data Exchange (ETDEWEB)
Hashimoto, M.; /SIMES, Stanford /Stanford U., Geballe Lab. /LBNL, ALS; He, R.-H.; /aff SIMES, Stanford /Stanford U., Geballe Lab.; Tanaka, K.; /aff SIMES, Stanford /Stanford U., Geballe Lab. /LBNL, ALS /Osaka U.; Testaud, J.P.; /SIMES, Stanford /Stanford U., Geballe Lab. /LBNL, ALS; Meevasana1, W.; Moore, R.G.; Lu, D.H.; /SIMES, Stanford /Stanford U., Geballe Lab.; Yao, H.; /SIMES, Stanford; Yoshida, Y.; Eisaki, H.; /AIST, Tsukuba; Devereaux, T.P.; /SIMES, Stanford /Stanford U., Geballe Lab.; Hussain, Z.; /LBNL, ALS; Shen, Z.-X.; /SIMES, Stanford /Stanford U., Geballe Lab.
2011-08-19
In conventional superconductors, a gap exists in the energy absorption spectrum only below the transition temperature (T{sub c}), corresponding to the energy price to pay for breaking a Cooper pair of electrons. In high-T{sub c} cuprate superconductors above T{sub c}, an energy gap called the pseudogap exists, and is controversially attributed either to pre-formed superconducting pairs, which would exhibit particle-hole symmetry, or to competing phases which would typically break it. Scanning tunnelling microscopy (STM) studies suggest that the pseudogap stems from lattice translational symmetry breaking and is associated with a different characteristic spectrum for adding or removing electrons (particle-hole asymmetry). However, no signature of either spatial or energy symmetry breaking of the pseudogap has previously been observed by angle-resolved photoemission spectroscopy (ARPES). Here we report ARPES data from Bi2201 which reveals both particle-hole symmetry breaking and dramatic spectral broadening indicative of spatial symmetry breaking without long range order, upon crossing through T* into the pseudogap state. This symmetry breaking is found in the dominant region of the momentum space for the pseudogap, around the so-called anti-node near the Brillouin zone boundary. Our finding supports the STM conclusion that the pseudogap state is a broken-symmetry state that is distinct from homogeneous superconductivity.
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.
Isospin-symmetry-breaking effects in A∼70 nuclei within beyond-mean-field approach
Energy Technology Data Exchange (ETDEWEB)
Petrovici, A.; Andrei, O. [National Institute for Physics and Nuclear Engineering, R-077125 Bucharest (Romania)
2015-02-24
Particular isospin-symmetry-breaking probes including Coulomb energy differences (CED), mirror energy differences (MED), and triplet energy differences (TED) manifest anomalies in the A∼70 isovector triplets of nuclei. The structure of proton-rich nuclei in the A∼70 mass region suggests shape coexistence and competition between pairing correlations in different channels. Recent results concerning the interplay between isospin-mixing and shape-coexistence effects on exotic phenomena in A∼70 nuclei obtained within the beyond-mean-field complex Excited Vampir variational model with symmetry projection before variation using a realistic effective interaction in a relatively large model space are presented. Excited Vampir predictions concerning the Gamow-Teller β decay to the odd-odd N=Z {sup 66}As and {sup 70}Br nuclei correlated with the pair structure analysis in the T=1 and T=0 channel of the involved wave functions are discussed.
Symmetry breaking, and the effect of matter density on neutrino oscillation
Mohseni Sadjadi, H.; Khosravi Karchi, A. P.
2018-04-01
A proposal for the neutrino mass, based on neutrino-scalar field interaction, is introduced. The scalar field is also non-minimally coupled to the Ricci scalar, and hence relates the neutrino mass to the matter density. In a dense region, the scalar field obeys the Z2 symmetry, and the neutrino is massless. In a dilute region, the Z2 symmetry breaks and neutrino acquires mass from the non-vanishing expectation value of the scalar field. We consider this scenario in the framework of a spherical dense object whose outside is a dilute region. In this background, we study the neutrino flavors oscillation, along with the consequences of the theory on oscillation length and MSW effect. This preliminary model may shed some lights on the existing anomalies within the neutrino data, concerning the different oscillating behavior of the neutrinos in regions with different densities.
Kink-induced symmetry breaking patterns in brane-world SU(3)3 trinification models
International Nuclear Information System (INIS)
Demaria, Alison; Volkas, Raymond R.
2005-01-01
The trinification grand unified theory (GUT) has gauge group SU(3) 3 and a discrete symmetry permuting the SU(3) factors. In common with other GUTs, the attractive nature of the fermionic multiplet assignments is obviated by the complicated multiparameter Higgs potential apparently needed for phenomenological reasons, and also by vacuum expectation value (VEV) hierarchies within a given multiplet. This motivates the rigorous consideration of Higgs potentials, symmetry breaking patterns, and alternative symmetry breaking mechanisms in models with this gauge group. Specifically, we study the recently proposed 'clash of symmetries' brane-world mechanism to see if it can help with the symmetry breaking conundrum. This requires a detailed analysis of Higgs potential global minima and kink or domain wall solutions interpolating between the disconnected global minima created through spontaneous discrete symmetry breaking. Sufficiently long-lived metastable kinks can also be considered. We develop what we think is an interesting, albeit speculative, brane-world scheme whereby the hierarchical symmetry breaking cascade, trinification to left-right symmetry to the standard model to color cross electromagnetism, may be induced without an initial hierarchy in vacuum expectation values. Another motivation for this paper is simply to continue the exploration of the rich class of kinks arising in models that are invariant under both discrete and continuous symmetries
Dynamics of symmetry breaking during quantum real-time evolution in a minimal model system.
Heyl, Markus; Vojta, Matthias
2014-10-31
One necessary criterion for the thermalization of a nonequilibrium quantum many-particle system is ergodicity. It is, however, not sufficient in cases where the asymptotic long-time state lies in a symmetry-broken phase but the initial state of nonequilibrium time evolution is fully symmetric with respect to this symmetry. In equilibrium, one particular symmetry-broken state is chosen as a result of an infinitesimal symmetry-breaking perturbation. From a dynamical point of view the question is: Can such an infinitesimal perturbation be sufficient for the system to establish a nonvanishing order during quantum real-time evolution? We study this question analytically for a minimal model system that can be associated with symmetry breaking, the ferromagnetic Kondo model. We show that after a quantum quench from a completely symmetric state the system is able to break its symmetry dynamically and discuss how these features can be observed experimentally.
The nucleon- nucleon interaction and symmetries
International Nuclear Information System (INIS)
Van Oers, W.T.H.
1992-11-01
With the advent of the possibility to study nucleon-nucleon scattering at medium energies, its extension to investigate fundamental symmetries was recognized early on. It was precisely the introduction of rotational invariance, parity conservation, time reversal invariance, and isotopic spin conversation that led to the description of the N - N scattering matrix in terms of five complex amplitudes: one set of five for proton-proton scattering and one set of five for neutron-proton scattering, or alternatively, one set for the isotopic spin state ι=ο and the other for the isotopic spin state ι=1. Clearly, if one or more of the above constraints are removed, there are additional amplitudes that need to be considered. To be meaningful, experiment requires observables that are particularly sensitive to the violation of a conservation law or symmetry principle. During the last decade a series of precision experiments has been performed to measure charge- symmetry breaking in n - p elastic scattering (corresponding to isotopic spin non-conservation), and to measure parity violation in p-p scattering. For a particle-anti-particle system,like the pp or λλ system one can raise the question of CP violation in a system other than the neutral kaon system may become possible in the near future through pp →λλ and pp→ ≡ ≡. A description is given of the ongoing efforts to measure charge symmetry breaking, parity violation and CP violation.(author). 42 refs., 6 figs
International Nuclear Information System (INIS)
Bertolami, Orfeu; Paramos, Jorge
2006-01-01
The vacuum solutions arising from a spontaneous breaking of Lorentz symmetry due to the acquisition of a vacuum expectation value by a vector field are derived. These include the purely radial Lorentz symmetry breaking (LSB), radial/temporal LSB and axial/temporal LSB scenarios. It is found that the purely radial LSB case gives rise to new black hole solutions. Whenever possible. Parametrized Post-Newtonian (PPN) parameters are computed and compared to observational bounds, in order to constrain the Lorentz symmetry breaking scale
A theoretical study of symmetry-breaking organic overlayers on single- and bi-layer graphene
Morales-Cifuentes, Josue; Einstein, T. L.
2013-03-01
An ``overlayer'' of molecules that breaks the AB symmetry of graphene can produce (modify) a band gap in single- (bi-) layer graphene.[2] Since the triangular shaped trimesic acid (TMA) molecule forms two familiar symmetry breaking configurations, we are motivated to model TMA physisorption on graphene surfaces in conjunction with experiments by Groce et al. at UMD. Using VASP, with ab initio van der Waals density functionals (vdW-DF), we simulate adsorption of TMA onto a graphene surface in several symmetry-breaking arrangements in order to predict/understand the effect of TMA adsorption on experimental observables. Supported by NSF-MRSEC Grant DMR 05-20471.
A Generalized Yang-Mills Model and Dynamical Breaking of Gauge Symmetry
International Nuclear Information System (INIS)
Wang Dianfu; Song Heshan
2005-01-01
A generalized Yang-Mills model, which contains, besides the vector part V μ , also a scalar part S, is constructed and the dynamical breaking of gauge symmetry in the model is also discussed. It is shown, in terms of Nambu-Jona-Lasinio (NJL) mechanism, that the gauge symmetry breaking can be realized dynamically in the generalized Yang-Mills model. The combination of the generalized Yang-Mills model and the NJL mechanism provides a way to overcome the difficulties related to the Higgs field and the Higgs mechanism in the usual spontaneous symmetry breaking theory.
Roles of dynamical symmetry breaking in driving oblate-prolate transitions of atomic clusters
International Nuclear Information System (INIS)
Oka, Yurie; Yanao, Tomohiro; Koon, Wang Sang
2015-01-01
This paper explores the driving mechanisms for structural transitions of atomic clusters between oblate and prolate isomers. We employ the hyperspherical coordinates to investigate structural dynamics of a seven-atom cluster at a coarse-grained level in terms of the dynamics of three gyration radii and three principal axes, which characterize overall mass distributions of the cluster. Dynamics of gyration radii is governed by two kinds of forces. One is the potential force originating from the interactions between atoms. The other is the dynamical forces called the internal centrifugal forces, which originate from twisting and shearing motions of the system. The internal centrifugal force arising from twisting motions has an effect of breaking the symmetry between two gyration radii. As a result, in an oblate isomer, activation of the internal centrifugal force that has the effect of breaking the symmetry between the two largest gyration radii is crucial in triggering structural transitions into prolate isomers. In a prolate isomer, on the other hand, activation of the internal centrifugal force that has the effect of breaking the symmetry between the two smallest gyration radii is crucial in triggering structural transitions into oblate isomers. Activation of a twisting motion that switches the movement patterns of three principal axes is also important for the onset of structural transitions between oblate and prolate isomers. Based on these trigger mechanisms, we finally show that selective activations of specific gyration radii and twisting motions, depending on the isomer of the cluster, can effectively induce structural transitions of the cluster. The results presented here could provide further insights into the control of molecular reactions
International Nuclear Information System (INIS)
Truong, T.N.
1981-01-01
It is shown that discrepancies between soft pion current algebra (or chiral symmetry) calculations in Kl 4 and experiments are mostly due to the square root threshold singularity of the pion-pion interaction. For the same reason, chiral symmetry breaking calculations of the scalar Kl 3 form factor cannot be extended to the threshold of tau → Kπν decay. (orig.)
Translational Symmetry Breaking and Gapping of Heavy-Quasiparticle Pocket in URu2Si2
Yoshida, Rikiya; Tsubota, Koji; Ishiga, Toshihiko; Sunagawa, Masanori; Sonoyama, Jyunki; Aoki, Dai; Flouquet, Jacques; Wakita, Takanori; Muraoka, Yuji; Yokoya, Takayoshi
2013-01-01
URu2Si2 is a uranium compound that exhibits a so-called ‘hidden-order’ transition at ~17.5 K. However, the order parameter of this second-order transition as well as many of its microscopic properties remain unclarified despite considerable research. One of the key questions in this regard concerns the type of spontaneous symmetry breaking occurring at the transition; although rotational symmetry breaking has been detected, it is not clear whether another type of symmetry breaking also occurs. Another key question concerns the property of Fermi-surface gapping in the momentum space. Here we address these key questions by a momentum-dependent observation of electronic states at the transition employing ultrahigh-resolution three-dimensional angle-resolved photoemission spectroscopy. Our results provide compelling evidence of the spontaneous breaking of the lattice's translational symmetry and particle-hole asymmetric gapping of a heavy quasiparticle pocket at the transition. PMID:24084937
Mode structure symmetry breaking of energetic particle driven beta-induced Alfvén eigenmode
Lu, Z. X.; Wang, X.; Lauber, Ph.; Zonca, F.
2018-01-01
The mode structure symmetry breaking of energetic particle driven Beta-induced Alfvén Eigenmode (BAE) is studied based on global theory and simulation. The weak coupling formula gives a reasonable estimate of the local eigenvalue compared with global hybrid simulation using XHMGC. The non-perturbative effect of energetic particles on global mode structure symmetry breaking in radial and parallel (along B) directions is demonstrated. With the contribution from energetic particles, two dimensional (radial and poloidal) BAE mode structures with symmetric/asymmetric tails are produced using an analytical model. It is demonstrated that the symmetry breaking in radial and parallel directions is intimately connected. The effects of mode structure symmetry breaking on nonlinear physics, energetic particle transport, and the possible insight for experimental studies are discussed.
Spontaneous chiral symmetry breaking and effective quark masses in quantum chromodynamics
International Nuclear Information System (INIS)
Miransky, V.A.
1982-01-01
The ultraviolet asymptotics of the dynamical effective quark mass is determined directly from the equation for the fermion mass function. The indications about the character of the dynamics of the spontaneous chiral symmetry breaking in QCD are obtained
Ten dimensional SO(10) G.U.T. models with dynamical symmetry breaking
International Nuclear Information System (INIS)
Hanlon, B.E.; Joshi, G.C.
1993-01-01
To date, considerations on SO (10) models within Coset Space Dimensional Reduction (CSDR) have been diagonalized to the standard model or rely upon imaginative applications of Wilson lines so as to avoid the problem of the nonexistence of an intermediate Higgs mechanism. However, there is an alternative approach involving four fermion condensates, breaking symmetries by a dynamical mechanism. Indeed, dynamical symmetry breaking has been the direction taken in some SU(5) models within this framework in order to avoid the problems of electroweak symmetry breaking at the compactification scale. This paper presents realistic models which utilize this mechanism. It is shown that the appropriate fermionic representations can emerge from CSDR and the construction of such condensates within the constraints of this scheme is presented. By introducing discrete symmetries onto the internal manifold a strong breaking of the SO(10) G.U.T. is produced and, more importantly, eliminate Higgs fields of geometrical origin. 31 refs
Spontaneous Symmetry Breaking and Nambu-Goldstone Bosons in Quantum Many-Body Systems
Czech Academy of Sciences Publication Activity Database
Brauner, Tomáš
2010-01-01
Roč. 2, č. 2 (2010), s. 609-657 ISSN 2073-8994 Institutional support: RVO:61389005 Keywords : spontaneous symmetry breaking * Nambu-Goldstone bosons * effective field theory Subject RIV: BE - Theoretical Physics
Comment to: "Particle-hole symmetry breaking in the pseudogap state of Bi2201"
Panas, Itai
2010-01-01
Shen et al. [1] recently reported on ARPES data from Pb-Bi2201 revealing both particle-hole symmetry breaking and pronounced spectral broadening, which they interpret to be indicative of spatial symmetry breaking without long-range order at the opening of the pseudogap. Here is demonstrated how their results could be interpreted to reflect static and dynamic inhomogeneous crystal fields causing inter-band transfer of holes upon cooling below T*. Possible relevance to formation of charge carri...
Aspects of Chiral Symmetry Breaking in Lattice QCD
Horkel, Derek P.
In this thesis we describe two studies concerting lattice quantum chromodynamics (LQCD): first, an analysis of the phase structure of Wilson and twisted-mass fermions with isospin breaking effects, second a computational study measuring non-perturbative Greens functions. We open with a brief overview of the formalism of QCD and LQCD, focusing on the aspects necessary for understanding how a lattice computation is performed and how discretization effects can be understood. Our work in Wilson and twisted-mass fermions investigates an increasingly relevant regime where lattice simulations are performed with quarks at or near their physical masses and both the mass difference of the up and down quarks and their differing electric charges are included. Our computation of a non-perturbative Greens functions on the lattice serves as a first attempt to validate recent work by Dine et. al. [24] in which they calculate Greens functions which vanish in perturbation theory, yet have a contribution from the one instanton background. In chapter 2, we determine the phase diagram and pion spectrum for Wilson and twisted-mass fermions in the presence of non-degeneracy between the up and down quark and discretization errors, using Wilson and twisted-mass chiral perturbation theory. We find that the CP-violating phase of the continuum theory (which occurs for sufficiently large non-degeneracy) is continuously connected to the Aoki phase of the lattice theory with degenerate quarks. We show that discretization effects can, in some cases, push simulations with physical masses closer to either the CP-violating phase or another phase not present in the continuum, so that at sufficiently large lattice spacings physical-point simulations could lie in one of these phases. In chapter 3, we extend the work in chapter 2 to include the effects of electromagnetism, so that it is applicable to recent simulations incorporating all sources of isospin breaking. For Wilson fermions, we find that the
Mirror Symmetry Breaking and Restoration: The Role of Noise and Chiral Bias
International Nuclear Information System (INIS)
Hochberg, David
2009-01-01
The nonequilibrium effective potential is computed for the Frank model of spontaneous mirror symmetry breaking (SMSB) in chemistry in which external noise is introduced to account for random environmental effects. When these fluctuations exceed a critical magnitude, mirror symmetry is restored. The competition between ambient noise and the chiral bias due to physical fields and polarized radiation can be explored with this potential.
Energy Technology Data Exchange (ETDEWEB)
Pique, C; Blanco, J A; Abad, E [Departamento de Fisica, Universidad de Oviedo, Campus de Viesques, E-33204 Gijon (Spain); Burriel, R; Artigas, M [Instituto de Ciencia de Materiales de Aragon (CSIC-Universidad de Zaragoza), E-50009 Zaragoza (Spain); Fernandez-RodrIguez, J [European Synchrotron Radiation Facility, BP 220, F-38043 Grenoble Cedex (France)], E-mail: pique@uniovi.es
2008-08-27
Using adiabatic calorimetry the heat capacity of a series of RFe{sub x}Mn{sub 12-x} (R = Gd, Tb and Dy) compounds has been measured from 3 to 350 K. The substitution of Fe for Mn in RFe{sub x}Mn{sub 12-x} influences both the magnetic interactions on the 3d sublattice and the magnetism of R (the Neel temperature doubles on going from x = 0 to 6 and the compounds become ferromagnetic for x = 8 with Curie temperatures of around 300 K). In pure TbMn{sub 12} the heat-capacity data shows a {lambda}-type anomaly associated with the independent cooperative magnetic ordering of the R sublattice ({approx}5 K), while the anomaly related to the Mn magnetic ordering ({approx}100 K) is rather smooth, as observed in other itinerant magnetic systems such as YMn{sub 12}. In contrast, the substitution of Fe for Mn leads, on the one hand, to a more localized magnetic behaviour of the 3d sublattice, and, on the other, to magnetic polarization effects between the 3d and 4f sublattices, together with the disappearance of the cooperative magnetic ordering of the R sublattice due to the breaking of the antiferromagnetic symmetry in the 3d sublattice. This is reflected in the heat-capacity curve through a smooth Schottky-like anomaly. In the case of Gd compounds the magnitude of the exchange molecular-field parameter has been deduced by fitting the magnetic contribution to the heat capacity within a simple mean-field model. From this analysis we found that this molecular field acting on the rare-earth site increases with the iron concentration, reaching values as large as 48 T for the concentration x = 6. A similar analysis of the heat capacity in the ordered phase on the Tb compounds also leads to an enhancement of the molecular field with increasing Fe content. These results allow checking the possible crystal-field parameters for these RFe{sub x}Mn{sub 12-x} compounds.
Zou, Li; Tian, Shou-Fu; Feng, Lian-Li
2017-12-01
In this paper, we consider the (2+1)-dimensional breaking soliton equation, which describes the interaction of a Riemann wave propagating along the y-axis with a long wave along the x-axis. By virtue of the truncated Painlevé expansion method, we obtain the nonlocal symmetry, Bäcklund transformation and Schwarzian form of the equation. Furthermore, by using the consistent Riccati expansion (CRE), we prove that the breaking soliton equation is solvable. Based on the consistent tan-function expansion, we explicitly derive the interaction solutions between solitary waves and cnoidal periodic waves.
Unified symmetry-breaking theory of Bose-Einstein condensation in superfluids
International Nuclear Information System (INIS)
Olinto, A.C.
1991-01-01
The usual symmetry-breaking procedures for Bose condensed systems, namely, the Bogoliubov prescription, the symmetry-breaking term added to the Hamiltonian, and the canonical shift transformation are unified into a single formalism. By taking into account the condensate reservoir as a source and sink of excited particles, exact Ward identities are solved in the shielded-potential approximation. A relationship between the condensate density n 0 and the superfluid density n S is obtained in closed form. It is shown that the Bogoliubov prescription yields n 0 congruent n S and nU 0 much-lt |μ|, where n is the total density, U 0 the interaction constant, and μ the chemical potential. On the other hand, for the canonical shift transformation one has n 0 much-lt n S and nU 0 much-gt |μ|. The latter, applied to superfluid 4 He at saturated vapor pressure, gives excellent agreement between theory and experiment, without any adjustable parameter. The condensate density turns out to be strongly dependent on pressure as observed experimentally. The formalism provides in a natural way a consistent description of Bose systems in arbitrary D-dimensional space
The nucleon- nucleon interaction and symmetries
Energy Technology Data Exchange (ETDEWEB)
Van Oers, W T.H.
1992-11-01
With the advent of the possibility to study nucleon-nucleon scattering at medium energies, its extension to investigate fundamental symmetries was recognized early on. It was precisely the introduction of rotational invariance, parity conservation, time reversal invariance, and isotopic spin conversation that led to the description of the N - N scattering matrix in terms of five complex amplitudes: one set of five for proton-proton scattering and one set of five for neutron-proton scattering, or alternatively, one set for the isotopic spin state {iota}={omicron} and the other for the isotopic spin state {iota}=1. Clearly, if one or more of the above constraints are removed, there are additional amplitudes that need to be considered. To be meaningful, experiment requires observables that are particularly sensitive to the violation of a conservation law or symmetry principle. During the last decade a series of precision experiments has been performed to measure charge- symmetry breaking in n - p elastic scattering (corresponding to isotopic spin non-conservation), and to measure parity violation in p-p scattering. For a particle-anti-particle system,like the pp or {lambda}{lambda} system one can raise the question of CP violation in a system other than the neutral kaon system may become possible in the near future through pp {yields}{lambda}{lambda} and pp{yields} {identical_to} {identical_to}. A description is given of the ongoing efforts to measure charge symmetry breaking, parity violation and CP violation.(author). 42 refs., 6 figs.
Supersymmetry and intermediate symmetry breaking in SO(10) superunification
International Nuclear Information System (INIS)
Asatryan, H.M.; Ioannisyan, A.N.
1985-01-01
A scheme of simultaneous breakdown of intermediate symmetry SO(10) → SU(3)sub(c) x U(1) x SU(2)sub(L) x SU(2)sub(R) and supersymmetry by means of a single scale parameter is suggested. This intermediate symmetry, which is preferable physically, owing to the broken supersymmetry has a minimum lying lower than SU(4) x SU(2)sub(L) x SU(2)sub(R). The intermediate symmetry is broken by the vacuum expectation value of the Higgs superfields. Owing to the quantum corrections the potential minimum turns out to correspond to breakdown of the intermediate symmetry up to the standard group SU(3)sub(c) x SU(2)sub(L) x U(1)sub(y). The value of the Weinberg angle is less than that in the supersymmetric SU(5) model and agrees with the experiment
Confinement, Chiral Symmetry Breaking and it's Restoration using Dual QCD Formalism
Directory of Open Access Journals (Sweden)
Punetha Garima
2018-01-01
Full Text Available Utilizing the dual QCD model in term of magnetic symmetry structure of non- Abelian gauge theories, the dynamical chiral-symmetry breaking using Schwinger-Dyson equation has been investigated. A close relation among the color confinement and chiralsymmetry breaking has been observed and demonstrated by computing dynamical parameters. The recovery of the chiral symmetry has also been discussed at finite temperature through the variation of quark mass function and quark condensate which gradually decreases with temperature and vanishes suddenly near the critical temperature.
Traces of Lorentz symmetry breaking in a hydrogen atom at ground state
Borges, L. H. C.; Barone, F. A.
2016-02-01
Some traces of a specific Lorentz symmetry breaking scenario in the ground state of the hydrogen atom are investigated. We use standard Rayleigh-Schrödinger perturbation theory in order to obtain the corrections to the ground state energy and the wave function. It is shown that an induced four-pole moment arises, due to the Lorentz symmetry breaking. The model considered is the one studied in Borges et al. (Eur Phys J C 74:2937, 2014), where the Lorentz symmetry is broken in the electromagnetic sector.
Traces of Lorentz symmetry breaking in a hydrogen atom at ground state
Energy Technology Data Exchange (ETDEWEB)
Borges, L.H.C. [Universidade Federal do ABC, Centro de Ciencias Naturais e Humanas, Santo Andre, SP (Brazil); Barone, F.A. [IFQ-Universidade Federal de Itajuba, Itajuba, MG (Brazil)
2016-02-15
Some traces of a specific Lorentz symmetry breaking scenario in the ground state of the hydrogen atom are investigated. We use standard Rayleigh-Schroedinger perturbation theory in order to obtain the corrections to the ground state energy and the wave function. It is shown that an induced four-pole moment arises, due to the Lorentz symmetry breaking. The model considered is the one studied in Borges et al. (Eur Phys J C 74:2937, 2014), where the Lorentz symmetry is broken in the electromagnetic sector. (orig.)
Traces of Lorentz symmetry breaking in a hydrogen atom at ground state
International Nuclear Information System (INIS)
Borges, L.H.C.; Barone, F.A.
2016-01-01
Some traces of a specific Lorentz symmetry breaking scenario in the ground state of the hydrogen atom are investigated. We use standard Rayleigh-Schroedinger perturbation theory in order to obtain the corrections to the ground state energy and the wave function. It is shown that an induced four-pole moment arises, due to the Lorentz symmetry breaking. The model considered is the one studied in Borges et al. (Eur Phys J C 74:2937, 2014), where the Lorentz symmetry is broken in the electromagnetic sector. (orig.)
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.
Electroweak symmetry breaking in the light of LHC
International Nuclear Information System (INIS)
Kubik, B.
2012-10-01
The extra-dimensional extensions of the Standard Model (SM) of particles are now in a very active epoch of development. The motivations of introducing extra dimensions are based on one hand on string theories that require the existence of new dimensions to be consistent. On the other hand such theories can potentially explain the hierarchy problem, number of fermion generations, proton stability and other enigmas of the Standard Model. The common feature of these models is that they provide a new neutral weakly interacting particle - perfect candidate to the Dark Matter (DM). Its stability is preserved by the so-called KK parity which prohibits the decays of the the lightest Kaluza-Klein particle (LKP) into SM particles. The geometry of the underlying space determines the particle spectrum of the model, thus the mass and the spin of the DM candidate, which in turn plays the key role in the phenomenological studies We present a model with two universal extra dimensions compactified on a real projective plane. This particular geometry is chosen because chiral fermions can be defined on such orbifold and the stability of the neutral dark matter candidate arise naturally from the intrinsic geometrical properties of the space without adding any new symmetries ad hoc. We present the particle spectrum at loop order up to the second level in Kaluza-Klein expansion. The particularity of the spectrum is that the mass splittings within each KK level are highly degenerated providing a very interesting potential signatures in the LHC. We study the dark matter phenomenology in our model and constrain the parameter space by comparing our results with WMAP (Wilkinson Microwave Anisotropy Probe) data and direct detection experiments. Using the obtained bounds we focus on the collider phenomenology of our model. (author)
Spontaneous symmetry breaking in ΡΤ symmetric systems with nonlinear damping
International Nuclear Information System (INIS)
Karthiga, S.; Chandrasekar, V.K.; Senthilvelan, M.; Lakshmanan, M.
2016-01-01
In this talk, we discuss the remarkable role of position dependent damping in determining the parametric regions of symmetry breaking in nonlinear ΡΤ -symmetric systems. We illustrate the nature of ΡΤ-symmetry preservation and breaking with reference to a remarkable integrable scalar nonlinear system. In the two dimensional cases of such position dependent damped systems, we unveil the existence of a class of novel bi-ΡΤ -symmetric systems which have two fold ΡΤ symmetries. We discuss the dynamics of these systems and show how symmetry breaking occurs, that is whether the symmetry breaking of the two ΡΤ symmetries occurs in pair or occurs one by one. The addition of linear damping in these nonlinearly damped systems induces competition between the two types of damping. This competition results in a ΡΤ phase transition in which the ΡΤ symmetry is broken for lower loss/gain strength and is restored by increasing the loss/gain strength. We also show that by properly designing the form of the position dependent damping, we can tailor the ΡΤ-symmetric regions of the system. (author)
Classification of a Supersolid: Trial Wavefunctions, Symmetry Breakings and Excitation Spectra
Chen, Yu; Ye, Jinwu; Tian, Guangshan
2012-11-01
A state of matter is characterized by its symmetry breaking and elementary excitations. A supersolid is a state which breaks both translational symmetry and internal U(1) symmetry. Here, we review some past and recent works in phenomenological Ginsburg-Landau theories, ground state trial wavefunctions and microscopic numerical calculations. We also write down a new effective supersolid Hamiltonian on a lattice. The eigenstates of the Hamiltonian contains both the ground state wavefunction and all the excited states (supersolidon) wavefunctions. We contrast various kinds of supersolids in both continuous systems and on lattices, both condensed matter and cold atom systems. We provide additional new insights in studying their order parameters, symmetry breaking patterns, the excitation spectra and detection methods.
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
Explicit chiral symmetry breaking in Gross-Neveu type models
International Nuclear Information System (INIS)
Boehmer, Christian
2011-01-01
This thesis is devoted to the study of a 1+1-dimensional, fermionic quantum field theory with Lagrangian L= anti ψiγ μ ∂ μ ψ-m 0 anti ψψ+(g 2 )/(2)(anti ψψ) 2 +(G 2 )/(2)(anti ψiγ 5 ψ) 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 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 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 2 model in (μ,T,γ) space, where γ arises from m 0 through mass renormalization. In the 2nd half of the thesis we have studied a generalization of the massless NJL 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 ξ 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 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-known that the massless NJL 2 model can be solved analytically. The same is true for the GN model, be it massless or massive. Here, the
Symmetries and Interactions in Matrix String Theory
Hacquebord, F.H.
1999-01-01
This PhD-thesis reviews matrix string theory and recent developments therein. The emphasis is put on symmetries, interactions and scattering processes in the matrix model. We start with an introduction to matrix string theory and a review of the orbifold model that flows out of matrix string theory
Some aspects of fundamental symmetries and interactions
Jungmann, KP; Grzonka, D; Czyzykiewicz, R; Oelert, W; Rozek, T; Winter, P
2005-01-01
The known fundamental symmetries and interactions are well described by the Standard Model. Features of this powerful theory, which are described but not deeper explained, are addressed in a variety of speculative models. Experimental tests of the predictions in such approaches can be either through
Fundamental symmetries and interactions-selected topics
Jungmann, Klaus P.
2015-01-01
In the field of fundamental interactions and symmetries numerous experiments are underway or planned in order to verify the standard model in particle physics, to search for possible extensions to it or to exploit the standard model for extracting most precise values for fundamental constants. We
Chiral Symmetry Breaking in Peptide Systems During Formation of Life on Earth
Konstantinov, Konstantin K.; Konstantinova, Alisa F.
2018-03-01
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.
Imprints of supersymmetry in the Lorentz-symmetry breaking of Gauge Theories
Energy Technology Data Exchange (ETDEWEB)
Belich, H [Universidade Federal do Espirito Santo (UFES), Vitoria, ES (Brazil); Dias, G S; Leal, F J.L. [Instituto Federal de Educacao, Ciencia e Tecnologia do Espirito Santo (IFES), Vitoria, ES (Brazil); Durand, L G; Helayel-Neto, Jose Abdalla; Spalenza, W [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil); Grupo de Fisica Teorica Jose Leite Lopes (GFT-JLL), Petropolis, RJ (Brazil)
2011-07-01
Full text: The breaking of Lorentz symmetry that may take place at very high energies opens up a venue for the discussion of the interplay between the violations of supersymmetry and relativistic symmetry. Recently, there have appeared in the literature models which propose a residual (non-relativistic) supersymmetry after Lorentz symmetry has been broken in a Horava gravity scenario. We here propose an N=1-supersymmetric Abelian gauge model which realises the breaking of Lorentz invariance by means of a CPT-even term. Our attempt assumes the point of view that supersymmetry and Lorentz symmetry are broken down at the same scale. If this is the case, the fermionic sector of the supermultiplets that accomplish the breaking of the symmetries into consideration may give rise to condensates that play an important role in the photon and photino dispersion relations. Contemporarily, they may also point to a more fundamental origin for the (bosonic) tensors usually associated to the backgrounds that parametrize Lorentz-symmetry breaking. We also highlight that, by studying the the violation of Lorentz symmetry in connection with supersymmetry, we find out that the Myers-Pospelov Electrodynamics, proposed on the basis of an analysis of the set of dimension-five operators, naturally appears in the bosonic sector of our model. Also, as a result of the interconnection between the supersymmetry and Lorentz-symmetry breakings, the photino-photino and photon-photino mixings that correspond to the supersymmetric completion of the Myers-Pospelov purely photonic terms come out. Finally, we present some comments on the possible modifications the supersymmetric fermions may introduce in the dispersion relations for particles at (high) energies close to the scale where supersymmetry and Lorentz symmetry are broken. (author)
Imprints of supersymmetry in the Lorentz-symmetry breaking of Gauge Theories
International Nuclear Information System (INIS)
Belich, H.; Dias, G.S.; Leal, F.J.L.; Durand, L.G.; Helayel-Neto, Jose Abdalla; Spalenza, W.
2011-01-01
Full text: The breaking of Lorentz symmetry that may take place at very high energies opens up a venue for the discussion of the interplay between the violations of supersymmetry and relativistic symmetry. Recently, there have appeared in the literature models which propose a residual (non-relativistic) supersymmetry after Lorentz symmetry has been broken in a Horava gravity scenario. We here propose an N=1-supersymmetric Abelian gauge model which realises the breaking of Lorentz invariance by means of a CPT-even term. Our attempt assumes the point of view that supersymmetry and Lorentz symmetry are broken down at the same scale. If this is the case, the fermionic sector of the supermultiplets that accomplish the breaking of the symmetries into consideration may give rise to condensates that play an important role in the photon and photino dispersion relations. Contemporarily, they may also point to a more fundamental origin for the (bosonic) tensors usually associated to the backgrounds that parametrize Lorentz-symmetry breaking. We also highlight that, by studying the the violation of Lorentz symmetry in connection with supersymmetry, we find out that the Myers-Pospelov Electrodynamics, proposed on the basis of an analysis of the set of dimension-five operators, naturally appears in the bosonic sector of our model. Also, as a result of the interconnection between the supersymmetry and Lorentz-symmetry breakings, the photino-photino and photon-photino mixings that correspond to the supersymmetric completion of the Myers-Pospelov purely photonic terms come out. Finally, we present some comments on the possible modifications the supersymmetric fermions may introduce in the dispersion relations for particles at (high) energies close to the scale where supersymmetry and Lorentz symmetry are broken. (author)
Performance improvements of symmetry-breaking reflector structures in nonimaging devices
Winston, Roland
2004-01-13
A structure and method for providing a broken symmetry reflector structure for a solar concentrator device. The component of the optical direction vector along the symmetry axis is conserved for all rays propagated through a translationally symmetric optical device. This quantity, referred to as the translational skew invariant, is conserved in rotationally symmetric optical systems. Performance limits for translationally symmetric nonimaging optical devices are derived from the distributions of the translational skew invariant for the optical source and for the target to which flux is to be transferred. A numerically optimized non-tracking solar concentrator utilizing symmetry-breaking reflector structures can overcome the performance limits associated with translational symmetry.
Spontaneous symmetry breaking in the $S_3$-symmetric scalar sector
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.
Charge symmetry breaking in parton distribution functions from lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Horsley, R.; Zanotti, J.M. [Edinburgh Univ. (United Kingdom). School of Physics and Astronomy; Nakamura, Y. [Regensburg Univ. (Germany). Inst. fuer Theoretische Physik; Tsukuba Univ., Ibaraki (Japan). Center for Computational Sciences; Pleiter, D. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Rakow, P.E.L. [Liverpool Univ. (United Kingdom). Theoretical Physics Div.; Schierholz, G. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Stueben, H. [Konrad-Zuse-Zentrum fuer Informationstechnik Berlin (Germany); Thomas, A.W.; Young, R.D. [Adelaide Univ. SA (Australia). School of Physics and Chemistry; Winter, F. [Edinburgh Univ. (United Kingdom). School of Physics and Astronomy; Regensburg Univ. (Germany). Inst. fuer Theoretische Physik
2010-12-15
By determining the quark momentum fractions of the octet baryons from N{sub f}=2+1 lattice simulations, we are able to predict the degree of charge symmetry violation in the parton distribution functions of the nucleon. This is of importance, not only as a probe of our understanding of the non-perturbative structure of the proton but also because such a violation constrains the accuracy of global ts to parton distribution functions and hence the accuracy with which, for example, cross sections at the LHC can be predicted. A violation of charge symmetry may also be critical in cases where symmetries are used to guide the search for physics beyond the Standard Model. (orig.)
Charge symmetry breaking in parton distribution functions from lattice QCD
International Nuclear Information System (INIS)
Horsley, R.; Zanotti, J.M.; Rakow, P.E.L.; Stueben, H.; Thomas, A.W.; Young, R.D.; Winter, F.; Regensburg Univ.
2010-12-01
By determining the quark momentum fractions of the octet baryons from N f =2+1 lattice simulations, we are able to predict the degree of charge symmetry violation in the parton distribution functions of the nucleon. This is of importance, not only as a probe of our understanding of the non-perturbative structure of the proton but also because such a violation constrains the accuracy of global ts to parton distribution functions and hence the accuracy with which, for example, cross sections at the LHC can be predicted. A violation of charge symmetry may also be critical in cases where symmetries are used to guide the search for physics beyond the Standard Model. (orig.)
Symmetry Relations and the Nonperturbative Form of Interactions
Institute of Scientific and Technical Information of China (English)
2001-01-01
Applying QCD to study and understand hadronic physics and nuclear physics is one of basic goals of modern nuclear physics. Developing nonperturbative approach of QCD to understand the dynamical chiral-symmetry breaking and color confinement then becomes one of our most important challenges. Besides the lattice gauge theory, the Dyson-Schwinger equation (DSE) formalism is such an appropriate nonperturbative approach. In undertaking nonperturbative studies using DSEs, we immediately have to confront the issue of what is the nonperturbative form of interactions. In recent 20 years, there have been considerable efforts to solve this open problem, however, all such attempts
Chiral and herringbone symmetry breaking in water-surface monolayers
DEFF Research Database (Denmark)
Peterson, I.R.; Kenn, R.M.; Goudot, A.
1996-01-01
We report the observation from monolayers of eicosanoic acid in the L(2)' phase of three distinct out-of-plane first-order diffraction peaks, indicating molecular tilt in a nonsymmetry direction and hence the absence of mirror symmetry. At lower pressures the molecules tilt in the direction of th...
Is radiative electroweak symmetry breaking consistent with a 125 GeV Higgs mass?
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.
Rencontres de Moriond EW 2012: Addressing symmetry breaking and mass hierarchy
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...
Non-minimal CW inflation, electroweak symmetry breaking and the 750 GeV anomaly
Energy Technology Data Exchange (ETDEWEB)
Marzola, L. [National Institute of Chemical Physics and Biophysics,Rävala 10, 10143 Tallinn (Estonia); Laboratory of Theoretical Physics, Institute of Physics, University of Tartu,Ravila 14c, 50411 Tartu (Estonia); Racioppi, A. [National Institute of Chemical Physics and Biophysics,Rävala 10, 10143 Tallinn (Estonia); Raidal, M. [National Institute of Chemical Physics and Biophysics,Rävala 10, 10143 Tallinn (Estonia); Laboratory of Theoretical Physics, Institute of Physics, University of Tartu,Ravila 14c, 50411 Tartu (Estonia); Urban, F.R.; Veermäe, H. [National Institute of Chemical Physics and Biophysics,Rävala 10, 10143 Tallinn (Estonia)
2016-03-29
We study whether the hinted 750 GeV resonance at the LHC can be a Coleman-Weinberg inflaton which is non-minimally coupled to gravity. Since the inflaton must couple to new charged and coloured states to reproduce the LHC diphoton signature, the same interaction can generate its effective potential and trigger the electroweak symmetry breaking via the portal coupling to the Higgs boson. This inflationary scenario predicts a lower bound on the tensor-to-scalar ratio of r≳0.006, where the minimal value corresponds to the measured spectral index n{sub s}≃0.97. However, we find that the compatibility with the LHC diphoton signal requires exotic new physics at energy scales accessible at the LHC. We study and quantify the properties of the predicted exotic particles.
Time-reversal symmetry breaking by ac field: Effect of ...
Indian Academy of Sciences (India)
deviate from 2 thus signalling on the time-reversal breaking by the ac field. ... is also the parity effect: the enchancement is only present if either P or Q is even. ... analysis (see figure 1) is possible and the ergodic zero-dimensional approx-.
Vacuum polarization and dynamical chiral symmetry breaking in quantum electrodynamics
International Nuclear Information System (INIS)
Gusynin, V.P.
1989-01-01
The Schwinger-Dyson equation in the ladder approximation is considered for the fermion mass function taking into account the vacuum polarization effects. It is shown that even in the 'zero-charge' situation there exists, at rather large coupling constant (α>α c >0), a solution with spontaneously broken chiral symmetry. The existence of the local limit in the model concerned is discussed. 30 refs.; 1 fig
Flavour symmetries and SUSY soft breaking in the LHC era
International Nuclear Information System (INIS)
Vives, O
2008-01-01
The so-called supersymmetric flavour problem does not exist in isolation to the Standard Model flavour problem. We show that a realistic flavour symmetry can simultaneously solve both problems without ad hoc modifications of the SUSY model. Furthermore, departures from the SM expectations in these models can be used to discriminate among different possibilities. In particular we present the expected values for the electron EDM in a flavour model solving the supersymmetric flavour and CP problems
International Nuclear Information System (INIS)
Fischer, I.; Hollik, W.; Roth, M.; Stoeckinger, D.
2004-01-01
Supersymmetric Slavnov-Taylor and Ward identities are investigated in the presence of soft and spontaneous symmetry breaking. We consider an Abelian model where soft supersymmetry breaking yields a mass splitting between electron and selectron and triggers spontaneous symmetry breaking, and we derive the corresponding identities that relate the electron and selectron masses to the Yukawa coupling. We demonstrate that the identities are valid in dimensional reduction and invalid in dimensional regularization and compute the necessary symmetry-restoring counterterms
International Nuclear Information System (INIS)
Fischer, I.; Hollik, W.; Roth, M.; Stoeckinger, D.
2003-12-01
Supersymmetric Slavnov-Taylor and Ward identities are investigated in presence of soft and spontaneous symmetry breaking. We consider an abelian model where soft supersymmetry breaking yields a mass splitting between electron and selectron and triggers spontaneous symmetry breaking, and we derive corresponding identities that relate the electron and selectron masses with the Yukawa coupling. We demonstrate that the identities are valid in dimensional reduction and invalid in dimensional regularization and compute the necessary symmetry-restoring counterterms. (orig.)
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.
Symmetry Breaking in Photonic Crystals: On-Demand Dispersion from Flatband to Dirac Cones.
Nguyen, H S; Dubois, F; Deschamps, T; Cueff, S; Pardon, A; Leclercq, J-L; Seassal, C; Letartre, X; Viktorovitch, P
2018-02-09
We demonstrate that symmetry breaking opens a new degree of freedom to tailor energy-momentum dispersion in photonic crystals. Using a general theoretical framework in two illustrative practical structures, we show that breaking symmetry enables an on-demand tuning of the local density of states of the same photonic band from zero (Dirac cone dispersion) to infinity (flatband dispersion), as well as any constant density over an adjustable spectral range. As a proof of concept, we demonstrate experimentally the transformation of the very same photonic band from a conventional quadratic shape to a Dirac dispersion, a flatband dispersion, and a multivalley one. This transition is achieved by finely tuning the vertical symmetry breaking of the photonic structures. Our results provide an unprecedented degree of freedom for optical dispersion engineering in planar integrated photonic devices.
Effective potential and spontaneous symmetry breaking in the noncommutative φ6 model
International Nuclear Information System (INIS)
Barbosa, G.D.
2004-01-01
We study the conditions for spontaneous symmetry breaking of the (2+1)-dimensional noncommutative φ 6 model in the small-θ limit. In this regime, considering the model as a cutoff theory, it is reasonable to assume translational invariance as a property of the vacuum state and study the conditions for spontaneous symmetry breaking by an effective potential analysis. An investigation of up to the two-loop level reveals that noncommutative effects can modify drastically the shape of the effective potential. Under reasonable conditions, the nonplanar sector of the theory can become dominant and induce symmetry breaking for values of the mass and coupling constants not reached by the commutative counterpart
Cooperation and competition between two symmetry breakings in a coupled ratchet
Li, Chen-Pu; Chen, Hong-Bin; Fan, Hong; Xie, Ge-Ying; Zheng, Zhi-Gang
2018-03-01
We investigate the collective mechanism of coupled Brownian motors in a flashing ratchet in the presence of coupling symmetry breaking and space symmetry breaking. The dependences of directed current on various parameters are extensively studied in terms of numerical simulations and theoretical analysis. Reversed motion can be achieved by modulating multiple parameters including the spatial asymmetry coefficient, the coupling asymmetry coefficient, the coupling free length and the coupling strength. The dynamical mechanism of these transport properties can be reasonably explained by the effective potential theory and the cooperation or competition between two symmetry breakings. Moreover, adjusting the Gaussian white noise intensity, which can induce weak reversed motion under certain condition, can optimize and manipulate the directed transport of the ratchet system.
Maximally Generalized Yang-Mills Model and Dynamical Breaking of Gauge Symmetry
International Nuclear Information System (INIS)
Wang Dianfu; Song Heshan
2006-01-01
A maximally generalized Yang-Mills model, which contains, besides the vector part V μ , also an axial-vector part A μ , a scalar part S, a pseudoscalar part P, and a tensor part T μν , is constructed and the dynamical breaking of gauge symmetry in the model is also discussed. It is shown, in terms of the Nambu-Jona-Lasinio mechanism, that the gauge symmetry breaking can be realized dynamically in the maximally generalized Yang-Mills model. The combination of the maximally generalized Yang-Mills model and the NJL mechanism provides a way to overcome the difficulties related to the Higgs field and the Higgs mechanism in the usual spontaneous symmetry breaking theory.
Isospin-symmetry breaking in masses of N≃Z nuclei
Directory of Open Access Journals (Sweden)
P. Bączyk
2018-03-01
Full Text Available Effects of the isospin-symmetry breaking (ISB beyond mean-field Coulomb terms are systematically studied in nuclear masses near the N=Z line. The Coulomb exchange contributions are calculated exactly. We use extended Skyrme energy density functionals (EDFs with proton–neutron-mixed densities, to which we add new terms breaking the isospin symmetry. Two parameters associated with the new terms are determined by fitting mirror and triplet displacement energies (MDEs and TDEs of isospin multiplets. The new EDFs reproduce MDEs for the T=12 doublets and T=1 triplets, and TDEs for the T=1 triplets. Relative strengths of the obtained isospin-symmetry-breaking terms are not consistent with the differences in the NN scattering lengths, ann, app, and anp. Based on low-energy experimental data, it seems thus impossible to delineate the strong-force ISB effects from beyond-mean-field Coulomb-energy corrections.
Isospin-symmetry breaking in masses of N ≃ Z nuclei
Bączyk, P.; Dobaczewski, J.; Konieczka, M.; Satuła, W.; Nakatsukasa, T.; Sato, K.
2018-03-01
Effects of the isospin-symmetry breaking (ISB) beyond mean-field Coulomb terms are systematically studied in nuclear masses near the N = Z line. The Coulomb exchange contributions are calculated exactly. We use extended Skyrme energy density functionals (EDFs) with proton-neutron-mixed densities, to which we add new terms breaking the isospin symmetry. Two parameters associated with the new terms are determined by fitting mirror and triplet displacement energies (MDEs and TDEs) of isospin multiplets. The new EDFs reproduce MDEs for the T = 1/2 doublets and T = 1 triplets, and TDEs for the T = 1 triplets. Relative strengths of the obtained isospin-symmetry-breaking terms are not consistent with the differences in the NN scattering lengths, ann, app, and anp. Based on low-energy experimental data, it seems thus impossible to delineate the strong-force ISB effects from beyond-mean-field Coulomb-energy corrections.
Effective field theory of emergent symmetry breaking in deformed atomic nuclei
International Nuclear Information System (INIS)
Papenbrock, T; Weidenmüller, H A
2015-01-01
Spontaneous symmetry breaking in non-relativistic quantum systems has previously been addressed in the framework of effective field theory. Low-lying excitations are constructed from Nambu–Goldstone modes using symmetry arguments only. We extend that approach to finite systems. The approach is very general. To be specific, however, we consider atomic nuclei with intrinsically deformed ground states. The emergent symmetry breaking in such systems requires the introduction of additional degrees of freedom on top of the Nambu–Goldstone modes. Symmetry arguments suffice to construct the low-lying states of the system. In deformed nuclei these are vibrational modes each of which serves as band head of a rotational band. (paper)
Abelian Duality, Confinement, and Chiral-Symmetry Breaking in a SU(2) QCD-Like Theory
International Nuclear Information System (INIS)
Uensal, Mithat
2008-01-01
We analyze the vacuum structure of SU(2) QCD with multiple massless adjoint representation fermions formulated on a small spatial S 1 xR 3 . The absence of thermal fluctuations, and the fact that quantum fluctuations favor the vacuum with unbroken center symmetry in a weakly coupled regime, renders the interesting dynamics of these theories analytically calculable. Confinement and the generation of the mass gap in the gluonic sector are shown analytically. In this regime, theory exhibits confinement without continuous chiral-symmetry breaking. However, a flavor singlet chiral condensate (which breaks a discrete chiral symmetry) persists at arbitrarily small S 1 . Under certain reasonable assumptions, we show that the theory exhibits a zero temperature chiral phase transition in the absence of any change in spatial center symmetry realizations
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.
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.
Chiral symmetry breaking in d=3 NJL model in external gravitational and magnetic fields
Gitman, D. M.; Odintsov, S. D.; Shil'nov, Yu. I.
1996-01-01
The phase structure of $d=3$ Nambu-Jona-Lasinio model in curved spacetime with magnetic field is investigated in the leading order of the $1/N$-expansion and in linear curvature approximation (an external magnetic field is treated exactly). The possibility of the chiral symmetry breaking under the combined action of the external gravitational and magnetic fields is shown explicitly. At some circumstances the chiral symmetry may be restored due to the compensation of the magnetic field by the ...
Kink-induced symmetry breaking patterns in brane-world SU(3)^3 trinification models
Demaria, Alison; Volkas, Raymond R.
2005-01-01
The trinification grand unified theory (GUT) has gauge group SU(3)^3 and a discrete symmetry permuting the SU(3) factors. In common with other GUTs, the attractive nature of the fermionic multiplet assignments is obviated by the complicated multi-parameter Higgs potential apparently needed for phenomenological reasons, and also by vacuum expectation value (VEV) hierarchies within a given multiplet. This motivates the rigorous consideration of Higgs potentials, symmetry breaking patterns and a...
International Nuclear Information System (INIS)
Jiang Yu; Lozada-Cassou, M.; Vinet, A.
2003-01-01
The spatiotemporal dynamics of networks based on a ring of coupled oscillators with regular shortcuts beyond the nearest-neighbor couplings is studied by using master stability equations and numerical simulations. The generic criterion for dynamic synchronization has been extended to arbitrary network topologies with zero row-sum. The symmetry-breaking oscillation patterns that resulted from the Hopf bifurcation from synchronous states are analyzed by the symmetry group theory
Tschierske, Carsten; Ungar, Goran
2016-01-04
Spontaneous mirror symmetry breaking is an efficient way to obtain homogeneously chiral agents, pharmaceutical ingredients and materials. It is also in the focus of the discussion around the emergence of uniform chirality in biological systems. Tremendous progress has been made by symmetry breaking during crystallisation from supercooled melts or supersaturates solutions and by self-assembly on solid surfaces and in other highly ordered structures. However, recent observations of spontaneous mirror symmetry breaking in liquids and liquid crystals indicate that it is not limited to the well-ordered solid state. Herein, progress in the understanding of a new dynamic mode of symmetry breaking, based on chirality synchronisation of transiently chiral molecules in isotropic liquids and in bicontinuous cubic, columnar, smectic and nematic liquid crystalline phases is discussed. This process leads to spontaneous deracemisation in the liquid state under thermodynamic control, giving rise to long-term stable symmetry-broken fluids, even at high temperatures. These fluids form conglomerates that are capable of extraordinary strong chirality amplification, eventually leading to homochirality and providing a new view on the discussion of emergence of uniform chirality in prebiotic systems. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Hierarchy of symmetry-breaking scales in SO(10) grand unification and particle masses
International Nuclear Information System (INIS)
Asatryan, G.M.; Ioannisyan, A.N.
1987-01-01
An SO(10) grand unification model is proposed in which the introduction of an additional discrete symmetry solves the problem of the quark mass spectrum arising in SO(10) breaking schemes with intermediate SU(4) x SU(2)/sub L/ x SU(2)/sub R/ or SU(3)/sub C/ x U(1)/sub B//sub -//sub L/ x SU(2)/sub L/ x SU(2)/sub R/ symmetry. When the breaking of this discrete symmetry is taken into account the condition that there exist only a single light Higgs boson leads to a relation between the b- and t-quark masses which makes it possible to fix the ratio of the grand unification scale M/sub X/ and the quark--lepton symmetry-breaking scale M/sub C/. The specific values of M/sub X/ and M/sub C/ and also the scale of the SU(2)/sub R/ symmetry breaking M/sub R/ depend on the experimental value of the Weinberg angle and are in agreement with the experimental data on proton decay
Baryon axial-vector couplings and SU(3)-symmetry breaking in chiral quark models
International Nuclear Information System (INIS)
Horvat, D.; Ilakovac, A.; Tadic, D.
1986-01-01
SU(3)-symmetry breaking is studied in the framework of the chiral bag models. Comparisons are also made with the MIT bag model and the harmonic-oscillator quark model. An important clue for the nature of the symmetry breaking comes from the isoscalar axial-vector coupling constant g/sub A//sup S/ which can be indirectly estimated from the Bjorken sum rules for deep-inelastic scattering. The chiral bag model with two radii reasonably well accounts for the empirical values of g/sub A//sup S/ and of the axial-vector coupling constants measured in hyperon semileptonic decays
Minimal supersymmetric grand unified theory: Symmetry breaking and the particle spectrum
International Nuclear Information System (INIS)
Bajc, Borut; Melfo, Alejandra; Senjanovic, Goran; Vissani, Francesco
2004-01-01
We discuss in detail the symmetry breaking and related issues in the minimal renormalizable supersymmetric grand unified theory. We find all the possible patterns of symmetry breaking, compute the associated particle spectrum and study its impact on the physical scales of the theory. In particular, the complete mass matrices of the SU(2) doublets and the color triplets are computed in connection with the doublet-triplet splitting and the d=5 proton decay. We explicitly construct the two light Higgs doublets as a function of the Higgs superpotential parameters. This provides a framework for the analysis of phenomenological implications of the theory, to be carried out in a second paper
Competition between the symmetry breaking and onset of collapse in weakly coupled atomic condensates
International Nuclear Information System (INIS)
Salasnich, L.; Toigo, F.; Malomed, B. A.
2010-01-01
We analyze the symmetry breaking of matter-wave solitons in a pair of cigar-shaped traps coupled by tunneling of atoms. The model is based on a system of linearly coupled nonpolynomial Schroedinger equations. Unlike the well-known spontaneous-symmetry-breaking (SSB) bifurcation in coupled cubic equations, in the present model the SSB competes with the onset of collapse in this system. Stability regions of symmetric and asymmetric solitons, as well as the collapse region, are identified in the system's parameter space.
Symmetry breaking in clogging for oppositely driven particles
Glanz, Tobias; Wittkowski, Raphael; Löwen, Hartmut
2016-11-01
The clogging behavior of a symmetric binary mixture of colloidal particles that are driven in opposite directions through constrictions is explored by Brownian dynamics simulations and theory. A dynamical state with a spontaneously broken symmetry occurs where one species is flowing and the other is blocked for a long time, which can be tailored by the size of the constrictions. Moreover, we find self-organized oscillations in clogging and unclogging of the two species. Apart from statistical physics, our results are of relevance for fields like biology, chemistry, and crowd management, where ions, microparticles, pedestrians, or other particles are driven in opposite directions through constrictions.
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.
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.
Quark condensation, induced symmetry breaking and color superconductivity at high density
International Nuclear Information System (INIS)
Langfeld, Kurt; Rho, Mannque
1999-01-01
The phase structure of hadronic matter at high density relevant to the physics of compact stars and relativistic heavy-ion collisions is studied in a low-energy effective quark theory. The relevant phases that figure are (1) chiral condensation, (2) diquark color condensation (color superconductivity) and (3) induced Lorentz-symmetry breaking (''ISB''). For a reasonable strength for the effective four-Fermi current-current interaction implied by the low-energy effective quark theory for systems with a Fermi surface we find that the ''ISB'' phase sets in together with chiral symmetry restoration (with the vanishing quark condensate) at a moderate density while color superconductivity associated with scalar diquark condensation is pushed up to an asymptotic density. Consequently, color superconductivity seems rather unlikely in heavy-ion collisions although it may play a role in compact stars. Lack of confinement in the model makes the result of this analysis only qualitative but the hierarchy of the transitions we find seems to be quite robust
Spontaneous symmetry breaking of Bose-Fermi mixtures in double-well potentials
International Nuclear Information System (INIS)
Adhikari, S. K.; Malomed, B. A.; Salasnich, L.; Toigo, F.
2010-01-01
We study the spontaneous symmetry breaking (SSB) of a superfluid Bose-Fermi (BF) mixture in a double-well potential (DWP). The mixture is described by the Gross-Pitaevskii equation (GPE) for the bosons, coupled to an equation for the order parameter of the Fermi superfluid, which is derived from the respective density functional in the unitarity limit (a similar model applies to the BCS regime, too). Straightforward SSB in the degenerate Fermi gas loaded into a DWP is impossible, as it requires an attractive self-interaction, and the intrinsic nonlinearity in the Fermi gas is repulsive. Nonetheless, we demonstrate that the symmetry breaking is possible in the mixture with attraction between fermions and bosons, like 40 K and 87 Rb. Numerical results are represented by dependencies of asymmetry parameters for both components on particle numbers of the mixture, N F and N B , and by phase diagrams in the (N F ,N B ) plane, which displays regions of symmetric and asymmetric ground states. The dynamical picture of the SSB, induced by a gradual transformation of the single-well potential into the DWP, is reported too. An analytical approximation is proposed for the case when the GPE for the boson wave function may be treated by means of the Thomas-Fermi (TF) approximation. Under a special linear relationship between N F and N B , the TF approximation allows us to reduce the model to a single equation for the fermionic function, which includes competing repulsive and attractive nonlinear terms. The latter one directly displays the mechanism of the generation of the effective attraction in the Fermi superfluid, mediated by the bosonic component of the mixture.
PT symmetry breaking in non-central potentials
International Nuclear Information System (INIS)
Levai, G.
2007-01-01
Complete text of publication follows. PT-symmetric systems represent a special example for non-hermitian problems in quantum mechanics. The Hamiltonian of these systems is invariant under the simultaneous action of the P space and T time inversion operations. They resemble hermitian problems in that they typically possess real energy spectrum. However, increasing non-hermiticity, e.g. the imaginary potential component the real energy eigenvalues merge pairwise and turn into complex conjugate pairs and at the same time, the energy eigenstates cease to be eigenstates of the PT operator. The mechanism of this spontaneous breakdown of PT symmetry has been investigated in one spatial dimension, and our aim was to extend these studies to higher dimensions. Assuming that the solutions of the Schroedinger equation -Δψ(r) + V (r)ψ(r) = Eψ(r) can be obtained by the separation of the radial and angular variables, we substitute ψ(r,θ,φ) = r -1 φ(r) sin -1/2 ω(θ)τ(ψ) in (4), where r [0,∞), θ [0,π] and ψ [0,2π]. Further, we assume that the angular components of the wave function satisfy ω' = (P(θ) - p)ω, τ' = (K(ψ) - k)τ, where τ(ψ) has to be defined with periodic boundary conditions. Then the complete three-dimensional problem becomes solvable if the non-central potential takes the form V(r,θ,ψ) = V 0 (r)+ K(ψ)/r 2 sin 2 θ + P(θ)/r 2 - k-1/4/r 2 sin 2 θ. Here V 0 (r) is a central potential appearing in -φ'+[V 0 (r) + 1/r 2 (p - 1/4] φ - Eφ = 0. Note that is formally identical with a conventional radial Schroedinger equation complete with a centrifugal term. In order to solve properly, the state dependence of has to be eliminated, i.e. its dependence on k has to be cancelled by combining the last two terms. This effectively means that has to be solved with a potential P(θ) that contains a sin -2 θ type term. Next we investigate under which conditions the non-central potential exhibits PT symmetry. It is seen that space reflection P : r → -r
Chains of benzenes with lithium-atom adsorption: Vibrations and spontaneous symmetry breaking
Ortiz, Yenni P.; Stegmann, Thomas; Klein, Douglas J.; Seligman, Thomas H.
2017-09-01
We study effects of different configurations of adsorbates on the vibrational modes as well as symmetries of polyacenes and poly-p-phenylenes focusing on lithium atom adsorption. We found that the spectra of the vibrational modes distinguish the different configurations. For more regular adsorption schemes the lowest states are bending and torsion modes of the skeleton, which are essentially followed by the adsorbate. On poly-p-phenylenes we found that lithium adsorption reduces and often eliminates the torsion between rings thus increasing symmetry. There is spontaneous symmetry breaking in poly-p-phenylenes due to double adsorption of lithium atoms on alternating rings.
Gauging MSSM global symmetries and SUSY breaking in de Sitter vacuum
Antoniadis, Ignatios
2016-01-01
We elaborate on a recent study of a model of supersymmetry breaking we proposed recently, in the presence of a tunable positive cosmological constant, based on a gauged shift symmetry of a string modulus, external to the Standard Model (SM) sector. Here, we identify this symmetry with a global symmetry of the SM and work out the corresponding phenomenology. A particularly attracting possibility is to use a combination of Baryon and Lepton number that contains the known matter parity and guarantees absence of dimension-four and five operators that violate B and L.
Current-Current Interactions, Dynamical Symmetry - and Quantum Chromodynamics.
Neuenschwander, Dwight Edward, Jr.
Quantum Chromodynamics with massive gluons (gluon mass (TBOND) xm(,p)) in a contact-interaction limit called CQCD (strong coupling g (--->) (INFIN); x (--->) (INFIN)), despite its non-renormalizability and lack of hope of confinement, is nevertheless interesting for at least two reasons. (1) Some authors have suggested a relation between 4-Fermi and Yang-Mills theories. If g/x('2) slavery, perturbative evaluation of QCD in the infrared is a dubious practice. However, if g('2)/x('2) << 1 in CQCD, then the simplest 4-Fermi interaction is dominant, and CQCD admits perturbative treatment, but only in the infrared. With the dominant interaction, a dynamical Nambu-Goldstone realization of chiral symmetry -breaking (XSB) is found. Although in QCD the relation between confinement and XSB is controversial, XSB occurs in CQCD provided confinement is sacrificed.
Symmetry breaking due to quantum fluctuations in massless field theories
International Nuclear Information System (INIS)
Ghose, P.; Datta, A.
1977-10-01
It is shown that quantum fluctuations can act as the driving mechanism for the spontaneous breakdown of both scale and the discrete phi→-phi symmetries in a lamdaphi 4 theory which is massless and scale invariant in the tree approximation. Consequently dimensional transformation occurs and the dimensionless and only parameter lambda in the theory is fixed and replaced by the vacuum expectation value of the field. These results are shown to be consistent with the appropriate renormalization group equation for the theory. A scalar electrodynamics which is massless and scale invariant in the tree approximation is also considered, and it is shown that the Higgs meson in such a theory is much heavier than the vector meson for small values of the gauge coupling constant e. Another interesting consequence of such a theory is that it possesses vortex-line solutions only when quantum fluctuations are taken into account
Symmetry breaking in a bull and bear financial market model
International Nuclear Information System (INIS)
Sushko, Iryna; Tramontana, Fabio; Westerhoff, Frank; Avrutin, Viktor
2015-01-01
We investigate bifurcation structures in the parameter space of a one-dimensional piecewise linear map with two discontinuity points. This map describes endogenous bull and bear market dynamics arising from a simple asset-pricing model. An important feature of our model is that some speculators only enter the market if the price is sufficiently distant to its fundamental value. Our analysis starts with the investigation of a particular case in which the map is symmetric with respect to the origin, associated with equal market entry thresholds in the bull and bear market. We then generalize our analysis by exploring how novel bifurcation structures may emerge when the map’s symmetry is broken.
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.
Symmetry remnants in the face of competing interactions in nuclei
Energy Technology Data Exchange (ETDEWEB)
Leviatan, A., E-mail: ami@phys.huji.ac.il [Racah Institute of Physics, The Hebrew University, Jerusalem 91904 (Israel); Macek, M., E-mail: michal.macek@yale.edu [Center for Theoretical Physics, Sloane Physics Laboratory, Yale University, New Haven, CT 06520-8120 (United States)
2015-10-15
Detailed description of nuclei necessitates model Hamiltonians which break most dynamical symmetries. Nevertheless, generalized notions of partial and quasi dynamical symmetries may still be applicable to selected subsets of states, amidst a complicated environment of other states. We examine such scenarios in the context of nuclear shape-phase transitions.
Bifurcation to a chiral-symmetry-breaking state in continuum quantum electrodynamics
International Nuclear Information System (INIS)
Rembiesa, P.
1990-01-01
Dyson-Schwinger equations for a fermion propagator in the Landau gauge are studied in the approximation of a small-momentum-transfer vertex function. There exists a critical value of the coupling constant above which the ordinary solution bifurcates to another, chiral-symmetry-breaking solution. The new solution does not require either infrared or ultraviolet momentum cutoffs
A study of charge symmetry breaking effects in elastic π+-d scattering
International Nuclear Information System (INIS)
Rinat, A.S.; Alexander, Y.
1982-06-01
We computed external Coulomb and some strong charge symmetry breaking (CSB) effects in π +- d→π +- d. These appear to account for charge asymmetry of differential cross sections, while approximate CSB spoils the agreement. We further report on a critical study of CSB effects extracted from π +- d total cross section differences. (author)
Chiral symmetry breaking in QED3: bifurcation of the fermionic self-energy
International Nuclear Information System (INIS)
Almeida, L.D.; Natale, A.A.
1989-01-01
The existence of a bifurcation point in the Scwinger-Dyson equation of 2+1 dimensional quantum electrodynamics with N fermions, is studied. It is found an evidence for the existence of a critical behavior, such that chiral symmetry breaking may occur only for a small number of flavors. (author) [pt
Spontaneous symmetry breaking and self-consistent equations for the free-energy
International Nuclear Information System (INIS)
Lovesey, S.W.
1980-03-01
A variational procedure for the free-energy is used to derive self-consistent equations that allow for spontaneous symmetry breaking. For an N-component phi 4 -model the equations are identical to those obtained by summing all loops to order 1/N. (author)
Gieseking, Rebecca L.; Ravva, Mahesh Kumar; Coropceanu, Veaceslav; Bredas, Jean-Luc
2016-01-01
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
Symmetry-breaking intramolecular charge transfer in the excited state of meso-linked BODIPY dyads
Whited, Matthew T.; Patel, Niral M.; Roberts, Sean T.; Allen, Kathryn; Djurovich, Peter I.; Bradforth, Stephen E.; Thompson, Mark E.
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.
International Nuclear Information System (INIS)
Chanowitz, M.S.
1987-01-01
Low energy theorems are derived for scattering of longitudinally polarized W and Z's, providing the basis for an estimate of the observable signal at the SSC if electroweak symmetry breaking is due to new physics at the TeV scale
International Nuclear Information System (INIS)
Zimmer, F.M.; Magalhaes, S.G.
2007-01-01
The one-step replica symmetry breaking is used to study the competition between spin glass (SG) and antiferromagnetic order (AF) in two-sublattice fermionic Ising SG models in the presence of a transverse Γ and a parallel H magnetic fields. Inter- and intra-sublattice exchange interactions following Gaussian distributions are considered. The problem is formulated in a Grassmann path integral formalism within the static ansatz. Results show that H favors the non-ergodic mixed phase (AF+SG) and it destroys the AF. The Γ suppresses the magnetic orders, and the intra-sublattice interaction can introduce a discontinuous phase transition
International Nuclear Information System (INIS)
Gupta, Abhishekh; Lloyd-Price, Jason; Oliveira, Samuel M D; Yli-Harja, Olli; Muthukrishnan, Anantha-Barathi; Ribeiro, Andre S
2014-01-01
The morphological symmetry of the division process of Escherichia coli is well-known. Recent studies verified that, in optimal growth conditions, most divisions are symmetric, although there are exceptions. We investigate whether such morphological asymmetries in division introduce functional asymmetries between sister cells, and assess the robustness of the symmetry in division to mild chemical stresses and sub-optimal temperatures. First, we show that the difference in size between daughter cells at birth is positively correlated to the difference between the numbers of fluorescent protein complexes inherited from the parent cell. Next, we show that the degree of symmetry in division observed in optimal conditions is robust to mild acidic shift and to mild oxidative stress, but not to sub-optimal temperatures, in that the variance of the difference between the sizes of sister cells at birth is minimized at 37 °C. This increased variance affects the functionality of the cells in that, at sub-optimal temperatures, larger/smaller cells arising from asymmetric divisions exhibit faster/slower division times than the mean population division time, respectively. On the other hand, cells dividing faster do not do so at the cost of morphological symmetry in division. Finally we show that at suboptimal temperatures the mean distance between the nucleoids increases, explaining the increased variance in division. We conclude that the functionality of E. coli cells is not immune to morphological asymmetries at birth, and that the effectiveness of the mechanism responsible for ensuring the symmetry in division weakens at sub-optimal temperatures. (paper)
Symmetry breaking of adjacent tracks in perpendicular recording system
International Nuclear Information System (INIS)
Xie Huang; Wei Dan
2007-01-01
The track density increase in a perpendicular magnetic recording system is limited by the adjacent-track interference (ATI). In this work, a composite micromagnetic simulation model of the read/write process is developed to analyse ATI by the symmetry of signal and noise in two adjacent W = 60 nm tracks with the track pitch of the order of 100 nm. Based on the two-dimensional medium noise distribution of dibit recording, it is found that the noise in the first and later recorded tracks start to be asymmetric when the track pitch is lower than 2 W; if the read width is limited within 2/3 of the write width, the asymmetry of noise appears when the track pitch is less than 1.5 W. At higher recording densities, the signal-to-noise ratio degradation is mainly due to the noise caused by the interference from the signal of the adjacent track. Side writing can be effectively eliminated by the use of a guard band whose width is at least half the track width
Spontaneous symmetry breaking in local gauge quantum field theory; the Higgs mechanism
International Nuclear Information System (INIS)
Strocchi, F.
1977-01-01
Spontaneous symmetry breakings in indefinite metric quantum field theories are analyzed and a generalization of the Goldstone theorem is proved. The case of local gauge quantum field theories is discussed in detail and a characterization is given of the occurrence of the Higgs mechanism versus the Goldstone mechanism. The Higgs phenomenon is explained on general grounds without the introduction of the so-called Higgs fields. The basic property is the relation between the local internal symmetry group and the local group of gauge transformations of the second kind. Spontaneous symmetry breaking of c-number gauge transformations of the second kind is shown to always occur if there are charged local fields. The implications about the absence of mass gap in the Wightman functions and the occurrence of massless particles associated with the unbroken generators in the Higgs phenomenon are discussed. (orig.) [de
PT-symmetry breaking in complex nonlinear wave equations and their deformations
International Nuclear Information System (INIS)
Cavaglia, Andrea; Fring, Andreas; Bagchi, Bijan
2011-01-01
We investigate complex versions of the Korteweg-deVries equations and an Ito-type nonlinear system with two coupled nonlinear fields. We systematically construct rational, trigonometric/hyperbolic and elliptic solutions for these models including those which are physically feasible in an obvious sense, that is those with real energies, but also those with complex energy spectra. The reality of the energy is usually attributed to different realizations of an antilinear symmetry, as for instance PT-symmetry. It is shown that the symmetry can be spontaneously broken in two alternative ways either by specific choices of the domain or by manipulating the parameters in the solutions of the model, thus leading to complex energies. Surprisingly, the reality of the energies can be regained in some cases by a further breaking of the symmetry on the level of the Hamiltonian. In many examples, some of the fixed points in the complex solution for the field undergo a Hopf bifurcation in the PT-symmetry breaking process. By employing several different variants of the symmetries we propose many classes of new invariant extensions of these models and study their properties. The reduction of some of these models yields complex quantum mechanical models previously studied.
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.
Energy transparency and symmetries in the beam-beam interaction
Krishnagopal, S
2000-01-01
We have modified the beam-beam simulation code CBI to handle asymmetric beams and used it to look at energy transparency and symmetries in the beam-beam interaction. We find that even a small violation of energy transparency, or of the symmetry between the two beams, changes the character of the collective (coherent) motion; in particular, period-n oscillations are no longer seen. We speculate that the one-time observation of these oscillations at LEP, and the more ubiquitous observation of the flip-flop instability in colliders around the world, may be a consequence of breaking the symmetry between the electron and positron beams. We also apply this code to the asymmetric collider PEP-II, and find that for the nominal parameters of PEP-II, in particular, the nominal tune-shift parameter of xi /sub 0/=0.03, there are no collective beam-beam issues. Collective quadrupole motion sets in only at xi /sub 0/=0.06 and above, consistent with earlier observations for symmetric beams. (6 refs).
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.
More on cosmological constraints on spontaneous R-symmetry breaking models
International Nuclear Information System (INIS)
Hamada, Yuta; Kobayashi, Tatsuo; Kamada, Kohei; Ecole Polytechnique Federale de Lausanne; Ookouchi, Yutaka
2013-10-01
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) R breaking scale f a is constrained as f a 12-14 GeV regardless of the value of R-axion mass.
Symmetry Breaking, Unification, and Theories Beyond the Standard Model
Energy Technology Data Exchange (ETDEWEB)
Nomura, Yasunori
2009-07-31
A model was constructed in which the supersymmetric fine-tuning problem is solved without extending the Higgs sector at the weak scale. We have demonstrated that the model can avoid all the phenomenological constraints, while avoiding excessive fine-tuning. We have also studied implications of the model on dark matter physics and collider physics. I have proposed in an extremely simple construction for models of gauge mediation. We found that the {mu} problem can be simply and elegantly solved in a class of models where the Higgs fields couple directly to the supersymmetry breaking sector. We proposed a new way of addressing the flavor problem of supersymmetric theories. We have proposed a new framework of constructing theories of grand unification. We constructed a simple and elegant model of dark matter which explains excess flux of electrons/positrons. We constructed a model of dark energy in which evolving quintessence-type dark energy is naturally obtained. We studied if we can find evidence of the multiverse.
Zheng, Guo-Qing
Spontaneous symmetry breaking is an important concept for understanding physics ranging from the elementary particles to states of matter. For example, the superconducting state breaks global gauge symmetry, and unconventional superconductors can break additional symmetries. In particular, spin rotational symmetry is expected to be broken in spin-triplet superconductors. However, experimental evidence for such symmetry breaking has not been obtained so far in any candidate compounds. We report 77Se nuclear magnetic resonance measurements which showed that spin rotation symmetry is spontaneously broken in the hexagonal plane of the electron-doped topological insulator Cu0.3Bi2Se3 below the superconducting transition temperature Tc =3.4 K. Our results not only establish spin-triplet (odd parity) superconductivity in this compound, but also serve to lay a foundation for the research of topological superconductivity (Ref.). We will also report the doping mechanism and superconductivity in Sn1-xInxTe.
Symmetry breaking and the fermionic fractional Chern insulator in topologically trivial bands
Kourtis, Stefanos
2018-02-01
We describe a mechanism by which fermions in topologically trivial bands can form correlated states exhibiting a fractional quantum Hall (FQH) effect upon introduction of strong repulsive interactions. These states are solid-liquid composites, in which a FQH liquid is induced by the formation of charge order (CO), following a recently proposed paradigm of symmetry-breaking topological (SBT) order [Phys. Rev. Lett. 113, 216404 (2014), 10.1103/PhysRevLett.113.216404]. We devise a spinless fermion model on a triangular lattice, featuring a topologically trivial phase when interactions are omitted. Adding strong short-range repulsion, we first establish a repulsion-driven CO phase at density ρCO=2 /3 particles per site, then dope the model to higher densities ρ =ρCO+ν /6 . At ν =1 /3 ,2 /5 (ρ =13 /18 ,11 /15 ) we observe definitive signatures of both CO and the FQH effect—a sharply peaked static structure factor, gapped and degenerate energy spectrum, and fractionally quantized Hall conductivity σH=1 /3 ,2 /5 in units of e2/h —over a range of all model parameters. We thus obtain direct evidence for fermionic SBT order of FQH type in topologically trivial bands.
International Nuclear Information System (INIS)
Vlahovic, B.; Soldi, A.
1993-01-01
The differences between the n-d and the p-d analyzing powers lend themselves to investigate Coulomb and charge symmetry breaking effects in the nucleon-nucleon interaction. We examine these differences over a range of angles, bracketing the Λ y maximum around 120 degrees, for energies from 3 to 14 MeV. We conclude that a correction of the data to account for the slowing down of tile proton under the Coulomb affect does not account for these differences and this suggests that charge symmetry breaking effect are possibly responsible
Top and Higgs masses from dynamical electroweak symmetry breaking
International Nuclear Information System (INIS)
Kahana, D.E.
1993-01-01
The standard model of electroweak interactions, with the gauge and Higgs bosons appearing as composites, is derived from a Nambu-Jona-Lasinio-type four-fermion interaction, assumed to be valid above a high scale μ. Simple relationships are found for the composite boson top quark mass ratios and for the weak angle. Assuming three generations and a 'desert' hypothesis, these relationships are evolved with the full renormalization group down to present experimental energies, yielding predictions for the top quark and Higgs-boson masses, near 155 GeV for the former and near 140 GeV for the latter. In this fashion, fermion-antifermion condensates can be shown to yield a top mass consistent with that indicated from electroweak loop corrections for LEP data. (author) 23 refs
Xiao, R. C.; Cheung, C. H.; Gong, P. L.; Lu, W. J.; Si, J. G.; Sun, Y. P.
2018-06-01
k paths exactly with symmetry allow to find triply degenerate points (TDPs) in band structures. The paths that host the type-II Dirac points in PtSe2 family materials also have the spatial symmetry. However, due to Kramers degeneracy (the systems have both inversion symmetry and time reversal symmetry), the crossing points in them are Dirac ones. In this work, based on symmetry analysis, first-principles calculations, and method, we predict that PtSe2 family materials should undergo topological transitions if the inversion symmetry is broken, i.e. the Dirac fermions in PtSe2 family materials split into TDPs in PtSeTe family materials (PtSSe, PtSeTe, and PdSeTe) with orderly arranged S/Se (Se/Te). It is different from the case in high-energy physics that breaking inversion symmetry I leads to the splitting of Dirac fermion into Weyl fermions. We also address a possible method to achieve the orderly arranged in PtSeTe family materials in experiments. Our study provides a real example that Dirac points transform into TDPs, and is helpful to investigate the topological transition between Dirac fermions and TDP fermions.
Impact of local symmetry breaking on the physical properties of tetrahedral liquids.
Shi, Rui; Tanaka, Hajime
2018-02-27
Water and silica are the most important materials with local tetrahedral symmetry. They have similar crystalline polymorphs and exhibit anomalous density maximum in the liquid state. However, water and silica also show very different characteristics. For instance, the density of water varies much more sharply than that of liquid silica near the maximum as temperature changes. More notably, silica is a very good glass-former, but water is an extremely poor one. The physical origins of these similarities and differences still remain elusive, due to the lack of a microscopic understanding of the structural ordering in these two important liquids. Here, by accessing microscopic structural information by computer simulations, we reveal that local translational symmetry breaking is responsible for the density anomalies. On the other hand, the difference in the degree of local orientational symmetry breaking between water and silica, which originates from the difference in their bonding nature, causes not only the difference in the sharpness of density anomalies, but also their distinct glass-forming abilities. Our work not only shows the crucial roles of local translational and orientational symmetry breaking in the physical properties of the two extremely important materials, water and silica, but also provides a unified scenario applicable for other tetrahedral liquids such as Si, Ge, C, BeF 2 , and GeO 2 .
Localized Symmetry Breaking for Tuning Thermal Expansion in ScF _{3} Nanoscale Frameworks
Energy Technology Data Exchange (ETDEWEB)
Hu, Lei [Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083, China; Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States; Qin, Feiyu [Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083, China; Sanson, Andrea [Department of Physics and Astronomy, University of Padova, Padova I-35131, Italy; Huang, Liang-Feng [Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States; Pan, Zhao [Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083, China; Li, Qiang [Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083, China; Sun, Qiang [International Laboratory for Quantum Functional Materials of Henan, School of Physics and Engineering, Zhengzhou University, Zhengzhou 450001, China; Wang, Lu [Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083, China; Guo, Fangmin [X-Ray Science Division, Argonne National Laboratory, Argonne, Illinois 60439, United States; Aydemir, Umut [Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States; Department of Chemistry, Koc University, Sariyer, Istanbul 34450, Turkey; Ren, Yang [X-Ray Science Division, Argonne National Laboratory, Argonne, Illinois 60439, United States; Sun, Chengjun [X-Ray Science Division, Argonne National Laboratory, Argonne, Illinois 60439, United States; Deng, Jinxia [Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083, China; Aquilanti, Giuliana [Elettra Sincrotrone Trieste, Basovizza, Trieste I-34149, Italy; Rondinelli, James M. [Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, United States; Chen, Jun [Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083, China; Xing, Xianran [Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083, China
2018-03-15
The local symmetry, beyond the averaged crystallographic structure, tends to bring unu-sual performances. Negative thermal expansion is a peculiar physical property of solids. Here, we report the delicate design of the localized symmetry breaking to achieve the controllable thermal expansion in ScF3 nano-scale frameworks. Intriguingly, an isotropic zero thermal expansion is concurrently engi-neered by localized symmetry breaking, with a remarkably low coefficient of thermal expansion of about +4.0×10-8/K up to 675K. This mechanism is investigated by the joint analysis of atomic pair dis-tribution function of synchrotron X-ray total scattering and extended X-ray absorption fine structure spectra. A localized rhombohedral distortion presumably plays a critical role in stiffening ScF3 nano-scale frameworks and concomitantly suppressing transverse thermal vibrations of fluorine atoms. This physical scenario is also theoretically corroborated by the extinction of phonon modes with negative Grüneisen parameters in the rhombohedral ScF3. The present work opens an untraditional chemical modification to achieve controllable thermal expansion by breaking local symmetries of materials.
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...... blockade regime. This results in the appearance of a so-called blocking state, which gives rise to negative-differential resistance (NDR). We show that the appearance of NDR and its magnitude in the symmetry-broken benzene SET depends in a complicated way on the interplay between the many-body matrix...
Crossover driven by time-reversal symmetry breaking in quantum chaos
International Nuclear Information System (INIS)
Taniguchi, N.; Hashimoto, A.; Simons, B.D.; Altshuler, B.L.
1994-01-01
Parametric correlations of the energy spectra of quantum chaotic systems are presented in the presence of time-reversal symmetry-breaking perturbations. The spectra disperse as a function of two external perturbations, one of which preserves time-reversal symmetry, while the other violates it. Exact analytical expressions for the parametric two-point autocorrelation function of the density of states are derived in the crossover region by means of the supermatrix method. For the orthogonal-unitary crossover, the velocity distribution is determined and shown to deviate from Gaussian. (orig.)
International Nuclear Information System (INIS)
Yuan Qingxin; Ding Guohui
2005-01-01
We investigate the phenomena of symmetry breaking and phase transition in the ground state of Bose-Einstein condensates (BECs) trapped in a double square well and in an optical lattice well, respectively. By using standing-wave expansion method, we present symmetric and asymmetric ground state solutions of nonlinear Schroedinger equation (NLSE) with a symmetric double square well potential for attractive nonlinearity. In particular, we study the ground state wave function's properties by changing the depth of potential and atomic interactions (here we restrict ourselves to the attractive regime). By using the Fourier grid Hamiltonian method, we also reveal a phase transition of BECs trapped in one-dimensional optical lattice potential.
International Nuclear Information System (INIS)
Yuan Qingxin; Ding Guohui
2005-01-01
We investigate the phenomena of symmetry breaking and phase transition in the ground state of Bose-Einstein condensates (BECs). For BECs trapped in a double square well potential, we present symmetric and asymmetric ground states by using standing-wave expansion method. For BECs trapped in an optical lattice well potential (created by a standing laser wave, and not just an extension of the double square well potential), we reveal a phase transition by using plane-wave expansion method. At the same time we also study the ground state properties with changing the depth of potential and atomic interactions (restrict ourselves to the attractive regime)
Spontaneous symmetry breaking and vector-meson dominance
International Nuclear Information System (INIS)
Caldi, D.G.; Pagels, H.
1977-01-01
This article is a continuation of our previous work on the rho-π puzzle. It examines further consequences of the unification of partial conservation of axial-vector current (PCAC) and vector-meson dominance (VMD) in which the pion is a Goldstone state and the rho is a ''dormant'' Goldstone state. Our new picture of the vector mesons does not require an A 1 meson although such a state is not ruled out. The Weinberg sum rules which provide the raison d'etre for the A 1 are reexamined. The first Weinberg sum rule can be accommodated without a narrow A 1 state although some enhancement seems required. Examining the J/sup P C/ = 1 +- nonet we conclude that a new state, the isoscalar octet partner of the B (1235) should exist around 1.7 GeV assuming ideal mixing. Without a detailed assumption on the mixing angle, its mass should be in the range 1.4 to 1.7 GeV. We also discuss the photon-rho interactions. In the standard VMD picture the predicted rate for rho → π + γ fails by five standard deviations, while in our picture this undesired result is averted
Field-induced cluster spin glass and inverse symmetry breaking enhanced by frustration
Schmidt, M.; Zimmer, F. M.; Magalhaes, S. G.
2018-03-01
We consider a cluster disordered model to study the interplay between short- and long-range interactions in geometrically frustrated spin systems under an external magnetic field (h). In our approach, the intercluster long-range disorder (J) is analytically treated to get an effective cluster model that is computed exactly. The clusters follow a checkerboard lattice with first-neighbor (J1) and second-neighbor (J2) interactions. We find a reentrant transition from the cluster spin-glass (CSG) state to a paramagnetic (PM) phase as the temperature decreases for a certain range of h. This inverse symmetry breaking (ISB) appears as a consequence of both quenched disorder with frustration and h, that introduce a CSG state with higher entropy than the polarized PM phase. The competitive scenario introduced by antiferromagnetic (AF) short-range interactions increases the CSG state entropy, leading to continuous ISB transitions and enhancing the ISB regions, mainly in the geometrically frustrated case (J1 =J2). Remarkably, when strong AF intracluster couplings are present, field-induced CSG phases can be found. These CSG regions are strongly related to the magnetization plateaus observed in this cluster disordered system. In fact, it is found that each field-induced magnetization jump brings a CSG region. We notice that geometrical frustration, as well as cluster size, play an important role in the magnetization plateaus and, therefore, are also relevant in the field-induced glassy states. Our findings suggest that competing interactions support ISB and field-induced CSG phases in disordered cluster systems under an external magnetic field.
Ultra-large distance modification of gravity from Lorentz symmetry breaking at the Planck scale
International Nuclear Information System (INIS)
Gorbunov, Dmitry S.; Sibiryakov, Sergei 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 gravitational attraction between static point masses becomes gradually weaker with increasing of separation and gets replaced by repulsion (antigravity) at exponentially large distances
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.
Soft A4 → Z3 symmetry breaking and cobimaximal neutrino mixing
Ma, Ernest
2016-04-01
I propose a model of radiative charged-lepton and neutrino masses with A4 symmetry. The soft breaking of A4 to Z3 lepton triality is accomplished by dimension-three terms. The breaking of Z3 by dimension-two terms allows cobimaximal neutrino mixing (θ13 ≠ 0, θ23 = π / 4, δCP = ± π / 2) to be realized with only very small finite calculable deviations from the residual Z3 lepton triality. This construction solves a long-standing technical problem inherent in renormalizable A4 models since their inception.
Javvaji, Brahmanandam; He, Bo; Zhuang, Xiaoying
2018-06-01
Graphene is a non-piezoelectric material. Engineering the piezoelectricity in graphene is possible with the help of impurities, defects and structural modifications. This study reports the mechanism of strain induced polarization and the estimation of piezoelectric and flexoelectric coefficients for graphene system. The combination of charge-dipole potential and the strong many-body potential is employed for describing the inter-atomic interactions. The breaking of symmetry in graphene material is utilized to generate the polarization. Pristine graphene, graphene with circular defect, graphene with triangular defect and trapezium-shaped graphene are considered. Molecular dynamics simulations are performed for straining the graphene atomic systems. The optimization of charge-dipole potential functions measure the polarization for these systems. Pristine and circular defect graphene systems show a constant polarization with strain. The polarization is varying with strain for a triangular defected and trapezium-shaped graphene system. The local atomic deformation produces a change in polarization with respect to the strain gradient. Estimated piezo and flexo coefficients motivate the usage of graphene in electro-mechanical devices.
Z → bb-bar probability and asymmetry in a model of dynamical electroweak symmetry breaking
International Nuclear Information System (INIS)
Arbuzov, B.A.; Osipov, M.Yu.
1997-01-01
The deviations from the standard model in the probability of Z → bb-bar decay and in the forward-backward asymmetry in the reaction e + e - → bb-bar are studied in the framework of the model of dynamical electroweak symmetry breaking, the basic point of which is the existence of a triple anomalous W-boson vertex in a region of momenta restricted by a cutoff. A set of equations for additional terms in the W b t-bar vertex is obtained and its solution to the process Z → bb-bar is applied. It is shown that it is possible to obtain a consistent description of both deviations, which is quite nontrivial because these effects are not simply correlated. The necessary value of the anomalous W interaction coupling, λ = -0.22 ± 0.01, is consistent with existing limitations and leads to definite predictions, e.g., for pair W production in e + e - collisions at LEP 200
Javvaji, Brahmanandam; He, Bo; Zhuang, Xiaoying
2018-06-01
Graphene is a non-piezoelectric material. Engineering the piezoelectricity in graphene is possible with the help of impurities, defects and structural modifications. This study reports the mechanism of strain induced polarization and the estimation of piezoelectric and flexoelectric coefficients for graphene system. The combination of charge-dipole potential and the strong many-body potential is employed for describing the inter-atomic interactions. The breaking of symmetry in graphene material is utilized to generate the polarization. Pristine graphene, graphene with circular defect, graphene with triangular defect and trapezium-shaped graphene are considered. Molecular dynamics simulations are performed for straining the graphene atomic systems. The optimization of charge-dipole potential functions measure the polarization for these systems. Pristine and circular defect graphene systems show a constant polarization with strain. The polarization is varying with strain for a triangular defected and trapezium-shaped graphene system. The local atomic deformation produces a change in polarization with respect to the strain gradient. Estimated piezo and flexo coefficients motivate the usage of graphene in electro-mechanical devices.
Symmetry breaking of a Bose–Fermi mixture in a triple-well potential
International Nuclear Information System (INIS)
Yan, Pei-Gen; Wang, Yuan-Sheng; Ji, Shen-Tong; Liu, Xue-Shen
2012-01-01
We investigate the properties of a one-dimensional Bose–Fermi mixture in a triple-well potential with two equally populated spin components at zero temperature. Based on the coupled equations for a Bose–Fermi mixture, we illustrate the symmetry breaking of the Bose–Fermi mixture with different strengths of interspecies and intraspecies interactions that are induced by changing the particle numbers of bosons and fermions. The several novel density profiles of symmetric and asymmetric ground states in the phase diagram of the (N F ,N B ) plane are demonstrated. In addition, the variation of density as a function of N B at fixed N F , which clearly shows the transition among distinct types of symmetric and asymmetric ground states, is illustrated. -- Highlights: ► We demonstrate the phase diagram in (N F ,N B ) plane. ► We then illustrate distinct regions in the phase diagram of the (N F ,N B ) plane and the corresponding novel typical density profiles of ground states. ► The novel density profiles of symmetric and asymmetric ground states are demonstrated. ► We illustrate the novel phase transitions among some of these ground states.
A self-consistent mean-field approach to the dynamical symmetry breaking
International Nuclear Information System (INIS)
Kunihiro, Teiji; Hatsuda, Tetsuo.
1984-01-01
The dynamical symmetry breaking phenomena in the Nambu and Jona-Lasimio model are reexamined in the framework of a self-consistent mean-field (SCMF) theory. First, we formulate the SCMF theory in a lucid manner based on a successful decomposition of the Lagrangian into semiclassical and residual interaction parts by imposing a condition that ''the dangerous term'' in Bogoliubov's sense should vanish. Then, we show that the difference of the energy density between the super and normal phases, the correct expression of which the original authors failed to give, can be readily obtained by applying the SCMF theory. Futhermore, it is shown that the expression thus obtained is identical to that of the effective potential (E.P.) given by the path-integral method with an auxiliary field up to the one loop order in the loop expansion, then one finds a new and simple way to get the E.P. Some numerical results of the E.P. and the dynamically generated mass of fermion are also shown. As another demonstration of the powerfulness of the SCMF theory, we derive, in the Appendix, the energy density of the O(N)-phi 4 model including the higher order corrections in the sense of large N expansion. (author)
Spatial and Spin Symmetry Breaking in Semidefinite-Programming-Based Hartree-Fock Theory.
Nascimento, Daniel R; DePrince, A Eugene
2018-05-08
The Hartree-Fock problem was recently recast as a semidefinite optimization over the space of rank-constrained two-body reduced-density matrices (RDMs) [ Phys. Rev. A 2014 , 89 , 010502(R) ]. This formulation of the problem transfers the nonconvexity of the Hartree-Fock energy functional to the rank constraint on the two-body RDM. We consider an equivalent optimization over the space of positive semidefinite one-electron RDMs (1-RDMs) that retains the nonconvexity of the Hartree-Fock energy expression. The optimized 1-RDM satisfies ensemble N-representability conditions, and ensemble spin-state conditions may be imposed as well. The spin-state conditions place additional linear and nonlinear constraints on the 1-RDM. We apply this RDM-based approach to several molecular systems and explore its spatial (point group) and spin ( Ŝ 2 and Ŝ 3 ) symmetry breaking properties. When imposing Ŝ 2 and Ŝ 3 symmetry but relaxing point group symmetry, the procedure often locates spatial-symmetry-broken solutions that are difficult to identify using standard algorithms. For example, the RDM-based approach yields a smooth, spatial-symmetry-broken potential energy curve for the well-known Be-H 2 insertion pathway. We also demonstrate numerically that, upon relaxation of Ŝ 2 and Ŝ 3 symmetry constraints, the RDM-based approach is equivalent to real-valued generalized Hartree-Fock theory.
Spontaneous symmetry breaking of (1+1)-dimensional φ4 theory in light-front field theory. II
International Nuclear Information System (INIS)
Pinsky, S.S.; van de Sande, B.
1994-01-01
We discuss spontaneous symmetry breaking of (1+1)-dimensional φ 4 theory in light-front field theory using a Tamm-Dancoff truncation. We show that, even though light-front field theory has a simple vacuum state which is an eigenstate of the full Hamiltonian, the field can develop a nonzero vacuum expectation value. This occurs because the zero mode of the field must satisfy an operator-valued constraint equation. In the context of (1+1)-dimensional φ 4 theory we present solutions to the constraint equation using a Tamm-Dancoff truncation to a finite number of particles and modes. We study the behavior of the zero mode as a function of coupling and Fock space truncation. The zero mode introduces new interactions into the Hamiltonian which breaks the Z 2 symmetry of the theory when the coupling is stronger than the critical coupling. We investigate the energy spectrum in the symmetric and broken phases, show that the theory does not break down in the vicinity of the critical coupling, and discuss the connection to perturbation theory. Finally, we study the spectrum of the field φ and show that, in the broken phase, the field is localized away from φ=0 as one would expect from equal-time calculations. We explicitly show that tunneling occurs
Introduction to the workshop: Electroweak symmetry breaking at the TeV scale
International Nuclear Information System (INIS)
Gaillard, M.K.
1984-01-01
As viewed from today's perspective, electroweak symmetry breaking is both the central issue to be addressed by physics in the TeV region, and the most compelling argument for the need to explore that region. While the picture may change considerably over the next decade, it seems reasonable to focus theoretical attention on this issue which is in fact very broad in terms of its possible ramifications. Such a concerted effort can help to sharpen the scientific case for the SSC and provide fresh theoretical input to the ongoing series of workshops and studies aimed at forming a consensus on a choice of SSC design parameters. To set the mood of the workshop the author reviews briefly the physics to be explored prior to the SSC as well as the motivations for exploration of the TeV region for hard collisions. He follows with an example of a possible scenario for the first manifestation of electroweak symmetry breaking at the SSC
Noncritical generation of nonclassical frequency combs via spontaneous rotational symmetry breaking
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.
Local symmetry breaking and spin–phonon coupling in SmCrO3 orthochromite
International Nuclear Information System (INIS)
El Amrani, M.; Zaghrioui, M.; Ta Phuoc, V.; Gervais, F.; Massa, Néstor E.
2014-01-01
Raman scattering and infrared reflectivity performed on polycrystalline SmCrO 3 support strong influence of the antiferromagnetic order on phonon modes. Both measurements show softening of some modes below T 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 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
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.
Symmetry breaking in superstring theories: applications in cosmology and particle physics
International Nuclear Information System (INIS)
Catelin-Julien, T.
2008-10-01
This thesis is devoted to the study of some applications of superstring theory in cosmology and in particle physics. The unifying principle of our work is the stringy spontaneous (super)symmetry breaking mechanism. Our manuscript starts with a general overview of string theory, where the emphasis is put on the aspects that will be important throughout our work. We introduce then our first work, in which we exhibit a new symmetry of the vacua of N = 1 heterotic string theory, exchanging the vectorial and spinorial representations of the grand unified gauge group. In a second part, we consider stringy cosmological evolutions, at non-zero temperature and in the presence of a supersymmetry breaking scale. We also give arguments for a stabilization of the compactification moduli. (author)
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.
Penrose limit, spontaneous symmetry breaking, and holography in a pp-wave background
International Nuclear Information System (INIS)
Das, Sumit R.; Gomez, Cesar; Rey, Soo-Jong
2002-01-01
We argue that the gauge theory dual to the type IIB string theory in a ten-dimensional pp-wave background resides on a Euclidean subspace spanning four of the eight transverse coordinates. We then show that the evolution of the string along one of the light cone directions in the bulk is identifiable as the RG flow of the gauge theory, a relation facilitating the 'holography' of the pp-wave background. The 'holography' reorganizes the dual gauge theory into theories defined over Hilbert subspaces of fixed R charge. The reorganization breaks the SO(4,2)xSO(6) symmetry to a maximal subgroup SO(4)xSO(4) spontaneously. We argue that the low-energy string modes may be regarded as Goldstone modes resulting from such a symmetry breaking pattern
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.
Recent progress for Linear Collider SM/BSM Higgs/electroweak symmetry breaking calculations
International Nuclear Information System (INIS)
Reuter, Juergen
2012-01-01
In this paper I review the calculations (and partially simulations and theoretical studies) that have been made and published during the last two to three years focusing on the electroweak symmetry breaking sector and the Higgs boson(s) within the Standard Model and models beyond the Standard Model (BSM) at or relevant for either the International Linear Collider (ILC) or the Compact Linear Collider (CLIC), commonly abbreviated as Linear Collider (LC). (orig.)
International Nuclear Information System (INIS)
Nojiri, Shin'ichi; Odintsov, Sergei D.; Sugamoto, Akio
2004-01-01
There exists a freedom in a class of four-dimensional electroweak theories proposed by Arkani-Hamed et al. relying on deconstruction and Coleman-Weinberg mechanism. The freedom comes from the winding modes of the link variable (Wilson operator) connecting non-nearest neighbours in the discrete fifth dimension. Using this freedom, dynamical breaking of SU(2) gauge symmetry, mass hierarchy patterns of fermions and Cabbibo-Kobayashi-Maskawa matrix may be obtained
Symmetry-breaking in the response of the parametrically excited pendulum model
International Nuclear Information System (INIS)
Bishop, S.R.; Sofroniou, A.; Shi, P.
2005-01-01
A planar pendulum is considered which is parametrically excited by a periodic vertical force. The amplitude and frequency of the excitation are used as control parameters. The downward, hanging and the upward, inverted positions correspond to equilibrium positions if we only consider the variation in angle measured from the downward position. For moderate levels of forcing, there are zones that exist in the space of control parameters, where the downward hanging position is unstable and initial conditions that are close to the hanging position lead to steady state oscillations of period-2. To review this situation, this paper describes the development of these oscillations as the amplitude of forcing is varied. In the largest zone, a symmetry-breaking occurs which brings about a pair of asymmetric oscillations. This break in symmetry of the period-2 solution can lead to either an increase or decrease in the amplitude of the forthcoming swing and reference to the experimental significance of this angle change is noted in this paper. Typically, further increases of the parameter produce a cascade of period doubling bifurcations, before most oscillating solutions eventually lose their stability so that the system must experience a rotation. As a result, symmetry-breaking becomes an effective precursor to escape from the local potential well around the hanging position. Here we compare this behaviour with that in other resonance zones. The change of geometric structure when the symmetry-breaking bifurcation occurs is examined and graphically represented as a 'pinched' cylinder-like shape, compared with the Moebius strip that has been associated with the period-doubling bifurcation. The paper also refers to practical problems, where the introduction of nonlinearity means that potentially all frequencies below the main zone of the control space lead to dangerous effects and in some scenarios disastrous outcomes
Non-ladder extended renormalization group analysis of the dynamical chiral symmetry breaking
Energy Technology Data Exchange (ETDEWEB)
Aoki, Ken-Ichi; Takagi, Kaoru; Terao, Haruhiko; Tomoyose, Masashi [Kanazawa Univ., Inst. for Theoretical Physics, Kanazawa, Ishikawa (Japan)
2000-04-01
The order parameters of dynamical chiral symmetry breaking in QCD, the dynamical mass of quarks and the chiral condensates, are evaluated by numerically solving the non-perturbative renormalization group (NPRG) equations. We employ an approximation scheme beyond 'the ladder', that is, beyond the (improved) ladder Schwinger-Dyson equations. The chiral condensates are enhanced in comparison with the ladder approximation, which is phenomenologically favorable. The gauge dependence of the order parameters is reduced significantly in this scheme. (author)
Non-ladder extended renormalization group analysis of the dynamical chiral symmetry breaking
International Nuclear Information System (INIS)
Aoki, Ken-Ichi; Takagi, Kaoru; Terao, Haruhiko; Tomoyose, Masashi
2000-01-01
The order parameters of dynamical chiral symmetry breaking in QCD, the dynamical mass of quarks and the chiral condensates, are evaluated by numerically solving the non-perturbative renormalization group (NPRG) equations. We employ an approximation scheme beyond 'the ladder', that is, beyond the (improved) ladder Schwinger-Dyson equations. The chiral condensates are enhanced in comparison with the ladder approximation, which is phenomenologically favorable. The gauge dependence of the order parameters is reduced significantly in this scheme. (author)
Socci, Luciano; Sorianello, Vito; Romagnoli, Marco
2015-07-27
Adiabatic polarization splitter-rotators are investigated exploiting continuous symmetry breaking thereby achieving significant device size and losses reduction in a single mask fabrication process for both SOI channel and ridge waveguides. A crosstalk lower than -25 dB is expected over 300nm bandwidth, making the device suitable for full grid CWDM and diplexer/triplexer FTTH applications at 1310, 1490 and 1550nm.
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.
Spontaneous symmetry breaking, quantization of the electric charge and the anomalies
International Nuclear Information System (INIS)
Abbas, Afsar
1990-01-01
Cancellation of anomalies and on ensuring that fermions are massive, one obtains quantization of the electric charge, which is shown to be independent of the hypercharge quantum number of the Higgs doublet in the Standard Model. Ignorance of this fact can lead to pitfalls. It is shown that contrary to the popular belief, charge quantization is not a consequence of the anomalies but that in addition spontaneous symmetry breaking is essential. (author)
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}.
Neutrino masses and a low breaking scale of left-right symmetry
International Nuclear Information System (INIS)
Khasanov, Oleg; Perez, Gilad
2002-01-01
In left-right symmetric models (LRSMs) the light neutrino masses arise from two sources: the seesaw mechanism and a vacuum expectation value of an SU(2) L triplet. If the left-right symmetry breaking v R is low, v R (less-or-similar sign)15 TeV, the contributions to the light neutrino masses from both the seesaw mechanism and the triplet Yukawa couplings are expected to be well above the experimental bounds. We present a minimal LRSM with an additional U(1) symmetry in which the masses induced by the two sources are below the eV scale and the twofold problem is solved. We further show that, if the U(1) symmetry is also responsible for the lepton flavor structure, the model yields a small mixing angle within the first two lepton generations
Dynamical mechanism of symmetry breaking and particle mass generation in gauge field theories
International Nuclear Information System (INIS)
Miranskij, V.A.; Fomin, P.I.
1985-01-01
The dynamics of the spotaneous symmetry breaking and the particle mass generation in gauge theories with no fundamental scalar fields is considered. The emphasis is on the consideration of the symmetry breaking mechanism connected with the dynamics of the supercritical Coulomb-like forces caused by the gauge boson exchange between fermions. This mechanism is applied to different gauge theories, in particular, to the description of the spontaneous chira symmetry breaking in quantum chromodynamics. The mass relations for pseudoscalar meson nonet are obtained and it is shown that this mechanism resuls in the dynamical realisation of the hypothesis of the partial conservation of the axial-vector currents. The qualitative description of scalar mesons is given. The nature of the ultraviolet divergencies in quantum electrodynamics (QED) is investigated from the viewpoint of the dynamics of the fermion mass generation. The mechanism of the appearance of the additional (in comparison with perturbation theory) ultraviolet divergencies in QED with large bare coupling constant is indicated. The physical phenomenon underlying this mechanism is identified as the field theory analogue of the quantum mechanical ''fall into the centre'' (collapse) phenomenon. The similr phenomenon is shown to take place in some two-dimensional quantum field models. The dynamics of the bifermion condensates formation in tumblin gauge theories is briefly discussed
Dynamical instability induced by the zero mode under symmetry breaking external perturbation
International Nuclear Information System (INIS)
Takahashi, J.; Nakamura, Y.; Yamanaka, Y.
2014-01-01
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. - 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
Spontaneous symmetry breaking due to the trade-off between attractive and repulsive couplings.
Sathiyadevi, K; Karthiga, S; Chandrasekar, V K; Senthilkumar, D V; Lakshmanan, M
2017-04-01
Spontaneous symmetry breaking is an important phenomenon observed in various fields including physics and biology. In this connection, we here show that the trade-off between attractive and repulsive couplings can induce spontaneous symmetry breaking in a homogeneous system of coupled oscillators. With a simple model of a system of two coupled Stuart-Landau oscillators, we demonstrate how the tendency of attractive coupling in inducing in-phase synchronized (IPS) oscillations and the tendency of repulsive coupling in inducing out-of-phase synchronized oscillations compete with each other and give rise to symmetry breaking oscillatory states and interesting multistabilities. Further, we provide explicit expressions for synchronized and antisynchronized oscillatory states as well as the so called oscillation death (OD) state and study their stability. If the Hopf bifurcation parameter (λ) is greater than the natural frequency (ω) of the system, the attractive coupling favors the emergence of an antisymmetric OD state via a Hopf bifurcation whereas the repulsive coupling favors the emergence of a similar state through a saddle-node bifurcation. We show that an increase in the repulsive coupling not only destabilizes the IPS state but also facilitates the reentrance of the IPS state.
Spontaneous symmetry breaking and fermion chirality in higher-dimensional gauge theory
International Nuclear Information System (INIS)
Wetterich, C.
1985-01-01
The number of chiral fermions may change in the course of spontaneous symmetry breaking. We discuss solutions of a six-dimensional Einstein-Yang-Mills theory based on SO(12). In the resulting effective four-dimensional theory they can be interpreted as spontaneous breaking of a gauge group SO(10) to H=SU(3)sub(C)xSU(2)sub(L)xU(1)sub(R)xU(1)sub(B-L). For all solutions, the fermions which are chiral with respect to H form standard generations. However, the number of generations for the solutions with broken SO(10) may be different compared to the symmetric solutions. All solutions considered here exhibit a local generation group SU(2)sub(G)xU(1)sub(G). For the solutions with broken SO(10) symmetry, the leptons and quarks within one generation transform differently with respect to SU(2)sub(G)xU(1)sub(G). Spontaneous symmetry breaking also modifies the SO(10) relations among Yukawa couplings. All this has important consequences for possible fermion mass relations obtained from higher-dimensional theories. (orig.)
Infrared aspects of spontaneous symmetry breaking of gauge theories in two and three dimensions
International Nuclear Information System (INIS)
Cho, H.T.
1987-01-01
The spontaneous chiral symmetry breaking in SU(N) quantum chromodynamics (QCD) in two dimensions is investigated by calculating the order parameter , where psi is the fermion in the theory, in the authors approximation. In the chiral limit, where the mass of the fermion m → O, is found to be non-zero both in the finite N and N → infinity cases. This implies that chiral symmetry is spontaneously broken by infrared effects in all these cases. The Wilson loop expectation value is calculated for again SU(N) QCD in two dimensions, without fermions. In two dimensions, the Coulomb potential is linear, and thus confining. Under the authors approximation, the area law of the Wilson loop is indeed obtained as expected, for all values of N; in addition, the N-dependent polynomial multiplying the Wilson exponential is also obtained. In quantum electrodynamics (QED) in three dimensions there is a possibility of spontaneous breaking of parity. The authors consider this possibility by studying and the photon propagator. It is found that in the limit m → O, is zero and the photon has a zero mass pole. Therefore, there is no sign of spontaneous parity violation in (QED) in three dimensions induced by infrared effects, in contrast to the positive result of chiral symmetry breaking in two dimensions
Dynamical symmetry breaking of λφ4 theory in the two loop effective potential
International Nuclear Information System (INIS)
Yang Jifeng; Ruan Jianhong
2002-01-01
The two loop effective potential of massless λφ 4 theory is presented in several regularization and renormalization prescriptions and the dynamical symmetry breaking solution is obtained in the strong-coupling situation in several prescriptions except the Coleman-Weinberg prescription. The beta function in the broken phase becomes negative and the UV fixed point turns out to be a strong-coupling one, and its numeric value varies with the renormalization prescriptions, a detail which is different from the asymptotic-free solution in the one loop case. The symmetry-breaking phase is shown to be an entirely strong-coupling phase. The reason for the relevance of the renormalization prescriptions is shown to be due to the nonperturbative nature of the effective potential. We also reanalyze the two loop effective potential by adopting a differential equation approach based on the understanding that all the quantum field theories are ill-defined formulations of the 'low-energy' effective theories of a complete underlying theory. The relevance of the prescriptions of fixing the local ambiguities to physical properties such as symmetry breaking is further emphasized. We also tentatively propose a rescaling insensitivity argument for fixing the quadratic ambiguities. Some detailed properties of the strongly coupled broken phase and related issues are discussed
International Nuclear Information System (INIS)
Weber, Norbert; Galindo, Vladimir; Stefani, Frank; Weier, Tom
2015-01-01
The Tayler instability is a kink-type, current driven instability that plays an important role in plasma physics but might also be relevant in liquid metal applications with high electrical currents. In the framework of the Tayler–Spruit dynamo model of stellar magnetic field generation (Spruit 2002 Astron. Astrophys. 381 923–32), the question of spontaneous helical (chiral) symmetry breaking during the saturation of the Tayler instability has received considerable interest (Zahn et al 2007 Astron. Astrophys. 474 145–54; Gellert et al 2011 Mon. Not. R. Astron. Soc. 414 2696–701; Bonanno et al 2012 Phys. Rev. E 86 016313). Focusing on fluids with low magnetic Prandtl numbers, for which the quasistatic approximation can be applied, we utilize an integro-differential equation approach (Weber et al 2013 New J. Phys.15 043034) in order to investigate the saturation mechanism of the Tayler instability. Both the exponential growth phase and the saturated phase are analysed in terms of the action of the α and β effects of mean-field magnetohydrodynamics. In the exponential growth phase we always find a spontaneous chiral symmetry breaking which, however, disappears in the saturated phase. For higher degrees of supercriticality, we observe helicity oscillations in the saturated regime. For Lundquist numbers in the order of one we also obtain chiral symmetry breaking of the saturated magnetic field. (paper)
The spectral density of the QCD Dirac operator and patterns of chiral symmetry breaking
International Nuclear Information System (INIS)
Toublan, D.; Verbaarschot, J.J.M.
1999-01-01
We study the spectrum of the QCD Dirac operator for two colors with fermions in the fundamental representation and for two or more colors with adjoint fermions. For N f flavors, the chiral flavor symmetry of these theories is spontaneously broken according to SU (2N f → Sp (2N f ) and SU (N f → O (N f ), respectively, rather than the symmetry breaking pattern SU (N f ) x SU (N f ) → SU (N f ) for QCD with three or more colors and fundamental fermions. In this paper we study the Dirac spectrum for the first two symmetry breaking patterns. Following previous work for the third case we find the Dirac spectrum in the domain λ QCD by means of partially quenched chiral perturbation theory. In particular, this result allows us to calculate the slope of the Dirac spectrum at λ = 0. We also show that for λ 2 Λ QCD (wing L the linear size of the system) the Dirac spectrum is given by a chiral Random Matrix Theory with the symmetries of the Dirac operator
Neutrino masses in an SO(10) model with an intermediate stage of symmetry breaking
International Nuclear Information System (INIS)
Svetovoi, V.B.
1982-01-01
The effect on neutrino masses of an intermediate stage in symmetry breaking different from SU(5) is investigated in detail for the SO(10) model. There are two possibilities depending on the contents of the Higgs sector: i) m/sub ν/approx.m/sub f/(M/sub W//M 1 ); ii) m/sub ν/approx.m/sub f/(M/sub W//M 1 )(M/M 1 ), where M, M 1 and M/sub W/ are the scales of the breaking of the original SO(10) symmetry, the intermediate symmetry, and the standard SU/sub c/(3) x SU/sub L/(2) x U(1) symmetry, respectively, and m/sub f/ is a typical fermion mass. It is shown that a Majorana mass of the right-handed-neutrino (ν/sub R/) of a purely loop origin would result in too large a mass of the usual neutrinos, so a tree-graph contribution to the mass of ν/sub R/ is necessary. Numerical estimates for the neutrino masses are discussed
Charge symmetry breaking in the dd → {sup 4}Heπ{sup 0} reaction with WASA-at-COSY
Energy Technology Data Exchange (ETDEWEB)
Zurek, Maria [Forschungszentrum Juelich, Juelich (Germany); Collaboration: WASA-at-COSY-Collaboration
2015-07-01
Investigations of charge symmetry breaking is one of the key topics for the WASA-at-COSY experiment. The study concentrates on the charge symmetry forbidden dd → {sup 4}Heπ{sup 0} reaction. The aim is to compare the experimental results with Chiral Perturbation Theory predictions, probing hadronic effects of the up and down quarks mass difference. It was found that previous data taken close to the reaction threshold were consistent with s-wave. In order to probe also p-wave contributions, new data at sufficiently high energy were required. The measurement should comprise the charge symmetry forbidden dd → {sup 4}Heπ{sup 0} reaction and the charge symmetry conserving reaction dd → {sup 3}Henπ{sup 0} to provide additionally the experimental input for the description of the initial state interactions. Results on the dd → {sup 3}Henπ{sup 0} and dd → {sup 4}Heπ{sup 0} reactions with the WASA detector setup at a beam momentum of 1.2 GeV/c are presented. In addition, the status of the recent high statistics run in spring 2014 is discussed.
Effect of orbital symmetry on the anisotropic superexchange interaction
International Nuclear Information System (INIS)
Kim, Beom Hyun; Min, B I
2011-01-01
Employing the microscopic superexchange model incorporating the effect of spin-orbit interaction, we have investigated the Dzyaloshinsky-Moriya (DM) interaction in perovskite transition-metal (TM) oxides and explored the interplay between the DM interaction and the TM-3d orbital symmetry. For d 3 and d 5 systems with isotropic orbital symmetry, the DM vectors are well described by a simple symmetry analysis considering only the bond geometry. In contrast, the DM interaction for d 4 systems with anisotropic orbital symmetry shows slightly different behavior, which does not obey simple symmetry analysis. The direction as well as the strength of the DM vector varies depending on the occupied orbital shape. We have understood this behavior based on the orbital symmetry induced by local crystal field variation.
Schertzer, D. J. M.; Tchiguirinskaia, I.
2016-12-01
Multifractal fields, whose definition is rather independent of their domain dimension, have opened a new approach of geophysics enabling to explore its spatial extension that is of prime importance as underlined by the expression "spatial chaos". However multifractals have been until recently restricted to be scalar valued, i.e. to one-dimensional codomains. This has prevented to deal with the key question of complex component interactions and their non trivial symmetries. We first emphasize that the Lie algebra of stochastic generators of cascade processes enables us to generalize multifractals to arbitrarily large codomains, e.g. flows of vector fields on large dimensional manifolds. In particular, we have recently investigated the neat example of stable Levy generators on Clifford algebra that have a number of seductive properties, e.g. universal statistical and robust algebra properties, both defining the basic symmetries of the corresponding fields (Schertzer and Tchiguirinskaia, 2015). These properties provide a convenient multifractal framework to study both the symmetries of the fields and how they stochastically break the symmetries of the underlying equations due to boundary conditions, large scale rotations and forcings. These developments should help us to answer to challenging questions such as the climatology of (exo-) planets based on first principles (Pierrehumbert, 2013), to fully address the question of the limitations of quasi- geostrophic turbulence (Schertzer et al., 2012) and to explore the peculiar phenomenology of turbulent dynamics of the atmosphere or oceans that is neither two- or three-dimensional. Pierrehumbert, R.T., 2013. Strange news from other stars. Nature Geoscience, 6(2), pp.8183. Schertzer, D. et al., 2012. Quasi-geostrophic turbulence and generalized scale invariance, a theoretical reply. Atmos. Chem. Phys., 12, pp.327336. Schertzer, D. & Tchiguirinskaia, I., 2015. Multifractal vector fields and stochastic Clifford algebra
Super symmetry in strong and weak interactions
International Nuclear Information System (INIS)
Seshavatharam, U.V.S.; Lakshminarayana, S.
2010-01-01
For strong interaction two new fermion mass units 105.32 MeV and 11450 MeV are assumed. Existence of "Integral charge quark bosons", "Integral charge effective quark fermions", "Integral charge (effective) quark fermi-gluons" and "Integral charge quark boso-gluons" are assumed and their masses are estimated. It is noticed that, characteristic nuclear charged fermion is X s · 105.32 = 938.8 MeV and corresponding charged boson is X s (105.32/x) = 415.0 where X s = 8.914 is the inverse of the strong coupling constant and x = 2.26234 is a new number by using which "super symmetry" can be seen in "strong and weak" interactions. 11450 MeV fermion and its boson of mass = 11450/x = 5060 MeV plays a crucial role in "sub quark physics" and "weak interaction". 938.8 MeV strong fermion seems to be the proton. 415 MeV strong boson seems to be the mother of the presently believed 493,496 and 547 MeV etc, strange mesons. With 11450 MeV fermion "effective quark-fermi-gluons" and with 5060 MeV boson "quark boso-gluon masses" are estimated. "Effective quark fermi-gluons" plays a crucial role in ground state charged baryons mass generation. Light quark bosons couple with these charged baryons to form doublets and triplets. "Quark boso-gluons" plays a crucial role in ground state neutral and charged mesons mass generation. Fine and super-fine rotational levels can be given by [I or (I/2)] power(1/4) and [I or (I/2)] power(1/12) respectively. Here, I = n(n+1) and n = 1, 2, 3, … (author)
Spontaneous Symmetry-Breaking in a Network Model for Quadruped Locomotion
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.
Neutrino masses in the SO(10) model with intermediate stage of the symmetry breaking
International Nuclear Information System (INIS)
Svetovoj, V.B.
1982-01-01
An effect for the neutrino masses of an intermediate stage in the symmetry spontaneous breaking, different from SU(5), is investigated in some detail for the SO(1O) model. There are two possibilities depending on the composition of the Higgs sector: i) msub(ν) approximately msub(f)(Msub(W)/Msub(1)); ii) msub(ν) approximately msub(f)sub(b)/Msub(1))(M/Msub(1)), where M, M 1 and Msub) are the scales of the breaking of the original SO(10) simmetry, the intermediate symmetry, and the standard SUsub(c)(3)xSUsub(L)(2)xU(1) symmetry, respectively, and msub(f) is a typical fermion mass. It as shown that a Majorana mass of the right neutrino (νsub(R)) of a purely loop origin would result in a too large mass of the usual neutrinos, so a tree-graph contribution to the mass of νsub(R) is necessary. Numerical estimates for the neutrino masses are discussed [ru
The pseudo-conformal universe: scale invariance from spontaneous breaking of conformal symmetry
International Nuclear Information System (INIS)
Hinterbichler, Kurt; Khoury, Justin
2012-01-01
We present a novel theory of the very early universe which addresses the traditional horizon and flatness problems of big bang cosmology and predicts a scale invariant spectrum of perturbations. Unlike inflation, this scenario requires no exponential accelerated expansion of space-time. Instead, the early universe is described by a conformal field theory minimally coupled to gravity. The conformal fields develop a time-dependent expectation value which breaks the flat space so(4,2) conformal symmetry down to so(4,1), the symmetries of de Sitter, giving perturbations a scale invariant spectrum. The solution is an attractor, at least in the case of a single time-dependent field. Meanwhile, the metric background remains approximately flat but slowly contracts, which makes the universe increasingly flat, homogeneous and isotropic, akin to the smoothing mechanism of ekpyrotic cosmology. Our scenario is very general, requiring only a conformal field theory capable of developing the appropriate time-dependent expectation values, and encompasses existing incarnations of this idea, specifically the U(1) model of Rubakov and the Galileon Genesis scenario. Its essential features depend only on the symmetry breaking pattern and not on the details of the underlying lagrangian. It makes generic observational predictions that make it potentially distinguishable from standard inflation, in particular significant non-gaussianities and the absence of primordial gravitational waves
Mixed Mediation of Supersymmetry Breaking in Models with Anomalous U(1) Gauge Symmetry
International Nuclear Information System (INIS)
Choi, Kiwoon
2010-01-01
There can be various built-in sources of supersymmetry breaking in models with anomalous U(1) gauge symmetry, e.g. the U(1) D-term, the F-components of the modulus superfield required for the Green-Schwarz anomaly cancellation mechanism and the chiral matter superfields required to cancel the Fayet-Iliopoulos term, and finally the supergravity auxiliary component which can be parameterized by the F-component of chiral compensator. The relative strength between these supersymmetry breaking sources depends crucially on the characteristics of D-flat direction and also on how the D-flat direction is stabilized at a vacuum with nearly vanishing cosmological constant. We examine the possible pattern of the mediation of supersymmetry breaking in models with anomalous U(1) gauge symmetry, and find that various different mixed mediation scenarios can be realized, including the mirage mediation which corresponds to a mixed modulus-anomaly mediation, D-term domination giving a split sparticle spectrum, and also a mixed gauge-D-term mediation scenario.
On the origin of the narrow peak and the isospin symmetry breaking of the X(3872)
International Nuclear Information System (INIS)
Takeuchi, Sachiko; Shimizu, Kiyotaka; Takizawa, Makoto
2014-01-01
The X(3872) formation and decay processes in B-decay are investigated by a cc-bar–two-meson hybrid model. The two-meson state consists of the D 0 D-bar ∗0 , D + D ∗− , J / ψρ, and J / ψω channels. The energy-dependent decay widths of the ρ and ω mesons are introduced. The D–D-bar ∗ interaction is taken to be consistent with a lack of the BB-bar ∗ bound state. The coupling between the DD-bar ∗ and J / ψρ or the DD-bar ∗ and J / ψω channels is obtained from a quark model. The cc-bar–DD-bar ∗ coupling is taken as a parameter to fit the X(3872) mass. The spectrum is calculated up to 4 GeV. It is found that very narrow J / ψρ and J / ψω peaks appear around the D 0 D-bar ∗0 threshold. The size of the J / ψπ 3 peak that we calculated is 1.27–2.24 times as large as that of J / ψπ 2 . The isospin symmetry breaking in the present model comes from the mass difference of the charged and neutral D and D ∗ mesons, which gives a sufficiently large isospin mixing to explain the experiments. It is also found that values of the ratios of the transfer strengths can give information on the X(3872) mass or the size of the cc-bar–DD-bar ∗ coupling
Symmetry breaking in the opinion dynamics of a multi-group project organization
International Nuclear Information System (INIS)
Zhu Zhen-Tao; Zhou Jing; Chen Xing-Guang; Li Ping
2012-01-01
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
Symmetry breaking in the opinion dynamics of a multi-group project organization
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.
Lucarini, Valerio; Fraedrich, Klaus
2009-08-01
Starting from the classical Saltzman two-dimensional convection equations, we derive via a severe spectral truncation a minimal 10 ODE system which includes the thermal effect of viscous dissipation. Neglecting this process leads to a dynamical system which includes a decoupled generalized Lorenz system. The consideration of this process breaks an important symmetry and couples the dynamics of fast and slow variables, with the ensuing modifications to the structural properties of the attractor and of the spectral features. When the relevant nondimensional number (Eckert number Ec) is different from zero, an additional time scale of O(Ec(-1)) is introduced in the system, as shown with standard multiscale analysis and made clear by several numerical evidences. Moreover, the system is ergodic and hyperbolic, the slow variables feature long-term memory with 1/f(3/2) power spectra, and the fast variables feature amplitude modulation. Increasing the strength of the thermal-viscous feedback has a stabilizing effect, as both the metric entropy and the Kaplan-Yorke attractor dimension decrease monotonically with Ec. The analyzed system features very rich dynamics: it overcomes some of the limitations of the Lorenz system and might have prototypical value in relevant processes in complex systems dynamics, such as the interaction between slow and fast variables, the presence of long-term memory, and the associated extreme value statistics. This analysis shows how neglecting the coupling of slow and fast variables only on the basis of scale analysis can be catastrophic. In fact, this leads to spurious invariances that affect essential dynamical properties (ergodicity, hyperbolicity) and that cause the model losing ability in describing intrinsically multiscale processes.
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.
Symmetry breaking patterns of the 3-3-1 model at finite temperature
Energy Technology Data Exchange (ETDEWEB)
Borges, J.S. [Universidade do Estado do Rio de Janeiro, Departamento de Fisica de Altas Energias, Rio de Janeiro, RJ (Brazil); Ramos, Rudnei O. [Universidade do Estado do Rio de Janeiro, Departamento de Fisica Teorica, Rio de Janeiro, RJ (Brazil)
2016-06-15
We consider the minimal version of an extension of the standard electroweak model based on the SU(3){sub c} x SU(3){sub L} x U(1){sub X} gauge symmetry (the 3-3-1 model). We analyze the most general potential constructed from three scalars in the triplet representation of SU(3){sub L}, whose neutral components develop nonzero vacuum expectation values, giving mass for all the model's massive particles. For different choices of parameters, we obtain the particle spectrum for the two symmetry breaking scales: one where the SU(3){sub L} x U(1){sub X} group is broken down to SU(2){sub L} x U(1){sub Y} and a lower scale similar to the standard model one. Within the considerations used, we show that the model encodes two first-order phase transitions, respecting the pattern of symmetry restoration. The last transition, corresponding to the standard electroweak one, is found to be very weak first-order, most likely turning second-order or a crossover in practice. However, the first transition in this model can be strongly first-order, which might happen at a temperature not too high above the second one. We determine the respective critical temperatures for symmetry restoration for the model. (orig.)
Finite size effects and symmetry breaking in the evolution of networks of competing Boolean nodes
International Nuclear Information System (INIS)
Liu, M; Bassler, K E
2011-01-01
Finite size effects on the evolutionary dynamics of Boolean networks are analyzed. In the model considered, Boolean networks evolve via a competition between nodes that punishes those in the majority. Previous studies have found that large networks evolve to a statistical steady state that is both critical and highly canalized, and that the evolution of canalization, which is a form of robustness found in genetic regulatory networks, is associated with a particular symmetry of the evolutionary dynamics. Here, it is found that finite size networks evolve in a fundamentally different way than infinitely large networks do. The symmetry of the evolutionary dynamics of infinitely large networks that selects for canalizing Boolean functions is broken in the evolutionary dynamics of finite size networks. In finite size networks, there is an additional selection for input-inverting Boolean functions that output a value opposite to the majority of input values. The reason for the symmetry breaking in the evolutionary dynamics is found to be due to the need for nodes in finite size networks to behave differently in order to cooperate so that the system collectively performs as efficiently as possible. The results suggest that both finite size effects and symmetry are fundamental for understanding the evolution of real-world complex networks, including genetic regulatory networks.
Topological defect formation and spontaneous symmetry breaking in ion Coulomb crystals.
Pyka, K; Keller, J; Partner, H L; Nigmatullin, R; Burgermeister, T; Meier, D M; Kuhlmann, K; Retzker, A; Plenio, M B; Zurek, W H; del Campo, A; Mehlstäubler, T E
2013-01-01
Symmetry breaking phase transitions play an important role in nature. When a system traverses such a transition at a finite rate, its causally disconnected regions choose the new broken symmetry state independently. Where such local choices are incompatible, topological defects can form. The Kibble-Zurek mechanism predicts the defect densities to follow a power law that scales with the rate of the transition. Owing to its ubiquitous nature, this theory finds application in a wide field of systems ranging from cosmology to condensed matter. Here we present the successful creation of defects in ion Coulomb crystals by a controlled quench of the confining potential, and observe an enhanced power law scaling in accordance with numerical simulations and recent predictions. This simple system with well-defined critical exponents opens up ways to investigate the physics of non-equilibrium dynamics from the classical to the quantum regime.
Truncation effects in the functional renormalization group study of spontaneous symmetry breaking
International Nuclear Information System (INIS)
Defenu, N.; Mati, P.; Márián, I.G.; Nándori, I.; Trombettoni, A.
2015-01-01
We study the occurrence of spontaneous symmetry breaking (SSB) for O(N) models using functional renormalization group techniques. We show that even the local potential approximation (LPA) when treated exactly is sufficient to give qualitatively correct results for systems with continuous symmetry, in agreement with the Mermin-Wagner theorem and its extension to systems with fractional dimensions. For general N (including the Ising model N=1) we study the solutions of the LPA equations for various truncations around the zero field using a finite number of terms (and different regulators), showing that SSB always occurs even where it should not. The SSB is signalled by Wilson-Fisher fixed points which for any truncation are shown to stay on the line defined by vanishing mass beta functions.
Electroweak symmetry breaking studies at the pp colliders of the 1990's and beyond
International Nuclear Information System (INIS)
Chanowitz, M.S.
1989-01-01
Within the conventional framework of a spontaneously broken gauge theory, general principles establish that the electroweak symmetry is broken by a new force that may be weak with associated new quanta below 1 TeV or strong with quanta above 1 TeV. The SSC parameters, √s = 40 TeV and L = 10 33 cm/sup /minus/2/s/sup /minus/1/, define a minimal facility with assured capability to observe the signals of symmetry breaking by a strong force above 1 TeV. Foreseeable luminosity upgrades would not be able to compensate a much lower collider energy for these physics signals. If the strong WW scattering signal were seen at the SSC in the 1990's it would provide a clear imperative for a collider with the physics reach of the ELOISATRON to begin detailed studies of the new force and quanta early in the next century. 35 refs., 7 figs., 4 tabs
Chiral symmetry breaking and the Banks-Casher relation in lattice QCD with Wilson quarks
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.
Bose-Einstein condensation and symmetry breaking of a complex charged scalar field
International Nuclear Information System (INIS)
Matos, Tonatiuh; Castellanos, Elias; Suarez, Abril
2017-01-01
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.)
Chiral symmetry breaking for domain wall fermions in quenched lattice QCD
International Nuclear Information System (INIS)
Wu Lingling
2001-01-01
The domain wall fermion formulation exhibits full chiral symmetry for finite lattice spacing except for the effects of mixing between the domain walls. Close to the continuum limit these symmetry breaking effects should be described by a single residual mass. We determine this mass from the conservation law obeyed by the conserved axial current in quenched simulations with β = 5.7 and 6.0 and domain wall separations varying between 12 and 48 on 8 3 x 32 and 16 3 x 32 lattices. Using the resulting values for the residual mass we perform two complete and independent calculations of the pion decay constant. Good agreement is found between these two methods and with experiment
Spontaneous symmetry breaking and neutral stability in the noncanonical Hamiltonian formalism
International Nuclear Information System (INIS)
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
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.)
International Nuclear Information System (INIS)
Schröck, M.
2013-01-01
Within the framework of this thesis, the interrelation between the two characteristic phenomena of quantum chromodynamics (QCD), i.e., dynamical chiral symmetry breaking and confinement, is investigated. To this end, we apply lattice gauge field theory techniques and adopt a method to artificially restore the dynamically broken chiral symmetry. The low-mode part of the Dirac eigenspectrum is tied to the dynamical breaking of the chiral symmetry according to the Banks--Casher relation. Utilizing two-flavor dynamical lattice gauge field configurations, we construct valence quark propagators that exclude a variable sized part of the low-mode Dirac spectrum, with the aim of using these as an input for meson and baryon interpolating fields. Subsequently, we explore the behavior of ground and excited states of the low-mode truncated hadrons using the variational analysis method. We look for the existence of confined hadron states and extract effective masses where applicable. Moreover, we explore the evolution of the quark wavefunction renormalization function and the renormalization point invariant mass function of the quark propagator under Dirac low-mode truncation in a gauge fixed setting. Motivated by the necessity of fixing the gauge in the aforementioned study of the quark propagator, we also developed a flexible high performance code for lattice gauge fixing, accelerated by graphic processing units (GPUs) using NVIDIA CUDA (Compute Unified Device Architecture). Lastly, more related but unpublished work on the topic is presented. This includes a study of the locality violation of low-mode truncated Dirac operators, a discussion of the possible extension of the low-mode truncation method to the sea quark sector based on a reweighting scheme, as well as the presentation of an alternative way to restore the dynamically broken chiral symmetry. (author) [de
Chiral symmetry breaking and the spin content of the {rho} and {rho}{sup '} mesons
Energy Technology Data Exchange (ETDEWEB)
Glozman, L.Ya., E-mail: leonid.glozman@uni-graz.at [Institut fuer Physik, FB Theoretische Physik, Universitaet Graz, A-8010 Graz (Austria); Lang, C.B., E-mail: christian.lang@uni-graz.at [Institut fuer Physik, FB Theoretische Physik, Universitaet Graz, A-8010 Graz (Austria); Limmer, M., E-mail: markus.limmer@uni-graz.at [Institut fuer Physik, FB Theoretische Physik, Universitaet Graz, A-8010 Graz (Austria)
2011-11-03
Using interpolators with different SU(2){sub L}xSU(2){sub R} transformation properties we study the chiral symmetry and spin contents of the {rho} and {rho}{sup '} mesons in lattice simulations with dynamical quarks. A ratio of couplings of the q-bar {gamma}{sup i}{tau}q and q-bar {sigma}{sup 0}i{tau}q interpolators to a given meson state at different resolution scales tells one about the degree of chiral symmetry breaking in the meson wave function at these scales. Using a Gaussian gauge invariant smearing of the quark fields in the interpolators, we are able to extract the chiral content of mesons up to the infrared resolution of {approx}1 fm. In the ground state {rho} meson the chiral symmetry is strongly broken with comparable contributions of both the (0,1)+(1,0) and (1/2,1/2){sub b} chiral representations with the former being the leading contribution. In contrast, in the {rho}{sup '} meson the degree of chiral symmetry breaking is manifestly smaller and the leading representation is (1/2,1/2){sub b}. Using a unitary transformation from the chiral basis to the {sup 2S+1}L{sub J} basis, we are able to define and measure the angular momentum content of mesons in the rest frame. This definition is different from the traditional one which uses parton distributions in the infinite momentum frame. The {rho} meson is practically a {sup 3}S{sub 1} state with no obvious trace of a 'spin crisis'. The {rho}{sup '} meson has a sizeable contribution of the {sup 3}D{sub 1} wave, which implies that the {rho}{sup '} meson cannot be considered as a pure radial excitation of the {rho} meson.
Chiral symmetry breaking and the spin content of the ρ and ρ‧ mesons
Glozman, L. Ya.; Lang, C. B.; Limmer, M.
2011-11-01
Using interpolators with different SU(2)L × SU(2)R transformation properties we study the chiral symmetry and spin contents of the ρ and ρ‧ mesons in lattice simulations with dynamical quarks. A ratio of couplings of the qbarγi τq and qbarσ0i τq interpolators to a given meson state at different resolution scales tells one about the degree of chiral symmetry breaking in the meson wave function at these scales. Using a Gaussian gauge invariant smearing of the quark fields in the interpolators, we are able to extract the chiral content of mesons up to the infrared resolution of ∼ 1 fm. In the ground state ρ meson the chiral symmetry is strongly broken with comparable contributions of both the (0 , 1) + (1 , 0) and (1 / 2 , 1 / 2) b chiral representations with the former being the leading contribution. In contrast, in the ρ‧ meson the degree of chiral symmetry breaking is manifestly smaller and the leading representation is (1 / 2 , 1 / 2) b. Using a unitary transformation from the chiral basis to the LJ2S+1 basis, we are able to define and measure the angular momentum content of mesons in the rest frame. This definition is different from the traditional one which uses parton distributions in the infinite momentum frame. The ρ meson is practically a 3S1 state with no obvious trace of a "spin crisis". The ρ‧ meson has a sizeable contribution of the 3D1 wave, which implies that the ρ‧ meson cannot be considered as a pure radial excitation of the ρ meson.
Chiral symmetry breaking and the spin content of the ρ and ρ' mesons
International Nuclear Information System (INIS)
Glozman, L.Ya.; Lang, C.B.; Limmer, M.
2011-01-01
Using interpolators with different SU(2) L xSU(2) R transformation properties we study the chiral symmetry and spin contents of the ρ and ρ ' mesons in lattice simulations with dynamical quarks. A ratio of couplings of the q-bar γ i τq and q-bar σ 0i τq interpolators to a given meson state at different resolution scales tells one about the degree of chiral symmetry breaking in the meson wave function at these scales. Using a Gaussian gauge invariant smearing of the quark fields in the interpolators, we are able to extract the chiral content of mesons up to the infrared resolution of ∼1 fm. In the ground state ρ meson the chiral symmetry is strongly broken with comparable contributions of both the (0,1)+(1,0) and (1/2,1/2) b chiral representations with the former being the leading contribution. In contrast, in the ρ ' meson the degree of chiral symmetry breaking is manifestly smaller and the leading representation is (1/2,1/2) b . Using a unitary transformation from the chiral basis to the 2S+1 L J basis, we are able to define and measure the angular momentum content of mesons in the rest frame. This definition is different from the traditional one which uses parton distributions in the infinite momentum frame. The ρ meson is practically a 3 S 1 state with no obvious trace of a 'spin crisis'. The ρ ' meson has a sizeable contribution of the 3 D 1 wave, which implies that the ρ ' meson cannot be considered as a pure radial excitation of the ρ meson.
Kurihara, Takayuki; Watanabe, Hiroshi; Nakajima, Makoto; Karube, Shutaro; Oto, Kenichi; Otani, YoshiChika; Suemoto, Tohru
2018-03-01
We exploit an intense terahertz magnetic near field combined with femtosecond laser excitation to break the symmetry of photoinduced spin reorientation paths in ErFeO3 . We succeed in aligning macroscopic magnetization reaching up to 80% of total magnetization in the sample to selectable orientations by adjusting the time delay between terahertz and optical pump pulses. The spin dynamics are well reproduced by equations of motion, including time-dependent magnetic potential. We show that the direction of the generated magnetization is determined by the transient direction of spin tilting and the magnetic field at the moment of photoexcitation.
Symmetry breaking effect on determination of polarized and unpolarized parton distributions
International Nuclear Information System (INIS)
Arbabifar, F.; Khorramian, Ali N.; Khanpour, H.; Atashbar Tehrani, S.
2013-01-01
We perform a new extraction for unpolarized and polarized parton distribution functions considering a flavor decompositions for sea quarks and applying very recent deep inelastic scattering (DIS) and semi inclusive deep inelastic scattering (SIDIS) data in the fixed flavor number scheme (FFNS) framework. In the new symmetry breaking scenario the light quark and antiquark densities are extracted separately and new parametrization forms are determined for them. The heavy flavors contribution, including charm and bottom quarks, are also taken to be account for unpolarized distributions
Monopoles and chiral symmetry breaking in compact and noncompact QED3
International Nuclear Information System (INIS)
Fiebig, H.R.
1990-11-01
A comparison of the compact and the noncompact lattice action for 2+1 dimensional QED is made. In particular, the chiral order parameter and the monopole density ρ m are computed as functions of β for N f = 0.2 fermion flavours. The results reveal a strong correlation between and ρ m . Moreover, this correlation is identical for the compact and noncompact theories. This is interpreted as evidence that monopole condensation drives chiral symmetry breaking in lattice QED 3 . (Author) (6 refs., 5 figs.)
Symmetry breaking and uniqueness for the incompressible Navier-Stokes equations
International Nuclear Information System (INIS)
Dascaliuc, Radu; Thomann, Enrique; Waymire, Edward C.; Michalowski, Nicholas
2015-01-01
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
Charge symmetry breaking in the reaction np→dπ0
International Nuclear Information System (INIS)
Niskanen, J.A.; Sebestyen, M.; Thomas, A.W.
1988-01-01
By extending a coupled channels model which has proven successful in describing the reaction pp→π + d, we make predictions for charge symmetry breaking effects in the reaction np→dπ 0 . We find that nucleon and delta mass differences at vertices where pions are emitted or absorbed are important (as for np elastic scattering). However, eta-π 0 mixing is also important in pion production. We predict forward-backward asymmetries in the pion production differential cross section as large as 1% (for laboratory energies below 800 MeV). The asymmetries induced in polarization observables are small
Relativistic Hydrodynamics of Color-Flavor Locking Phase with Spontaneous Symmetry Breaking
Institute of Scientific and Technical Information of China (English)
ZHANG Sun; WANG Fan
2004-01-01
We study the hydrodynamics of color-flavor locking phase of three flavors of light quarks in high density QCD with spontaneous symmetry breaking. The basic hydrodynamic equations are presented based on the Poisson bracket method and the Goldstone phonon and the thermo phonon are compared. The dissipative equations are constructed in the frame of the first-order theory and all the transport coefficients are also defined, which could be looked on as the general case including the Landau's theory and the Eckart's theory
Flavor distributions in the nucleons: SU(2) sea asymmetry or isospin symmetry breaking?
International Nuclear Information System (INIS)
Ma, B.; Schaefer, A.; Greiner, W.
1993-01-01
The Gottfried sum-rule violation reported by the New Muon Collaboration was interpreted as an indication for a flavor asymmetry of the sea quark in the nucleon. We investigate the alternative possibility that isospin symmetry between the proton and the neutron is breaking for small x. We examine systematically the consequences of this possibility for several processes, namely, neutrino deep inelastic scattering, the charged pion Drell-Yan process, the proton Drell-Yan process, and semi-inclusive deep inelastic scattering, and conclude that a decision between the two alternative explanations is possible
Quintessence and inflation from the symmetry breaking transition of the internal manifold
International Nuclear Information System (INIS)
Biswas, Tirthabir; Jaikumar, Prashanth
2004-01-01
We show that even in the simple framework of pure Kaluza-Klein gravity the shape moduli can generate potentials supporting inflation and/or quintessence. Using the shape moduli as the inflaton or quintessence field has the additional benefit of being able to explain symmetry breaking in a natural geometric way. A numerical analysis suggests that in these models it may be possible to obtain sufficient e-foldings during inflation as well as a small cosmological constant at the current epoch (without fine-tuning), while preserving the constraint coming from the fine structure constant
Theories of Electroweak Symmetry Breaking : A Post LHC Run-I Perspective (1/3)
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?
Dynamical symmetry breaking in the Jackiw-Johnson model and the gauge technique
International Nuclear Information System (INIS)
Singh, J.P.
1984-01-01
The Jackiw-Johnson model of dynamical gauge symmetry breaking has been re-examined in the light of the gauge technique. In the limit where the ratio of the axial to vector coupling constants becomes small, or, consistently, in the limit where the ratio of the axial-vector-boson mass to the fermion mass becomes small, an approximate solution for the fermion spectral function has been derived. This gives an extremely small ratio of the axial-vector-boson mass to the fermion mass. (author)
Symmetry breaking and uniqueness for the incompressible Navier-Stokes equations.
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.
Left-right gauge symmetry breaking by radiative corrections in supergravity
International Nuclear Information System (INIS)
Moxhay, P.; Yamamoto, K.
1984-01-01
A supersymmetric SU(2)sub(L) x SU(2)sub(R) x U(1)sub(B-L) gauge theory coupled to N = 1 supergravity is investigated. The scale of left-right gauge symmetry breaking is determined as Msub(R) proportional Msub(P) esup(-1/α) by radiative corrections through the logarithmic evolution of soft supersymmetry breakings. SU(2)sub(L) x SU(2)sub(R) x U(1)sub(B-L) may be embedded in SO(10) grand unification. Cosmological implications intrinsic to the present model are also discussed, which may give a constraint Msub(R) approx.= 10 9-12 GeV. (orig.)
Tests of fundamental symmetries and interactions - using nuclei and lasers
Jungmann, Klaus Peter
State of the art laser technology and modern spectroscopic methods allow to address issues of fundamental symmetries and fundamental interactions in atoms with high precision experiments. In particular the discrete symmetries Parity (P), Charge Conjugation (C), Time Reversal (T) as well as their
Symmetry breaking of SO(10) and constraints on Higgs potential, (1)
International Nuclear Information System (INIS)
Yasue, Masaki.
1980-08-01
The symmetry breaking of SO(10) is studied in the tree approximation of the potential for an adjoint (45) representation and a spinorial (16) representation. The potential can break SO(10) down to SU(3)sub(c) x SU(2)sub(L) x U(1). It is not allowed to break SO(10) down to SU(3)sub(c) x U(1)sub(em) via SU(3)sub(c) x SU(2)sub(L) x U(1) even in the presence of a cubic (16) (16*) (45) coupling. Instead, SU(3) x U(1) comes from SU(4) x U(1). The masses for the physical Higgs scalars are calculated in SU(3)sub(c) x SU(2)sub(L) x U(1). The dynamically allowed region of the vacuum expectation values of the (45) is found to be strongly restricted. As a result, SO(6) and SO(4) cannot show up in the course of the breaking. (author)
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)
Energy Technology Data Exchange (ETDEWEB)
Ito, Yuta [KEK Theory Center, High Energy Accelerator Research Organization,1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Nishimura, Jun [KEK Theory Center, High Energy Accelerator Research Organization,1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Graduate University for Advanced Studies (SOKENDAI),1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan)
2016-12-05
In many interesting physical systems, the determinant which appears from integrating out fermions becomes complex, and its phase plays a crucial role in the determination of the vacuum. An example of this is QCD at low temperature and high density, where various exotic fermion condensates are conjectured to form. Another example is the Euclidean version of the type IIB matrix model for 10d superstring theory, where spontaneous breaking of the SO(10) rotational symmetry down to SO(4) is expected to occur. When one applies the complex Langevin method to these systems, one encounters the singular-drift problem associated with the appearance of nearly zero eigenvalues of the Dirac operator. Here we propose to avoid this problem by deforming the action with a fermion bilinear term. The results for the original system are obtained by extrapolations with respect to the deformation parameter. We demonstrate the power of this approach by applying it to a simple matrix model, in which spontaneous symmetry breaking from SO(4) to SO(2) is expected to occur due to the phase of the complex fermion determinant. Unlike previous work based on a reweighting-type method, we are able to determine the true vacuum by calculating the order parameters, which agree with the prediction by the Gaussian expansion method.
Sum rules for the spontaneous chiral symmetry breaking parameters of QCD
International Nuclear Information System (INIS)
Craigie, N.S.; Stern, J.
1981-03-01
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 starts off with the operators anti qq or (anti qq) 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) (250MeV) 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 seem only to make sense for an A 1 mass close to 1.3GeV and it makes little sense with the current algebra mass Msub(A)=anti 2M. We also give an estimate for the chiral symmetry breaking parameters μ 1 6 =2 2 (anti qsub(L) lambda sup(a)γsub(μ)qsub(L))(anti qsub(R) lambdasup(a) γsup(μ)qsub(R)) >sub(vac) entering in the Weinberg sum rules and μ 2 6 =g 2 sub(vac) entering in a new sum rule we propose involving antisymmetric tensor currents J=anti q σsub(μnu) q. (author)
Universality in random matrix theory and chiral symmetry breaking in QCD
International Nuclear Information System (INIS)
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.)
Breaking of axial symmetry in excited heavy nuclei as identified in giant dipole resonance data
Energy Technology Data Exchange (ETDEWEB)
Grosse, E.; Massarczyk, R. [Technische Universitaet Dresden, Institute of Nuclear and Particle Physics, Dresden (Germany); Junghans, A.R. [Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiation Physics, Dresden (Germany)
2017-11-15
A recent theoretical prediction of a breaking of axial symmetry in quasi all heavy nuclei is confronted to a new critical analysis of photon strength functions of nuclei in the valley of stability. For the photon strength in the isovector giant dipole resonance (IVGDR) regime a parameterization of GDR shapes by the sum of three Lorentzians (TLO) is extrapolated to energies below and above the IVGDR. The impact of non-GDR modes adding to the low energy slope of photon strength is discussed including recent data on photon scattering and other radiative processes. These are shown to be concentrated in energy regions where various model calculations predict intermediate collective strength; thus they are obviously separate from the IVGDR tail. The triple Lorentzian (TLO) ansatz for giant dipole resonances is normalized in accordance to the dipole sum rule. The nuclear droplet model with surface dissipation accounts well for positions and widths without local, nuclide specific, parameters. Very few and only global parameters are needed when a breaking of axial symmetry already in the valley of stability is admitted and hence a reliable prediction for electric dipole strength functions also outside of it is expected. (orig.)
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.
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.
Cathcart, Nicole; Kitaev, Vladimir
2016-09-01
A powerful approach to augment the diversity of well-defined metal nanoparticle (MNP) morphologies, essential for MNP advanced applications, is symmetry breaking combined with seeded growth. Utilizing this approach enabled the formation of bimorphic silver nanoparticles (bi-AgNPs) consisting of two shapes linked by one regrowth point. Bi-AgNPs were formed by using an adsorbing polymer, poly(acrylic acid), PAA, to block the surface of a decahedral AgNP seed and restricting growth of new silver to a single nucleation point. First, we have realized 2-D growth of platelets attached to decahedra producing nanoscale shapes reminiscent of apples, fishes, mushrooms and kites. 1-D bimorphic growth of rods (with chloride) and 3-D bimorphic growth of cubes and bipyramids (with bromide) were achieved by using halides to induce preferential (100) stabilization over (111) of platelets. Furthermore, the universality of the formation of bimorphic nanoparticles was demonstrated by using different seeds. Bi-AgNPs exhibit strong SERS enhancement due to regular cavities at the necks. Overall, the reported approach to symmetry breaking and bimorphic nanoparticle growth offers a powerful methodology for nanoscale shape design.
Mass textures and wolfenstein parameters from breaking the flavour permutational symmetry
Energy Technology Data Exchange (ETDEWEB)
Mondragon, A; Rivera, T. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico,Mexico D.F. (Mexico); Rodriguez Jauregui, E. [Deutsches Elekronen-Synchrotron, Theory Group, Hamburg (Germany)
2001-12-01
We will give an overview of recent progress in the phenomenological study of quark mass matrices, quark flavour mixings and CP-violation with emphasis on the possibility of an underlying discrete, flavour permutational symmetry and its breaking, from which realistic models of mass generation could be built. The quark mixing angles and CP-violating phase, as well as the Wolfenstein parameters are given in terms of four quark mass ratios and only two parameters (Z{sup 1}/2, {phi}) characterizing the symmetry breaking pattern. Excellent agreement with all current experimental data is found. [Spanish] Daremos una visita panoramica del progreso reciente en el estudio fenomenologico de las matrices de masas y de mezclas del sabor de los quarks y la violacion de PC, con enfasis en la posibilidad de que, subyacentes al problema, se halle una simetria discreta, permutacional del sabor y su rompimiento a partir de las cuales se puedan construir modelos realistas de la generacion de las masas. Los angulos de mezcla de los quarks y la fase que viola CP, asi como los parametros de Wolfenstein se dan en terminos de cuatro razones de masas de los quarks y solamente dos parametros (Z{sup 1}/2, {phi}) que caracterizan el patron del rompimiento de la simetria. Los resultados se encuentran en excelente acuerdo con todos los datos experimentales mas recientes.
Symmetry Breaking and transition form factors from {eta} and {omega} decays
Energy Technology Data Exchange (ETDEWEB)
Roy, Ankhi, E-mail: ankhi@iiti.ac.in [IIT Indore (India); Collaboration: WASA-at-COSY Collaboration
2013-03-15
The WASA-at-COSY collaboration uses meson production and the decays for the realization of the physics goals. Different rare decay channels of the mesons have to be analyzed in order to investigate symmetry breaking patterns. The combination of high intensity COSY (COoler SYnchrotron) beams and the WASA 4{pi} detector setup allows us to study the rare decay channels of light mesons. We are analyzing different symmetry breaking decay channels of {eta} mesons. One rare decay channel {eta}{yields}{pi}{sup + }{pi}{sup -} e{sup + }e{sup -} is being used to test CP violation. The asymmetry in the angle between the electron and pion planes can give insight about the degree of CP violation. The study of another rare decay channel {eta}{yields}{pi}{sup 0}e{sup + }e{sup -} is a test of C-parity violation. Our analysis of transition form factors of different mesons via conversion decays ({eta}{yields}{gamma}{gamma}{sup *}{yields}e{sup + }e{sup -} {gamma}, {omega}{yields}{pi}{sup 0}e{sup + }e{sup -}) provides insight about hadron structure. The transition form-factor of the {omega} meson provides information about the form factor in the time-like region where the two vector particles (the {omega} and the intermediate virtual photon) have an invariant mass squared will be discussed.
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.
“Electroweak symmetry breaking: to Higgs or not to Higgs” (3/3)
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.
“Electroweak symmetry breaking: to Higgs or not to Higgs” (2/3)
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.
“Electroweak symmetry breaking: to Higgs or not to Higgs” (1/3)
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.
Higgs Bosons, Electroweak Symmetry Breaking, and the Physics of the Large Hadron Collider
Quigg, Chris
2007-01-01
The Large Hadron Collider, a 7 + 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?
Quark model with chiral-symmetry breaking and confinement in the Covariant Spectator Theory
Energy Technology Data Exchange (ETDEWEB)
Biernat, Elmer P. [CFTP, Instituto Superior TÃ©cnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal; Pena, Maria Teresa [CFTP, Instituto Superior TÃ©cnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal; Departamento de FÃsica, Instituto Superior TÃ©cnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal; Ribiero, Jose' Emilio F. [CeFEMA, Instituto Superior TÃ©cnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal; Stadler, Alfred [Departamento de FÃsica, Universidade de Ãvora, 7000-671 Ãvora, 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.
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.
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.)
Novel probe of charge symmetry breaking: Deuteron-induced deuteron breakup
International Nuclear Information System (INIS)
Howell, C.R.; Felsher, P.D.; Tornow, W.; Roberts, M.L.; Hanly, J.M.; Weisel, G.J.; Al Ohali, M.; Walter, R.L.; Slaus, I.; Lambert, J.M.; Treado, P.A.; Mertens, G.
1993-01-01
The present paper identifies unique symmetry properties of the rvec d+d→d+p+n breakup reaction that make it an excellent probe for studying charge-symmetry breaking. Measurements were made for two configurations of the ejected particles in the breakup reaction to obtain values of the spin observables A y , A yy , and A zz . These observables are compared for the mirror reactions 2 H(rvec d,dp)n and 2 H(rvec d,dn)p for the two angle pairs (θ d ,φ d ,θ N ,φ N )=(17.0 degree,0 degree,17.0 degree,180 degree) and (17.0 degree,0 degree,34.5 degree,180 degree) for an incident deutron energy of 12 MeV. In addition, spin observables for the 2 H(rvec d,pn)d reaction at θ p =θ n and φ p =φ n +180 degree are shown to provide a particularly good test of charge symmetry. Our A y , A yy , and A zz data for the 2 H(rvec d,pn)d reaction at (θ p ,φ p ,θ n ,φ n )=(17.0 degree,0 degree,17.0 degree,180 degree) are used to illustrate this latter point. Of the ten charge-symmetric sets of observables measured, two were found to differ by 2.5 standard deviations
Double symmetry breaking of solitons in one-dimensional virtual photonic crystals
International Nuclear Information System (INIS)
Li Yongyao; Malomed, Boris A.; Feng Mingneng; Zhou Jianying
2011-01-01
We demonstrate that spatial solitons undergo two consecutive spontaneous symmetry breakings (SSBs), with the increase of the total power, in nonlinear photonic crystals (PhCs) built as arrays of alternating linear and nonlinear stripes, in the case when the maxima of the effective refractive index coincide with the minima of the self-focusing coefficient and vice versa (i.e., the corresponding linear and nonlinear periodic potentials are in competition). This setting may be induced, as a virtual PhC, by means of the electromagnetically induced-transparency (EIT) technique, in a uniform optical medium. It may also be realized as a Bose-Einstein condensate (BEC) subject to the action of the combined periodic optical potential and periodically modulated Feshbach resonance. The first SSB happens at the center of a linear stripe, pushing a broad low-power soliton into an adjacent nonlinear stripe and gradually suppressing side peaks in the soliton's shape. Then the soliton restores its symmetry, being pinned to the midpoint of the nonlinear stripe. The second SSB occurs at higher powers, pushing the narrow soliton off the center of the nonlinear channel, while the soliton keeps its internal symmetry. The results are obtained by means of numerical and analytical methods. They may be employed to control switching of light beams by means of the varying power.
Symmetry breaking and asymptotic freedom in colour SU(3) gauge models
International Nuclear Information System (INIS)
Ma, E.
1976-01-01
A class of quark models based on the colour gauge group SU(3) is shown to be asymptotically free despite the complete breakdown of local symmetry to guarantee infrared stability. The symmetry breakdown is achieved by the presence of elementary scalar fields either through the Higgs mechanism or dynamically as first proposed by Coleman and Weinberg. Asymptotic freedom is preserved by imposing eigenvalue conditions on the coupling constants as first proposed by Chang. New quark species must be present, but below their production threshold, colour can still be a global symmetry which is approximate under SU(3), but exact under SU(2). Among the many implications of this class of models is the possibility of producing isolated quarks and gluons of non-zero mass without altering the short-distance behaviour of the superstrong interaction which binds them. (Auth.)
Investigations of chiral symmetry breaking and topological aspects of lattice QCD
International Nuclear Information System (INIS)
Garcia Ramos, Elena
2013-01-01
The spontaneous breaking of chiral symmetry is a fascinating phenomenon of QCD whose mechanism is still not well understood and it has fundamental phenomenological implications. It is, for instance, responsible for the low mass of the pions which are effectively Goldstone bosons of the spontaneously broken symmetry. Since these phenomena belong to the low energy regime of QCD, non-perturbative techniques have to be applied in order to study them. In this work we use the twisted mass lattice QCD regularization to compute the chiral condensate, the order parameter of spontaneous chiral symmetry breaking. To this end we apply the recently introduced method of spectral projectors which allows us to perform calculations in large volumes due to its inherently low computational cost. This approach, moreover, enables a direct calculation of the chiral condensate based on a theoretically clean definition of the observable via density chains. We thus present a continuum limit determination of the chirally extrapolated condensate for N f =2 and N f =2+1+1 flavours of twisted mass fermions at maximal twist. In addition we study the chiral behavior of the topological susceptibility, a measure of the topological fluctuations of the gauge fields. We again apply the spectral projector method for this calculation. We comment on the difficulties which appear in the calculation of this observable due to the large autocorrelations involved. Finally we present the continuum limit result of the topological susceptibility in the pure gluonic theory which allows us to perform a test of the Witten-Veneziano relation. We found that this relation is well satisfied. Our results support the validity of the Witten-Veneziano formula which relates the topological fluctuations of the gauge fields with the unexpectedly large value of the η' mass.
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.
Weak interaction models with spontaneously broken left-right symmetry
International Nuclear Information System (INIS)
Mohapatra, R.H.
1978-01-01
The present status of weak interaction models with spontaneously broken left-right symmetry is reviewed. The theoretical basis for asymptotic parity conservation, manifest left-right symmetry in charged current weak interactions, natural parity conservation in neutral currents and CP-violation in the context of SU(2)/sub L/ circled x SU (2)/sub R/ circled x U(1) models are outlined in detail. Various directions for further research in the theoretical and experimental side are indicated
New origin for approximate symmetries from distant breaking in extra dimensions
International Nuclear Information System (INIS)
Arkani-Hamed, Nima; Dimopoulos, Savas
2002-01-01
The recently proposed theories with TeV-scale quantum gravity do not have the usual ultraviolet desert between ∼10 3 -10 19 GeV where effective field theory ideas apply. Consequently, the success of the desert in explaining approximate symmetries is lost, and theories of flavor, neutrino masses, proton longevity or supersymmetry breaking lose their usual habitat. In this paper we show that these ideas can find a new home in an infrared desert: the large space in the extra dimensions. The main idea is that symmetries are primordially exact on our brane, but are broken at O(1) on distant branes. This breaking is communicated to us in a distance-suppressed way by bulk messengers. We illustrate these ideas in a number of settings: (1) We construct theories for the fermion mass hierarchy which avoid problems with large flavor-changing neutral currents; (2) we reiterate that proton stability can arise if baryon number is gauged in the bulk; (3) we study limits on light gauge fields and scalars in the bulk coming from rare decays, astrophysics and cosmology; (4) we remark that the same ideas can be used to explain small neutrino masses, as well as hierarchical supersymmetry breaking; (5) we construct a theory with bulk technicolor, avoiding the difficulties with extended technicolor. There are also a number of interesting experimental signals of these ideas: (1) attractive or repulsive, isotope dependent sub-millimeter forces ∼10 6 times gravitational strength, from the exchange of light bulk particles; (2) novel Higgs decays to light generation fermions plus bulk scalars; (3) collider production of bulk vector and scalar fields, leading to γ or jet+ missing energy signals as in the case of bulk graviton production, with comparable or larger rates
New origin for approximate symmetries from distant breaking in extra dimensions
International Nuclear Information System (INIS)
Arkani-Hamed, Nima
1998-01-01
The recently proposed theories with TeV-scale quantum gravity do not have the usual ultraviolet desert between approximately 10 3 -10 19 GeV where effective field theory ideas apply. Consequently, the success of the desert in explaining approximate symmetries is lost, and theories of flavor, neutrino masses, proton longevity or supersymmetry breaking, lose their usual habitat. In this paper we show that these ideas can find a new home in an infrared desert: the large space in the extra dimensions. The main idea is that symmetries are primordially exact on our brane, but are broken at O(1) on distant branes. This breaking is communicated to us in a distance-suppressed way by bulk messengers. We illustrate these ideas in a number of settings: (1) We construct theories for the fermion mass hierarchy which avoid problems with large flavor-changing neutral currents. (2) We re-iterate that proton stability can arise if baryon number is gauged in the bulk. (3) We study limits on light gauge fields and scalars in the bulk coming from rare decays, astrophysics and cosmology. (4) We remark that the same ideas can be used to explain small neutrino masses, as well as hierarchical supersymmetry breaking. (5) We construct a theory with bulk technicolor, avoiding the difficulties with extended technicolor. There are also a number of interesting experimental signals of these ideas: (1) Attractive or repulsive, isotope dependent sub-millimeter forces approximately 10 6 times gravitational strength, from the exchange of light bulk particles. (2) Novel Higgs decays to light generation fermions plus bulk scalars. (3) Collider production of bulk vector and scalar fields, leading to γ or jet+ missing energy signals as in the case of bulk graviton production, with comparable or larger rates
Directory of Open Access Journals (Sweden)
David J. Luitz, Nicolas Laflorencie
2017-03-01
Full Text Available Using quantum Monte Carlo simulations, we compute the participation (Shannon-R\\'enyi entropies for groundstate wave functions of Heisenberg antiferromagnets for one-dimensional (line subsystems of length $L$ embedded in two-dimensional ($L\\times L$ square lattices. We also study the line entropy at finite temperature, i.e. of the diagonal elements of the density matrix, for three-dimensional ($L\\times L\\times L$ cubic lattices. The breaking of SU(2 symmetry is clearly captured by a universal logarithmic scaling term $l_q\\ln L$ in the R\\'enyi entropies, in good agreement with the recent field-theory results of Misguish, Pasquier and Oshikawa [arXiv:1607.02465]. We also study the dependence of the log prefactor $l_q$ on the R\\'enyi index $q$ for which a transition is detected at $q_c\\simeq 1$.
Accretion of a symmetry-breaking scalar field by a Schwarzschild black hole.
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).
Constraints on the minimal N=1 supergravity theory from electroweak symmetry breaking
International Nuclear Information System (INIS)
Giudice, G.F.; Ridolfi, G.
1988-01-01
We reanalyze the constraints on the minimal N=1 supergravity extension of the standard model arising from the requirement of a correct spontaneous breakdown of the electroweak symmetry. Driven by recent experimental results, we devote special attention to the case of a top quark much heavier than the conventional choice of 40 GeV, used in previous analyses. Our results are stated in a space of phenomenologically meaningful parameters, providing a direct comparison between the constraints from SU(2) x U(1) breaking and the predictions for supersymmetric particle production. Moreover, an upper bound for the ratio of the two Higgs vacuum expectation values is given, for any value of the top quark mass. (orig.)
Enhancement of neutral tc transitions in the model of dynamical breaking of electroweak symmetry
International Nuclear Information System (INIS)
Arbuzov, B.A.; Osipov, M.Yu.
1999-01-01
The problem of possible deviations from the standard model is considered in the framework of a variant of dynamical electroweak symmetry breaking. It comes clear, that the parameters of the theory, being obtained earlier and describing deviations from standard model in Z → b-barb decay, are also consistent with the existence of a nontrivial solution for vertex t-bar (Z, γ)c. The occurrence of this solution leads to a significant enhancement in neutral flavor changing transition t → c. The intensity of this transition is connected with the c-quark mass, that leads to estimates of probabilities of exotic decays t → c(Z, γ) and of the cross section of a single t-quark production in process e + e - → tc-bar, which threshold is already overcome at LEP2. The model is shown to be consistent with the totality of the existing data, the predictions allow its unambiguous check [ru
Chiral symmetry breaking and nonperturbative scale anomaly in gauge field theories
International Nuclear Information System (INIS)
Miranskij, V.A.; Gusynin, V.P.
1987-01-01
The nonperturbative dynamics of chiral and scale symmetry breaking in asymtotically free and non-asymptotically free (with an ultraviolet stable fixed point) vector-like gauge theories is investigated. In the two-loop approximation analytical expressions for the chiral and gluon condensates are obtained. The hypothesis about a soft behaviour at small distances of composite operators in non-asymptotically free gauge theories with a fixed point is put forward and substantiated. It is shown that in these theories the form of the scale anomaly depends on the type of the phase in coupling constant to which it relates. A new dilaton effective lagrangian for glueball and chiral fields is suggested. The mass relation for the single scalar fermion-antifermion bound state is obtained. The important ingredient of this approach is a large (d≅ 2) dynamical dimension of composite chiral fields. The application of this approach to QCD and technicolour models is discussed