Chiral symmetry and chiral-symmetry breaking
Energy Technology Data Exchange (ETDEWEB)
Peskin, M.E.
1982-12-01
These lectures concern the dynamics of fermions in strong interaction with gauge fields. Systems of fermions coupled by gauge forces have a very rich structure of global symmetries, which are called chiral symmetries. These lectures will focus on the realization of chiral symmetries and the causes and consequences of thier spontaneous breaking. A brief introduction to the basic formalism and concepts of chiral symmetry breaking is given, then some explicit calculations of chiral symmetry breaking in gauge theories are given, treating first parity-invariant and then chiral models. These calculations are meant to be illustrative rather than accurate; they make use of unjustified mathematical approximations which serve to make the physics more clear. Some formal constraints on chiral symmetry breaking are discussed which illuminate and extend the results of our more explicit analysis. Finally, a brief review of the phenomenological theory of chiral symmetry breaking is presented, and some applications of this theory to problems in weak-interaction physics are discussed. (WHK)
Chiral symmetry breaking and monopoles
Di Giacomo, Adriano; Pucci, Fabrizio
2015-01-01
To understand the relation between the chiral symmetry breaking and monopoles, the chiral condensate which is the order parameter of the chiral symmetry breaking is calculated in the $\\overline{\\mbox{MS}}$ scheme at 2 [GeV]. First, we add one pair of monopoles, varying the monopole charges $m_{c}$ from zero to four, to SU(3) quenched configurations by a monopole creation operator. The low-lying eigenvalues of the Overlap Dirac operator are computed from the gauge links of the normal configurations and the configurations with additional monopoles. Next, we compare the distributions of the nearest-neighbor spacing of the low-lying eigenvalues with the prediction of the random matrix theory. The low-lying eigenvalues not depending on the scale parameter $\\Sigma$ are compared to the prediction of the random matrix theory. The results show the consistency with the random matrix theory. Thus, the additional monopoles do not affect the low-lying eigenvalues. Moreover, we discover that the additional monopoles increa...
Catalysis of Dynamical Chiral Symmetry Breaking by Chiral Chemical Potential
Braguta, V V
2016-01-01
In this paper we study the properties of media with chiral imbalance parameterized by chiral chemical potential. It is shown that depending on the strength of interaction between constituents in the media the chiral chemical potential either creates or enhances dynamical chiral symmetry breaking. Thus the chiral chemical potential plays a role of the catalyst of dynamical chiral symmetry breaking. Physically this effect results from the appearance of the Fermi surface and additional fermion states on this surface which take part in dynamical chiral symmetry breaking. An interesting conclusion which can be drawn is that at sufficiently small temperature chiral plasma is unstable with respect to condensation of Cooper pairs and dynamical chiral symmetry breaking even for vanishingly small interactions between constituents.
Implications of Local Chiral Symmetry Breaking
La, H S
2003-01-01
The spontaneous symmetry breaking of a local chiral symmetry to its diagonal vector symmetry naturally realizes a complete geometrical structure more general than that of Yang-Mills (YM) theory, rather similar to that of gravity. A good example is the Quantum Chromodynamics (QCD) with respect to the Chiral Color model. Also, a new anomaly-free particle content for a Chiral Color model is introduced: the Chiral Color can be realized without introducing whole new generations of quarks and leptons, but by simply enlarging each generation with new exotic fermions.
Spontaneous chiral symmetry breaking in metamaterials
Liu, Mingkai; Powell, David A.; Shadrivov, Ilya V.; Lapine, Mikhail; Kivshar, Yuri S.
2014-07-01
Spontaneous chiral symmetry breaking underpins a variety of areas such as subatomic physics and biochemistry, and leads to an impressive range of fundamental phenomena. Here we show that this prominent effect is now available in artificial electromagnetic systems, enabled by the advent of magnetoelastic metamaterials where a mechanical degree of freedom leads to a rich variety of strong nonlinear effects such as bistability and self-oscillations. We report spontaneous symmetry breaking in torsional chiral magnetoelastic structures where two or more meta-molecules with opposite handedness are electromagnetically coupled, modifying the system stability. Importantly, we show that chiral symmetry breaking can be found in the stationary response of the system, and the effect is successfully demonstrated in a microwave pump-probe experiment. Such symmetry breaking can lead to a giant nonlinear polarization change, energy localization and mode splitting, which provides a new possibility for creating an artificial phase transition in metamaterials, analogous to that in ferrimagnetic domains.
Chiral Symmetry Breaking from Center Vortices
Höllwieser, Roman; Schweigler, Thomas; Heller, Urs M
2014-01-01
We analyze the creation of near-zero modes from would-be zero modes of various topological charge contributions from classical center vortices in SU(2) lattice gauge theory. We show that colorful spherical vortex and instanton configurations have very similar Dirac eigenmodes and also vortex intersections are able to give rise to a finite density of near-zero modes, leading to chiral symmetry breaking via the Banks-Casher formula. We discuss the influence of the magnetic vortex fluxes on quarks and how center vortices may break chiral symmetry.
A strict QCD inequality and mechanisms for chiral symmetry breaking
International Nuclear Information System (INIS)
A strict QCD inequality allows one to discuss mechanisms proposed for breaking the chiral symmetry in QCD. ''Order parameters'' are identified such that if sufficiently many gauge field configurations contribute to them, spontaneous chiral symmetry breaking follows. As an application the role of instantons is discussed in chiral symmetry breaking in QCD. (orig.)
Magnetic rotation and chiral symmetry breaking
Indian Academy of Sciences (India)
Ashok Kumar Jain; Amita
2001-08-01
The deformed mean ﬁeld of nuclei exhibits various geometrical and dynamical symmetries which manifest themselves as various types of rotational and decay patterns. Most of the symmetry operations considered so far have been deﬁned for a situation wherein the angular momentum coincides with one of the principal axes and the principal axis cranking may be invoked. New possibilities arise with the observation of rotational features in weakly deformed nuclei and now interpreted as magnetic rotational bands. More than 120 MR bands have now been identiﬁed by ﬁltering the existing data. We present a brief overview of these bands. The total angular momentum vector in such bands is tilted away from the principal axes. Such a situation gives rise to several new possibilities including breaking of chiral symmetry as discussed recently by Frauendorf. We present the outcome of such symmetries and their possible experimental veriﬁcation. Some possible examples of chiral bands are presented.
Spontaneous Planar Chiral Symmetry Breaking in Cells
Hadidjojo, Jeremy; Lubensky, David
Recent progress in animal development has highlighted the central role played by planar cell polarity (PCP) in epithelial tissue morphogenesis. Through PCP, cells have the ability to collectively polarize in the plane of the epithelium by localizing morphogenetic proteins along a certain axis. This allows direction-dependent modulation of tissue mechanical properties that can translate into the formation of complex, non-rotationally invariant shapes. Recent experimental observations[1] show that cells, in addition to being planar-polarized, can also spontaneously develop planar chirality, perhaps in the effort of making yet more complex shapes that are reflection non-invariant. In this talk we will present our work in characterizing general mechanisms that can lead to spontaneous chiral symmetry breaking in cells. We decompose interfacial concentration of polarity proteins in a hexagonal cell packing into irreducible representations. We find that in the case of polar concentration distributions, a chiral state can only be reached from a secondary instability after the cells are polarized. However in the case of nematic distributions, we show that a finite-amplitude (subcritical, or ``first-order'') nematic transition can send the system from disorder directly to a chiral state. In addition, we find that perturbing the system by stretching the hexagonal packing enables direct (supercritical, or ``second-order'') chiral transition in the nematic case. Finally, we do a Landau expansion to study competition between stretch-induced chirality and the tendency towards a non-chiral state in packings that have retained the full 6-fold symmetry.
On chiral symmetry breaking, topology and confinement
Energy Technology Data Exchange (ETDEWEB)
Shuryak, Edward
2014-08-15
We start with the relation between the chiral symmetry breaking and gauge field topology. New lattice results further enhance the notion of Zero Mode Zone, a very narrow strip of states with quasizero Dirac eigenvalues. Then we move to the issue of “origin of mass” and Brown–Rho scaling: a number of empirical facts contradicts to the idea that masses of quarks and such hadrons as ρ,N decrease near T{sub c}. We argue that while at T=0 the main contribution to the effective quark mass is chirally odd m{sub χ/}, near T{sub c} it rotates to chirally-even component m{sub χ}, because “infinite clusters” of topological solitons gets split into finite ones. Recent progress in understanding of topology require introduction of nonzero holonomy 〈A{sub 0}〉≠0, which splits instantons into N{sub c} (anti)selfdual “instanton–dyons”. Qualitative progress, as well as first numerical studies of the dyon ensemble are reported. New connections between chiral symmetry breaking and confinement are recently understood, since instanton–dyons generate holonomy potential with a minimum at confining value, if the ensemble is dense enough.
Chiral symmetry breaking in QCD Lite
Engel, Georg P; Lottini, Stefano; Sommer, Rainer
2014-01-01
A distinctive feature of the presence of spontaneous chiral symmetry breaking in QCD is the condensation of low modes of the Dirac operator near the origin. The rate of condensation must be equal to the slope of (Mpi^2 Fpi^2)/2 with respect to the quark mass m in the chiral limit, where Mpi and Fpi are the mass and the decay constant of the Nambu-Goldstone bosons. We compute the spectral density of the (Hermitian) Dirac operator, the quark mass, the pseudoscalar meson mass and decay constant by numerical simulations of lattice QCD with two light degenerate Wilson quarks. We use CLS lattices at three values of the lattice spacing in the range 0.05-0.08 fm, and for several quark masses corresponding to pseudoscalar mesons masses down to 190 MeV. Thanks to this coverage of parameters space, we can extrapolate all quantities to the chiral and continuum limits with confidence. The results show that the low quark modes do condense in the continuum as expected by the Banks-Casher mechanism, and the rate of condensat...
Hadron physics and dynamical chiral symmetry breaking
Chang, Lei; Wilson, David J
2012-01-01
Physics is an experimental science; and a constructive feedback between theory and extant and forthcoming experiments is necessary if an understanding of nonperturbative QCD is to be achieved. The Dyson-Schwinger equations connect confinement with dynamical chiral symmetry breaking, both with the observable properties of hadrons, and hence can plausibly provide a means of elucidating the empirical content of strong QCD. We illustrate these points via comments on: in-hadron condensates; dressed-quark anomalous chromo- and electro-magnetic moments; the self-limiting magnitudes of such moments and pion-loop contributions to the gap equation; deep inelastic scattering; the spectra of mesons and baryons; the critical role played by hadron-hadron interactions in producing these spectra; and nucleon elastic and transition form factors.
Personal recollections on chiral symmetry breaking
Kobayashi, Makoto
2016-07-01
The author's work on the mass of pseudoscalar mesons is briefly reviewed. The emergence of the study of CP violation in the renormalizable gauge theory from consideration of chiral symmetry in the quark model is discussed.
Inhomogeneous chiral symmetry breaking in dense neutron-star matter
Buballa, Michael
2015-01-01
An increasing number of model results suggests that chiral symmetry is broken inhomogeneously in a certain window at intermediate densities in the QCD phase diagram. This could have significant effects on the properties of compact stars, possibly leading to new astrophysical signatures. In this contribution we discuss this idea by reviewing recent results on inhomogeneous chiral symmetry breaking under an astrophysics-oriented perspective. After introducing two commonly studied spatial modulations of the chiral condensate, the chiral density wave and the real kink crystal, we focus on their properties and their effect on the equation of state of quark matter. We also describe how these crystalline phases are affected by different elements which are required for a realistic description of a compact star, such as charge neutrality, the presence of magnetic fields, vector interactions and the interplay with color-superconductivity. Finally, we discuss possible signatures of inhomogeneous chiral symmetry breaking...
Mapping chiral symmetry breaking in the excited baryon spectrum
Bicudo, Pedro; Llanes-Estrada, Felipe J; Van Cauteren, Tim
2016-01-01
We study the conjectured "Insensitivity to Chiral Symmetry Breaking" in the highly excited light baryon spectrum. While the experimental spectrum is being measured at JLab and CBELSA/TAPS, this insensitivity remains to be computed theoretically in detail. As the only existing option to have both confinement, highly excited states and chiral symmetry, we adopt the truncated Coulomb gauge formulation of QCD, considering a linearly confining Coulomb term. Adopting a systematic and numerically intensive variational treatment up to 12 harmonic oscillator shells we are able to access several angular and radial excitations. We compute both the excited spectra of $I=1/2$ and $I=3/2$ baryons, up to large spin $J=13/2$, and study in detail the proposed chiral multiplets. While the static-light and light-light spectra clearly show chiral symmetry restoration high in the spectrum, the realization of chiral symmetry is more complicated in the baryon spectrum than earlier expected.
Chiral symmetry breaking with the Curtis-Pennington vertex
Atkinson, D.; Gusynin, V. P.; Maris, P.
1992-01-01
Published in: Phys. Lett. B 303 (1993) 157-162 citations recorded in [Science Citation Index] Abstract: We study chiral symmetry breaking in quenched QED$_4$, using a vertex Ansatz recently proposed by Curtis and Pennington. Bifurcation analysis is employed to establish the existence of a critical c
Examining a possible cascade effect in chiral symmetry breaking
Fariborz, Amir H
2016-01-01
We examine a toy model and a cascade effect for confinement and chiral symmetry breaking which consists in several phase transitions corresponding to the formation of bound states and chiral condensates with different number of fermions for a strong group. We analyze two examples: regular QCD where we calculate the "four quark" vacuum condensate and a preon composite model based on QCD at higher scales. In this context we also determine the number of flavors at which the second chiral and confinement phase transitions occur and discuss the consequences.
Partial quenching and chiral symmetry breaking
Creutz, Michael
2014-01-01
Partially quenched chiral perturbation theory assumes that valence quarks propagating on gauge configurations prepared with sea quarks of different masses will form a chiral condensate as the valence quark mass goes to zero. I present a counterexample involving non-degenerate sea quarks where the valence condensate does not form.
Baryon and chiral symmetry breaking in holographic QCD
Gorsky, Alexander; Krikun, Alexander
2015-01-01
We study the relationship between chiral symmetry breaking and baryons in holographic QCD. We construct a soliton with unit baryon charge in the presence of a nonzero mean value of the scalar bifundamental field, which is dual to the chiral condensate. We obtain a relation between the chiral condensate and the mass of the baryon and find in a clear-cut way that at large values of the condensate the holographic soliton is no longer located on the IR wall. Instead it is split into two halves, which are symmetrically located on the left and right flavor branes. On the other hand we find that the local value of the quark condensate is suppressed in the core of the soliton, which is evidence for a partial chiral symmetry restoration inside the baryon.
Domain Walls and Vortices in Chiral Symmetry Breaking
Eto, Minoru; Nitta, Muneto
2013-01-01
We study domain walls and vortices in chiral symmetry breaking in QCD with N flavors in the chiral limit. If the axial anomaly was absent, there exist stable Abelian axial vortices winding around the spontaneously broken U(1)_A symmetry and non-Abelian axial vortices winding around both the U(1)_A and non-Abelian SU(N) chiral symmetries. In the presence of the axial anomaly term, metastable domain walls are present and Abelian axial vortices must be attached by N domain walls, forming domain wall junctions. We show that a domain wall junction decays into N non-Abelian vortices attached by domain walls, implying its metastability. We also show that domain walls decay through the quantum tunneling by creating a hole bounded by a closed non-Abelian vortex.
Inhomogeneous chiral symmetry breaking in dense neutron-star matter
International Nuclear Information System (INIS)
An increasing number of model results suggests that chiral symmetry is broken inhomogeneously in a certain window at intermediate densities in the QCD phase diagram. This could have significant effects on the properties of compact stars, possibly leading to new astrophysical signatures. In this contribution we discuss this idea by reviewing recent results on inhomogeneous chiral symmetry breaking under an astrophysics-oriented perspective. After introducing two commonly studied spatial modulations of the chiral condensate, the chiral density wave and the real kink crystal, we focus on their properties and their effect on the equation of state of quark matter. We also describe how these crystalline phases are affected by different elements which are required for a realistic description of a compact star, such as charge neutrality, the presence of magnetic fields, vector interactions and the interplay with color superconductivity. Finally, we discuss possible signatures of inhomogeneous chiral symmetry breaking in the core of compact stars, considering the cases of mass-radius relations and neutrino emissivity explicitly. (orig.)
Inhomogeneous chiral symmetry breaking in dense neutron-star matter
Energy Technology Data Exchange (ETDEWEB)
Buballa, Michael; Carignano, Stefano [Technische Universitaet Darmstadt, Theoriezentrum, Institut fuer Kernphysik, Darmstadt (Germany)
2016-03-15
An increasing number of model results suggests that chiral symmetry is broken inhomogeneously in a certain window at intermediate densities in the QCD phase diagram. This could have significant effects on the properties of compact stars, possibly leading to new astrophysical signatures. In this contribution we discuss this idea by reviewing recent results on inhomogeneous chiral symmetry breaking under an astrophysics-oriented perspective. After introducing two commonly studied spatial modulations of the chiral condensate, the chiral density wave and the real kink crystal, we focus on their properties and their effect on the equation of state of quark matter. We also describe how these crystalline phases are affected by different elements which are required for a realistic description of a compact star, such as charge neutrality, the presence of magnetic fields, vector interactions and the interplay with color superconductivity. Finally, we discuss possible signatures of inhomogeneous chiral symmetry breaking in the core of compact stars, considering the cases of mass-radius relations and neutrino emissivity explicitly. (orig.)
Intrinsic transverse momentum and dynamical chiral symmetry breaking
Energy Technology Data Exchange (ETDEWEB)
Christian Weiss, Peter Schweitzer, Mark Strikman
2013-01-01
We study the effect of QCD vacuum structure on the intrinsic transverse momentum distribution of partons in the nucleon at a low scale. The dynamical breaking of chiral symmetry is caused by non-perturbative interactions at distances of the order rho ~ 0.2 - 0.3 fm, much smaller than the typical nucleon size R ~ 1 fm, resulting in a two-scale picture of nucleon structure. Using an effective dynamical model based on chiral constituent quark degrees of freedom and the 1/N_c expansion (chiral quark-soliton model), we calculate the transverse momentum distribution of quarks and antiquarks at a low scale. The distribution of valence quarks is localized at p_T ~ 1/R. The distribution of flavor-singlet unpolarized sea quarks exhibits a power-like tail extending up to the chiral-symmetry-breaking scale 1/{rho}. A similar tail is present in the flavor-nonsinglet polarized sea. These features are model-independent and represent the imprint of the QCD vacuum on the nucleon's partonic structure. At the level of the nucleon's light-cone wave function, we show that sea quarks partly exist in correlated pairs of transverse size {rho} << R, analogous to short-range NN correlations in nuclei. We discuss the implications of our findings for the transverse momentum distributions in hard scattering processes (semi-inclusive DIS, Drell-Yan pair production) and possible experimental tests of the non-perturbative parton correlations induced by QCD vacuum structure.
Chiral symmetry breaking in lattice QED model with fermion brane
Shintani, E
2012-01-01
We propose a novel approach of spontaneous chiral symmetry breaking at near zero temperature in 4 dimensional QED model with 3+1 dimensional fermion brane using Hybrid Monte Carlo simulation. We consider an anisotropic QED coupling in non-compact QED action with the manifest gauge invariant interaction and fermi-velocity which is less than speed of light. This model allows for the scaling study at low temperature and strong coupling region with reduced computational cost. We compute the chiral condensate and its susceptibility with different coupling constant, velocity parameter and flavor number, and therefore obtain a compatible behavior with gap equation in broken phase. We also discuss about the comparison of Graphene model.
Spontaneous chiral symmetry breaking of Hall magnetohydrodynamic turbulence.
Meyrand, Romain; Galtier, Sébastien
2012-11-01
Hall magnetohydrodynamics (MHD) is investigated through three-dimensional direct numerical simulations. We show that the Hall effect induces a spontaneous chiral symmetry breaking of the turbulent dynamics. The normalized magnetic polarization is introduced to separate the right- (R) and left-handed (L) fluctuations. A classical k(-7/3) spectrum is found at small scales for R magnetic fluctuations which corresponds to the electron MHD prediction. A spectrum compatible with k(-11/3) is obtained at large-scales for the L magnetic fluctuations; we call this regime the ion MHD. These results are explained heuristically by rewriting the Hall MHD equations in a succinct vortex dynamical form. Applications to solar wind turbulence are discussed.
Spontaneous chiral symmetry breaking of Hall magnetohydrodynamic turbulence.
Meyrand, Romain; Galtier, Sébastien
2012-11-01
Hall magnetohydrodynamics (MHD) is investigated through three-dimensional direct numerical simulations. We show that the Hall effect induces a spontaneous chiral symmetry breaking of the turbulent dynamics. The normalized magnetic polarization is introduced to separate the right- (R) and left-handed (L) fluctuations. A classical k(-7/3) spectrum is found at small scales for R magnetic fluctuations which corresponds to the electron MHD prediction. A spectrum compatible with k(-11/3) is obtained at large-scales for the L magnetic fluctuations; we call this regime the ion MHD. These results are explained heuristically by rewriting the Hall MHD equations in a succinct vortex dynamical form. Applications to solar wind turbulence are discussed. PMID:23215387
Dynamical symmetry breaking in chiral gauge theories with direct-product gauge groups
Shi, Yan-Liang; Shrock, Robert
2016-09-01
We analyze patterns of dynamical symmetry breaking in strongly coupled chiral gauge theories with direct-product gauge groups G . If the gauge coupling for a factor group Gi⊂G becomes sufficiently strong, it can produce bilinear fermion condensates that break the Gi symmetry itself and/or break other gauge symmetries Gj⊂G . Our comparative study of a number of strongly coupled direct-product chiral gauge theories elucidates how the patterns of symmetry breaking depend on the structure of G and on the relative sizes of the gauge couplings corresponding to factor groups in the direct product.
Dynamical Symmetry Breaking in Chiral Gauge Theories with Direct-Product Gauge Groups
Shi, Yan-Liang
2016-01-01
We analyze patterns of dynamical symmetry breaking in strongly coupled chiral gauge theories with direct-product gauge groups $G$. If the gauge coupling for a factor group $G_i \\subset G$ becomes sufficiently strong, it can produce bilinear fermion condensates that break the $G_i$ symmetry itself and/or break other gauge symmetries $G_j \\subset G$. Our comparative study of a number of strongly coupled direct-product chiral gauge theories elucidates how the patterns of symmetry breaking depend on the structure of $G$ and on the relative sizes of the gauge couplings corresponding to factor groups in the direct product.
Chiral symmetry breaking and chiral polarization: Tests for finite temperature and many flavors
Directory of Open Access Journals (Sweden)
Andrei Alexandru
2015-02-01
Full Text Available It was recently conjectured that, in SU(3 gauge theories with fundamental quarks, valence spontaneous chiral symmetry breaking is equivalent to condensation of local dynamical chirality and appearance of chiral polarization scale Λch. Here we consider more general association involving the low-energy layer of chirally polarized modes which, in addition to its width (Λch, is also characterized by volume density of participating modes (Ω and the volume density of total chirality (Ωch. Few possible forms of the correspondence are discussed, paying particular attention to singular cases where Ω emerges as the most versatile characteristic. The notion of finite-volume “order parameter”, capturing the nature of these connections, is proposed. We study the effects of temperature (in Nf=0 QCD and light quarks (in Nf=12, both in the regime of possible symmetry restoration, and find agreement with these ideas. In Nf=0 QCD, results from several volumes indicate that, at the lattice cutoff studied, the deconfinement temperature Tc is strictly smaller than the overlap–valence chiral transition temperature Tch in real Polyakov line vacuum. Somewhat similar intermediate phase (in quark mass is also seen in Nf=12. It is suggested that deconfinement in Nf=0 is related to indefinite convexity of absolute X-distributions.
Sea quark transverse momentum distributions and dynamical chiral symmetry breaking
Energy Technology Data Exchange (ETDEWEB)
Schweitzer, Peter [Univ. of Connecticut, Storrs, CT (United States); Strikman, Mark [Penn State Univ., State College, PA (United States); Weiss, Christian [JLAB Newport News, VA (United States)
2014-01-01
Recent theoretical studies have provided new insight into the intrinsic transverse momentum distributions of valence and sea quarks in the nucleon at a low scale. The valence quark transverse momentum distributions (q - qbar) are governed by the nucleon's inverse hadronic size R{sup -1} ~ 0.2 GeV and drop steeply at large p{sub T}. The sea quark distributions (qbar) are in large part generated by non-perturbative chiral-symmetry breaking interactions and extend up to the scale rho{sup -1} ~ 0.6 GeV. These findings have many implications for modeling the initial conditions of perturbative QCD evolution of TMD distributions (starting scale, shape of p{sub T}. distributions, coordinate-space correlation functions). The qualitative difference between valence and sea quark intrinsic p{sub T}. distributions could be observed experimentally, by comparing the transverse momentum distributions of selected hadrons in semi-inclusive deep-inelastic scattering, or those of dileptons produced in pp and pbar-p scattering.
Magnetic catalysis of chiral symmetry breaking and the Pauli problem
Ng, Y. Jack
1998-01-01
The non-perturbative Schwinger-Dyson equation is used to show that chiral symmetry is dynamically broken in QED at weak gauge couplings when an external uniform magnetic field is present. A complete analysis of this phenomenon may shed light on the Pauli problem, namely, why $\\alpha$ = 1/137.
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
Ecker, G
1999-01-01
Broken chiral symmetry has become the basis for a unified treatment of hadronic interactions at low energies. After reviewing mechanisms for spontaneous chiral symmetry breaking, I outline the construction of the low--energy effective field theory of the Standard Model called chiral perturbation theory. The loop expansion and the renormalization procedure for this nonrenormalizable quantum field theory are developed. Evidence for the standard scenario with a large quark condensate is presented, in particular from high--statistics lattice calculations of the meson mass spectrum. Elastic pion--pion scattering is discussed as an example of a complete calculation to O(p^6) in the low--energy expansion. The meson--baryon system is the subject of the last lecture. After a short summary of heavy baryon chiral perturbation theory, a recent analysis of pion--nucleon scattering to O(p^3) is reviewed. Finally, I describe some very recent progress in the chiral approach to the nucleon--nucleon interaction.
Cutoff effects of Wilson fermions in the absence of spontaneous chiral symmetry breaking
Della Morte, M; Luz, Magdalena; Morte, Michele Della
2006-01-01
We simulate two dimensional QED with two degenerate Wilson fermions and plaquette gauge action. As a consequence of the Mermin-Wagner theorem, in the continuum limit chiral symmetry is realized a la Wigner. This property affects also the size of the cutoff effects. That can be understood in view of the fact that the leading lattice artifacts are described, in the continuum Symanzik effective theory, by chirality breaking terms. In particular, vacuum expectation values of non-chirality-breaking operators are expected to be O(a) improved in the chiral limit. We provide a numerical confirmation of this expectation by performing a scaling test.
Chiral symmetry breaking in d=3 NJL model in external gravitational and magnetic fields
Gitman, D M
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 gravitational field.
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 ...
Tschierske, Carsten; Ungar, Goran
2016-01-01
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. PMID:26416335
Chiral symmetry of heavy-light scalar mesons with UA(1) symmetry breaking
Dmitrašinović, V.
2012-07-01
In a previous paper, based on a calculation in the nonrelativistic quark model, we advanced the hypothesis that the Ds(2317), D0(2308) mesons are predominantly four-quark states lowered in mass by the flavor-dependent Kobayashi-Kubo-Maskawa ’t Hooft UA(1) symmetry breaking effective interaction. Here we show similar results and conclusions in a relativistic effective chiral model calculation, based on three-light-quark (i.e., two q plus one q¯) local interpolators. To this end we classify the four-quark (three light plus one heavy quark) local interpolators according to their chiral transformation properties and then construct chiral invariant interactions. We evaluate the diagonal matrix elements of the Kobayashi-Kubo-Maskawa ’t Hooft interaction between different interpolating fields and show that the lowest-lying one is always the (antisymmetric) SU(3)F antitriplet belonging to the chiral (3, 3) multiplet. We predict bottom-strange Bs0 and the bottom-nonstrange B0 scalar mesons with equal masses at 5720 MeV, the strange meson being some 100 MeV lower than in most of the quark potential models. We also predict the JP=1+ bottom-nonstrange B1 and the bottom-strange Bs1 meson masses as 5732 MeV and 5765 MeV, respectively, using the Bardeen-Hill-Nowak-Rho-Zahed scalar-vector mass relation.
Spontaneous chiral-symmetry breaking of lattice QCD with massless dynamical quarks
Institute of Scientific and Technical Information of China (English)
2007-01-01
One of the most challenging issues in QCD is the investigation of spontaneous chiral-symmetry breaking, which is characterized by the non-vanishing chiral condensate when the bare fermion mass is zero. In standard methods of the lattice gauge theory, one has to perform expensive simulations at multiple bare quark masses, and employ some modeled functions to extrapolate the data to the chiral limit. This paper applies the probability distribution function method to computing the chiral condensate in lattice QCD with massless dynamical quarks, without any ambiguous mass extrapolation. The results for staggered quarks indicate that this might be a promising and efficient method for investigating the spontaneous chiral-symmetry breaking in lattice QCD, which deserves further investigation.
Chiral-symmetry breaking and confinement in Minkowski space
International Nuclear Information System (INIS)
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
Biernat, Elmar P; Ribeiro, J E; Stadler, Alfred; Gross, Franz
2014-01-01
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.
Chiral-symmetry breaking and confinement in Minkowski space
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.
Aoki, Ken-Ichi; Sato, Daisuke
2016-01-01
We analyze the dynamical chiral symmetry breaking in gauge theory with the nonperturbative renormalization group equation (NPRGE), which is a first order nonlinear partial differential equation (PDE). In case that the spontaneous chiral symmetry breaking occurs, the NPRGE encounters some non-analytic singularities at the finite critical scale even though the initial function is continuous and smooth. Therefore there is no usual solution of the PDE beyond the critical scale. In this paper, we newly introduce the notion of a weak solution which is the global solution of the weak NPRGE. We show how to evaluate the physical quantities with the weak solution.
Explicit versus Dynamical Chiral Symmetry Breaking and Mass Matrix of Quarks and Leptons
Handa, O.; Ishida, S.; Sekiguchi, M.
1992-02-01
By recourse to an analogy between strong and weak interactions, quark mass-matrices consisting of the two parts are proposed, which represent, respectively, dynamical chiral symmetry breaking and explicit one due to small preon mass. The sum rules among quark masses and mixing-matrix elements derived from it seem consistent with present experiments.
Comments on the Chiral Symmetry Breaking in Soft Wall Holographic QCD
DEFF Research Database (Denmark)
Bechi, Jacopo
2009-01-01
In this paper we describe qualitatively some aspects of the holographic QCD. Inspired by a successfull 4D description, we try to separate the Confinement and the Chiral Symmetry Breaking dynamics. We also discuss the realization of the baryons as skyrmions in Soft Wall Holographic QCD, and the...
Chiral symmetry breaking and vacuum polarization in a bag
Yasui, S
2006-01-01
We study the effects of a finite quark mass in the hedgehog configuration in the two phase chiral bag model. We discuss the chiral properties, such as the fractional baryon number and the chiral Casimir energy, by using the Debye expansion for the analytical calculation and the Strutinsky's smearing method for the numerical computation. It is shown that the fractional baryon number carried by massive quarks in the vacuum is canceled by that in the meson sector. A finite term of the chiral Casimir energy is obtained with subtraction of the logarithmic divergence term.
Chiral symmetry breaking from Ginsparg-Wilson fermions
Hernández, Pilar; Lellouch, L P; Hernandez, Pilar; Jansen, Karl; Lellouch, Laurent
2000-01-01
We calculate the large-volume and small-mass dependences of the quark condensate in quenched QCD using Neuberger's operator. We find good agreement with the predictions of quenched chiral perturbation theory, enabling a determination of the chiral lagrangian parameter \\Sigma, up to a multiplicative renormalization.
International Nuclear Information System (INIS)
Claims that spontaneous chiral symmetry breaking in Q.C.D. is mediated by the U(1) axial anomaly are examined from the viewpoint of effective chiral lagrangians. The proofs are seen to arise from a use of effective chiral lagrangians in which the U(1) axial symmetry is explicitly broken by effects of the anomaly. A U(1) axial invariant chiral lagrangian (to be presented) offers no such proof. (author)
New method for dynamical fermions and chiral-symmetry breaking
International Nuclear Information System (INIS)
The reasons for the feasibility of the Microcanonical Fermionic Average (M F A) approach to lattice gauge theory with dynamical fermions are discussed. We then present a new exact algorithm, which is free from systematic errors and convergent even in the chiral limit. (orig.)
Weber, Norbert; 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, the question of spontaneous helical (chiral) symmetry breaking during the saturation of the Tayler instability has received considerable interest. Focusing on fluids with low magnetic Prandtl numbers, for which the quasistatic approximation can be applied, we utilize an integro-differential equation approach in order to investigate the saturation mechanism of the Tayler instability. Both the exponential growth phase and the saturated phase are analyzed in terms of the action of the alpha and beta 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 h...
Patterns of chiral symmetry breaking and a candidate for a C-theorem in four dimensions
Levinsen, J
2002-01-01
We test a candidate for a four-dimensional C-function. This is done by considering all asymptotically free, vectorlike gauge theories with N_f flavors and fermions in arbitrary representations of any simple Lie group. Assuming spontaneous breaking of chiral symmetry in the infrared limit and that the value of the C-function in this limit is determined by the number of Goldstone bosons, we find that only in the case of a theory with two colors and fermions in one single pseudo-real representation of SU(2) the C-theorem seems to be violated. Conversely, this might also be a sign of new constraints, restricting the number of flavors consistent with spontaneous chiral symmetry breaking. For all other groups and representations we find that this candidate C-function decreases along the renormalization group flow.
Anomalies, instantons and chiral symmetry breaking at a Lifshitz point
Bakas, Ioannis
2012-01-01
We give a new twist to an old-fashioned topic in quantum field theory describing violations of the chiral charge conservation of massless fermions through Adler-Bell-Jackiw anomalies in the background of instanton fields in the context of non-relativistic Lifshitz theories. The results we report here summarize in a nut-shell our earlier work on the subject found in arXiv:1103.5693 and arXiv:1110.1332. We present simple examples where index computations can be carried out explicitly focusing, in particular, to gravitational models of Lifshitz type and highlight their differences from ordinary gravity in four space-time dimensions.
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...
Chiral Symmetry Breaking and External Fields in the Kuperstein-Sonnenschein Model
Alam, M Sohaib; Kundu, Arnab
2012-01-01
A novel holographic model of chiral symmetry breaking has been proposed by Kuperstein and Sonnenschein by embedding non-supersymmetric probe D7 and anti-D7 branes in the Klebanov-Witten background. We study the dynamics of the probe flavours in this model in the presence of finite temperature and a constant electromagnetic field. In keeping with the weakly coupled field theory intuition, we find the magnetic field promotes spontaneous breaking of chiral symmetry whereas the electric field restores it. The former effect is universally known as the "magnetic catalysis" in chiral symmetry breaking. In the presence of an electric field such a condensation is inhibited and a current flows. Thus we are faced with a steady-state situation rather than a system in equilibrium. We conjecture a definition of thermodynamic free energy for this steady-state phase and using this proposal we study the detailed phase structure when both electric and magnetic fields are present in two representative configurations: mutually p...
A new Perspective on the Scalar meson Puzzle, from Spontaneous Chiral Symmetry Breaking Beyond BCS
Bicudo, P J A
1998-01-01
We introduce coupled channels of Bethe-Salpeter mesons both in the mass gap equation for chiral symmetry breaking and in the boundstate equation for mesons. Consistency is insured by the Ward Identities for axial currents, which preserve the Goldstone boson nature of the pion. We find that the coupling of channels yields the widths of resonances and contributes to mass splittings, but it does not shift globally the hadron spectrum. We find that coupled channels reduce the breaking of chiral symmetry. This reduction is constrained by the coupling of a scalar meson to a pair of pseudoscalar mesons. The light and wide $\\sigma-f_0(600)$, the narrow $f_0(980)$ and the relatively heavy $f_0(1370)$ are studied in order to comply with the spontaneous breaking of chiral symmetry. Exact calculations are performed in a particular model. In this model we find that the $f_0(980)$ is the best candidate for the groundstate quark antiquark meson . In particular its width is naturally small. In this case the coupled channels ...
Residual Chiral Symmetry Breaking in Domain-Wall Fermions
International Nuclear Information System (INIS)
We study the effective quark mass induced by the finite separation of the domain walls in the domain-wall formulation of chiral fermion as the function of the size of the fifth dimension (Ls), the gauge coupling (β) and the physical volume (V). We measure the mass by calculating the small eigenvalues of the hermitian domain-wall Dirac operator (HDWF(m0 = 1.8)) in the topologically-nontrivial quenched SU(3) gauge configurations. We find that the induced quark mass is nearly independent of the physical volume, decays exponentially as a function of Ls, and has a strong dependence on the size of quantum fluctuations controlled by β. The effect of the choice of the lattice gluon action is also studied
Residual Chiral Symmetry Breaking in Domain-Wall Fermions
International Nuclear Information System (INIS)
The authors study the effective quark mass induced by the finite separation of the domain walls in the domain-wall formulation of chiral fermion as the function of the size of the fifth dimension ($L-s$), the gauge coupling $beta$ and the physical volume $V$. They measure the mass by calculating the small eigenvalues of the hermitian domain-wall Dirac operator ($H-[rm DWF](m-0))$ in the topologically-nontrivial quenched SU(3) gauge configurations. The authors find that the induced quark mass is nearly independent of the physical volume, decays exponentially as a function of $L-s$, and has a strong dependence on the size of quantum fluctuations controlled by $beta$. The effect of the choice of the lattice gluon action is also studied
Chirality and its spontaneous symmetry breaking in two liquid crystal systems
Kang, Louis
Chirality, or handedness, is a key concept spanning all fields of natural science, from biology to mathematics. Chiral structures can arise from achiral building blocks that lack a handedness if their assembly is unstable to chiral deformations, a phenomenon called spontaneous symmetry breaking. We theoretically study the role of chirality in two systems composed of liquid crystals dissolved or suspended in water, and our results match those obtained experimentally by our collaborators. In the first system, we study achiral liquid crystals whose Frank twist modulus is much lower than their splay and bend Frank moduli and which are confined in capillaries. Under homeotropic anchoring, their ground state configuration undergoes spontaneous chiral symmetry breaking when the twist modulus decreases enough relative to the splay and bend moduli. Under degenerate planar anchoring, a small twist-to-saddle-splay ratio of elastic moduli leads to degenerate twisted configurations even though an undeformed configuration is possible. Measuring the twist profile of an experimental system produces a value for the saddle-splay constant, which has been difficult to achieve previously. Under either boundary condition, domain walls and point defects, whose topological charges depend on chirality, separate domains with different degenerate configurations, and certain ones are energetically preferred over others. In the second system, we study filamentous viruses acting as colloidal liquid crystals under the influence of depletion, which promotes condensation of the viruses into 2D colloidal monolayers. These membranes have tunable chirality and show a rich array of emergent behaviors, including a transition from a circular shape to a striking starfish shape upon changing the chirality of constituent viruses, partial coalescence via domain walls through which the viruses twist by 180 degrees, and phase-separated rafts of a particular size when two virus species with different lengths
Lattice QCD analysis for relation between quark confinement and chiral symmetry breaking
Doi, Takahiro M.; Suganuma, Hideo; Iritani, Takumi
2016-01-01
The Polyakov loop and the Dirac modes are connected via a simple analytical relation on the temporally odd-number lattice, where the temporal lattice size is odd with the normal (nontwisted) periodic boundary condition. Using this relation, we investigate the relation between quark confinement and chiral symmetry breaking in QCD. In this paper, we discuss the properties of this analytical relation and numerically investigate each Dirac-mode contribution to the Polyakov loop in both confinement and deconfinement phases at the quenched level. This relation indicates that low-lying Dirac modes have little contribution to the Polyakov loop, and we numerically confirmed this fact. From our analysis, it is suggested that there is no direct one-to-one corresponding between quark confinement and chiral symmetry breaking in QCD. Also, in the confinement phase, we numerically find that there is a new "positive/negative symmetry" in the Dirac-mode matrix elements of link-variable operator which appear in the relation and the Polyakov loop becomes zero because of this symmetry. In the deconfinement phase, this symmetry is broken and the Polyakov loop is non-zero.
Spontaneous chiral symmetry breaking in QCD:a finite-size scaling study on the lattice
Giusti, Leonardo; Giusti, Leonardo; Necco, Silvia
2007-01-01
Spontaneous chiral symmetry breaking in QCD with massless quarks at infinite volume can be seen in a finite box by studying, for instance, the dependence of the chiral condensate from the volume and the quark mass. We perform a feasibility study of this program by computing the quark condensate on the lattice in the quenched approximation of QCD at small quark masses. We carry out simulations in various topological sectors of the theory at several volumes, quark masses and lattice spacings by employing fermions with an exact chiral symmetry, and we focus on observables which are infrared stable and free from mass-dependent ultraviolet divergences. The numerical calculation is carried out with an exact variance-reduction technique, which is designed to be particularly efficient when spontaneous symmetry breaking is at work in generating a few very small low-lying eigenvalues of the Dirac operator. The finite-size scaling behaviour of the condensate in the topological sectors considered agrees, within our stati...
Chiral symmetry breaking with a confining propagator and dynamically massive gluons
Natale, A A; Machado, F A
2011-01-01
Chiral symmetry breaking in QCD is studied introducing a confining effective propagator, as proposed recently by Cornwall, and considering the effect of dynamically massive gluons. The effective confining propagator has the form $1/(k^2+m^2)^2$ and we study the bifurcation equation finding limits on the parameter $m$ below which a satisfactory fermion mass solution is generated. Since the coupling constant and gluon propagator are damped in the infrared, due to the presence of a dynamical gluon mass, the major part of the chiral breaking is only due to the confining propagator and related to the low momentum region of the gap equation. We study the asymptotic behavior of the gap equation containing this confinement effect and massive gluon exchange, and find that the symmetry breaking can be approximated by an effective four-fermion interaction generated by the confining propagator. We compute some QCD chiral parameters as a function of $m$, finding values compatible with the experimental data. We find a simp...
Shape Transitions and Chiral Symmetry Breaking in the Energy Landscape of the Mitotic Chromosome.
Zhang, Bin; Wolynes, Peter G
2016-06-17
We derive an unbiased information theoretic energy landscape for chromosomes at metaphase using a maximum entropy approach that accurately reproduces the details of the experimentally measured pairwise contact probabilities between genomic loci. Dynamical simulations using this landscape lead to cylindrical, helically twisted structures reflecting liquid crystalline order. These structures are similar to those arising from a generic ideal homogenized chromosome energy landscape. The helical twist can be either right or left handed so chiral symmetry is broken spontaneously. The ideal chromosome landscape when augmented by interactions like those leading to topologically associating domain formation in the interphase chromosome reproduces these behaviors. The phase diagram of this landscape shows that the helical fiber order and the cylindrical shape persist at temperatures above the onset of chiral symmetry breaking, which is limited by the topologically associating domain interaction strength.
Shape Transitions and Chiral Symmetry Breaking in the Energy Landscape of the Mitotic Chromosome
Zhang, Bin; Wolynes, Peter G.
2016-06-01
We derive an unbiased information theoretic energy landscape for chromosomes at metaphase using a maximum entropy approach that accurately reproduces the details of the experimentally measured pairwise contact probabilities between genomic loci. Dynamical simulations using this landscape lead to cylindrical, helically twisted structures reflecting liquid crystalline order. These structures are similar to those arising from a generic ideal homogenized chromosome energy landscape. The helical twist can be either right or left handed so chiral symmetry is broken spontaneously. The ideal chromosome landscape when augmented by interactions like those leading to topologically associating domain formation in the interphase chromosome reproduces these behaviors. The phase diagram of this landscape shows that the helical fiber order and the cylindrical shape persist at temperatures above the onset of chiral symmetry breaking, which is limited by the topologically associating domain interaction strength.
Chiral-Symmetry Breaking in Pseudo Quantum Electrodynamics at Finite Temperature
Nascimento, Leandro O; Peña, Francisco; Smith, C Morais; Marino, E C
2015-01-01
We use the Schwinger-Dyson equations in the presence of a thermal bath, in order to study chiral symmetry breaking in a system of massless Dirac fermions interacting through pseudo quantum electrodynamics (PQED3), in (2+1) dimensions. We show that there is a critical temperature $T_c$, below which chiral symmetry is broken, and a corresponding mass gap is dynamically generated, provided the coupling is above a certain, temperature dependent, critical value $\\alpha_c$. The ratio between the energy gap and the critical temperature for this model is estimated to be $2 \\pi$. These results are confirmed by analytical and numerical investigations of the Schwinger-Dyson equation for the electron. In addition, we calculate the first finite-temperature corrections to the static Coulomb interaction. The relevance of this result in the realm of condensed matter systems, like graphene, is briefly discussed.
Shape Transitions and Chiral Symmetry Breaking in the Energy Landscape of the Mitotic Chromosome
Zhang, Bin
2015-01-01
We derive an unbiased information theoretic energy landscape for chromosomes at metaphase using a maximum entropy approach that accurately reproduces the details of the experimentally measured pair-wise contact probabilities between genomic loci. Dynamical simulations using this landscape lead to cylindrical, helically twisted structures reflecting liquid crystalline order. These structures are similar to those arising from a generic ideal homogenized chromosome energy landscape. The helical twist can be either right or left handed so chiral symmetry is broken spontaneously. The ideal chromosome landscape when augmented by interactions like those leading to topologically associating domain (TAD) formation in the interphase chromosome reproduces these behaviors. The phase diagram of this landscape shows the helical fiber order and the cylindrical shape persist at temperatures above the onset of chiral symmetry breaking which is limited by the TAD interaction strength.
International Nuclear Information System (INIS)
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)
Tortora, Luana; Lavrentovich, Oleg D
2011-03-29
In many colloidal systems, an orientationally ordered nematic (N) phase emerges from the isotropic (I) melt in the form of spindle-like birefringent tactoids. In cases studied so far, the tactoids always reveal a mirror-symmetric nonchiral structure, sometimes even when the building units are chiral. We report on chiral symmetry breaking in the nematic tactoids formed in molecularly nonchiral polymer-crowded aqueous solutions of low-molecular weight disodium cromoglycate. The parity is broken by twisted packing of self-assembled molecular aggregates within the tactoids as manifested by the observed optical activity. Fluorescent confocal microscopy reveals that the chiral N tactoids are located at the boundaries of cells. We explain the chirality induction as a replacement of energetically costly splay packing of the aggregates within the curved bipolar tactoidal shape with twisted packing. The effect represents a simple pathway of macroscopic chirality induction in an organic system with no molecular chirality, as the only requirements are orientational order and curved shape of confinement.
Lattice QCD analysis for relation between quark confinement and chiral symmetry breaking
International Nuclear Information System (INIS)
The Polyakov loop and the Dirac modes are connected via a simple analytical relation on the temporally odd-number lattice, where the temporal lattice size is odd with the normal (nontwisted) periodic boundary condition. Using this relation, we investigate the relation between quark confinement and chiral symmetry breaking in QCD. In this paper, we discuss the properties of this analytical relation and numerically investigate each Dirac-mode contribution to the Polyakov loop in both confinement and deconfinement phases at the quenched level. This relation indicates that low-lying Dirac modes have little contribution to the Polyakov loop, and we numerically confirmed this fact. From our analysis, it is suggested that there is no direct one-to-one corresponding between quark confinement and chiral symmetry breaking in QCD. Also, in the confinement phase, we numerically find that there is a new “positive/negative symmetry” in the Dirac-mode matrix elements of link-variable operator which appear in the relation and the Polyakov loop becomes zero because of this symmetry. In the deconfinement phase, this symmetry is broken and the Polyakov loop is non-zero
Lattice QCD analysis for relation between quark confinement and chiral symmetry breaking
Energy Technology Data Exchange (ETDEWEB)
Doi, Takahiro M.; Suganuma, Hideo [Department of Physics, Graduate School of Science, Kyoto University, Kitashirakawa-oiwake, Sakyo, Kyoto 606-8502 (Japan); Iritani, Takumi [Yukawa Institute for Theoretical Physics, Kyoto University, Kitashirakawa-Oiwake, Sakyo, Kyoto 606-8502 (Japan)
2016-01-22
The Polyakov loop and the Dirac modes are connected via a simple analytical relation on the temporally odd-number lattice, where the temporal lattice size is odd with the normal (nontwisted) periodic boundary condition. Using this relation, we investigate the relation between quark confinement and chiral symmetry breaking in QCD. In this paper, we discuss the properties of this analytical relation and numerically investigate each Dirac-mode contribution to the Polyakov loop in both confinement and deconfinement phases at the quenched level. This relation indicates that low-lying Dirac modes have little contribution to the Polyakov loop, and we numerically confirmed this fact. From our analysis, it is suggested that there is no direct one-to-one corresponding between quark confinement and chiral symmetry breaking in QCD. Also, in the confinement phase, we numerically find that there is a new “positive/negative symmetry” in the Dirac-mode matrix elements of link-variable operator which appear in the relation and the Polyakov loop becomes zero because of this symmetry. In the deconfinement phase, this symmetry is broken and the Polyakov loop is non-zero.
Imaging dynamical chiral symmetry breaking: pion wave function on the light front
Chang, Lei; Cobos-Martinez, J J; Roberts, C D; Schmidt, S M; Tandy, P C
2013-01-01
We project onto the light-front the pion's Poincare'-covariant Bethe-Salpeter wave-function, obtained using two different approximations to the kernels of QCD's Dyson-Schwinger equations. At an hadronic scale both computed results are concave and significantly broader than the asymptotic distribution amplitude, \\phi_\\pi^{asy}(x)=6 x(1-x); e.g., the integral of \\phi_\\pi(x)/\\phi_\\pi^{asy}(x) is 1.8 using the simplest kernel and 1.5 with the more sophisticated kernel. Independent of the kernels, the emergent phenomenon of dynamical chiral symmetry breaking is responsible for hardening the amplitude.
Imaging dynamical chiral-symmetry breaking: pion wave function on the light front.
Chang, Lei; Cloët, I C; Cobos-Martinez, J J; Roberts, C D; Schmidt, S M; Tandy, P C
2013-03-29
We project onto the light front the pion's Poincaré-covariant Bethe-Salpeter wave function obtained using two different approximations to the kernels of quantum chromodynamics' Dyson-Schwinger equations. At an hadronic scale, both computed results are concave and significantly broader than the asymptotic distribution amplitude, φ(π)(asy)(x)=6x(1-x); e.g., the integral of φ(π)(x)/φ(π)(asy)(x) is 1.8 using the simplest kernel and 1.5 with the more sophisticated kernel. Independent of the kernels, the emergent phenomenon of dynamical chiral-symmetry breaking is responsible for hardening the amplitude.
Chiral symmetry breaking in three-dimensional quantum electrodynamics as fixed point annihilation
Herbut, Igor F
2016-01-01
Spontaneous chiral symmetry breaking in three dimensional ($d=3$) quantum electrodynamics is understood as annihilation of an infrared-stable fixed point that describes the large-N conformal phase by another unstable fixed point at a critical number of fermions $N=N_c$. We discuss the root of universality of $N_c$ in this picture, together with some features of the phase boundary in the $(d,N)$ plane. In particular, it is shown that as $d\\rightarrow 4$, $N_c\\rightarrow 0$ with a constant slope, our best estimate of which suggests that $N_c = 2.89$ in $d=3$.
Chiral symmetry breaking in three-dimensional quantum electrodynamics as fixed point annihilation
Herbut, Igor F.
2016-07-01
Spontaneous chiral symmetry breaking in three-dimensional (d =3 ) quantum electrodynamics is understood as annihilation of an infrared-stable fixed point that describes the large-N conformal phase by another unstable fixed point at a critical number of fermions N =Nc. We discuss the root of universality of Nc in this picture, together with some features of the phase boundary in the (d ,N ) plane. In particular, it is shown that as d →4 , Nc→0 with a constant slope, our best estimate of which suggests that Nc=2.89 in d =3 .
Symmetries, Symmetry Breaking, Gauge Symmetries
Strocchi, Franco
2015-01-01
The concepts of symmetry, symmetry breaking and gauge symmetries are discussed, their operational meaning being displayed by the observables {\\em and} the (physical) states. For infinitely extended systems the states fall into physically disjoint {\\em phases} characterized by their behavior at infinity or boundary conditions, encoded in the ground state, which provide the cause of symmetry breaking without contradicting Curie Principle. Global gauge symmetries, not seen by the observables, are nevertheless displayed by detectable properties of the states (superselected quantum numbers and parastatistics). Local gauge symmetries are not seen also by the physical states; they appear only in non-positive representations of field algebras. Their role at the Lagrangian level is merely to ensure the validity on the physical states of local Gauss laws, obeyed by the currents which generate the corresponding global gauge symmetries; they are responsible for most distinctive physical properties of gauge quantum field ...
Imaging chiral symmetry breaking from Kekulé bond order in graphene
Gutiérrez, Christopher; Kim, Cheol-Joo; Brown, Lola; Schiros, Theanne; Nordlund, Dennis; Lochocki, Edward B.; Shen, Kyle M.; Park, Jiwoong; Pasupathy, Abhay N.
2016-10-01
Chirality--or `handedness’--is a symmetry property crucial to fields as diverse as biology, chemistry and high-energy physics. In graphene, chiral symmetry emerges naturally as a consequence of the carbon honeycomb lattice. This symmetry can be broken by interactions that couple electrons with opposite momenta in graphene. Here we directly visualize the formation of Kekulé bond order, one such phase of broken chiral symmetry, in an ultraflat graphene sheet grown epitaxially on a copper substrate. We show that its origin lies in the interactions between individual vacancies in the copper substrate that are mediated electronically by the graphene. We show that this interaction causes the bonds in graphene to distort, creating a phase with broken chiral symmetry. The Kekulé ordering is robust at ambient temperature and atmospheric conditions, indicating that intercalated atoms may be harnessed to drive graphene and other two-dimensional materials towards electronically desirable and exotic collective phases.
Fischer, Tobias; Hempel, Matthias
2016-01-01
The thermodynamic bag model (tdBag) has been applied widely to model quark matter properties in both heavy-ion and astrophysics communities. Several fundamental physics aspects are missing in tdBag, e.g., dynamical chiral symmetry breaking (D$\\chi$SB) and repulsions due to the vector interaction are both included explicitly in the novel vBag quark matter model of Kl\\"ahn and Fischer (2015) (Astrophys. J. 810, 134 (2015)). An important feature of vBag is the simultaneous D$\\chi$SB and deconfinement, where the latter links vBag to a given hadronic model for the construction of the phase transition. In this article we discuss the extension to finite temperatures and the resulting phase diagram for the isospin symmetric medium.
Stefani, F; Giesecke, A; Weber, N; Weier, T
2016-01-01
The current-driven, kink-type Tayler instability (TI) is a key ingredient of the Tayler-Spruit dynamo model for the generation of stellar magnetic fields, but is also discussed as a mechanism that might hamper the up-scaling of liquid metal batteries. Under some circumstances, the TI involves a helical flow pattern which goes along with some alpha effect. Here we focus on the chiral symmetry breaking and the related impact on the alpha effect that would be needed to close the dynamo loop in the Tayler-Spruit model. For low magnetic Prandtl numbers, we observe intrinsic oscillations of the alpha effect. These oscillations serve then as the basis for a synchronized Tayler-Spruit dynamo model, which could possibly link the periodic tidal forces of planets with the oscillation periods of stellar dynamos.
Symmetries and Symmetry Breaking
Van Oers, W T H
2003-01-01
In understanding the world of matter, the introduction of symmetry principles following experimentation or using the predictive power of symmetry principles to guide experimentation is most profound. The conservation of energy, linear momentum, angular momentum, charge, and CPT involve fundamental symmetries. All other conservation laws are valid within a restricted subspace of the four interactions: the strong, the electromagnetic, the weak, and the gravitational interaction. In this paper comments are made regarding parity violation in hadronic systems, charge symmetry breaking in two nucleon and few nucleon systems, and time-reversal-invariance in hadronic systems.
Optically probed symmetry breaking in the chiral magnet Cu2OSeO3
Versteeg, R. B.; Vergara, I.; Schaefer, S. D.; Bischoff, D.; Aqeel, A.; Palstra, T. T. M.; Grueninger, M.; van Loosdrecht, P. H. M.
2016-01-01
We report on the linear optical properties of the chiral magnet Cu2OSeO3, specifically associated with the absence of inversion symmetry, the chiral crystallographic structure, and magnetic order. Through spectroscopic ellipsometry, we observe local crystal-field excitations below the charge-transfe
Vanderheyden, B J; Vanderheyden, Benoit
2000-01-01
We consider a random matrix model which describes the competition between chiral symmetry breaking and the formation of quark Cooper pairs in QCD at finite density. We study the evolution of the phase structure in temperature and chemical potential with variations of the strength of the interaction in the quark-quark channel and demonstrate that the phase diagram can realize a total of six different topologies. A vector interaction representing single-gluon exchange reproduces a topology commonly encountered in previous QCD models, in which a low-density chiral broken phase is separated from a high-density diquark phase by a first-order line. The other five topologies either do not possess a diquark phase or display a new phase and new critical points. Since these five cases require large variations of the coupling constants away from the values expected for a vector interaction, we conclude that the phase diagram of finite density QCD has the topology suggested by single-gluon exchange and that this topology...
Peters, Kirstin
2010-01-01
A well-known result by Palamidessi tells us that {\\pi}mix (the {\\pi}-calculus with mixed choice) is more expressive than {\\pi}sep (its subset with only separate choice). The proof of this result argues with their different expressive power concerning leader election in symmetric networks. Later on, Gorla of- fered an arguably simpler proof that, instead of leader election in symmetric networks, employed the reducibility of "incestual" processes (mixed choices that include both enabled senders and receivers for the same channel) when running two copies in parallel. In both proofs, the role of breaking (ini- tial) symmetries is more or less apparent. In this paper, we shed more light on this role by re-proving the above result-based on a proper formalization of what it means to break symmetries-without referring to another layer of the distinguishing problem domain of leader election. Both Palamidessi and Gorla rephrased their results by stating that there is no uniform and reason- able encoding from {\\pi}mix i...
Charge symmetry breaking from a chiral extrapolation of moments of quark distribution functions
Shanahan, P. E.; Thomas, A. W.; Young, R.D.(ARC Centre of Excellence for Particle Physics at the Terascale and CSSM, School of Chemistry and Physics, University of Adelaide, Adelaide, SA 5005, Australia)
2013-01-01
We present a determination, from lattice QCD, of charge symmetry violation in the spin- independent and spin-dependent parton distribution functions of the nucleon. This is done by chirally extrapolating recent QCDSF/UKQCD Collaboration lattice simulations of the first several Mellin moments of the parton distribution functions of octet baryons to the physical point. We find small chiral corrections for the polarized moments, while the corrections are quantitatively significant in the unpolar...
Global Currents, Phase Transitions, and Chiral Symmetry Breaking in Large N_c Gauge Theory
Albash, T; Johnson, C V; Kundu, A; Albash, Tameem; Filev, Veselin; Johnson, Clifford V.; Kundu, Arnab
2006-01-01
We study the finite temperature dynamics of SU(N_c) gauge theory for large N_c, with fundamental quark flavours in a quenched approximation, in the presence of a fixed charge under a global current. We observe several notable phenomena. There is a first order phase transition where the quark condensate jumps discontinuously at finite quark mass, generalizing similar transitions seen at zero charge. We find a non-zero condensate at zero quark mass above a critical value of the charge, corresponding to an analogue of spontaneous chiral symmetry breaking at finite number density. We find that the spectrum of mesons contains the expected associated Goldstone (``pion'') degrees of freedom with a mass dependence on the quark mass that is consistent with the Gell-Mann-Oakes-Renner relation. Our tool in these studies is holography, the string dual of the gauge theory being the geometry of $N_c$ spinning D3-branes at finite temperature, probed by a D7-brane.
Institute of Scientific and Technical Information of China (English)
CHEN Wan-Chun; CHEN Xiao-Long
2007-01-01
@@ We investigate the influence of dc electric field on chiral symmetry breaking during the growing process of NaClO3 crystal. Nucleation and growth of NaClO3 are completed from an aqueous solution by a fast cooling temperature technology. A pair of polarization microscopes are used to identify a distribution of chiral crystals. Experimental results indicate that the dc electric field has an effect on distribution of chirality, but the direction of the dc electric field is not sensitive to the chiral autocatalysis and selectivity, i.e. the nature convection driving by the gravity does not play an important role on a thin layer of NaClO3 solution. The experimental phenomena may be elucidated by the ECSN mechanism.
Extended partially conserved axial-vector current hypothesis and chiral-symmetry breaking
International Nuclear Information System (INIS)
An extended partially conserved axial-vector current (PCAC) hypothesis that incorporates a family of heavy bosons in a model-independent way is proposed. This is motivated by the impossibility of accounting for the corrections to Goldberger-Treiman relations, both in SU(2) x SU(2) and SU(3) x SU(3), by means of ordinary dynamical mechanisms (many-particle intermediate states). This new hypothesis coupled with an assumption on the strong-coupling constants of the heavy bosons leads to the following results: (i) A universality among the corrections to Goldberger-Treiman relations for ΔS = 0 decays, Δ/sub π/, on the one hand and for ΔS not-equal 0 decays, Δ/sub K/, on the other. (ii) From this universality there follow two sets of sum rules involving masses and strong and weak coupling constants. These sum rules become identities in the chiral as well as in the SU(3) limit and although a definite check has to await for the advent of accurate hyperon data, there are indications that they might be saturated. (iii) By studying the Dashen-Weinstein sum rules, new sets of sum rules involving only strong coupling constants are predicted as well as an expression for Δ/sub π//Δ/sub K/ in good agreement with present data. (iv) It is found that Δ/sub π/ and Δ/sub K/, which are a measure of chiral-symmetry breaking, determine completely the on-mass-shell corrections to soft-meson theorems. Since both Δ/sub π/ and Δ/sub K/ are known experimentally, a calculation is made of the on-mass-shell amplitudes for π0 → γγ, eta → γγ, eta → ππγ, γ → πππ,and γγ → πππ starting from the zero-mass limits implied by anomalous Ward identities. In particular, it is found that the results for the radiative eta decays are in agreement with present experimental data without the need for invoking eta-eta' mixing
International Nuclear Information System (INIS)
In this thesis we consider two main subjects, both of them utilizing lattice QCD. This is a rigorously defined approach to quantum field theory and allows for both, for a theoretical analysis and subsequent numerical studies. All techniques and quantities, which need to be introduced, are shortly discussed in the first chapter, in order to fix the notation. Two of the key features of QCD, which are still challenging questions, are chiral symmetry breaking and confinement. For the spontaneous breaking of chiral symmetry the situation is clearer. The main part of this work focuses on gluonic quantities, like the Polyakov loop or the potential of two static color charged particles. They are all either order parameters or give a clear distinguishable signal as one crosses the phase transition from the confined to the deconfined phase. It will be shown that we can reconstruct these quantities out of Dirac spectra in a mathematically exact way. An essential part of the spectral representation is the use of various fermionic boundary conditions for the compactified time direction. When varying the boundary conditions the spectrum undergoes a shift and out of these shifts we can reconstruct our gluonic quantities. As a first observable we consider the thin Polyakov loop P, which signals the deconfinement transition, and analyse its spectral representation in full and quenched QCD. For SU(3) gauge theory the spectral representation of P is made from three Dirac spectra, each one for a different boundary condition in the temporal direction. We examine several aspects of the spectral representation of P, such as eigenvalue distributions, shifts due to varying boundary conditions, individual and accumulated contributions from particular eigenmodes. It turns out that the thin Polyakov loop P is, in both phases, strongly dominated from the ultraviolet part of the spectrum. Furthermore we observe a suppressed sensitivity of the spectrum to varying boundary conditions in the
Chiral Symmetry Breaking on the Lattice a Study of the Strongly Coupled Lattice Schwinger Model
Berruto, F; Semenoff, Gordon W; Sodano, P
1998-01-01
We revisit the strong coupling limit of the Schwinger model on the lattice using staggered fermions and the hamiltonian approach to lattice gauge theories. Although staggered fermions have no continuous chiral symmetry, they posses a discrete axial invari ance which forbids fermion mass and which must be broken in order for the lattice Schwinger model to exhibit the features of the spectrum of the continuum theory. We show that this discrete symmetry is indeed broken spontaneously in the strong coupling li mit. Expanding around a gauge invariant ground state and carefully considering the normal ordering of the charge operator, we derive an improved strong coupling expansion and compute the masses of the low lying bosonic excitations as well as the chiral co ndensate of the model. We find very good agreement between our lattice calculations and known continuum values for these quantities already in the fourth order of strong coupling perturbation theory. We also find the exact ground state of the antiferromag ...
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.
Quark model with chiral-symmetry breaking and confinement in the Covariant Spectator Theory
Directory of Open Access Journals (Sweden)
Biernat Elmar P.
2016-01-01
Full Text Available 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 π-π-scattering imposed by chiral symmetry.
Quark model with chiral-symmetry breaking and confinement in the Covariant Spectator Theory
Biernat, Elmar P; Ribeiro, J E; Stadler, A; Gross, F
2015-01-01
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.
Quark model with chiral-symmetry breaking and confinement in the Covariant Spectator Theory
Biernat, Elmar P.; Peña, M. T.; Ribeiro, J. E.; Stadler, A.; Gross, F.
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 π-π-scattering imposed by chiral symmetry.
Chiral symmetry breaking from two-loop effective potential of the holographic non-local NJL model
International Nuclear Information System (INIS)
We calculate the two-loop effective potential of the non-local Nambu–Jona–Lasinio (NJL) model derived from the Sakai–Sugimoto model in string theory. In contrast to the conventional NJL with 4-fermion contact interaction, the chiral symmetry was previously found to be dynamically broken for an arbitrary weak coupling at the one-loop level. As a confirmation, the approximate numerical solutions to the gap equation at the one-loop level are explicitly demonstrated for weak couplings. We then calculate the one- and two-loop contributions to the effective potential of the non-local NJL model and found that the two-loop contribution is negative. The two-loop potential for the chiral-symmetric vacuum is also negative but larger than the combined effective potential of the chiral broken vacuum at the two-loop level. The chiral symmetry breaking thus persists for the arbitrary weak coupling at the two-loop level. (paper)
Liu, Keh-Fei
2016-01-01
The relevance of chiral symmetry in baryons is highlighted in three examples in the nucleon spectroscopy and structure. The first one is the importance of chiral dynamics in understanding the Roper resonance. The second one is the role of chiral symmetry in the lattice calculation of $\\pi N \\sigma$ term and strangeness. The third one is the role of chiral $U(1)$ anomaly in the anomalous Ward identity in evaluating the quark spin and the quark orbital angular momentum. Finally, the chiral effective theory for baryons is discussed.
Mishra, H
2001-01-01
We discuss in this note simultaneous existence of chiral symmetry breaking and color superconductivity at finite temperature and density in a Nambu-Jona-Lasinio type model. The methodology involves an explicit construction of a variational ground state and minimisation of the thermodynamic potential. There exist nontrivial solutions to the gap equations at finite densities with both quark-antiquark as well as diquark condensates for the 'ground' state. However, such a phase is thermodynamically unstable with the pressure being negative in this region. We also compute the equation of state, and obtain the structure of the phase diagram in the model.
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.
Chiral symmetry breaking and confinement in Minkowski space QED2+1
International Nuclear Information System (INIS)
Without any analytical assumption we solve the ladder QED2+1 in Minkowski space. Obtained complex fermion propagator exhibits confinement in the sense that it has no pole. Further, we transform Greens functions to the Temporal Euclidean space, wherein we show that in the special case of ladder QED2+1 the solution is fully equivalent to the Minkowski one. Obvious invalidity of Wick rotation is briefly discussed. The infrared value of the dynamical mass is compared with other known approaches, e. g. with the standard Euclidean calculation. We have presented for the first analysis of the electron gap equation in Minkowski and Temporal Euclidean space. The dynamical generation of imaginary part of the fermion mass leads to the absence of Khallen-Lehmann representation, providing thus confining solution for all value of m. Apart very small κ the real pole in the propagator is absent as well. Similarly to Euclidean QED3 Minkowski QED2+1 exhibits spontaneous chiral symmetry breaking the mass function has nontrivial solution in the limit m = 0, however the mass is complex function. Furthermore, we compare with QED solved in similar approximation in spacelike Euclidean and Temporal Euclidean space. As a interesting results, although based on the simple ladder approximation, is the proof of the exact equivalence between the theories defined in Minkowski 2+1 and 3D Temporal Euclidean space. We expect large quantitative changes when the polarization effect is taken account, especially the existence of critical number of flavors can be different when compared to the known Euclidean space estimates. Opposite to naive belief we showed and explained that the Wick rotation -the well known calculational trick in quantum theory- provides continuation of Schwinger function of the Euclidean theory which do not correspond with the Greens function calculated directly in the original Minkowski space. We can note our finding has a little to do with the know usefulness of various
Ebert, D; Klimenko, K G
2016-01-01
In this paper we investigate the phase structure of a (1+1)-dimensional schematic quark model with four-quark interaction and in the presence of baryon ($\\mu_B$), isospin ($\\mu_I$) and chiral isospin ($\\mu_{I5}$) chemical potentials. It is established that in the large-$N_c$ limit ($N_c$ is the number of colored quarks) there exists a duality correspondence between the chiral symmetry breaking phase and the charged pion condensation (PC) one. The role and influence of this property on the phase structure of the model are studied. Moreover, it is shown that the chemical potential $\\mu_{I5}$ promotes the appearance of the charged PC phase with nonzero baryon density.
Katanin, A.
2016-01-01
In this paper, we consider the possibility of chiral (charge or spin density wave) symmetry breaking in graphene due to long-range Coulomb interaction by comparing the results of the Bethe-Salpeter and functional renormalization-group approaches. The former approach performs a summation of ladder diagrams in the particle-hole channel and reproduces the results of the Schwinger-Dyson approach for the critical interaction strength of the quantum phase transition. The renormalization-group approach combines the effect of different channels and allows to study the role of vertex corrections. The critical interaction strength, which is necessary to induce the symmetry breaking in the latter approach, is found in the static approximation to be αc=e2/(ɛ vF) ≈1.05 without considering the Fermi velocity renormalization, and αc=3.7 with accounting the renormailzation of the Fermi velocity. The latter value is expected to be, however, reduced, when the dynamic screening effects are taken into account, yielding the critical interaction, which may be comparable to the one in freely suspended graphene. We show that the vertex corrections are crucially important to obtain the mentioned values of critical interactions.
Applications of chiral symmetry
Energy Technology Data Exchange (ETDEWEB)
Pisarski, R.D.
1995-03-01
The author discusses several topics in the applications of chiral symmetry at nonzero temperature. First, where does the rho go? The answer: up. The restoration of chiral symmetry at a temperature T{sub {chi}} implies that the {rho} and a{sub 1} vector mesons are degenerate in mass. In a gauged linear sigma model the {rho} mass increases with temperature, m{sub {rho}}(T{sub {chi}}) > m{sub {rho}}(0). The author conjectures that at T{sub {chi}} the thermal {rho} - a{sub 1}, peak is relatively high, at about {approximately}1 GeV, with a width approximately that at zero temperature (up to standard kinematic factors). The {omega} meson also increases in mass, nearly degenerate with the {rho}, but its width grows dramatically with temperature, increasing to at least {approximately}100 MeV by T{sub {chi}}. The author also stresses how utterly remarkable the principle of vector meson dominance is, when viewed from the modern perspective of the renormalization group. Secondly, he discusses the possible appearance of disoriented chiral condensates from {open_quotes}quenched{close_quotes} heavy ion collisions. It appears difficult to obtain large domains of disoriented chiral condensates in the standard two flavor model. This leads to the last topic, which is the phase diagram for QCD with three flavors, and its proximity to the chiral critical point. QCD may be very near this chiral critical point, and one might thereby generated large domains of disoriented chiral condensates.
Symmetry Breaking in Chiral Ionic Liquids Evidenced by Vibrational Optical Activity.
Oulevey, Patric; Luber, Sandra; Varnholt, Birte; Bürgi, Thomas
2016-09-19
Ionic liquids (ILs) are receiving increasing interest for their use in synthetic laboratories and industry. Being composed of charged entities, they show a complex and widely unexplored dynamic behavior. Chiral ionic liquids (CILs) have a high potential as solvents for use in asymmetric synthesis. Chiroptical methods, owing to their sensitivity towards molecular conformation, offer unique possibilities to study the structure of these chiral ionic liquids. Raman optical activity proved particularly useful to study ionic liquids composed of amino acids and the achiral 1-ethyl-3-methylimidazolium counterion. We could substantiate, supported by selected theoretical methods, that the achiral counterion adopts an overall chiral conformation in the presence of chiral amino acid ions. These findings suggest that in the design of chiral ionic liquids for asymmetric synthesis, the structure of the achiral counter ion also has to be carefully considered.
Complete chiral symmetry breaking of an amino acid derivative directed by circularly polarized light
Noorduin, Wim L.; Bode, Arno A.C.; Meijden, Maarten van der; Meekes, Hugo; Etteger, Albert F. van; Enckevort, Willem J.P. van; Christianen, Peter C.M.; Kaptein, Bernard; Kellogg, Richard M.; Rasing, Theo; Vlieg, Elias
2009-01-01
Circularly polarized light (CPL) emitted from star-forming regions is an attractive candidate as a cause of single chirality in nature. It has remained difficult, however, to translate the relatively small chemical effects observed on irradiation of molecular systems with CPL into high enantiomeric
Chiral symmetry in hadron physics methods and ideas of chiral symmetry
International Nuclear Information System (INIS)
Methods and ideas of chiral symmetry is presented based on a lecture note to help the future researches in hadron dynamics along with the chiral symmetry. The chiral symmetry was originally developed as the symmetry between currents before the discovery of QCD. It has come to be understood in principle by now that the symmetry is spontaneously broken and only the part of flavor symmetry remains explicitly. In QCD, however, the chiral symmetry has come to be regarded as the base of the symmetry of the global flavor space of quarks. One of the recent topics of the lattice gauge theory is how the hadron properties will change when the broken symmetry is going to be restored. Since the chiral symmetry is global, it is different from gauge symmetry which is local. It explains the degeneracy of hadron masses and relations between the elements of S-matrix in which same number of particles are included. In practice, however, the symmetry of the axial part is spontaneously broken and pions which behave like gauge particles come to play. Chiral symmetry is defined as the (internal) flavor symmetry for the two independent chirality states of quarks. It discriminates two different fundamental quarks defined for the Lorentz groups O(4) - SL(2, C). The symmetry transformation itself is, however, different from the chirality. They should not be confused. In this lecture note, fundamental properties of pions are described on the basis of the interaction with nucleons at first. General properties of the chiral symmetry and some of the low energy theorems on current algebra are introduced. Then, linear sigma model and nonlinear sigma model are introduced. Then the Skyrme-model, which provides an idea as important as quarks, is explained. One of the interesting topics at present is to restore the broken axial symmetry experimentally to investigate the mechanism of symmetry breaking. (S. Funahashi)
On the role of dynamical quark mass generation in chiral symmetry breaking in QCD
Sazdjian, H
2015-01-01
The phenomenon of dynamical quark mass generation is studied in QCD within the framework of a gauge invariant formalism. An exact relationship is established between the equation satisfied by the scalar part of the two-point gauge invariant quark Green's function and the quark-antiquark bound state equation in the chiral limit. A possible nontrivial solution of the former yields a massless pseudoscalar solution of the bound state equation with vanishing total momentum. The result is also corroborated by the corresponding Ward-Takahashi identity. The problem is explicitly solved in two-dimensional QCD in the large-$N_c$ limit.
Blanco, Celia; Ribó, Josep M; Hochberg, David
2015-02-01
We derive the class of population balance equations (PBE), recently applied to model the Viedma deracemization experiment, from an underlying microreversible kinetic reaction scheme. The continuum limit establishing the relationship between the micro- and macroscopic processes and the associated particle fluxes erases the microreversible nature of the molecular interactions in the population growth rate functions and limits the scope of such PBE models to strict kinetic control. The irreversible binary agglomeration processes modeled in those PBEs contribute an additional source of kinetic control. These limitations are crucial regarding the question of the origin of biological homochirality, where the interest in any model lies precisely in its ability for absolute asymmetric synthesis and the amplification of the tiny inherent statistical chiral fluctuations about the ideal racemic composition up to observable enantiometric excess levels.
What the Gribov copy tells on the confinment and the theory of dynamical chiral symmetry breaking
Furui, S; Furui, Sadataka; Nakajima, Hideo
2004-01-01
We performed lattice Landau gauge QCD simulation on $\\beta=6.0, 16^4, 24^4, 32^4$ and $\\beta=6.4, 32^4, 48^4$ and $56^4$ by adopting the gauge fixing that minimizes the norm of the gauge field, and measured the running coupling by using the gluon propagator and the ghost propagator. It has a maximum $\\alpha_s(q)\\simeq 1.1$ at around $q=0.5$ GeV and decreases as $q$ approaches 0. The infrared exponent of the ghost propagator is $\\kappa=0.2$ in the gauge fixing, but there is an exceptional configuration $\\kappa=0.27$, and the running coupling using this configuration is consistent with the Dyson-Schwinger approach with infrared fixed point $\\alpha_0=1.5$. The features of the exceptional configuration are investigated by measuring one-dimensional Fourier transform(1-d FT) of the gluon propagator transverse to 4 lattice axes. We observe that the rotational symmetry of the exceptional configuration is broken and the 1-d FT along a specific axis violates reflection positivity and the average of the Cartan subalgebr...
The Effect of Retardation on the Spontaneous Breaking of Chiral Symmetry in GCM
Institute of Scientific and Technical Information of China (English)
YANG Sheng-Dong; ZHAI Chen-Yang; ZHOU Zhi-Ning; YANG Ze-Sen
2001-01-01
An effective Hamiltonian including current-current coupling from the global color symmetry model is -R2 2derived.Retardation effects are introduced by the factor ( R/ ) e ,instead of δ (r) in the correlation kernel,from which the retardation gap equation with α-α coupling in the 3po vacuum is obtained,qq condensations of different retardation parameters R with or without the α-α term are calculated.The results show the effects of retardation,and indicate that the typical value of R is about 2 fm-1 at reasonable value of qq condensation.And while taking typical value 1 fm-1 of R,the condensation 1/3 is about 13% larger than that with no retardation effect.With the α-αterms,the condensation (qq) 1/3 is about 17%o larger than that without it for all values of the parameter R.This shows that the retardation effects and the α-α terms are important for further studying in the Iow-energy region.``
Energy Technology Data Exchange (ETDEWEB)
Chanowitz, M.S.
1990-09-01
The Higgs mechanism is reviewed in its most general form, requiring the existence of a new symmetry-breaking force and associated particles, which need not however be Higgs bosons. The first lecture reviews the essential elements of the Higgs mechanism, which suffice to establish low energy theorems for the scattering of longitudinally polarized W and Z gauge bosons. An upper bound on the scale of the symmetry-breaking physics then follows from the low energy theorems and partial wave unitarity. The second lecture reviews particular models, with and without Higgs bosons, paying special attention to how the general features discussed in lecture 1 are realized in each model. The third lecture focuses on the experimental signals of strong WW scattering that can be observed at the SSC above 1 TeV in the WW subenergy, which will allow direct measurement of the strength of the symmetry-breaking force. 52 refs., 10 figs.
Quarks, baryons and chiral symmetry
Hosaka, Atsushi
2001-01-01
This book describes baryon models constructed from quarks, mesons and chiral symmetry. The role of chiral symmetry and of quark model structure with SU(6) spin-flavor symmetry are discussed in detail, starting from a pedagogic introduction. Emphasis is placed on symmetry aspects of the theories. As an application, the chiral bag model is studied for nucleon structure, where important methods of theoretical physics, mostly related to the semiclassical approach for a system of strong interactions, are demonstrated. The text is more practical than formal; tools and ideas are explained in detail w
International Nuclear Information System (INIS)
The suggestion by Jaffe that if σ is a light q2q-bar2 state 0++ then even the fundamental chiral transformation properties of the σ becomes unclear, has stimulated much interest. Adler pointed out that in fact the seminal work on chiral symmetry via PCAC consistency, is really quite consistent with the σ being predominantly q2q-bar2. This interpretation was actually backed by subsequent work on effective Lagrangian methods for linear and non linear realizations. More recent work of Achasov suggests that intermediate four-quark states determine amplitudes involving other scalars a0(980) and f0(980) below 1 GeV, and the report by Ning Wu that study on σ meson in J/ψ → ωπ+π- continue to support a non qq-bar σ with mass as low as 390 MeV. It is also noted that more recent re-analysis of πK scattering by S. Ishida et al. together with the work of the E791 Collaboration, support the existence of the scalar κ particle with comparatively light mass as well
Ribó, Josep M; El-Hachemi, Zoubir; Moyano, Albert; Blanco, Celia; Hochberg, David; 10.1089/ast.2012.0904
2013-01-01
The emergence of chirality in enantioselective autocatalysis for compounds unable to transform according to the Frank-like reaction network is discussed with respect to the controversial limited enantioselectivity (LES) model composed of coupled enantioselective and non-enantioselective autocatalyses. The LES model cannot lead to spontaneous mirror symmetry breaking (SMSB) either in closed systems with a homogeneous temperature distribution nor in closed systems with a stationary non-uniform temperature distribution. However, simulations of chemical kinetics in a two-compartment model demonstrate that SMSB may occur if both autocatalytic reactions are spatially separated at different temperatures in different compartments but coupled under the action of a continous internal flow. In such conditions the system can evolve, for certain reaction and system parameters, towards a chiral stationary state, i.e., the system is able to reach a bifurcation point leading to SMSB. Numerical simulations using reasonable ch...
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.
Dileptons and Chiral Symmetry Restoration
Hohler, P M
2015-01-01
We report on recent work relating the medium effects observed in dilepton spectra in heavy-ion collisions to potential signals of chiral symmetry restoration. The key connection remains the approach to spectral function degeneracy between the vector-isovector channel with its chiral partner, the axialvector-isovector channel. Several approaches are discussed to elaborate this connection, namely QCD and Weinberg sum rules with input for chiral order parameters from lattice QCD, and chiral hadronic theory to directly evaluate the medium effects of the axialvector channel and the pertinent pion decay constant as function of temperature. A pattern emerges where the chiral mass splitting between rho and a_1 burns off and is accompanied by a strong broadening of the spectral distributions.
Chiral symmetry on the lattice
International Nuclear Information System (INIS)
The author reviews some of the difficulties associated with chiral symmetry in the context of a lattice regulator. The author discusses the structure of Wilson Fermions when the hopping parameter is in the vicinity of its critical value. Here one flavor contrasts sharply with the case of more, where a residual chiral symmetry survives anomalies. The author briefly discusses the surface mode approach, the use of mirror Fermions to cancel anomalies, and finally speculates on the problems with lattice versions of the standard model
Chiral symmetry in rotating systems
Malik, Sham S.
2015-08-01
The triaxial rotating system at critical angular momentum I ≥Iband exhibits two enatiomeric (the left- and right-handed) forms. These enatiomers are related to each other through dynamical chiral symmetry. The chiral symmetry in rotating system is defined by an operator χ ˆ =Rˆy (π) T ˆ, which involves the product of two distinct symmetries, namely, continuous and discrete. Therefore, new guidelines are required for testing its commutation with the system Hamiltonian. One of the primary objectives of this study is to lay down these guidelines. Further, the possible impact of chiral symmetry on the geometrical arrangement of angular momentum vectors and investigation of observables unique to nuclear chiral-twins is carried out. In our model, the angular momentum components (J1, J2, J3) occupy three mutually perpendicular axes of triaxial shape and represent a non-planar configuration. At certain threshold energy, the equation of motion in angular momentum develops a second order phase transition and as a result two distinct frames (i.e., the left- and right-handed) are formed. These left- and right-handed states correspond to a double well system and are related to each other through chiral operator. At this critical angular momentum, the centrifugal and Coriolis interactions lower the barrier in the double well system. The tunneling through the double well starts, which subsequently lifts the degeneracy among the rotational states. A detailed analysis of the behavior of rotational energies, spin-staggering, and the electromagnetic transition probabilities of the resulting twin-rotational bands is presented. The ensuing model results exhibit similarities with many observed features of the chiral-twins. An advantage of our formalism is that it is quite simple and it allows us to pinpoint the understanding of physical phenomenon which lead to chiral-twins in rotating systems.
Random Matrices and Chiral Symmetry in QCD
Janik, R A; Papp, G; Zahed, I; Janik, Romuald A.; Nowak, Maciej A.; Papp, Gabor; Zahed, Ismail
1998-01-01
In this talk we review some recent results from random matrix models as applied to some non-perturbative issues in QCD. All of the issues we will discuss touched upon the important phenomenon related to the spontaneous breaking of chiral symmetry. The afore mentioned insights are: 1. Spontaneous breakdown of chiral symmetry and disorder. 2. Universal microscopic properties of the eigenvalues of the Dirac operator in the vacuum. 3. Universal microscopic properties of the eigenvalues of the Dirac operator in matter. 4. Structural changes of the Dirac spectrum - finite temperature. 5. Structural changes of the Dirac spectrum - finite baryonic density - ``phony vacua'' 6. Structural changes of the Dirac spectrum - finite baryonic density - ``true vacua'' . 7. Phase diagram. 8. Critical parameters. 9. Critical exponents. 10. $U(1)_A$ problem. 11. Screening of the pseudoscalar susceptibility. 12. Strong CP violation (finite $\\theta$).
Effective Chiral Symmetry Restoration for Heavy-Light Mesons
Sazonov, V K; Wagenbrunn, R F
2014-01-01
We study the spectrum of heavy-light mesons within a model with linear instantaneous confining potential. The single-quark Green function and spontaneous breaking of chiral symmetry are obtained from the Schwinger-Dyson (gap) equation. For the meson spectrum we derive a Bethe-Salpeter equation (BSE). We solve thiss equation numerically in the heavy-light limit and obtain effective restoration of chiral and $U(1)_A$ symmetries at large spins.
Sequential flavor symmetry breaking
International Nuclear Information System (INIS)
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.
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.
Symmetry breaking in molecular ferroelectrics.
Shi, Ping-Ping; Tang, Yuan-Yuan; Li, Peng-Fei; Liao, Wei-Qiang; Wang, Zhong-Xia; Ye, Qiong; Xiong, Ren-Gen
2016-07-11
Ferroelectrics are inseparable from symmetry breaking. Accompanying the paraelectric-to-ferroelectric phase transition, the paraelectric phase adopting one of the 32 crystallographic point groups is broken into subgroups belonging to one of the 10 ferroelectric point groups, i.e. C1, C2, C1h, C2v, C4, C4v, C3, C3v, C6 and C6v. The symmetry breaking is captured by the order parameter known as spontaneous polarization, whose switching under an external electric field results in a typical ferroelectric hysteresis loop. In addition, the responses of spontaneous polarization to other external excitations are related to a number of physical effects such as second-harmonic generation, piezoelectricity, pyroelectricity and dielectric properties. Based on these, this review summarizes recent developments in molecular ferroelectrics since 2011 and focuses on the relationship between symmetry breaking and ferroelectricity, offering ideas for exploring high-performance molecular ferroelectrics. PMID:27051889
CP breaking in lattice chiral gauge theories
International Nuclear Information System (INIS)
The CP symmetry is not manifestly implemented for the local and doubler-free Ginsparg-Wilson operator in lattice chiral gauge theory. We precisely identify where the effects of this CP breaking appear. We show that they appear in: (I) Overall constant phase of the fermion generating functional. (II) Overall constant coefficient of the fermion generating functional. (III) Fermion propagator appearing in external fermion lines and the propagator connected to Yukawa vertices. The first effect appears from the transformation of the path integral measure and it is absorbed into a suitable definition of the constant phase factor for each topological sector; in this sense there appears no 'CP anomaly'. The second constant arises from the explicit breaking in the action and it is absorbed by the suitable weights with which topological sectors are summed. The last one in the propagator is inherent to this formulation and cannot be avoided by a mere modification of the projection operator, for example, in the framework of the Ginsparg-Wilson operator. This breaking emerges as an (almost) contact term in the propagator when the Higgs field, which is treated perturbatively, has no vacuum expectation value. In the presence of the vacuum expectation value, however, a completely new situation arises and the breaking becomes intrinsically non-local, though this breaking may still be removed in a suitable continuum limit. This non-local CP breaking is expected to persist for a non-perturbative treatment of the Higgs coupling. (author)
Infinite Chiral Symmetry in Four Dimensions
Beem, Christopher; Liendo, Pedro; Peelaers, Wolfger; Rastelli, Leonardo; van Rees, Balt C
2015-01-01
We describe a new correspondence between four-dimensional conformal field theories with extended supersymmetry and two-dimensional chiral algebras. The meromorphic correlators of the chiral algebra compute correlators in a protected sector of the four-dimensional theory. Infinite chiral symmetry has far-reaching consequences for the spectral data, correlation functions, and central charges of any four-dimensional theory with ${\\mathcal N}=2$ superconformal symmetry.
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.
A model of intrinsic symmetry breaking
Energy Technology Data Exchange (ETDEWEB)
Ge, Li [Research Center for Quantum Manipulation, Department of Physics, Fudan University, Shanghai 200433 (China); Li, Sheng [Department of Physics, Zhejiang Normal University, Zhejiang 310004 (China); George, Thomas F., E-mail: tfgeorge@umsl.edu [Office of the Chancellor and Center for Nanoscience, Department of Chemistry and Biochemistry, University of Missouri-St. Louis, St. Louis, MO 63121 (United States); Department of Physics and Astronomy, University of Missouri-St. Louis, St. Louis, MO 63121 (United States); Sun, Xin, E-mail: xin_sun@fudan.edu.cn [Research Center for Quantum Manipulation, Department of Physics, Fudan University, Shanghai 200433 (China)
2013-11-01
Different from the symmetry breaking associated with a phase transition, which occurs when the controlling parameter is manipulated across a critical point, the symmetry breaking presented in this Letter does not need parameter manipulation. Instead, the system itself suddenly undergoes symmetry breaking at a certain time during its evolution, which is intrinsic symmetry breaking. Through a polymer model, it is revealed that the origin of the intrinsic symmetry breaking is nonlinearity, which produces instability at the instance when the evolution crosses an inflexion point, where this instability breaks the original symmetry.
Chlorophylls, Symmetry, Chirality, and Photosynthesis
Directory of Open Access Journals (Sweden)
Mathias O. Senge
2014-09-01
Full Text Available Chlorophylls are a fundamental class of tetrapyrroles and function as the central reaction center, accessory and photoprotective pigments in photosynthesis. Their unique individual photochemical properties are a consequence of the tetrapyrrole macrocycle, the structural chemistry and coordination behavior of the phytochlorin system, and specific substituent pattern. They achieve their full potential in solar energy conversion by working in concert in highly complex, supramolecular structures such as the reaction centers and light-harvesting complexes of photobiology. The biochemical function of these structures depends on the controlled interplay of structural and functional principles of the apoprotein and pigment cofactors. Chlorophylls and bacteriochlorophylls are optically active molecules with several chiral centers, which are necessary for their natural biological function and the assembly of their supramolecular complexes. However, in many cases the exact role of chromophore stereochemistry in the biological context is unknown. This review gives an overview of chlorophyll research in terms of basic function, biosynthesis and their functional and structural role in photosynthesis. It highlights aspects of chirality and symmetry of chlorophylls to elicit further interest in their role in nature.
Electroweak symmetry breaking at photon colliders
International Nuclear Information System (INIS)
The electroweak-symmetry-breaking sector of the standard model can be weakly-coupled or can be strongly-coupled, which is characterized by some kinds of strong interaction among the Goldstone bosons of the electroweak-symmetry-breaking sector. In this paper, we summarize an investigation of probing the strong electroweak-symmetry-breaking effects at photon colliders. ((orig.))
Symmetry Breaking in Finite Volume
Institute of Scientific and Technical Information of China (English)
LIU Chuan
2000-01-01
Spontaneous symmetry breaking is a cooperative phenomenon for systems with infinitely many degrees of freedom and it plays an essential role in quantum field theories. Lattice O(N) model is studied within the Hamiltonian approach using an adiabatic approximation. It is shown that the low-lying spectrum of the system in the broken phase can be understood by using the adiabatic, or Born-Oppenheimer approximation, which turns out to become an expansion in the inverse power of volume. In the infinite volume limit, the symmetry is broken while in the finite volume the slow rotation of the zero-momentum mode restores the symmetry and gives rise to the rotator spectrum, which has been observed in realistic Monte Carlo simulations.
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 ...
Relativistic dissipative hydrodynamics with spontaneous symmetry breaking
Energy Technology Data Exchange (ETDEWEB)
Pujol, C.; Davesne, D. [IPN - Lyon, 43 Bd du 11 Novembre 1918, F-69622 Villeurbanne Cedex (France)
2002-07-01
In this paper we consider dissipative hydrodynamic equations for systems with continuous broken symmetries. We first present the case of superfluidity, in which the symmetry U(1) is broken and then generalize to the chiral symmetry SU(2){sub L} x SU(2){sub R}. New transport coefficients are introduced and the consequences of their existence are discussed. (authors)
Relativistic dissipative hydrodynamics with spontaneous symmetry breaking
Pujol, C
2003-01-01
In this paper we consider dissipative hydrodynamic equations for systems with continuous broken symmetries. We first present the case of superfluidity, in which the symmetry U(1) is broken and then generalize to the chiral symmetry $SU(2)_L \\times SU(2)_R$. New transport coefficients are introduced and the consequences of their existence are discussed.
History of electroweak symmetry breaking
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.
Spontaneous Breaking of Flavor Symmetry
Törnqvist, N A
1996-01-01
It is shown that part of the quark masses of the standard model can be generated spontaneously within the strong interactions of QCD. After the breaking of U(Nf) x U(Nf) symmetry by the vacuum, also the resulting flavor symmetric, degenerate meson mass spectrum is shown to be unstable with respect to quantum loops, for rather general models. For a C-degenerate meson spectrum the stable mass spectrum obeys the Okubo-Zweig-Iizuka rule and the approximateequal spacing rule.
Renormalizable theories with symmetry breaking
Becchi, Carlo M
2016-01-01
The description of symmetry breaking proposed by K. Symanzik within the framework of renormalizable theories is generalized from the geometrical point of view. For an arbitrary compact Lie group, a soft breaking of arbitrary covariance, and an arbitrary field multiplet, the expected integrated Ward identities are shown to hold to all orders of renormalized perturbation theory provided the Lagrangian is suitably chosen. The corresponding local Ward identity which provides the Lagrangian version of current algebra through the coupling to an external, classical, Yang-Mills field, is then proved to hold up to the classical Adler-Bardeen anomaly whose general form is written down. The BPHZ renormalization scheme is used throughout in such a way that the algebraic structure analyzed in the present context may serve as an introduction to the study of fully quantized gauge theories.
Introduction to Electroweak Symmetry Breaking
Energy Technology Data Exchange (ETDEWEB)
Dawson,S.
2008-10-02
The Standard Model (SM) is the backbone of elementary particle physics-not only does it provide a consistent framework for studying the interactions of quark and leptons, but it also gives predictions which have been extensively tested experimentally. In these notes, I review the electroweak sector of the Standard Model, discuss the calculation of electroweak radiative corrections to observables, and summarize the status of SM Higgs boson searches. Despite the impressive experimental successes, however, the electroweak theory is not completely satisfactory and the mechanism of electroweak symmetry breaking is untested. I will discuss the logic behind the oft-repeated statement: 'There must be new physics at the TeV scale'. These lectures reflect my strongly held belief that upcoming results from the LHC will fundamentally change our understanding of electroweak symmetry breaking. In these lectures, I review the status of the electroweak sector of the Standard Model, with an emphasis on the importance of radiative corrections and searches for the Standard Model Higgs boson. A discussion of the special role of the TeV energy scale in electroweak physics is included.
Master formula approach to broken chiral U(3)xU(3) symmetry
Energy Technology Data Exchange (ETDEWEB)
Hiroyuki Kamano
2010-04-01
The master formula approach to chiral symmetry breaking proposed by Yamagishi and Zahed is extended to the U_R(3)xU_L(3) group, in which effects of the U_A(1) anomaly and the flavor symmetry breaking m_u \
Projective symmetry group classification of chiral spin liquids
Bieri, Samuel; Lhuillier, Claire; Messio, Laura
2016-03-01
We present a general review of the projective symmetry group classification of fermionic quantum spin liquids for lattice models of spin S =1 /2 . We then introduce a systematic generalization of the approach for symmetric Z2 quantum spin liquids to the one of chiral phases (i.e., singlet states that break time reversal and lattice reflection, but conserve their product). We apply this framework to classify and discuss possible chiral spin liquids on triangular and kagome lattices. We give a detailed prescription on how to construct quadratic spinon Hamiltonians and microscopic wave functions for each representation class on these lattices. Among the chiral Z2 states, we study the subset of U(1) phases variationally in the antiferromagnetic J1-J2-Jd Heisenberg model on the kagome lattice. We discuss static spin structure factors and symmetry constraints on the bulk spectra of these phases.
Mutual information and spontaneous symmetry breaking
Hamma, A.; Giampaolo, S. M.; Illuminati, F.
2015-01-01
We show that the metastable, symmetry-breaking ground states of quantum many-body Hamiltonians have vanishing quantum mutual information between macroscopically separated regions, and are thus the most classical ones among all possible quantum ground states. This statement is obvious only when the symmetry-breaking ground states are simple product states, e.g. at the factorization point. On the other hand, symmetry-breaking states are in general entangled along the entire ordered phase, and t...
Yet another symmetry breaking to be discovered
Yoshimura, M.
2016-07-01
The discovery of spontaneous symmetry breaking in particle physics was the greatest contribution in Nambu's achievements. There is another class of symmetries that exist in low-energy nature, yet is doomed to be broken at high energy, due to a lack of protection of the gauge symmetry. I shall review our approach to searching for this class of symmetry breaking, the lepton number violation linked to the generation of the matter-antimatter asymmetry in our universe.
Chiral symmetry and lattice fermions
Creutz, Michael
2013-01-01
Lattice gauge theory and chiral perturbation theory are among the primary tools for understanding non-perturbative aspects of QCD. I review several subtle and sometimes controversial issues that arise when combining these techniques. Among these are one failure of partially quenched chiral perturbation theory when the valence quarks become lighter than the average sea quark mass and a potential ambiguity in comparisons of perturbative and lattice properties of non-degenerate quarks.
Chiral symmetry and finite temperature effects in quantum theories
International Nuclear Information System (INIS)
A computer simulation of the harmonic oscillator at finite temperature has been carried out, using the Monte Carlo Metropolis algorithm. Accurate results for the energy and fluctuations have been obtained, with special attention to the manifestation of the temperature effects. Varying the degree of symmetry breaking, the finite temperature behaviour of the asymmetric linear model in a linearized mean field approximation has been studied. In a study of the effects of chiral symmetry on baryon mass splittings, reasonable agreement with experiment has been obtained in a non-relativistic harmonic oscillator model
Four Top Production and Electroweak Symmetry Breaking
Cheung, Kingman
1995-01-01
With the recent discovery of a heavy top quark $(m_t \\approx 175 - 200$ GeV), the top quark opens an window to electroweak symmetry breaking. We propose the study of four-top, $t\\bar t t\\bar t$, production at hadronic supercolliders as a probe to electroweak symmetry breaking.
Electroweak Symmetry Breaking and the Higgs Boson
Pich, Antonio
2015-01-01
The first LHC run has confirmed the Standard Model as the correct theory at the electroweak scale, and the existence of a Higgs-like particle associated with the spontaneous breaking of the electroweak gauge symmetry. These lectures overview the present knowledge on the Higgs boson and discuss alternative scenarios of electroweak symmetry breaking which are already being constrained by the experimental data.
Charge-symmetry-breaking nucleon form factors
Kubis, Bastian
2009-01-01
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 Helium-4.
Search for primordial symmetry breakings in CMB
Shiraishi, Maresuke
2016-06-01
There are possibilities to violate symmetries (e.g. parity and rotational invariance) in the primordial cosmological fluctuations. Such symmetry breakings can imprint very rich signatures in late-time phenomena, which may be possible to observe. Especially, Cosmic Microwave Background (CMB) will change its face drastically, corresponding to the symmetry-breaking types, since the harmonic-space representation is very sensitive to the statistical, spin and angular dependences of cosmological perturbations. Here, we discuss (1) general responses of CMB to the symmetry breakings, (2) some theoretical models creating interesting CMB signatures, and (3) aspects of the estimation from observational data.
Symmetry and symmetry breaking in quantum mechanics
International Nuclear Information System (INIS)
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
Instantons and chiral symmetry in string theory
Jensen, Steuard B.
The study of non-perturbative effects has played an important role in many recent developments in physics. String theory has proven to be an especially fertile ground for such studies: not only is its own non-perturbative structure interesting, but it has emerged as a framework in which to study the strongly coupled behavior of a variety of models in quantum field theory as well. In this thesis, I present results demonstrating the use of string theory in both these ways. First, I discuss non-perturbative corrections to the Kaluza-Klein monopole in string theory. As usually described, this object has an isometry around a compact circle and is related by T-duality to a "smeared" NS5-brane which retains that isometry. The true NS5-brane solution is localized at a point on the circle, so duality implies that the Kaluza-Klein monopole should show some corresponding behavior. By expressing the Kaluza-Klein monopole as a gauged linear sigma model in two dimensions, I show that worldsheet instantons give corrections to its geometry. These corrections can be understood as a localization in "winding space" which could be probed by strings with winding charge around the circle. Second, I discuss a configuration of D-branes in string theory whose low energy physics corresponds to a 3+1-dimensional quantum field theory with dynamically broken chiral symmetry. In a weakly coupled region of parameter space, this theory is a non-local generalization of the Nambu-Jona-Lasinio model. Indications are given that this model dynamically breaks chiral symmetry at arbitrarily weak 't Hooft coupling. At strong coupling this field theory is no longer solvable directly, but an alternate weakly coupled description can be found from the string theory model: the dynamics is determined by replacing a stack of D-branes by their near-horizon geometry and studying the low energy theory on probe D-branes in that background. In yet another region of parameter space, this D-brane configuration gives
Symmetry Breaking for Black-Scholes Equations
Institute of Scientific and Technical Information of China (English)
YANG Xuan-Liu; ZHANG Shun-Li; QU Chang-Zheng
2007-01-01
Black-Scholes equation is used to model stock option pricing. In this paper, optimal systems with one to four parameters of Lie point symmetries for Black-Scholes equation and its extension are obtained. Their symmetry breaking interaction associated with the optimal systems is also studied. As a result, symmetry reductions and corresponding solutions for the resulting equations are obtained.
Symmetry Breaking for Black-Scholes Equations
Yang, Xuan-Liu; Zhang, Shun-Li; Qu, Chang-Zheng
2007-06-01
Black-Scholes equation is used to model stock option pricing. In this paper, optimal systems with one to four parameters of Lie point symmetries for Black-Scholes equation and its extension are obtained. Their symmetry breaking interaction associated with the optimal systems is also studied. As a result, symmetry reductions and corresponding solutions for the resulting equations are obtained.
Symmetry Breaking for Black-Scholes Equations
International Nuclear Information System (INIS)
Black-Scholes equation is used to model stock option pricing. In this paper, optimal systems with one to four parameters of Lie point symmetries for Black-Scholes equation and its extension are obtained. Their symmetry breaking interaction associated with the optimal systems is also studied. As a result, symmetry reductions and corresponding solutions for the resulting equations are obtained.
Role of Chiral symmetry in nuclear physics
International Nuclear Information System (INIS)
Spurred by some recent experiments in electron scattering, we reassess the role that chiral symmetry plays in nuclear structure. Though difficult to formulate precisely, some of the ideas put forward many years ago, combined with the recent revival of the Skyrmion picture of the nucleon, are seen to be move relevant now than ever
Chiral symmetry and functional integral
Energy Technology Data Exchange (ETDEWEB)
Gamboa Saravi, R.E.; Muschietti, M.A.; Schaposnik, F.A.; Solomin, J.E.
1984-10-15
The change in the fermionic functional integral measure under chiral rotations is analyzed. Using the zeta-function method, the evaluation of chiral Jacobians to theories including non-hermitian Dirac operators D, can be extended in a natural way. (This being of interest, for example, in connection with the Weinberg-Salam model or with the relativistic string theory). Results are compared with those obtained following other approaches, the possible discrepancies are analyzed and the equivalence of the different methods under certain conditions on D is proved. Also shown is how to compute the Jacobian for the case of a finite chiral transformation and this result is used to develop a sort of path-integral version of bosonization in d = 2 space-time dimensions. This result is used to solve in a very simple and economical way relevant d = 2 fermionic models. Furthermore, some interesting features in connection with the theta-vacuum in d = 2,4 gauge theories are discussed.
Rotating optical microcavities with broken chiral symmetry
Sarma, Raktim; Wiersig, Jan; Cao, Hui
2014-01-01
We demonstrate in open microcavities with broken chiral symmetry, quasi-degenerate pairs of co-propagating modes in a non-rotating cavity evolve to counter-propagating modes with rotation. The emission patterns change dramatically by rotation, due to distinct output directions of CW and CCW waves. By tuning the degree of spatial chirality, we maximize the sensitivity of microcavity emission to rotation. The rotation-induced change of emission is orders of magnitude larger than the Sagnac effect, pointing to a promising direction for ultrasmall optical gyroscopes.
Chiral Perturbation in the Hidden Local Symmetry and Vector Manifestation of Chiral Symmetry
Harada, Masayasu
2001-01-01
In this talk I summarize our recent works on the chiral phase transition in the large flavor QCD studied by the hidden local symmetry (HLS). Bare parameters in the HLS are determined by matching the HLS with the underlying QCD at the matching scale through the Wilsonian matching. This leads to the vector manifestation of the Wigner realization of the chiral symmetry in which the symmetry is restored by the massless degenerate pion (and its flavor partners) and rho meson (and its flavor partne...
Mirror symmetry breaking at the molecular level.
Avetisov, V; Goldanskii, V.
1996-01-01
Reasoning from two basic principles of molecular physics, P invariance of electromagnetic interaction and the second law of thermodynamics, one would conclude that mirror symmetry retained in the world of chiral molecules. This inference is fully consistent with what is observed in inorganic nature. However, in the bioorganic world, the reverse is true. Mirror symmetry there is definitely broken. Is it possible to account for this phenomenon without going beyond conventional concepts of the k...
Chiral symmetry and strangeness at SIS energies
International Nuclear Information System (INIS)
In this talk we review the consequences of the chiral SU(3) symmetry for strangeness propagation in nuclear matter. Objects of crucial importance are the meson-baryon scattering amplitudes obtained within the chiral coupled-channel effective field theory. Results for antikaon and hyperon-resonance spectral functions in cold nuclear matter are presented and discussed. The importance of the Σ(1385) resonance for the subthreshold antikaon production in heavy-ion reaction at SIS is pointed out. The in-medium properties of the latter together with an antikaon spectral function based on chiral SU(3) dynamics suggest a significant enhancement of the π Λ → anti Κ N reaction in nuclear matter. (orig.)
Chimera Death: Symmetry Breaking in Dynamical Networks
Zakharova, Anna; Kapeller, Marie; Schöll, Eckehard
2014-01-01
For a network of generic oscillators with nonlocal topology and symmetry-breaking coupling we establish novel partially coherent inhomogeneous spatial patterns, which combine the features of chimera states (coexisting incongruous coherent and incoherent domains) and oscillation death (oscillation suppression), which we call chimera death. We show that due to the interplay of nonlocality and breaking of rotational symmetry by the coupling two distinct scenarios from oscillatory behavior to a s...
Gedanken Worlds without Higgs: QCD-Induced Electroweak Symmetry Breaking
Energy Technology Data Exchange (ETDEWEB)
Quigg, Chris; /Fermilab /Karlsruhe U., TTP; Shrock, Robert; /YITP, Stony Brook
2009-01-01
To illuminate how electroweak symmetry breaking shapes the physical world, we investigate toy models in which no Higgs fields or other constructs are introduced to induce spontaneous symmetry breaking. Two models incorporate the standard SU(3){sub c} {circle_times} SU(2){sub L} {circle_times} U(1){sub Y} gauge symmetry and fermion content similar to that of the standard model. The first class--like the standard electroweak theory--contains no bare mass terms, so the spontaneous breaking of chiral symmetry within quantum chromodynamics is the only source of electroweak symmetry breaking. The second class adds bare fermion masses sufficiently small that QCD remains the dominant source of electroweak symmetry breaking and the model can serve as a well-behaved low-energy effective field theory to energies somewhat above the hadronic scale. A third class of models is based on the left-right-symmetric SU(3){sub c} {circle_times} SU(2){sub L} {circle_times} SU(2){sub R} {circle_times} U(1)B?L gauge group. In a fourth class of models, built on SU(4){sub PS} {circle_times} SU(2){sub L} {circle_times} SU(2){sub R} gauge symmetry, lepton number is treated as a fourth color. Many interesting characteristics of the models stem from the fact that the effective strength of the weak interactions is much closer to that of the residual strong interactions than in the real world. The Higgs-free models not only provide informative contrasts to the real world, but also lead us to consider intriguing issues in the application of field theory to the real world.
Enhanced breaking of heavy quark spin symmetry
Guo, Feng-Kun; Shen, Cheng-Ping
2014-01-01
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 $O({\\Lambda_{\\rm QCD}/m_Q})$, with $\\Lambda_{\\rm QCD}$ the scale of QCD and $m_Q$ the heavy quark mass. In this paper, we propose a new mechanism to enhance the spin symmetry breaking. Taking the decays of the $\\Upsilon(10860)$ into the $\\chi_{bJ}\\omega\\, (J=0,1,2)$ as an example, we show that a small $S$- and $D$-wave mixing can induce a significant breaking of the spin symmetry relations for the ratios of the branching fractions of these decays, owing to an enhancement of the decays of the $D$-wave component due to nearby coupled channels.
Chiral symmetry and parametrization of scalar resonances
Arantes, L O
2005-01-01
The linear $\\s$-model is used to study the effects of chiral symmetry in unitarized amplitudes incorporating scalar resonances. When just a single resonance is present, we show that the iteration of a chiral tree amplitude by means of regularized two-pion loops preserves the smallness of $\\p\\p$ interaction at low energies and estimate the importance of pion off-shell contributions. The inclusion of a second resonance is performed by means of a chiral extension of the linear $\\s$-model lagrangian. The new $\\p\\p$ ampitude at tree level complies with low-energy theorems, depends on a mixing angle and has a zero for a given energy between the resonance masses. The unitarization of this amplitude by means of two-pion loops preserves both its chiral low energy behavior and the position of this zero confirming, in a lagrangian framework, conclusions drawn previously by T\\"ornqvist. Finally, we approximate and generalize our results and give a friendly expression that can be used in the parametrization of $N$ coupled...
From enemies to friends chiral symmetry on the lattice
Hernández, Pilar; Lellouch, L P; Hernandez, Pilar; Jansen, Karl; Lellouch, Laurent
2002-01-01
The physics of strong interactions is invariant under the exchange of left-handed and right-handed quarks, at least in the massless limit. This invariance is reflected in the chiral symmetry of quantum chromodynamics. Surprisingly, it has become clear only recently how to implement this important symmetry in lattice formulations of quantum field theories. We will discuss realizations of exact lattice chiral symmetry and give an example of the computation of a physical observable in quantum chromodynamics where chiral symmetry is important. This calculation is performed by relying on finite size scaling methods as predicted by chiral perturbation theory.
Chiral symmetry, constituent quarks and quasi-elastic electron-nucleus scattering
Henley, E. M.; Krein, G.
1989-11-01
The effects of chiral symmetry breaking are examined for quasi-elastic electron scattering on nuclei. Nucleons are assumed to be composed of constituent quarks with masses that depend on density. This density dependence is determined on the basis of the Nambu-Jona-Lasinio model. It is found that the effects of chiral symmetry breaking are in the right direction and the right order of magnitude to explain the discrepancies between theory and experiment. On leave from Departamento de Fisica, Universidade Federal de Santa Maria, 97100 Santa Maria, R.S., Brazil.
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.
Need for spontaneous breakdown of chiral symmetry
Energy Technology Data Exchange (ETDEWEB)
Salomone, A.; Schechter, J.; Tudron, T.
1981-07-15
The question of whether the chiral symmetry of the theory of strong interactions (with massless quarks) is required to be spontaneously broken is examined in the framework of a previously discussed effective Lagrangian for quantum chromodynamics. The assumption that physical masses of the theory be finite leads in a very direct way to the necessity of spontaneous breakdown. This result holds for all N/sub F/> or =2, where N/sub F/ is the number of different flavors of light quarks. The atypical cases N/sub F/ = 1,2 are discussed separately.
Effective dissipation: breaking time-reversal symmetry
Brown, Aidan I
2016-01-01
At molecular scales, fluctuations play a significant role and prevent biomolecular processes from always proceeding in a preferred direction, raising the question of how limited amounts of free energy can be dissipated to obtain directed progress. We examine the system and process characteristics that efficiently break time-reversal symmetry at fixed energy loss; in particular for a simple model of a molecular machine, an intermediate energy barrier produces unusually high asymmetry for a given dissipation. Such insight into symmetry-breaking factors that produce particularly high time asymmetry suggests generalizations to a broader class of systems.
The Scalar Mesons, Symmetry Breaking, Three Colors and Confinement
Törnqvist, N A
2006-01-01
The same, well known, det(Sigma)+det(Sigma)* term, which 't Hooft showed is generated by instantons in QCD and which resolves the U(1) problem giving mass in, particular, to the eta' is argued to be the dominant term in the spontaneous chiral symmetry breaking. It generates not one, but three classical minima along the axial U(1) circle which connect to color through Fermi-Dirac statistics. The term also contributes, in a similar way as the diquark model of Jaffe, to an inverted scalar mass spectrum for the light scalars, and suggests a simple confinement mechanism.
Which Chiral Symmetry is Restored in High Temperature QCD?
Bernard, C W; DeTar, C E; Gottlieb, S; Heller, U M; Hetrick, J E; Rummukainen, K; Sugar, R; Toussaint, D; Wingate, M; Bernard, Claude; Blum, Tom; Tar, Carleton De; Gottlieb, Steven; Heller, Urs M.; Hetrick, James E.; Wingate, Matthew
1996-01-01
Sigma models for the high temperature phase transition in quantum chromodynamics (QCD) suggest that at high temperature the SU(N_f) x SU(N_f) chiral symmetry becomes exact, but the anomalous axial U(1) symmetry need not be restored. In numerical lattice simulations, traditional methods for detecting symmetry restoration have sought multiplets in the screening mass spectrum. However, these methods were imprecise and the results, so far, incomplete. With improved statistics and methodology, we are now able to offer evidence for a restoration of the SU(2) x SU(2) chiral symmetry just above the crossover, but not of the axial U(1) chiral symmetry.
New aspects of scale and discrete flavor symmetry breaking
Energy Technology Data Exchange (ETDEWEB)
Lim, Kher Sham
2014-11-05
The Standard Model (SM) of particle physics is complete with the discovery of the Higgs particle. However the SM cannot be a complete theory of nature as it does not explain the origin of neutrino mass, dark matter (DM), dark energy, matter-antimatter asymmetry and smallness of the strong CP parameter. From theoretical point of view we do not understand the origin of the scale separation between the electroweak (EW) and the Planck scale, and also the flavor puzzle. In this work we tackle the hierarchy problem with scale symmetry and the flavor puzzle with discrete flavor symmetries, charting new symmetry groups and their breaking, while investigating their implied phenomenologies along the way. In the first part we provide two novel mechanisms to explain the origin of the EW scale generated by quantum effects from an anomalous breaking of a classical scale invariant extension of the SM. For the first model we utilize a direct scale transmission from condensation of a scalar, charged under a high representation of QCD, to trigger EW symmetry breaking (EWSB) dynamically. In the second model, we use the indirect scale transmission approach to generate the EW scale transmitted by a singlet scalar mediator which couples to the SM and a strongly coupled hidden sector. Chiral symmetry in the dark fermion sector is broken spontaneously due to nonperturbative effects of the running coupling in the hidden sector, triggering indirectly EWSB due to dimensional transmutation and providing stable DM candidates in the form of dark pions. In the last part of this work we focus on charting new discrete flavor symmetry groups to obtain experimentally acceptable leptonic and quark mixing patterns. The interesting new discrete groups that we have found are classified mathematically and provide a new starting point for model building in discrete flavor symmetry.
Insight into Phenomena of Symmetry Breaking Bifurcation
Institute of Scientific and Technical Information of China (English)
FANG Tong; ZHANG Ying
2008-01-01
@@ We show that symmetry-breaking (SB) bifurcation is just a transition of different forms of symmetry, while still preserving system's symmetry. SB bifurcation always associates with a periodic saddle-node bifurcation, identifiable by a zero maximum of the top Lyapunov exponent of the system. In addition, we show a significant phase portrait of a newly born periodic saddle and its stable and unstable invariant manifolds, together with their neighbouring flow pattern of Poincaré mapping points just after the periodic saddle-node bifurcation, thus gaining an insight into the mechanism of SB bifurcation.
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.
Physical implications of dynamical symmetry breaking
International Nuclear Information System (INIS)
Some model-independent physical implications of a class of hypercolorbased theories of dynamical symmetry-breaking are described and discussed. The role which e+e- colliders can play, in distinguishing between such theories and the canonical methodology, is underlined
Collective neutrino oscillations and spontaneous symmetry breaking
Duan, Huaiyu
2015-08-01
Neutrino oscillations in a hot and dense astrophysical environment such as a core-collapse supernova pose a challenging, seven-dimensional flavor transport problem. To make the problem even more difficult (and interesting), neutrinos can experience collective oscillations through nonlinear refraction in the dense neutrino medium in this environment. Significant progress has been made in the last decade towards the understanding of collective neutrino oscillations in various simplified neutrino gas models with imposed symmetries and reduced dimensions. However, a series of recent studies seem to have "reset" this progress by showing that these models may not be compatible with collective neutrino oscillations because the latter can break the symmetries spontaneously if they are not imposed. We review some of the key concepts of collective neutrino oscillations by using a few simple toy models. We also elucidate the breaking of spatial and directional symmetries in these models because of collective oscillations.
Collective neutrino oscillations and spontaneous symmetry breaking
Duan, Huaiyu
2015-01-01
Neutrino oscillations in a hot and dense astrophysical environment such as a core-collapse supernova pose a challenging, seven-dimensional flavor transport problem. To make the problem even more difficult (and interesting), neutrinos can experience collective oscillations through nonlinear refraction in the dense neutrino medium in this environment. Significant progress has been made in the last decade towards the understanding of collective neutrino oscillations in various simplified neutrino gas models with imposed symmetries and reduced dimensions. However, a series of recent studies seem to have "reset" this progress by showing that these models may not be compatible with collective neutrino oscillations because the latter can break the symmetries spontaneously if they are not imposed. We review some of the key concepts of collective neutrino oscillations by using a few simple toy models. We also elucidate the breaking of spatial and directional symmetries in these models because of collective oscillation...
On the Manifestation of Chiral Symmetry in Nuclei and Dense Nuclear Matter
Brown, G E; Rho, Mannque
2002-01-01
This article reviews our view on how chiral symmetry, its pattern of breaking and restoration under extreme conditions manifest themselves in the nucleon, nuclei, nuclear matter and dense hadronic matter. Topics treated are nucleon structure in terms of chiral symmetry, "first-principle" (QCD) calculations of the properties of finite nuclei effectuated by embedding the ``standard nuclear physics approach" into the framework of effective field theories of nuclei with predictions for certain astrophysical processes, a reinterpretation of the Brown-Rho (BR) scaling that implements chiral symmetry property of baryon-rich medium \\`a la "vector manifestation" of hidden local symmetry, evidences for BR scaling in nuclear processes at normal nuclear matter density and at higher density, the notion of "broadband equilibration" in heavy-ion processes, and the role of strangeness in the formation of compact stars and their collapse into black-holes. We revisit the "Cheshire-Cat phenomenon" recently revived in the form o...
Dynamical chiral symmetry breaking in QED3%三维 QED中的动力学手征对称破缺
Institute of Scientific and Technical Information of China (English)
周雨青
2014-01-01
In order to examine how a propagator behaves in non-perturbative theories and how its behavior is influenced by the choice of a covariant gauge a truncated Dyson-Schwinger equation is used to numerically investigate the properties of fermions and bosons in 3D quantum electrodynamics QED and a series of self-consistent solutions for the fermion propagator in the Nambu and Wigner phases are obtained. These numerical solutions show that the propagator behaves very differently in the Landau gauge domain and in the infrared energy region outside it.By using the propagators in the Nambu and Wigner phases under various gauges it is further investigated how the fermion equivalent pressure difference and fermion condensation change with the gauge parameters.These results indicate that the phase transition described by the CJT equivalent potential and the chiral phase transition described by the chiral condensation are not completely identical.%为了研究非微扰理论中的传播子行为，以及协变规范对其行为的影响，以常用的截断方案下的Dyson－Schwinger方程为基础，采用数值联立求解的方法研究了三维量子电动力学（ QED）中的费米子和玻色子的行为，并获得了一系列不同规范下费米传播子在Nambu和Wigner相中的自洽解。对这些数值解的分析表明，远离Landau规范的红外区处，传播子行为明显不同于Landau规范中的行为。基于Nambu和Wigner相中的不同规范下的传播子，进一步对等效压力差和费米凝聚随规范参数的变化做了比较，结果表明，采用CJT等效势描述的相变与手征凝聚描述的手征相变两者之间不完全自洽。
Explicit and Dynamical Chiral Symmetry Bresking in an Effective Quark-Quark Interaction Model
Institute of Scientific and Technical Information of China (English)
宗红石; 吴小华; 侯丰尧; 赵恩广
2004-01-01
A method for obtaining the small current quark mass effect on the dressed quark propagator from an effective quark-quark interaction model is developed. Within this approach both the explicit and dynamical chiral symmetry breakings are analysed. A comparison with the previous results is given.
Dynamical quarks effects on the gluon propagation and chiral symmetry restoration
Bashir, A; Rodríguez-Quintero, J
2014-01-01
We exploit the recent lattice results for the infrared gluon propagator with light dynamical quarks and solve the gap equation for the quark propagator. Chiral symmetry breaking and confinement (intimately tied with the analytic properties of QCD Schwinger functions) order parameters are then studied.
Cascading Multicriticality in Nonrelativistic Spontaneous Symmetry Breaking
Griffin, Tom; Horava, Petr; Yan, Ziqi
2015-01-01
Without Lorentz invariance, spontaneous global symmetry breaking can lead to multicritical Nambu-Goldstone modes with a higher-order low-energy dispersion $\\omega\\sim k^n$ ($n=2,3,\\ldots$), whose naturalness is protected by polynomial shift symmetries. Here we investigate the role of infrared divergences and the nonrelativistic generalization of the Coleman-Hohenberg-Mermin-Wagner (CHMW) theorem. We find novel cascading phenomena with large hierarchies between the scales at which the value of $n$ changes, leading to an evasion of the "no-go" consequences of the relativistic CHMW theorem.
Electroweak symmetry breaking: Higgs/whatever
International Nuclear Information System (INIS)
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
Symmetry breaking in non conservative systems
Martínez-Pérez, N E
2016-01-01
We apply Noether's theorem to show how the invariances of conservative systems are broken for nonconservative systems, in the variational formulation of Galley. This formulation considers a conservative action, extended by the inclusion of a time reversed sector and a nonconservative generalized potential. We assume that this potential is invariant under the symmetries of the initial conservative system. The breaking occurs because the time reversed sector requires inverse symmetry transformations, under which the nonconservative potential is not invariant. The resulting violation of the conservation laws is consistent with the equations of motion. We generalize this formulation for fermionic and sypersymmetric systems. In the case of a supersymmetric oscillator, the effect of damping is that the bosonic and fermionic components become different frequencies. Considering that initially the nonconservative action is invariant under supersymmetry, and that the breaking is associated to an instability, this resul...
Spontaneous symmetry breaking in loop quantum gravity
Energy Technology Data Exchange (ETDEWEB)
Helesfai, G [Institute for Theoretical Physics, Eoetvoes University, Pazmany Peter setany 1/A, H-1117 Budapest (Hungary)], E-mail: heles@manna.elte.hu
2008-12-07
In this paper we investigate the question of how spontaneous symmetry breaking works in the framework of loop quantum gravity and compare it to the results obtained in the case of the Proca field, where we were able to quantize the theory in loop quantum gravity without introducing a Higgs field. We obtained that the Hamiltonian of the two systems is very similar, the only difference is an extra scalar field in the case of spontaneous symmetry breaking. This field can be identified as the field that carries the mass of the vector field. In the quantum regime this becomes a well-defined operator, which turns out to be a self-adjoint operator with continuous spectrum. To calculate the spectrum we used a new representation in the case of scalar fields, which in addition enabled us to rewrite the constraint equations to a finite system of linear partial differential equations. This made it possible to solve part of the constraints explicitly.
Electroweak Symmetry Breaking Beyond the Standard Model
Bhattacharyya, Gautam
2012-01-01
In this talk, I shall address two key issues related to electroweak symmetry breaking. 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, I shall first review the fine-tuning aspects of the MSSM, NMSSM, generalized NMSSM and GMSB scenarios. I shall then compare and contrast the little Higgs, composite Higgs and the Higgsless models. Finally, I shall summariz...
Phenomenological approach to symmetry breaking pattern of democratic mass matrix
Harada, J
2002-01-01
We investigate the symmetry breaking pattern of the democratic mass matrix model, which leads to the small flavor mixing in quark sector and bi-large mixing in lepton sector. We present the symmetry breaking matrices in quark sector which are determined by alternative ways instead of conventional ansatz. These matrices might be useful for understanding the origin of democratic symmetry and its breaking.
A Fourth Chiral Generation And Susy Breaking
Wingerter, Akin
2011-01-01
We revisit four generations within the context of supersymmetry. We compute the perturbativity limits for the fourth generation Yukawa couplings and show that if the masses of the fourth generation lie within reasonable limits of their present experimental lower bounds, it is possible to have perturbativity only up to scales around 1000 TeV, i.e. the current experimental bounds and perturbative unification are mutually exclusive. Such low scales are ideally suited to incorporate gauge mediated supersymmetry breaking, where the mediation scale can be as low as 10-20 TeV. The minimal messenger model, however, is highly constrained. Lack of electroweak symmetry breaking rules out a large part of the parameter space, and in the remaining part, the fourth generation stau is tachyonic.
Medium effect on charge symmetry breaking
International Nuclear Information System (INIS)
We examine the nuclear medium effect on charge symmetry breaking (CSB) caused by isospin mixing of two neutral vector mesons interacting with nucleons in the nuclear medium. Isospin mixing is assumed to occur through the transition between isoscalar and isovector mesons. We use a quantum hadrodynamic nuclear model in the mean-field approximation for the meson fields involved. We find that (i) charge symmetry is gradually restored in nuclear matter in β equilibrium as the nucleon density increases; (ii) when the system departs from β equilibrium, CSB is much enhanced because the isospin mixing depends strongly on the nucleon isovector density; (iii) this leads to the symmetry energy coefficient of 32MeV, of which more than 50 percent arises from the mesonic mean fields; (iv) the Nolen-Schiffer anomaly regarding the masses of neighboring mirror nuclei can be resolved by considering these aspects of CSB in nuclear medium. copyright 1997 The American Physical Society
Higgsless approach to electroweak symmetry breaking
Grojean, Christophe
2007-01-01
Higgsless models are an attempt to achieve a breaking of the electroweak symmetry via boundary conditions at the end-points of a fifth dimension compactified on an interval, as an alternative to the usual Higgs mechanism. There is no physical Higgs scalar in the spectrum and the perturbative unitarity violation scale is delayed via the exchange of massive spin-1 KK resonances. The correct mass spectrum is reproduced in a model in warped space, which inherits a custodial symmetry from a left–right gauge symmetry in the bulk. Phenomenological challenges as well as collider signatures are presented. From the AdS/CFT perspective, this model appears as a weakly coupled dual to walking technicolour models.
Chiral and U(1) axial symmetry restoration in linear sigma models with two quark flavors
Michalski, S
2006-01-01
We study the restoration of chiral symmetry in linear sigma models with two quark flavors. The models taken into consideration have a U(2) x U(2) and an O(N) internal symmetry. The physical mesons of these models are sigma, pion, \\eta and a_0 where the latter two are not present in the O(N) model. Including two-loop contributions through sunset graphs we calculate the temperature behavior of the order parameter and the masses for explicit chiral symmetry breaking with and without a U(1) axial anomaly. Decay threshold effects introduced by the sunset graphs alter the temperature dependence of the condensate and consequently that of the masses as well. Chiral symmetry tends to be restored at higher temperatures in the two-loop approximation than in the Hartree-Fock approximation. To model a dynamical restoration of the U(1) axial symmetry we imply a temperature-dependent anomaly parameter that sharply drops at about 175 MeV. This triggers the restoration of chiral symmetry before the full symmetry is restored a...
Packing of Helices: Is Chirality the Highest Crystallographic Symmetry?
Directory of Open Access Journals (Sweden)
Romain Gautier
2016-08-01
Full Text Available Chiral structures resulting from the packing of helices are common in biological and synthetic materials. Herein, we analyze the noncentrosymmetry (NCS in such systems using crystallographic considerations. A comparison of the chiral structures built from helices shows that the chirality can be expected for specific building units such as 31/32 or 61/65 helices which, in hexagonal arrangement, will more likely lead to a chiral resolution. In these two systems, we show that the highest crystallographic symmetry (i.e., the symmetry which can describe the crystal structure from the smallest assymetric unit is chiral. As an illustration, we present the synthesis of two materials ([Zn(2,2’-bpy3](NbF62 and [Zn(2,2’-bpy3](TaF62 in which the 3n helices pack into a chiral structure.
Spontaneous spherical symmetry breaking in atomic confinement
Sveshnikov, K
2016-01-01
The effect of spontaneous breaking of initial SO(3) symmetry is shown to be possible for an H-like atom in the ground state, when it is confined in a spherical box under general boundary conditions of "not going out" through the box surface (i.e. third kind or Robin's ones), for a wide range of physically reasonable values of system parameters. The reason is that such boundary conditions could yield a large magnitude of electronic wavefunction in some sector of the box boundary, what in turn promotes atomic displacement from the box center towards this part of the boundary, and so the underlying SO(3) symmetry spontaneously breaks. The emerging Goldstone modes, coinciding with rotations around the box center, restore the symmetry by spreading the atom over a spherical shell localized at some distances from the box center. Atomic confinement inside the cavity proceeds dynamically -- due to the boundary condition the deformation of electronic wavefunction near the boundary works as a spring, that returns the at...
Symmetry Breaking in MILP Formulations for Unit Commitment Problems
Lima, Ricardo M.
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.
Edge states protected by chiral symmetry in disordered photonic graphene
Zeuner, Julia M; Nolte, Stefan; Szameit, Alexander
2013-01-01
We experimentally investigate the impact of uncorrelated composite and structural disorder in photonic graphene. We find that in case of structural disorder not only chiral symmetry, but also the vanishing of the density of states at zero energy is preserved. This is in contrast to composite disorder, where chiral symmetry as well as the vanishing of the density of states are destroyed. Our observations are experimentally proven by exciting edge states at the bearded edge in disordered photonic graphene.
Thick brane solitons breaking $Z_2$ symmetry
Peyravi, Marzieh; Lobo, Francisco S N
2015-01-01
New soliton solutions for thick branes in 4 + 1 dimensions are considered in this article. In particular, brane models based on the sine-Gordon (SG), $\\varphi^{4}$ and $\\varphi^{6}$ scalar fields are investigated; in some cases $Z_{2}$ symmetry is broken. Besides, these soliton solutions are responsible for supporting and stabilizing the thick branes. In these models, the origin of the symmetry breaking resides in the fact that the modified scalar field potential may have non-degenerate vacuua and these non-degenerate vacuua determine the cosmological constant on both sides of the brane. At last, in order to explore the particle motion in the neighborhood of the brane, the geodesic equations along the fifth dimension are studied.
Symmetry Breaking And The Nilpotent Dirac Equation
Rowlands, Peter
2004-08-01
A multivariate 4-vector representation for space-time and a quaternion representation for mass and the electric, strong and weak charges leads to a nilpotent form of the Dirac equation, which packages the entire physical information available about a fermion state. The nilpotent state vector breaks the symmetry between the strong, electric and weak interactions, by associating their respective charges with vector, scalar and pseudoscalar operators, leading directly to the SU(3) × SU(2)L × U(1) symmetry, and to particle structures and mass-generating states. In addition, the nilpotent Dirac equation has just three solutions for spherically-symmetric distance-dependent potentials, and these correspond once again to those that would be expected for the three interactions: linear for the strong interaction; inverse linear for the electromagnetic; and a harmonic oscillator-type solution, which can be equated with the dipolar annihilation and creation mechanisms of the weak interaction.
Dobado, A; Peláez, J R; Ruiz-Morales, Ester
2000-01-01
We present a unified analysis of the two main production processes of vector boson pairs at the CERN LHC, VV-fusion and qq annihilation, in a minimal strongly interacting electroweak symmetry breaking sector. Using a unitarized electroweak chiral Lagrangian formalism and modeling the final V/sub L/V/sub L/ strong rescattering effects by a form factor, we describe qq annihilation processes in terms of the two chiral parameters that govern elastic V/sub L/V/sub L/ scattering. Depending on the values of these two chiral parameters, the unitarized amplitudes may present resonant enhancements in different angular momentum-isospin channels. Scanning this two parameter space, we generate the general resonance spectrum of a minimal strongly interacting electroweak symmetry breaking sector and determine the regions that can be probed at the CERN LHC. (47 refs).
Electroweak symmetry breaking beyond the Standard Model
Indian Academy of Sciences (India)
Gautam Bhattacharyya
2012-10-01
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.
Extraordinary transmission caused by symmetry breaking
Hu, Dan; Liu, Ming; Zhang, Yan
2011-01-01
The terahertz transmission properties of H-shaped annular apertures arrays (AAAs) are investigated experimentally and numerically. It is found the only odd order resonances mode are observed in the symmetrical structures but both odd and even order resonances can be shown in the asymmetrical structures. Breaking the symmetry in H- shaped AAAs by gradual displacing from H-shaped to U-shaped AAAs allows an intensity modulation depth of 99% of the second order resonance. Simulation results verify the experimental conclusion well. This result provides a tremendous opportunities for terahertz wavelength tunable filters, sensing, and near-field imaging.
Spontaneous symmetry breaking in a classical particle
Sánchez, L A; Sanchez, Luis Alberto; Mahecha, Jorge
2003-01-01
Due to the fact that only matter fields have phase, frequently is believed that the gauge principle can induce gauge fields only in quantum systems. But this is not necessary. This paper, of pedagogical scope, presents a classical system constituted by a particle in a classical potential, which is used as a model to illustrate the gauge principle and the spontaneous symmetry breaking. Those concepts appear in the study of second order phase transitions. Ferroelectricity, ferromagnetism, superconductivity, plasmons in a free electron gas, and the mass of vector bosons in the gauge field Yang-Mills theories, are some of the phenomena in which these transitions occur.
Cosmology of biased discrete symmetry breaking
Gelmini, Graciela B.; Gleiser, Marcelo; Kolb, Edward W.
1988-01-01
The cosmological consequences of spontaneous breaking of an approximate discrete symmetry are studied. The breaking leads to formation of proto-domains of false and true vacuum separated by domain walls of thickness determined by the mass scale of the model. The cosmological evolution of the walls is extremely sensitive to the magnitude of the biasing; several scenarios are possible, depending on the interplay between the surface tension on the walls and the volume pressure from the biasing. Walls may disappear almost immediately after they form, or may live long enough to dominate the energy density of the Universe and cause power-law inflation. Limits are obtained on the biasing that characterizes each possible scenario.
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.
Hyperscaling violation and electroweak symmetry breaking
International Nuclear Information System (INIS)
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
Symmetry breaking: The standard model and superstrings
Energy Technology Data Exchange (ETDEWEB)
Gaillard, M.K.
1988-08-31
The outstanding unresolved issue of the highly successful standard model is the origin of electroweak symmetry breaking and of the mechanism that determines its scale, namely the vacuum expectation value (vev)v that is fixed by experiment at the value v = 4m//sub w//sup 2///g/sup 2/ = (..sqrt..2G/sub F/)/sup /minus/1/ approx. = 1/4 TeV. In this talk I will discuss aspects of two approaches to this problem. One approach is straightforward and down to earth: the search for experimental signatures, as discussed previously by Pierre Darriulat. This approach covers the energy scales accessible to future and present laboratory experiments: roughly (10/sup /minus/9/ /minus/ 10/sup 3/)GeV. The second approach involves theoretical speculations, such as technicolor and supersymmetry, that attempt to explain the TeV scale. 23 refs., 5 figs.
A (critical) overview of electroweak symmetry breaking
International Nuclear Information System (INIS)
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
Cosmic acceleration from Abelian symmetry breaking
International Nuclear Information System (INIS)
We discuss a consistent theory for a self-interacting vector field, breaking an Abelian symmetry in such a way to obtain an interesting behavior for its longitudinal polarization. In an appropriate decoupling limit, the dynamics of the longitudinal mode is controlled by Galileon interactions. The full theory away from the decoupling limit does not propagate ghost modes, and can be investigated in regimes where non-linearities become important. When coupled to gravity, this theory provides a candidate for dark energy, since it admits de Sitter cosmological solutions characterized by a technically natural value for the Hubble parameter. We also consider the homogeneous evolution when, besides the vector, additional matter in the form of perfect fluids is included. We find that the vector can have an important role in characterizing the universe expansion
Information Content of Spontaneous Symmetry Breaking
Gleiser, Marcelo
2012-01-01
We propose a measure of order in the context of nonequilibrium field theory and argue that this measure, which we call relative configurational entropy (RCE), may be used to quantify the emergence of coherent low-entropy configurations, such as time-dependent or time-independent topological and nontopological spatially-extended structures. As an illustration, we investigate the nonequilibrium dynamics of spontaneous symmetry-breaking in three spatial dimensions. In particular, we focus on a model where a real scalar field, prepared initially in a symmetric thermal state, is quenched to a broken-symmetric state. For a certain range of initial temperatures, spatially-localized, long-lived structures known as oscillons emerge in synchrony and remain until the field reaches equilibrium again. We show that the RCE correlates with the number-density of oscillons, thus offering a quantitative measure of the emergence of nonperturbative spatiotemporal patterns that can be generalized to a variety of physical systems.
Black Holes and Abelian Symmetry Breaking
Chagoya, Javier; Tasinato, Gianmassimo
2016-01-01
Black hole configurations offer insights on the non-linear aspects of gravitational theories, and can suggest testable predictions for modifications of General Relativity. In this work, we examine exact black hole configurations in vector-tensor theories, originally proposed to explain dark energy by breaking the Abelian symmetry with a non-minimal coupling of the vector to gravity. We are able to evade the no-go theorems by Bekenstein on the existence of regular black holes in vector-tensor theories with Proca mass terms, and exhibit regular black hole solutions with a profile for the longitudinal vector polarization, characterised by an additional charge. We analytically find the most general static, spherically symmetric black hole solutions with and without a cosmological constant, and study in some detail their features, such as how the geometry depends on the vector charges. We also include angular momentum, and find solutions describing slowly-rotating black holes. Finally, we extend some of these solu...
Time-symmetry breaking in turbulence
Jucha, Jennifer; Pumir, Alain; Bodenschatz, Eberhard
2014-01-01
In three-dimensional turbulent flows, the flux of energy from large to small scales breaks time symmetry. We show here that this irreversibility can be quantified by following the relative motion of several Lagrangian tracers. We find by analytical calculation, numerical analysis and experimental observation that the existence of the energy flux implies that, at short times, two particles separate temporally slower forwards than backwards, and the difference between forward and backward dispersion grows as $t^3$. We also find the geometric deformation of material volumes, surrogated by four points spanning an initially regular tetrahedron, to show sensitivity to the time-reversal with an effect growing linearly in $t$. We associate this with the structure of the strain rate in the flow.
Chiral symmetry and scalar meson in hadron and nuclear physics
Kunihiro, T
1995-01-01
After giving a short introduction to the Nambu-Jona-Lasinio model with an anomaly term, we show the importance of the scalar-scalar correlation in the low-energy hadron dynamics, which correlation may be summarized by a scalar-isoscalar meson, the sigma meson. The discussion is based on the chiral quark model with the sigma-meson degrees of freedom. Possible experiments are proposed to produce the elusive meson in a nucleus and detect it. In relation to a precursory soft mode for the chiral transition, the reason is clarified why the dynamic properties of the superconductor may be described by the diffusive time-dependent Ginzburg-Landau (TDGL) equation. We indicate the chiral symmetry plays a significant role also in nuclei; one may say that the stability of nuclei is due to the chiral symmetry of QCD.
Breaking temporal symmetries for emission and absorption
Hadad, Yakir; Soric, Jason C.; Alu, Andrea
2016-01-01
Time-reversal symmetries impose stringent constraints on emission and absorption. Antennas, from radiofrequencies to optics, are bound to transmit and receive signals equally well from the same direction, making a directive antenna prone to receive echoes and reflections. Similarly, in thermodynamics Kirchhoff’s law dictates that the absorptivity and emissivity are bound to be equal in reciprocal systems at equilibrium, e(ω,θ)=a(ω,θ), with important consequences for thermal management and energy applications. This bound requires that a good absorber emits a portion of the absorbed energy back to the source, limiting its overall efficiency. Recent works have shown that weak time modulation or mechanical motion in suitably designed structures may largely break reciprocity and time-reversal symmetry. Here we show theoretically and experimentally that a spatiotemporally modulated device can be designed to have drastically different emission and absorption properties. The proposed concept may provide significant advances for compact and efficient radiofrequency communication systems, as well as for energy harvesting and thermal management when translated to infrared frequencies. PMID:26984502
Isospin symmetry breaking in sd shell nuclei
International Nuclear Information System (INIS)
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)
Breaking of electroweak symmetry: origin and effects
International Nuclear Information System (INIS)
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 A4 non-Abelian discrete symmetry. It is shown that this model does not contradict the tests of electroweak precision. (A.C.)
Breaking temporal symmetries for emission and absorption.
Hadad, Yakir; Soric, Jason C; Alu, Andrea
2016-03-29
Time-reversal symmetries impose stringent constraints on emission and absorption. Antennas, from radiofrequencies to optics, are bound to transmit and receive signals equally well from the same direction, making a directive antenna prone to receive echoes and reflections. Similarly, in thermodynamics Kirchhoff's law dictates that the absorptivity and emissivity are bound to be equal in reciprocal systems at equilibrium, e(ω, θ)=a(ω, θ), with important consequences for thermal management and energy applications. This bound requires that a good absorber emits a portion of the absorbed energy back to the source, limiting its overall efficiency. Recent works have shown that weak time modulation or mechanical motion in suitably designed structures may largely break reciprocity and time-reversal symmetry. Here we show theoretically and experimentally that a spatiotemporally modulated device can be designed to have drastically different emission and absorption properties. The proposed concept may provide significant advances for compact and efficient radiofrequency communication systems, as well as for energy harvesting and thermal management when translated to infrared frequencies. PMID:26984502
Breaking temporal symmetries for emission and absorption
Hadad, Yakir; Soric, Jason C.; Alu, Andrea
2016-03-01
Time-reversal symmetries impose stringent constraints on emission and absorption. Antennas, from radiofrequencies to optics, are bound to transmit and receive signals equally well from the same direction, making a directive antenna prone to receive echoes and reflections. Similarly, in thermodynamics Kirchhoff's law dictates that the absorptivity and emissivity are bound to be equal in reciprocal systems at equilibrium, e(ω,θ)=a(ω,θ), with important consequences for thermal management and energy applications. This bound requires that a good absorber emits a portion of the absorbed energy back to the source, limiting its overall efficiency. Recent works have shown that weak time modulation or mechanical motion in suitably designed structures may largely break reciprocity and time-reversal symmetry. Here we show theoretically and experimentally that a spatiotemporally modulated device can be designed to have drastically different emission and absorption properties. The proposed concept may provide significant advances for compact and efficient radiofrequency communication systems, as well as for energy harvesting and thermal management when translated to infrared frequencies.
Golden Probe of Electroweak Symmetry Breaking
Chen, Yi; Spiropulu, Maria; Stolarski, Daniel; Vega-Morales, Roberto
2016-01-01
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...
Structure of the vacuum in the color dielectric model: confinement and chiral symmetry
International Nuclear Information System (INIS)
Two of the most important properties of Quantum Chromodynamic (QCD), spontaneous symmetry breaking of the vacuum and quark confinement at low energy, are first presented. Some important effective models for hadronic physics are then described. Putting QCD on the lattice and using the block-spin method, the color-dielectric model effective Lagrangian is obtained. The structure of the vacuum and the behaviour of uniform quark matter at high intensity are investigated in this model. Its original formulation is extended to handle chiral symmetry (by use of sigma model) and to include negative energy orbitals. At high baryonic density, the model describes the two phase transitions which are expected in QCD: deconfinement of quarks and chiral symmetry restoration. Finally, a heavy meson composed by a charmed quark anti-quark pair, is constructed, and the valence quarks confinement and the vacuum structure around them are studied
Chiral Symmetry in algebraic and analytic approaches
Vereshagin, V.; Dillig, M.; Vereshagin, A.
1996-01-01
We compare among themselves two different methods for the derivation of results following from the requirement of polynomial boundedness of tree-level chiral amplitudes. It is shown that the results of the algebraic approach are valid also in the framework of the analytical one. This means that the system of Sum Rules and Bootstrap equations previously obtained with the help of the latter approach can be analyzed in terms of reducible representations of the unbroken Chiral group with the know...
Electronic Localization Length of Carbon Nanotubes with Different Chiral Symmetries
Institute of Scientific and Technical Information of China (English)
杨化通; 董锦明; 邢定钰
2001-01-01
The electronic localization lengths λ of metallic carbon nanotubes with different chiral symmetries have been calculated by one parameter scaling method. It is found that λ is independent of the nanotube chirality, but depends linearly on the diameter. The dependence of λ on the disorder strength W has also been studied, and a power-law relation between λ and W is also found to be independent of the tube chirality. Our numerical results are in good agreement with recent experimental observations and other theoretical results for only the "armchair"nanotubes.
Thermal and Nonthermal Pion Enhancements with Chiral Symmetry Restoration
Zhuang, P
2001-01-01
The pion production by sigma decay and its relation with chiral symmetry restoration in a hot and dense matter are investigated in the framework of the Nambu-Jona-Lasinio model. The decay rate for the process sigma -> 2pion to the lowest order in a 1/N_c expansion is calculated as a function of temperature T and chemical potential mu. The thermal and nonthermal enhancements of pions generated by the decay before and after the freeze-out present only in the crossover region of the chiral symmetry transition. The strongest nonthermal enhancement is located in the vicinity of the endpoint of the first-order transition.
Chiral Lagrangian with Heavy Quark-Diquark Symmetry
Energy Technology Data Exchange (ETDEWEB)
Jie Hu; Thomas Mehen
2005-11-29
We construct a chiral Lagrangian for doubly heavy baryons and heavy mesons that is invariant under heavy quark-diquark symmetry at leading order and includes the leading O(1/m{sub Q}) symmetry violating operators. The theory is used to predict the electromagnetic decay width of the J=3/2 member of the ground state doubly heavy baryon doublet. Numerical estimates are provided for doubly charm baryons. We also calculate chiral corrections to doubly heavy baryon masses and strong decay widths of low lying excited doubly heavy baryons.
A new dynamics of electroweak symmetry breaking with classically scale invariance
Haba, Naoyuki; Kitazawa, Noriaki; Yamaguchi, Yuya
2015-01-01
We propose a new dynamics of the electroweak symmetry breaking in a classically scale invariant version of the standard model. The scale invariance is broken by the condensations of additional fermions under a strong coupling dynamics. The electroweak symmetry breaking is triggered by negative mass squared of the elementary Higgs doublet, which is dynamically generated through the bosonic seesaw mechanism. We introduce a real pseudo-scalar singlet field interacting with additional fermions and Higgs doublet in order to avoid massless Nambu-Goldstone bosons from the chiral symmetry breaking in a strong coupling sector. We investigate the mass spectra and decay rates of these pseudo-Nambu-Goldstone bosons, and show they can decay fast enough without cosmological problems. We further evaluate the energy dependences of the couplings between elementary fields perturbatively, and find that our model is the first one which realizes the flatland scenario with the dimensional transmutation by the strong coupling dynam...
A new dynamics of electroweak symmetry breaking with classically scale invariance
Directory of Open Access Journals (Sweden)
Naoyuki Haba
2016-04-01
Full Text Available We propose a new dynamics of the electroweak symmetry breaking in a classically scale invariant version of the standard model. The scale invariance is broken by the condensations of additional fermions under a strong coupling dynamics. The electroweak symmetry breaking is triggered by negative mass squared of the elementary Higgs doublet, which is dynamically generated through the bosonic seesaw mechanism. We introduce a real pseudo-scalar singlet field interacting with additional fermions and Higgs doublet in order to avoid massless Nambu–Goldstone bosons from the chiral symmetry breaking in a strong coupling sector. We investigate the mass spectra and decay rates of these pseudo-Nambu–Goldstone bosons, and show they can decay fast enough without cosmological problems. We further show that our model can make the electroweak vacuum stable.
Spontaneous Breaking of Spatial and Spin Symmetry in Spinor Condensates
DEFF Research Database (Denmark)
Scherer, M.; Lücke, B.; Gebreyesus, G.;
2010-01-01
Parametric amplification of quantum fluctuations constitutes a fundamental mechanism for spontaneous symmetry breaking. In our experiments, a spinor condensate acts as a parametric amplifier of spin modes, resulting in a twofold spontaneous breaking of spatial and spin symmetry in the amplified...
Salam-Weinberg symmetry breaking with superheavy Higgs particles
International Nuclear Information System (INIS)
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)
Dark Matter and Dark Energy from Gravitational Symmetry Breaking
Fuzfa, A
2010-01-01
We build a mechanism of gravitational symmetry breaking (GSB) of a global U(1) symmetry based on the relaxation of the equivalence principle due to the mass variation of pseudo Nambu-Goldstone dark matter (DM) particles. This GSB process is described by the modified cosmological convergence mechanism of the Abnormally Weighting Energy (AWE) Hypothesis previously introduced by the authors. Several remarkable constraints from the Hubble diagram of far-away supernovae are derived, notably on the explicit and gravitational symmetry breaking energy scales of the model. We then briefly present some consequences on neutrino masses when this mechanism is applied to the particular case of the breaking of lepton number symmetry.
Effective meson lagrangian with chiral and heavy quark symmetries from quark flavor dynamics
International Nuclear Information System (INIS)
By bosonization of an extended NJL model we derive an effective meson theory which describes the interplay between chiral symmetry and heavy quark dynamics. This effective theory is worked out in the low-energy regime using the gradient expansion. The resulting effective lagrangian describes strong and weak interactions of heavy B and D mesons with pseudoscalar Goldstone bosons and light vector and axial-vector mesons. Heavy meson weak decay constants, coupling constants and the Isgur-Wise function are predicted in terms of the model parameters partially fixed from the light quark sector. Explicit SU(3)F symmetry breaking effects are estimated and, if possible, confronted with experiment. ((orig.))
Lorentz symmetry breaking effects on relativistic EPR correlations
Energy Technology Data Exchange (ETDEWEB)
Belich, H. [Universidade Federal do Espirito Santo, Departamento de Fisica e Quimica, Vitoria, ES (Brazil); Furtado, C.; Bakke, K. [Universidade Federal da Paraiba, Departamento de Fisica, Caixa Postal 5008, Joao Pessoa, PB (Brazil)
2015-09-15
Lorentz symmetry breaking effects on relativistic EPR (Einstein-Podolsky-Rosen) correlations are discussed. From the modified Maxwell theory coupled to gravity, we establish a possible scenario of the Lorentz symmetry violation and write an effective metric for the Minkowski spacetime. Then we obtain the Wigner rotation angle via the Fermi-Walker transport of spinors and consider the WKB (Wentzel-Kramers-Brillouin) approximation in order to study the influence of Lorentz symmetry breaking effects on the relativistic EPR correlations. (orig.)
SU(3) Chiral Symmetry in Non-Relativistic Field Theory
Ouellette, S M
2001-01-01
Applications imposing SU(3) chiral symmetry on non-relativistic field theory are considered. The first example is a calculation of the self-energy shifts of the spin-3/2 decuplet baryons in nuclear matter, from the chiral effective Lagrangian coupling octet and decuplet baryon fields. Special attention is paid to the self-energy of the delta baryon near the saturation density of nuclear matter. We find contributions to the mass shifts from contact terms in the effective Lagrangian with coefficients of unknown value. As a second application, we formulate an effecive field theory with manifest SU(2) chiral symmetry for the interactions of K and eta mesons with pions at low energy. SU(3) chiral symmetry is imposed on the effective field theory by a matching calculation onto three-flavor chiral perturbation theory. The effective Lagrangian for the pi-K and pi-eta sectors is worked out to order Q^4; the effective Lagrangian for the K-K sector is worked out to order Q^2 with contact interactions to order Q^4. As an...
Charge symmetry breaking in $\\Lambda$ hypernuclei revisited
Gal, Avraham
2015-01-01
The large charge symmetry breaking (CSB) implied by the $\\Lambda$ binding energy difference $\\Delta B^{4}_{\\Lambda}(0^+_{\\rm g.s.})\\equiv B_{\\Lambda}(_{\\Lambda}^4$He)$-$$B_{\\Lambda}(_{\\Lambda}^4$H) = 0.35$\\pm$0.06 MeV of the $A=4$ mirror hypernuclei ground states, determined from emulsion studies, has defied theoretical attempts to reproduce it in terms of CSB in hyperon masses and in hyperon-nucleon interactions, including one pion exchange arising from $\\Lambda-\\Sigma^0$ mixing. Using a schematic strong-interaction $\\Lambda N\\leftrightarrow\\Sigma N$ coupling model developed by Akaishi and collaborators for $s$-shell $\\Lambda$ hypernuclei, we revisit the evaluation of CSB in the $A=4$ $\\Lambda$ hypernuclei and extend it to $p$-shell mirror $\\Lambda$ hypernuclei. The model yields values of $\\Delta B^{4}_{\\Lambda} (0^+_{\\rm g.s.})\\sim 0.25$ MeV. Smaller size and mostly negative $p$-shell binding energy differences are calculated for the $A=7-10$ mirror hypernuclei, in rough agreement with the few available dat...
Black holes and Abelian symmetry breaking
Chagoya, Javier; Niz, Gustavo; Tasinato, Gianmassimo
2016-09-01
Black hole configurations offer insights on the nonlinear aspects of gravitational theories, and can suggest testable predictions for modifications of General Relativity. In this work, we examine exact black hole configurations in vector–tensor theories, originally proposed to explain dark energy by breaking the Abelian symmetry with a non-minimal coupling of the vector to gravity. We are able to evade the no-go theorems by Bekenstein on the existence of regular black holes in vector–tensor theories with Proca mass terms, and exhibit regular black hole solutions with a profile for the longitudinal vector polarisation, characterised by an additional charge. We analytically find the most general static, spherically symmetric black hole solutions with and without a cosmological constant, and study in some detail their features, such as how the geometry depends on the vector charges. We also include angular momentum, and find solutions describing slowly-rotating black holes. Finally, we extend some of these solutions to higher dimensions.
Warped electroweak breaking without custodial symmetry
Cabrer, Joan A.; von Gersdorff, Gero; Quirós, Mariano
2011-03-01
We propose an alternative to the introduction of an extra gauge (custodial) symmetry to suppress the contribution of KK modes to the T parameter in warped theories of electroweak breaking. The mechanism is based on a general class of warped 5D metrics and a Higgs propagating in the bulk. The metrics are nearly AdS in the UV region but depart from AdS in the IR region, towards where KK fluctuations are mainly localized, and have a singularity outside the slice between the UV and IR branes. This gravitational background is generated by a bulk stabilizing scalar field which triggers a natural solution to the hierarchy problem. Depending on the model parameters, gauge-boson KK modes can be consistent with present bounds on EWPT for mKK≳1 TeV at 95% CL. The model contains a light Higgs mode which unitarizes the four-dimensional theory. The reduction in the precision observables can be traced back to a large wave function renormalization for this mode.
Warped Electroweak Breaking Without Custodial Symmetry
Cabrer, Joan A; Quiros, Mariano
2010-01-01
We propose an alternative to the introduction of an extra gauge (custodial) symmetry to suppress the contribution of KK modes to the T parameter in warped theories of electroweak breaking. The mechanism is based on a general class of warped 5D metrics and a Higgs propagating in the bulk. The metrics are nearly AdS in the UV region but depart from AdS in the IR region, towards where KK fluctuations are mainly localized, and have a singularity outside the slice between the UV and IR branes. This gravitational background is generated by a bulk stabilizing scalar field which triggers a natural solution to the hierarchy problem. Depending on the model parameters, gauge-boson KK modes can be consistent with present bounds on EWPT for m > 1 TeV at 95% CL. The model contains a light Higgs mode which unitarizes the four-dimensional theory. The reduction in the precision observables can be traced back to a large wave function renormalization for this mode.
Exploration of Chiral Aminophenols and Aminonaphthols with C2-Symmetry
Institute of Scientific and Technical Information of China (English)
Yan SUN; Zhi Min LI; Xiu Min SHEN; Feng Nian MA; Cong ZHANG
2005-01-01
The exploration of C2-symmetric chiral aminophenols and aminonaphthols is described.Seven new ligands have been successfully synthesized using Mannich reaction as a key step.Four of them have C2-symmetry and their structure has been fully characterized by means of NMR and X-ray crystallography.
Four-Fermion Theories with Exact Chiral Symmetry in Three Dimensions
Schmidt, Daniel; Wipf, Andreas
2016-01-01
We investigate a class of four-fermion theories which includes well-known models like the Gross-Neveu model and the Thirring model. In three spacetime dimensions, they are used to model interesting solid state systems like high temperature superconductors and graphene. Additionally, they serve as toy models to study chiral symmetry breaking (CSB). For any number of fermion flavours the Gross-Neveu model has a broken and a symmetric phase, while the existence of a broken phase in the Thirring model depends on the number of flavours. The critical number of fermion flavours beyond which there exists no CSB is still subject of ongoing discussions. Using SLAC fermions we simulate the Thirring model with exact chiral symmetry. To obtain a chiral condensate one can introduce a symmetry-breaking mass term and carefully study the limits of infinite lattice and zero-mass. So far, we did not see CSB within this approach for the Thirring model with 2 or more (reducible) flavours. The talk presents alternative approaches ...
ISOSPIN BREAKING AND THE CHIRAL CONDENSATE.
Energy Technology Data Exchange (ETDEWEB)
CREUTZ, M.
2005-07-25
With two degenerate quarks, the chiral condensate exhibits a jump as the quark masses pass through zero. I discuss how this single transition splits into two Ising like transitions when the quarks are made non-degenerate. The order parameter is the expectation of the neutral pion field. The transitions represent long distance coherent phenomena occurring without the Dirac operator having vanishingly small eigenvalues.
A UV-complete Composite Higgs model for Electroweak Symmetry Breaking: Minimal Conformal Technicolor
Tacchi, Ruggero Altair
The Large Hadron Collider is currently collecting data. One of the main goals of the experiment is to find evidence of the mechanism responsible for the breaking of the electroweak symmetry. There are many different models attempting to explain this breaking and traditionally most of them involve the use of supersymmetry near the scale of the breaking. This work is focused on exploring a viable model that is not based on a weakly coupled low scale supersymmetry sector to explain the electroweak symmetry breaking. We build a model based on a new strong interaction, in the fashion of theories commonly called "technicolor", name that is reminiscent of one of the first attempts of explaining the electroweak symmetry breaking using a strong interaction similar to the one whose charges are called colors. We explicitly study the minimal model of conformal technicolor, an SU(2) gauge theory near a strongly coupled conformal fixed point, with conformal symmetry softly broken by technifermion mass terms. Conformal symmetry breaking triggers chiral symmetry breaking in the pattern SU(4) → Sp (4), which gives rise to a pseudo-Nambu-Goldstone boson that can act as a composite Higgs boson. There is an additional composite pseudoscalar A with mass larger than mh and suppressed direct production at LHC. We discuss the electroweak fit in this model in detail. A good fit requires fine tuning at the 10% level. We construct a complete, realistic, and natural UV completion of the model, that explains the origin of quark and lepton masses and mixing angles. We embed conformal technicolor in a supersymmetric theory, with supersymmetry broken at a high scale. The effective theory below the supersymmetry breaking scale is minimal conformal technicolor with an additional light technicolor gaugino that might give rise to an additional pseudo Nambu-Goldstone boson that is observable at the LHC.
Accion dark matter in the post-inflationary Peccei-Quinn symmetry breaking scenario
Ringwald, Andreas
2015-01-01
We consider extensions of the Standard Model in which a spontaneously broken global chiral Peccei-Quinn (PQ) symmetry arises as an accidental symmetry of an exact $Z_N$ symmetry. For $N = 9$ or $10$, this symmetry can protect the accion - the Nambu-Goldstone boson arising from the spontaneous breaking of the accidental PQ symmetry - against semi-classical gravity effects, thus providing a proper solution of the strong CP problem, while it can at the same time provide for the small explicit symmetry breaking term needed to make models with domain wall number $N_{\\rm DW}>1$, such as the popular DFSZ model ($N_{\\rm DW}=6$), cosmologically viable even in the case where spontaneous PQ symmetry breaking occurred after inflation. We find that $N=10$ DFSZ accions with mass $m_A \\approx 3.5$-$4.2\\,\\mathrm{meV}$ can account for cold dark matter and simultaneously explain the hints for anomalous cooling of white dwarfs. The proposed helioscope IAXO - being sensitive to solar DFSZ accions with mass above a few meV - will...
Is Electroweak Symmetry Breaking Still Natural in the MSSM?
Dutta, Bhaskar
2016-01-01
The absence of any signal of supersymmetry (SUSY) at the LHC has raised the SUSY particle mass scale compared to $Z$ boson mass $M_Z$. We investigate the naturalness of the electroweak symmetry breaking after considering radiative symmetry breaking along with 125 GeV Higgs mass. We find that the important quantity to measure the naturalness of the hierarchy between the SUSY scale and $M_Z$ is the separation between the radiative symmetry breaking scale, i.e., where $m_{H_u}^2+\\mu^2$ turns negative for large $\\tan\\beta$ case ($\\mu$ is the Higgsino mass and $m_{H_u}$ is the SUSY breaking up-type Higgs boson mass) and the average stop mass. Using this measure, one can show that the electroweak symmetry breaking can be natural even if $\\mu$ is large contrary to the prevailing claim that $\\mu$ is needed to be small to maintain the naturalness.
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.
Ruggieri, M
2016-01-01
In this article we study restoration of chiral symmetry at finite temperature for quark matter with a chiral chemical potential, $\\mu_5$, by means of a nonlocal Nambu-Jona-Lasinio model. This model allows to introduce in the simplest way possible a Euclidean momentum, $p_E$, dependent quark mass function which decays (neglecting logarithms) as $1/p_E^2$ for large $p_E$ in agreement with asymptotic behaviour expected in presence of a nonperturbative quark condensate. We show that the momentum dependence of the quark mass function, which has been neglected in all of the previous model studies, drastically affects the dependence of the critical temperature versus $\\mu_5$. We explain this in terms of a natural removal of ultraviolet modes at $T>0$ in the gap equation, as well as of the natural addition of these modes at $T=0$ which help to catalyze chiral symmetry breaking. As a result we find that within this model the critical temperature increases with $\\mu_5$.
Alexandru, Andrei
2014-01-01
The validity of recently proposed equivalence between valence spontaneous chiral symmetry breaking (vSChSB) and chiral polarization of low energy Dirac spectrum (ChP) in SU(3) gauge theory, is examined for the case of twelve mass-degenerate fundamental quark flavors. We find that the vSChSB-ChP correspondence holds for regularized systems studied. Moreover, our results suggest that vSChSB occurs in two qualitatively different circumstances: there is a quark mass $m_c$ such that for $m > m_c$ the mode condensing Dirac spectrum exhibits standard monotonically increasing density, while for $m_{ch} < m < m_c$ the peak around zero separates from the bulk of the spectrum, with density showing a pronounced depletion at intermediate scales. Valence chiral symmetry restoration may occur at yet smaller masses $m < m_{ch}$, but this has not yet been seen by overlap valence probe, leaving the $m_{ch}=0$ possibility open. The latter option could place massless N$_f$=12 theory outside of conformal window. Anomalou...
Alexandru, Andrei; Horváth, Ivan
2016-01-01
The validity of recently proposed equivalence between valence spontaneous chiral symmetry breaking (vSChSB) and chiral polarization of low energy Dirac spectrum (ChP) in SU(3) gauge theory, is examined for the case of twelve mass-degenerate fundamental quark flavors. We find that the vSChSB-ChP correspondence holds for regularized systems studied. Moreover, our results suggest that vSChSB occurs in two qualitatively different circumstances: there is a quark mass mc such that for m > mc the mode condensing Dirac spectrum exhibits standard monotonically increasing density, while for mch < m < mc the peak around zero separates from the bulk of the spectrum, with density showing a pronounced depletion at intermediate scales. Valence chiral symmetry restoration may occur at yet smaller masses m < mch, but this has not yet been seen by overlap valence probe, leaving the mch = 0 possibility open. The latter option could place massless Nf=12 theory outside of conformal window. Anomalous behavior of overlap Dirac spectrum for mch < m < mc is qualitatively similar to one observed previously in zero and few-flavor theories as an effect of thermal agitation.
Testing Lorentz Symmetry using Chiral Perturbation Theory
Noordmans, J P
2016-01-01
We consider the low-energy effects of a selected set of Lorentz- and CPT-violating quark and gluon operators by deriving the corresponding chiral effective lagrangian. Using this effective lagrangian, low-energy hadronic observables can be calculated. We apply this to magnetometer experiments and derive the best bounds on some of the Lorentz-violating coefficients. We point out that progress can be made by studying the nucleon-nucleon potential, and by considering storage-ring experiments for deuterons and other light nuclei.
Possible chiral symmetry in $^{138}$Nd
Raduta, A A; Petrache, C M
2015-01-01
The pheomenological Generalized Coherent State Model Hamiltonian is amended with a many body term describing a set of nucleons moving in a shell model mean-field and interacting among themselves with paring, as well as with a particle-core interaction involving a quadrupole-quadrupole and a hexadecapole-hexdecapole force and a spin-spin interaction. The model Hamiltonian is treated in a restricted space consisting of the core projected states associated to the bands ground, $\\beta, \\gamma,\\widetilde{\\gamma}, 1^+$ and $\\widetilde{1^+}$ and two proton aligned quasiparticles coupled to the states of the ground band. The chirally transformed particle-core states are also included. The Hamiltonian contains two terms which are not invariant to the chiral transformations relating the right handed trihedral $({\\bf J_F}, {\\bf J_p}, {\\bf J_n})$ and the left handed ones $(-{\\bf J_F}, {\\bf J_p}, {\\bf J_n})$, $({\\bf J_F}, -{\\bf J_p}, {\\bf J_n})$, $({\\bf J_F}, {\\bf J_p}, -{\\bf J_n})$ where ${\\bf J_F}, {\\bf J_p}, {\\bf J_n}$...
Institute of Scientific and Technical Information of China (English)
刘成勇; 颜建新; 林以玑; 李丹; 方雪明; 章慧
2012-01-01
为了探究cis-[Ni(NCS)2tren] [tren:三(2-氨基乙基)胺]的手性来源,本文采用单晶X射线衍射、溶液紫外-可见-近红外(UV-Vis-NIR)光谱、固体紫外圆二色(CD)光谱和粉末X射线衍射(XRD)等对cis-[Ni(NCS )2tren]的一对手性晶体进行了表征.研究结果表明:该手性晶体由结晶过程中的镜面对称性破缺而形成;三角架型配体tren配位后的特殊手性构象(δδλ,λλδ)是cis-[Ni(NCS)2tren]的主要手性来源.络合物固体紫外CD谱所呈现的Cotton效应可能来自其螯环手性构象以及手性金属中心对NCS-配体的π-π*跃迁和荷移跃迁生色团的手性微扰.对20批次合成产物进行固体CD检测的统计结果表明:它们的对映体过量(ee)值在39％-100％之间.%In order to explore the chiral origin of c/s-[Ni(NCS)2tren] [tren: tris(2-aminoethyl) amine], a pair of chiral crystals of c;s-[Ni(NCS)jtren] was characterized by X-ray single crystal structural analysis, solution UV-Vis-near infrared (NIR) spectroscopy, solid state UV-circular dichiroism (CD), and powder X-ray diffraction (XRD) spectra. The results indicated that the chiral crystals of c/s-[Ni(NCS)2tren] were obtained by mirror symmetry-breaking crystallization, and the special chiral ring conformations (66A, AA6) of the coordinated tripod-type tren ligands are responsible for the chiral origin of c/s-[Ni(NCS)2tren]. The Cotton effects of Ni(ll) complexes in the solid-state UV-CD spectra are presumably attributed to the tt-tt* and charge-transfer chromophores of the NCS" ligands by the chiral perturbation of the helical ring conformations and metal-centered chirality. According to the statistical results of solid-state CD spectra of c/s-[Ni(NCS)2tren] for twenty batch syntheses, their enantiomeric excess (ee) values are between 39% and 100%.
Electroweak symmetry breaking in light of LHC results
Energy Technology Data Exchange (ETDEWEB)
Ellis, John [Physics Department, King' s College London (United Kingdom); Theory Division, CERN (Switzerland)
2012-07-01
The prospects for various proposed models of electroweak symmetry breaking are assessed in light of LHC results, and key experimental tests are discussed. Models discussed include the Standard Model, its supersymmetric extensions, and composite models with relatively light scalar bosons.
Geng, L S; Vacas, M J Vicente
2009-01-01
We calculate the SU(3)-breaking corrections to the hyperon vector coupling $f_1(0)$ up to $\\mathcal{O}(p^4)$ in covariant baryon chiral perturbation theory with dynamical octet and decuplet contributions. We find that the decuplet contributions are of similar or even larger size than the octet ones. Combining both, we predict positive SU(3)-breaking corrections to all the four independent $f_1(0)$'s (assuming isospin symmetry), which are consistent, within uncertainties, with the latest results form large $N_c$ fits, chiral quark models, and quenched lattice QCD calculations.
Axion dark matter in the post-inflationary Peccei-Quinn symmetry breaking scenario
Ringwald, Andreas; Saikawa, Ken'ichi
2016-04-01
We consider extensions of the Standard Model in which a spontaneously broken global chiral Peccei-Quinn (PQ) symmetry arises as an accidental symmetry of an exact ZN symmetry. For N =9 or 10, this symmetry can protect the accion—the Nambu-Goldstone boson arising from the spontaneous breaking of the accidental PQ symmetry—against semiclassical gravity effects, thus suppressing gravitational corrections to the effective potential, while it can at the same time provide for the small explicit symmetry breaking term needed to make models with domain wall number NDW>1 , such as the popular Dine-Fischler-Srednicki-Zhitnitsky (DFSZ) model (NDW=6 ), cosmologically viable even in the case where spontaneous PQ symmetry breaking occurred after inflation. We find that N =10 DFSZ accions with mass mA≈3.5 - 4.2 meV can account for cold dark matter and simultaneously explain the hints for anomalous cooling of white dwarfs. The proposed helioscope International Axion Observatory—being sensitive to solar DFSZ accions with mass above a few meV—will decisively test this scenario.
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.)
Impact of symmetry breaking in networks of globally coupled oscillators
Premalatha, K.; Chandrasekar, V. K.; Senthilvelan, M.; Lakshmanan, M.
2015-01-01
We analyze the consequences of symmetry breaking in the coupling in a network of globally coupled identical Stuart-Landau oscillators. We observe that symmetry breaking leads to increased disorderliness in the dynamical behavior of oscillatory states and consequently results in a rich variety of dynamical states. Depending on the strength of the nonisochronicity parameter, we find various dynamical states such as amplitude chimera, amplitude cluster, frequency chimera and frequency cluster st...
Concepts of electroweak symmetry breaking and Higgs physics
International Nuclear Information System (INIS)
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.)
Chiral Symmetry and the Nucleon-Nucleon Interaction
Directory of Open Access Journals (Sweden)
Ruprecht Machleidt
2016-04-01
Full Text Available We review how nuclear forces emerge from low-energy quantum chromodynamics (QCD via chiral effective field theory (EFT. During the past two decades, this approach has evolved into a powerful tool to derive nuclear two- and many-body forces in a systematic and model-independent way. We then focus on the nucleon-nucleon (N N interaction and show in detail how, governed by chiral symmetry, the long- and intermediate-range of the N N potential builds up order by order. We proceed up to sixth order in small momenta, where convergence is achieved. The final result allows for a full assessment of the validity of the chiral EFT approach to the N N interaction.
Spontaneous disordering and symmetry breaking in complex plasmas
Zhdanov, Sergey K; Morfill, Gregor E
2010-01-01
Spontaneous symmetry breaking is an essential feature of modern science. We demonstrate that it also plays an important role in the physics of complex plasmas. Complex plasmas can serve as a powerful tool for observing and studying discrete types of symmetry and disordering at the kinetic level that numerous many-body systems exhibit.
Symmetry Breaking of Vibrating Interfaces a Mechanism for Morphogenesis
García, N
2000-01-01
We show that very small-amplitude oscillations of a highly symmetric, spheric or cylindrical, interface (thin membrane) between two fluids can result in inhomogeneous instability and breaking of the interface symmetry: the frequency of the breathing vibration selects the spatial symmetry. This mechanism may govern morphogenesis.
Space Group Symmetry Fractionalization in a Chiral Kagome Heisenberg Antiferromagnet.
Zaletel, Michael P; Zhu, Zhenyue; Lu, Yuan-Ming; Vishwanath, Ashvin; White, Steven R
2016-05-13
The anyonic excitations of a spin liquid can feature fractional quantum numbers under space group symmetries. Detecting these fractional quantum numbers, which are analogs of the fractional charge of Laughlin quasiparticles, may prove easier than the direct observation of anyonic braiding and statistics. Motivated by the recent numerical discovery of spin-liquid phases in the kagome Heisenberg antiferromagnet, we theoretically predict the pattern of space group symmetry fractionalization in the kagome lattice SO(3)-symmetric chiral spin liquid. We provide a method to detect these fractional quantum numbers in finite-size numerics which is simple to implement in the density matrix renormalization group. Applying these developments to the chiral spin liquid phase of a kagome Heisenberg model, we find perfect agreement between our theoretical prediction and numerical observations. PMID:27232041
Chiral symmetry and its partial restoration in nuclei
International Nuclear Information System (INIS)
The Nambu-Jona-Lasinio (NJL) model is used to discuss the partial restoration of chiral symmetry in nuclear media at zero and finite temperatures. Effects considered are (a) the proton-neutron mass difference and the Nolen-Schiffer anomaly, (b) quasi-elastic electron scattering, and (c) the nuclear response function. Finally, the likely effects of confinement for the NJL model are examined. 8 refs., 14 figs
Lectures on Chiral Symmetries and Soft Pion Processes
Nambu, Y.
1966-08-01
At the Istanbul Summer School in 1962 I gave lectures on "Chiral Symmetries in Weak and Strong Interactions." It is only recently, however, that the basic ideas that were started several years ago have begun to bear fruit. We will cover in the present lectures more or less the same general field, but certainly there will be a lot more results to be discussed now than four years ago.
New Mechanism of Flavor Symmetry Breaking from Supersymmetric Strong Dynamics
Carone, C D; Moroi, T; Carone, Christopher D.; Hall, Lawrence J.; Moroi, Takeo
1997-01-01
We present a class of supersymmetric models in which flavor symmetries are broken dynamically, by a set of composite flavon fields. The strong dynamics that is responsible for confinement in the flavor sector also drives flavor symmetry breaking vacuum expectation values, as a consequence of a quantum-deformed moduli space. Yukawa couplings result as a power series in the ratio of the confinement to Planck scale, and the fermion mass hierarchy depends on the differing number of preons in different flavor symmetry-breaking operators. We present viable non-Abelian and Abelian flavor models that incorporate this mechanism.
Effect of symmetry breaking on transition strength distributions
International Nuclear Information System (INIS)
The quantum numbers of over 100 states in 30P have been determined from the ground state to 8 MeV. Previous measurements had provided complete spectroscopy in 26Al. 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
Symmetry-Break in Voronoi Tessellations
Directory of Open Access Journals (Sweden)
Valerio Lucarini
2009-08-01
Full Text Available We analyse in a common framework the properties of the Voronoi tessellations resulting from regular 2D and 3D crystals and those of tessellations generated by Poisson distributions of points, thus joining on symmetry breaking processes and the approach to uniform random distributions of seeds. We perturb crystalline structures in 2D and 3D with a spatial Gaussian noise whose adimensional strength is α and analyse the statistical properties of the cells of the resulting Voronoi tessellations using an ensemble approach. In 2D we consider triangular, square and hexagonal regular lattices, resulting into hexagonal, square and triangular tessellations, respectively. In 3D we consider the simple cubic (SC, body-centred cubic (BCC, and face-centred cubic (FCC crystals, whose corresponding Voronoi cells are the cube, the truncated octahedron, and the rhombic dodecahedron, respectively. In 2D, for all values α>0, hexagons constitute the most common class of cells. Noise destroys the triangular and square tessellations, which are structurally unstable, as their topological properties are discontinuous in α=0. On the contrary, the honeycomb hexagonal tessellation is topologically stable and, experimentally, all Voronoi cells are hexagonal for small but finite noise with α<0.12. Basically, the same happens in the 3D case, where only the tessellation of the BCC crystal is topologically stable even against noise of small but finite intensity. In both 2D and 3D cases, already for a moderate amount of Gaussian noise (α>0.5, memory of the specific initial unperturbed state is lost, because the statistical properties of the three perturbed regular tessellations are indistinguishable. When α>2, results converge to those of Poisson-Voronoi tessellations. In 2D, while the isoperimetric ratio increases with noise for the perturbed hexagonal tessellation, for the perturbed triangular and square tessellations it is optimised for specific value of noise intensity
Spontaneous symmetry breaking in 5D conformally invariant gravity
Moon, Taeyoon
2016-01-01
We explore the possibility of the spontaneous symmetry breaking in 5D conformally invariant gravity, whose action consists of a scalar field nonminimally coupled to the curvature with its potential. Performing dimensional reduction via ADM decomposition, we find that the model allows an exact solution giving rise to the 4D Minkowski vacuum. Exploiting the conformal invariance with Gaussian warp factor, we show that it also admits a solution which implement the spontaneous breaking of conformal symmetry. We investigate its stability by performing the tensor perturbation and find the resulting system is described by the conformal quantum mechanics. Possible applications to the spontaneous symmetry breaking of time-translational symmetry along the dynamical fifth direction and the brane-world scenario are discussed.
Experimental demonstration of decoherence-induced spontaneous symmetry breaking
International Nuclear Information System (INIS)
We experimentally investigate the variations of exchange-symmetry properties of the four Bell states in an exchange-symmetric pure dephasing process with a two-photon system generated from spontaneous parametric down-conversion (SPDC). Experiment results show that under such an exchange-symmetric local-noise Hamiltonian, the exchange-symmetry property remains unchanged for two of the three symmetric Bell states, i.e., the states |Φ>±=(1/√(2))(|00>±|11>). For the antisymmetric Bell state |Ψ>-=(1/√(2))(|01>-|10>), the exchange-symmetry property increases and achieves a maximum value of 0.5 at the asymptotic limit. However, for the third exchange-symmetric Bell state |Ψ>+=(1/√(2))(|01>+|10>), the exchange-symmetry property breaks, surviving with a probability of 0.5 at the asymptotic limit, which provides some evidence supporting such decoherence-induced spontaneous-symmetry-breaking phenomena.
Natural electroweak symmetry breaking in generalised mirror matter models
Foot, R
2007-01-01
It has recently been pointed out that the mirror or twin Higgs model is more technically natural than the standard model, thus alleviating the ``little'' hierarchy problem. In this paper we generalise the analysis to models with an arbitrary number of isomorphic standard model sectors, and demonstrate that technical naturalness increases with the number of additional sectors. We consider two kinds of models. The first has $N$ standard model sectors symmetric under arbitrary permutations thereof. The second has $p$ left-chiral standard model sectors and $p$ right-chiral or mirror standard model sectors, with $p$-fold permutation symmetries within both and a discrete parity transformation interchanging left and right.
Fermion condensates and Lorentz symmetry breaking in strongly-coupled large N gauge theories
Tomboulis, E T
2012-01-01
The possibility of Lorentz symmetry breaking (LSB) has attracted considerable attention in recent years. Spontaneous LSB, in particular, offers the attractive prospect of the graviton as a Nambu-Golstone boson. Here we consider the question of spontaneous LSB in lattice gauge theories via formation of fermion condensates in the strong coupling and large N limits. We employ naive massless fermions in a fermionic hopping expansion in the presence of sources coupled to various condensate operators of interest. The expansion is resumed in the large N limit in two equivalent ways: (i) direct resummation of all leading N graphs; and (ii) construction of the corresponding large N effective action for composite operators. When sources are turned off a variety of fermionic condensates is found to persist. These include the chiral symmetry breaking condensates, thus recovering previous results; but also some LSB condensates, in particular, axial vector and rank-2 tensor condensates. Furthermore, in the presence of inte...
Probing Emergent Scale-Chiral Symmetry in Nuclear Interactions
Paeng, Won-Gi
2016-01-01
In effective field theory for baryonic matter in which broken scale symmetry and hidden local symmetry are incorporated, both scale invariance and local gauge invariance, invisible or perhaps even absent in the QCD vacuum, could arise at high density as emergent symmetries, with a dilaton figuring as a scalar Nambu-Goldstone boson and the $\\rho$ and $a_1$ mesons as gauge fields, the former at the "dialton-limit (DL) fixed point" and the latter at the "vector manifestation (VM) fixed point." A novel phenomenon observed in a simplified model is that the dilaton condensate in nuclear medium "walks" as density increases beyond $n_{1/2}\\sim (2-3)n_0$ and induces the in-medium hidden gauge symmetry coupling, un-scaling up to density $n_{1/2}$, to start dropping rapidly towards the VM fixed point $n_{VM} >n_{1/2} $ at which the vector meson mass vanishes, coinciding, most likely, with chiral symmetry restoration. We discuss how to probe both VM and DL properties by means of the nuclear symmetry energy and the sound ...
Spontaneous breaking of spatial symmetries in collective neutrino oscillations
Duan, Huaiyu
2014-01-01
A dense neutrino medium can experience collective oscillations or self-induced flavor transformation through nonlinear neutrino-neutrino refraction. To make the problem of collective neutrino oscillations more tractable, all previous studies on this subject have assumed some spatial symmetry or symmetries in the neutrino medium (e.g., translation symmetries in the early universe and spherical symmetry in core-collapse supernovae). We point out that the collective oscillation modes studied in such models are very special. Using a simple toy model we show that spatial symmetries can be broken spontaneously in collective neutrino oscillations. We also show that the spatial-symmetry-breaking (SSB) modes of neutrino oscillations can exist for both neutrino mass hierarchies and even in the regimes where collective neutrino oscillations were previously thought to be suppressed. This finding calls for study of collective neutrino oscillations in multi-dimensional models.
Rotational symmetry breaking in baby Skyrme models
Hen, Itay
2007-01-01
We consider multisolitons with charges 1 =< B =< 5 in the baby Skyrme model for the one-parametric family of potentials U=\\mu^2 (1-\\phi_3)^s with 0symmetry is exhibited only in the small s region; above a certain critical value of s, this symmetry is broken and a strong repulsion between the constituent one-Skyrmions becomes apparent. We also compute the spatial energy distributions of these solutions.
Peripheral Nucleon-Nucleon Phase Shifts and Chiral Symmetry
Kaiser, N; Weise, W
1997-01-01
Within the one-loop approximation of baryon chiral perturbation theory we calculate all one-pion and two-pion exchange contributions to the nucleon-nucleon interaction. In fact we construct the elastic NN-scattering amplitude up to and including third order in small momenta. The phase shifts with orbital angular momentum $L\\geq2 $ and the mixing angles with $J\\geq2$ are given parameterfree and thus allow for a detailed test of chiral symmetry in the two-nucleon system. We find that for the D-waves the $2\\pi$-exchange corrections are too large as compared with empirical phase shifts, signaling the increasing importance of shorter range effects in lower partial waves. For higher partial waves, especially for G-waves, the model independent $2\\pi$-exchange corrections bring the chiral prediction close to empirical NN phase shifts. We propose to use the chiral NN phase shifts with $L\\geq 3$ as input in a future phase shift analysis. Furthermore, we compute the irreducible two-pion exchange NN-potentials in coordin...
Radiatively induced breaking of conformal symmetry in a superpotential
Arbuzov, A. B.; Cirilo-Lombardo, D. J.
2016-07-01
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.
Radiatively Induced Breaking of Conformal Symmetry in a Superpotential
Arbuzov, A B
2015-01-01
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.
Matter Representations and Gauge Symmetry Breaking via Compactified Space
Hatanaka, H
1999-01-01
We study dynamical gauge symmetry breaking via compactified space in the framework of SU($N$) gauge theory on $M^{d-1}\\times S^1$ ($d=4,5,6$) space-time. Especially, we study in detail the gauge symmetry breaking in SU(2) and SU(3) gauge theories when the models contain both fundamental and adjoint matters. As the result, we find that any pattern of gauge symmetry breaking is realized by selecting appropriate set of numbers $(\\Nf,\\Nad)$ in these cases. It is achieved without tuning boundary conditions of matter fields. As the by-product, in some cases we get effective potential which has no curvature at the minimum thus leading to massless Higgs scalars, irrespectively of the size of compactified space.
Massive photons from Super and Lorentz symmetry breaking
Bonetti, Luca; Helayël-Neto, José A; Spallicci, Alessandro D A M
2016-01-01
In the context of Standard Model Extensions (SMEs), we analyse four general classes of Super Symmetry (SuSy) and Lorentz Symmetry (LoSy) breaking, leading to {observable} imprints at our energy scales. The photon dispersion relations show a non-Maxwellian behaviour for the CPT (Charge-Parity-Time reversal symmetry) odd and even sectors. The group velocities exhibit also a directional dependence with respect to the breaking background vector (odd CPT) or tensor (even CPT). In the former sector, the group velocity may decay following an inverse squared frequency behaviour. Thus, we extract a massive and gauge invariant Carroll-Field-Jackiw photon term in the Lagrangian and show that the mass is proportional to the breaking vector. The latter is estimated by ground measurements and leads to a photon mass upper limit of $10^{-19}$ eV or $2 \\times 10^{-55}$ kg and thereby to a potentially measurable delay at low radio frequencies.
Deconfinement and Chiral Symmetry Restoration in a Strong Magnetic Background
Gatto, Raoul
2010-01-01
We perform a model study of deconfinement and chiral symmetry restoration in a strong magnetic background. We use a Nambu-Jona Lasinio model with the Polyakov loop, taking into account a possible dependence of the coupling on the Polyakov loop expectation value, as suggested by the recent literature. Our main result is that, within this model, the deconfinement and chiral crossovers of QCD in strong magnetic field are entangled even at the largest value of $eB$ considered here, namely $eB=30 m_\\pi^2$ (that is, $B \\approx 6\\times 10^{15}$ Tesla). The amount of split that we measure is, at this value of $eB$, of the order of 2%. We also study briefly the role of the 8-quark term on the entanglement of the two crossovers. We then compare the phase diagram of this model with previous results, as well as with available Lattice data.
Deconfinement and chiral symmetry restoration in a strong magnetic background
International Nuclear Information System (INIS)
We perform a model study of deconfinement and chiral symmetry restoration in a strong magnetic background. We use a Nambu-Jona-Lasinio model with the Polyakov loop, taking into account a possible dependence of the coupling on the Polyakov-loop expectation value, as suggested by the recent literature. Our main result is that, within this model, the deconfinement and chiral crossovers of QCD in strong magnetic field are entangled even at the largest value of eB considered here, namely eB=30mπ2 (that is, B≅6x1015 T). The amount of split that we measure is, at this value of eB, of the order of 2%. We also study briefly the role of the 8-quark term on the entanglement of the two crossovers. We then compare the phase diagram of this model with previous results, as well as with available lattice data.
Topological protection of defect states from semi-chiral symmetry
Poli, Charles; Bellec, Matthieu; Kuhl, Ulrich; Mortessagne, Fabrice
2015-01-01
Bipartite quantum systems from the chiral universality classes admit topologically protected zero modes at point defects. However, these states are difficult to separate from compacton-like localized states that arise from flat bands, formed if the two sublattices support a different number of sites within a unit cell. Here we identify a natural reduction of chiral symmetry, obtained by coupling sites on the majority sublattice, which gives rise to spectrally isolated point-defect states, topologically characterized as zero modes supported by the complementary minority sublattice. We observe these states in a microwave realization of a dimerized Lieb lattice with next-nearest neighbour coupling, and also demonstrate topological mode selection via sublattice-staggered absorption.
Symmetry breaking and restoration in Lifshitz type theories
Energy Technology Data Exchange (ETDEWEB)
Farakos, K., E-mail: kfarakos@central.ntua.gr [Department of Physics, National Technical University of Athens, Zografou Campus, 15780 Athens (Greece); Metaxas, D., E-mail: metaxas@central.ntua.gr [Department of Physics, National Technical University of Athens, Zografou Campus, 15780 Athens (Greece)
2012-02-07
We consider the one-loop effective potential at zero and finite temperature in scalar field theories with anisotropic space-time scaling. For z=2, there is a symmetry breaking term induced at one loop at zero temperature and we find symmetry restoration through a first-order phase transition at high temperature. For z=3, we considered at first the case with a positive mass term at tree level and found no symmetry breaking effects induced at one loop, and then we study the case with a negative mass term at tree level where we cannot conclude about symmetry restoration effects at high temperature because of the imaginary parts that appear in the effective potential for small values of the scalar field.
Symmetry breaking and restoration in Lifshitz type theories
Farakos, K.; Metaxas, D.
2012-02-01
We consider the one-loop effective potential at zero and finite temperature in scalar field theories with anisotropic space-time scaling. For z = 2, there is a symmetry breaking term induced at one loop at zero temperature and we find symmetry restoration through a first-order phase transition at high temperature. For z = 3, we considered at first the case with a positive mass term at tree level and found no symmetry breaking effects induced at one loop, and then we study the case with a negative mass term at tree level where we cannot conclude about symmetry restoration effects at high temperature because of the imaginary parts that appear in the effective potential for small values of the scalar field.
Symmetry breaking and restoration in Lifshitz type theories
Farakos, K
2011-01-01
We consider the one-loop effective potential at zero and finite temperature in scalar field theories with anisotropic space-time scaling. For $z=2$, there is a symmetry breaking term induced at one-loop at zero temperature and we find symmetry restoration through a first-order phase transition at high temperature. For $z=3$, we considered at first the case with a positive mass term at tree level and found no symmetry breaking effects induced at one-loop, and then we study the case with a negative mass term at tree level where we cannot conclude about symmetry restoration effects at high temperature because of the imaginary parts that appear in the effective potential for small values of the scalar field.
Symmetry breaking effects on spin and electronic transport in graphene
Asmar, Mahmoud M; Ulloa, Sergio E.
2015-01-01
The decoration of graphene samples with adatoms or nanoparticles leads to the enhancement of spin-orbit interactions as well as to the introduction of symmetry-breaking effects that could have drastic effects on spin and electronic transport phenomena. We present an analysis based on symmetry considerations and examine the impact on the scattering matrix for graphene systems containing defects that enhance spin-orbit interactions, while conserving the electronic total angular momentum. We sho...
Higgs mechanism without spontaneous symmetry breaking and quark confinement
Kondo, Kei-Ichi
2016-01-01
We propose a novel description for the Higgs mechanism by which a gauge boson acquires the mass in a manifestly gauge-invariant way. In the Higgs mechanism, we do not assume spontaneous breakdown of gauge symmetry signaled by a non-vanishing vacuum expectation value of the scalar field. The spontaneous symmetry breaking is sufficient but not necessary for the Higgs mechanism to work. This enables us to discuss the confinement-Higgs complementarity from a new perspective.
Mixed Mediation of Supersymmetry Breaking in Models with Anomalous U(1) Gauge Symmetry
International Nuclear Information System (INIS)
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.
Spontaneous symmetry breaking in correlated wave functions
Kaneko, Ryui; Tocchio, Luca F.; Valentí, Roser; Becca, Federico; Gros, Claudius
2016-03-01
We show that Jastrow-Slater wave functions, in which a density-density Jastrow factor is applied onto an uncorrelated fermionic state, may possess long-range order even when all symmetries are preserved in the wave function. This fact is mainly related to the presence of a sufficiently strong Jastrow term (also including the case of full Gutzwiller projection, suitable for describing spin models). Selected examples are reported, including the spawning of Néel order and dimerization in spin systems, and the stabilization of charge and orbital order in itinerant electronic systems.
Symmetry-Breaking Plasmonic Metasurfaces for Broadband Light Bending
DEFF Research Database (Denmark)
Ni, Xingjie; Emani, Naresh K.; Kildishev, Alexander V.;
2012-01-01
We experimentally demonstrate unparalleled wave-front control in a broadband, optical wavelength range from 1.0 μm to 1.9 μm, using a thin plasmonic layer (metasurface) consisting of a nanoantenna array that breaks the symmetry along the interface.......We experimentally demonstrate unparalleled wave-front control in a broadband, optical wavelength range from 1.0 μm to 1.9 μm, using a thin plasmonic layer (metasurface) consisting of a nanoantenna array that breaks the symmetry along the interface....
Finding strongly interacting symmetry breaking at the SSC
Energy Technology Data Exchange (ETDEWEB)
Golden, M.
1989-02-01
Pairs of gauge bosons, W and Z, are a probe of the electroweak symmetry-breaking sector, since the numbers of two gauge boson events are much larger in strongly coupled models than weak. The doubly charged channels W/sup +/W/sup +/ and W/sup /minus//W/sup/minus// are cleanest, since they do not suffer from q/bar q/ or gg fusion backgrounds. The like-charged gauge boson events are observable only if the symmetry breaking sector is strongly interacting. 19 refs., 4 figs., 2 tabs.
Modular Ground State for SU(8) Symmetry Breaking
Adler, Stephen L
2015-01-01
We elaborate on our recent proposal of a modular ground state structure for the first stage of $SU(8)$ symmetry breaking by a scalar in the 56 representation. We review the arguments for $U(1)$ generator modularity 15, and show that this can lead to a vanishing mass for the $U(1)$ gauge boson, as needed for the symmetry breaking pattern $SU(8) \\supset SU(3) \\times SU(5) \\times U(1)$. We then give a simplified form for the modulo 5 ground state obeying clustering, that we have conjectured to lead from broken $SU(8)$ to the flipped $SU(5)$ model. Generalizations of these results are also given.
Charge Symmetry Breaking in the Nucleon and Parity Violating Elastic Electron-Proton Scattering
Miller, Gerald A
2014-01-01
The basic facts of charge symmetry breaking (CSB) phenomena are reviewed. The relevance of CSB to parity-violating electron-proton scattering experiments that seek to extract strange elastic form factors is discussed. Experimentalists have stated and written that the current uncertainty in our knowledge of CSB limits the ability to push further on the strange form factors. I discuss recent calculations using relativistic chiral perturbation theory and realistic values of strong coupling constants which show that the uncertainties due to lack of knowledge of CSB are at least ten times smaller than present experimental uncertainties. Estimates of CSB effects are made for the JLab Qweak and Mainz P2 experiments.
Charge symmetry breaking in pn {yields} d {pi}{sup 0}
Energy Technology Data Exchange (ETDEWEB)
Filin, Arseniy [Institute for Theoretical and Experimental Physics, 117218, B. Cheremushkinskaya 25, Moscow (Russian Federation); Helmholtz-Institut fuer Strahlen- und Kernphysik (Theorie), Universitaet Bonn, D-53115 Bonn (Germany); Baru, Vadim [Institut fuer Kernphysik (Theorie), Juelich Center for Hadron Physics, Forschungszentrum Juelich, D-52425 Juelich (Germany); Institute for Theoretical and Experimental Physics, 117218, B. Cheremushkinskaya 25, Moscow (Russian Federation); Epelbaum, Evgeny [Institut fuer Kernphysik (Theorie), Juelich Center for Hadron Physics, Forschungszentrum Juelich, D-52425 Juelich (Germany); Helmholtz-Institut fuer Strahlen- und Kernphysik (Theorie), Universitaet Bonn, D-53115 Bonn (Germany); Bethe Center for Theoretical Physics, Universitaet Bonn, D-53115 Bonn (Germany); Haidenbauer, Johann; Hanhart, Christoph [Institut fuer Kernphysik (Theorie), Juelich Center for Hadron Physics, Forschungszentrum Juelich, D-52425 Juelich (Germany); Institute for Advanced Simulation, Forschungszentrum Juelich, D-52425 Juelich (Germany); Kudryavtsev, Alexander [Institute for Theoretical and Experimental Physics, 117218, B. Cheremushkinskaya 25, Moscow (Russian Federation); Meissner, Ulf G. [Institut fuer Kernphysik (Theorie), Juelich Center for Hadron Physics, Forschungszentrum Juelich, D-52425 Juelich (Germany); Helmholtz-Institut fuer Strahlen- und Kernphysik (Theorie), Universitaet Bonn, D-53115 Bonn (Germany); Bethe Center for Theoretical Physics, Universitaet Bonn, D-53115 Bonn (Germany); Institute for Advanced Simulation, Forschungszentrum Juelich, D-52425 Juelich (Germany)
2010-07-01
We study charge symmetry breaking (CSB) in the reaction pn {yields} d {pi}{sup 0}. CSB manifests itself in a forward-backward asymmetry of the differential cross section measured recently at TRIUMF. A complete calculation of CSB effects at leading order in chiral perturbation theory is performed. A new leading-order operator is included. This allowed us to extract the strong contribution to the neutron-proton mass difference. The value obtained is consistent with the result of Gasser and Leutwyler based on Cottingham sum rule and an extraction from lattice QCD.
Relating spontaneous and explicit symmetry breaking in the presence of the Higgs mechanism
Pedro, Leonardo
2016-01-01
One common way to define spontaneous symmetry breaking involves necessarily explicit symmetry breaking. We add explicit symmetry breaking terms to the Higgs potential, so that the spontaneous breaking of a global symmetry in multi-Higgs-doublet models is a particular case of explicit symmetry breaking. Then we show that it is possible to study the Higgs potential without assuming that the local gauge $SU(2)_L$ symmetry is spontaneously broken or not (it is known that gauge symmetries may not be possible to break spontaneously). We also discuss the physical spectrum of multi-Higgs-doublet models and the related custodial symmetry. We review background symmetries: these are symmetries that despite already explicitly broken, can still be spontaneously broken. We show that the CP background symmetry is not spontaneously broken, based on this fact: we explain in part a recent conjecture relating spontaneous and explicit breaking of the charge-parity (CP) symmetry; we also relate explicit and spontaneous geometric ...
Instabilities of Hexagonal Patterns with Broken Chiral Symmetry
Echebarria, B; Echebarria, Blas; Riecke, Hermann
1999-01-01
Three coupled Ginzburg-Landau equations for hexagonal patterns with broken chiral symmetry are investigated. They are relevant for the dynamics close to onset of rotating non-Boussinesq or surface-tension-driven convection. Steady and oscillatory, long- and short-wave instabilities of the hexagons are found. For the long-wave behavior coupled phase equations are derived. Numerical simulations of the Ginzburg-Landau equations indicate bistability between spatio-temporally chaotic patterns and stable steady hexagons. The chaotic state can, however, not be described properly with the Ginzburg-Landau equations.
Chiral symmetry and nuclear matter equation of state
Indian Academy of Sciences (India)
A B Santra
2001-08-01
We investigate the effect on the nuclear matter equation of state (EOS) due to modiﬁcation of meson and nucleon parameters in nuclear medium as a consequence of partial restoration of chiral symmetry. To get the EOS, we have used Brueckner–Bethe–Golstone formalism with Bonn- potential as two-body interaction and QCD sum rule and Brown–Rho scaling prescriptions for modiﬁcation of hadron parameters. We ﬁnd that EOS is very much sensitive to the meson parameters. We can ﬁt, with two body interaction alone, both the saturation density and the binding energy per nucleon.
Spontaneous Parity-Time Symmetry Breaking in Moving Media
Silveirinha, M G
2014-01-01
Optical instabilities in moving media are linked to a spontaneous parity-time symmetry breaking of the system. It is shown that in general the time evolution of the electromagnetic waves in moving media is determined by a non-Hermitian parity-time symmetric operator. For lossless systems the frequency spectrum of the time evolution operator may be complex valued, and has a mirror symmetry with respect to the real-frequency axis. The possibility of optical amplification of a light pulse in the broken parity-time symmetry regime is demonstrated.
Parity-Time Symmetry Breaking in Coupled Nanobeam Cavities
Zhang, Senlin; Zhang, Yuguang; He, Sailing
2015-01-01
The parity-time symmetry (PT symmetry) breaking phenomenon is investigated in a coupled nanobeam cavity system. An exceptional point is observed during the tuning of the relation of the gain/loss and coupling strength of the closely placed nanobeam pairs. The PT symmetry concept can be applied to realize unidirectional light propagation and single mode operation lasers, which may allow for a new way to harness the optical signal in photonic integrated circuits. Otherwise, operating at this particular exceptional point, sensitivity of tiny perturbation detection can be enhanced greatly compared with conventional sensors.
Relativistic symmetry breaking in light kaonic nuclei
Yang, Rong-Yao; Xiang, Qian-Fei; Zhang, Dong-Rui; Wei, Si-Na
2014-01-01
As the experimental data from kaonic atoms and $K^{-}N$ scatterings imply that the $K^{-}$-nucleon interaction is strongly attractive at saturation density, there is a possibility to form $K^{-}$-nuclear bound states or kaonic nuclei. In this work, we investigate the ground-state properties of the light kaonic nuclei with the relativistic mean field theory. It is found that the strong attraction between $K^{-}$ and nucleons reshapes the scalar and vector meson fields, leading to the remarkable enhancement of the nuclear density in the interior of light kaonic nuclei and the manifest shift of the single-nucleon energy spectra and magic numbers therein. As a consequence, the pseudospin symmetry is shown to be violated together with enlarged spin-orbit splittings in these kaonic nuclei.
Radiative breaking of conformal symmetry in the Standard Model
Arbuzov, A. B.; Nazmitdinov, R. G.; Pavlov, A. E.; Pervushin, V. N.; Zakharov, A. F.
2016-02-01
Radiative mechanism of conformal symmetry breaking in a comformal-invariant version of the Standard Model is considered. The Coleman-Weinberg mechanism of dimensional transmutation in this system gives rise to finite vacuum expectation values and, consequently, masses of scalar and spinor fields. A natural bootstrap between the energy scales of the top quark and Higgs boson is suggested.
Quantum electroweak symmetry breaking through loop quadratic contributions
Directory of Open Access Journals (Sweden)
Dong Bai
2015-06-01
Full Text Available Based on two postulations that (i the Higgs boson has a large bare mass mH≫mh≃125 GeV at the characteristic energy scale Mc which defines the Standard Model (SM in the ultraviolet region, and (ii quadratic contributions of Feynman loop diagrams in quantum field theories are physically meaningful, we show that the SM electroweak symmetry breaking is induced by the quadratic contributions from loop effects. As the quadratic running of Higgs mass parameter leads to an additive renormalization, which distinguishes from the logarithmic running with a multiplicative renormalization, the symmetry breaking occurs once the sliding energy scale μ moves from Mc down to a transition scale μ=ΛEW at which the additive renormalized Higgs mass parameter mH2(Mc/μ gets to change the sign. With the input of current experimental data, this symmetry breaking energy scale is found to be ΛEW≃760 GeV, which provides another basic energy scale for the SM besides Mc. Studying such a symmetry breaking mechanism could play an important role in understanding both the hierarchy problem and naturalness problem. It also provides a possible way to explore the experimental implications of the quadratic contributions as ΛEW lies within the probing reach of the LHC and the future Great Collider.
Comment on "Electromagnetic potential vectors and spontaneous symmetry breaking"
Dvoeglazov, V V
1993-01-01
The appearance of terms, which are analogous to ones required for symmetry breaking, in Lagrangian of Ref.~\\cite{Shebalin} is shown to be caused by gauge invariance of quantum electrodynamics (QED) and by inaccuracy of the author in a choice of canonical variables. These terms in the Lagrangian (18) of~\\cite{Shebalin} do not have physical meaning.
Nucleon Properties and Restoration of Chiral Symmetry at Finite\
Christov, C V; Göke, K; Christov, Chr.V.
1993-01-01
Modifications of baryon properties due to the restoration of the chiral symmetry in an external hot and dense baryon medium are investigated in an effective chiral quark-meson theory. The nucleon arises as a soliton of the Gell-Mann - L\\'evi $\\zs$-model, the parameters of which are chosen to be the medium-modified meson values evaluated within the Nambu - Jona-Lasinio model. The nucleon properties are obtained by means of variational projection techniques. The nucleon form factors as well as the nucleon delta transition form factors are evaluated for various densities and temperatures of the medium. Similar to the chiral phase transition line the critical curve in the $T-\\zr$ plane for delocalization of the nucleon is non-monotonic and this feature is reflected in all nucleon properties. At medium densities of about $(2-3) \\rnm$ the baryonic phase exists only at intermediate temperatures. For finite temperature and densities the nucleon form factors get strongly reduced at finite transfer momenta.
Ads/CFT correspondence and symmetry breaking
International Nuclear Information System (INIS)
We study, using the dual AdS description, the vacua of field theories where some of the gauge symmetry is broken by expectation values of scalar fields. In such vacua, operators built out of the scalar fields acquire expectation values, and we show how to calculate them from the behavior of perturbations to the AdS background near the boundary. Specific examples include the N = 4 SYM theory, and theories on D3-branes placed on orbifolds and conifolds. We also clarify some subtleties of the AdS/CFT correspondence that arise in this analysis. In particular, we explain how scalar fields in AdS space of sufficiently negative mass-squared can be associated with CFT operators of two possible dimensions. All dimensions are bounded from below by (d-2)/2; this is the unitarity bound for scalar operators in d-dimensional field theory. We further argue that the generating functional for correlators in the theory with one choice of operator dimension is a Legendre transform of the generating functional in the theory with the other choice
Spontaneous Symmetry Breaking in General Relativity. Brane World Concept
Meierovich, Boris E
2009-01-01
Gravitational properties of a hedge-hog type topological defect in two extra dimensions are considered in General Relativity employing a vector as the order parameter. The developed macroscopic theory of phase transitions with spontaneous symmetry breaking is applied to the analysis of possible "thick" brane structures. The previous considerations were done using the order parameter in the form of a multiplet in a target space of scalar fields. The difference of these two approaches is analyzed and demonstrated in detail. There are two different symmetries of regular solutions of Einstein equations for a hedgehog type vector order parameter. Both solutions are analyzed in parallel analytically and numerically. Regular configurations in cases of vector order parameter have one more free parameter in comparison with the scalar multiplet solutions. It is shown that the existence of a negative cosmological constant is sufficient for the spontaneous symmetry breaking of the initially plain bulk. Regular configurat...
Lorentz symmetry breaking as a quantum field theory regulator
Visser, Matt
2009-01-01
Perturbative expansions of relativistic quantum field theories typically contain ultraviolet divergences requiring regularization and renormalization. Many different regularization techniques have been developed over the years, but most regularizations require severe mutilation of the logical foundations of the theory. In contrast, breaking Lorentz invariance, while it is certainly a radical step, at least does not damage the logical foundations of the theory. We shall explore the features of a Lorentz symmetry breaking regulator in a simple polynomial scalar field theory, and discuss its implications. We shall quantify just "how much" Lorentz symmetry breaking is required to fully regulate the theory and render it finite. This scalar field theory provides a simple way of understanding many of the key features of Horava's recent article [arXiv:0901.3775 [hep-th
Energy Technology Data Exchange (ETDEWEB)
Filin, A.; Baru, V. [Institut fuer Kernphysik (Theorie) and Juelich Center for Hadron Physics, Forschungszentrum Juelich, D-52425 Juelich (Germany); Institute for Theoretical and Experimental Physics, 117218, B. Cheremushkinskaya 25, Moscow (Russian Federation); Epelbaum, E. [Institut fuer Kernphysik (Theorie) and Juelich Center for Hadron Physics, Forschungszentrum Juelich, D-52425 Juelich (Germany); Helmholtz-Institut fuer Strahlen- und Kernphysik (Theorie) and Bethe Center for Theoretical Physics, Universitaet Bonn, D-53115 Bonn (Germany); Haidenbauer, J., E-mail: j.haidenbauer@fz-juelich.d [Institut fuer Kernphysik (Theorie) and Juelich Center for Hadron Physics, Forschungszentrum Juelich, D-52425 Juelich (Germany); Institute for Advanced Simulation, Forschungszentrum Juelich, D-52425 Juelich (Germany); Hanhart, C. [Institut fuer Kernphysik (Theorie) and Juelich Center for Hadron Physics, Forschungszentrum Juelich, D-52425 Juelich (Germany); Institute for Advanced Simulation, Forschungszentrum Juelich, D-52425 Juelich (Germany); Kudryavtsev, A. [Institute for Theoretical and Experimental Physics, 117218, B. Cheremushkinskaya 25, Moscow (Russian Federation); Meissner, U.-G. [Institut fuer Kernphysik (Theorie) and Juelich Center for Hadron Physics, Forschungszentrum Juelich, D-52425 Juelich (Germany); Helmholtz-Institut fuer Strahlen- und Kernphysik (Theorie) and Bethe Center for Theoretical Physics, Universitaet Bonn, D-53115 Bonn (Germany); Institute for Advanced Simulation, Forschungszentrum Juelich, D-52425 Juelich (Germany)
2009-11-16
We perform a complete calculation of charge symmetry breaking effects for the reaction pn->dpi{sup 0} at leading order in chiral perturbation theory. A new leading-order operator is included. From our analysis we extract deltam{sub N}{sup str}, the strong contribution to the neutron-proton mass difference. The value obtained, deltam{sub N}{sup str}=(1.5+-0.8 (exp.)+-0.5 (th.)) MeV, is consistent with the result based on the Cottingham sum rule. This agreement provides a non-trivial test of our current understanding of the chiral structure of QCD.
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
Marini, A; Roy, S; Longhi, S; Biancalana, F
2013-01-01
We study analytically and numerically an optical analogue of tachyon condensation in amplifying plasmonic arrays. Optical propagation is modeled through coupled-mode equations, which in the continuous limit can be converted into a nonlinear one-dimensional Dirac-like equation for fermionic particles with imaginary mass, i.e. fermionic tachyons. We demonstrate that the vacuum state is unstable and acquires an expectation value with broken chiral symmetry, corresponding to the homogeneous nonlinear stationary solution of the system. The quantum field theory analogue of this process is the condensation of unstable fermionic tachyons into massive particles. This paves the way for using amplifying plasmonic arrays as a classical laboratory for spontaneous symmetry breaking effects in quantum field theory.
Lorentz Symmetry Breaking and its consequences on Thermodynamics
Energy Technology Data Exchange (ETDEWEB)
Costa-Soares, T.; Sales, J.A. de; Otoya, V.J. Vasques [Instituto Federal de Educacao, Ciencia e Tecnologia do Sudeste de Minas Gerais (IF Sudeste MG), MG (Brazil)
2011-07-01
Full text: In this work, we study the effects of Lorentz Symmetry Breaking on thermodynamics properties of ideal gases. We start from a dispersion relation obtained from the Carroll-Field-Jackiw model to Electrodynamics with Lorentz and CPT violation term. With this, we compute the thermodynamics quantities for a Boltzmann, Bose-Einstein and Fermi-Dirac distributions. Two regimes are analyzed: the non-relativistic and the relativistic one. In the first case we show that the topological mass induced by the Chern-Simons term behaves as a chemical potential. For the Bose-Einstein condensates with these Lorentz breaking, the critical values as particle number, and temperature, are modified. These results are the same that were obtained by Colladay et al, whose perform the non-relativistic limit directly in the Hamiltonian for a Lorentz symmetry violating theory and used this to study the Bose-Einstein condensate to obtain a bound for the background field which perform the breaking. The original contribution of these work is in the relativistic regime, where we show that a new phase transition for a Bose -Einstein gas, can be induced by the Lorentz Symmetry Breaking parameters. Some applications in cosmology and astrophysics are commented. (author)
3D toroidal physics: Testing the boundaries of symmetry breaking
Energy Technology Data Exchange (ETDEWEB)
Spong, Donald A., E-mail: spongda@ornl.gov [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6169 (United States)
2015-05-15
Toroidal symmetry is an important concept for plasma confinement; it allows the existence of nested flux surface MHD equilibria and conserved invariants for particle motion. However, perfect symmetry is unachievable in realistic toroidal plasma devices. For example, tokamaks have toroidal ripple due to discrete field coils, optimized stellarators do not achieve exact quasi-symmetry, the plasma itself continually seeks lower energy states through helical 3D deformations, and reactors will likely have non-uniform distributions of ferritic steel near the plasma. Also, some level of designed-in 3D magnetic field structure is now anticipated for most concepts in order to provide the plasma control needed for a stable, steady-state fusion reactor. Such planned 3D field structures can take many forms, ranging from tokamaks with weak 3D edge localized mode suppression fields to stellarators with more dominant 3D field structures. This motivates the development of physics models that are applicable across the full range of 3D devices. Ultimately, the questions of how much symmetry breaking can be tolerated and how to optimize its design must be addressed for all fusion concepts. A closely coupled program of simulation, experimental validation, and design optimization is required to determine what forms and amplitudes of 3D shaping and symmetry breaking will be compatible with the requirements of future fusion reactors.
Mode conversion by symmetry breaking of propagating spin waves.
Energy Technology Data Exchange (ETDEWEB)
Clausen, P.; Vogt, K.; Schultheiss, H.; Schafer, S.; Obry, B.; Wolf, G.; Pirro, P.; Leven, B.; Hillebrands, B. (Materials Science Division); (Technische Universitat Kaiserslautern); (Grad. School of Excellence Mater. Sci. in Mainz); (Univ. Albama)
2011-10-01
We study spin-wave transport in a microstructured Ni{sub 81}Fe{sub 19} waveguide exhibiting broken translational symmetry. We observe the conversion of a beam profile composed of symmetric spin-wave width modes with odd numbers of antinodes n = 1, 3,... into a mixed set of symmetric and asymmetric modes. Due to the spatial homogeneity of the exciting field along the used microstrip antenna, quantized spin-wave modes with an even number n of antinodes across the stripe's width cannot be directly excited. We show that a break in translational symmetry may result in a partial conversion of even spin-wave waveguide modes.
The QCD chiral transition, $\\ua$ symmetry and the Dirac spectrum using domain wall fermions
Buchoff, Michael I; Christ, Norman H; Ding, H -T; Jung, Chulwoo; Karsch, F; Mawhinney, R D; Mukherjee, Swagato; Petreczky, P; Renfrew, Dwight; Schroeder, Chris; Vranas, P M; Yin, Hantao; Lin, Zhongjie
2013-01-01
We report on a study of the finite-temperature QCD transition region for temperatures between 139 and 196 MeV, with a pion mass of 200 MeV and two space-time volumes: $24^3\\times8$ and $32^3\\times8$, where the larger volume varies in linear size between 5.6 fm (at T=139 MeV) and 4.0 fm (at T=195 MeV). These results are compared with the results of an earlier calculation using the same action and quark masses but a smaller, $16^3\\times8$ volume. The chiral domain wall fermion formulation with a combined Iwasaki and dislocation suppressing determinant ratio gauge action are used. This lattice action accurately reproduces the $\\sua$ and $\\ua$ symmetries of the continuum. Results are reported for the chiral condensates, connected and disconnected susceptibilities and the Dirac eigenvalue spectrum. We find a pseudo-critical temperature, $T_c$, of approximately 165 MeV consistent with previous results and strong finite volume dependence below $T_c$. Clear evidence is seen for $\\ua$ symmetry breaking above $T_c$ whi...
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.
Breaking discrete symmetries in the effective field theory of inflation
Energy Technology Data Exchange (ETDEWEB)
Cannone, Dario [Dipartimento di Fisica e Astronomia “G. Galilei”, Università degli Studi di Padova,Padova, I-35131 (Italy); INFN, Sezione di Padova,Padova, I-35131 (Italy); Gong, Jinn-Ouk [Asia Pacific Center for Theoretical Physics,Pohang, 790-784 (Korea, Republic of); Department of Physics,Postech, Pohang, 790-784 (Korea, Republic of); Tasinato, Gianmassimo [Department of Physics, Swansea University,Swansea, SA2 8PP (United Kingdom)
2015-08-03
We study the phenomenon of discrete symmetry breaking during the inflationary epoch, using a model-independent approach based on the effective field theory of inflation. We work in a context where both time reparameterization symmetry and spatial diffeomorphism invariance can be broken during inflation. We determine the leading derivative operators in the quadratic action for fluctuations that break parity and time-reversal. Within suitable approximations, we study their consequences for the dynamics of linearized fluctuations. Both in the scalar and tensor sectors, we show that such operators can lead to new direction-dependent phases for the modes involved. They do not affect the power spectra, but can have consequences for higher correlation functions. Moreover, a small quadrupole contribution to the sound speed can be generated.
Electroweak symmetry breaking after LEP1 and LEP2
Barbieri, Riccardo; Rattazzi, Riccardo; Strumia, Alessandro; Barbieri, Riccardo; Pomarol, Alex; Rattazzi, Riccardo; Strumia, Alessandro
2004-01-01
In a generic 'universal' theory of electroweak symmetry breaking, non fine-tuned heavy new physics affects the low-energy data through four parameters, which include and properly extend the generally insufficient S and T. Only by adding the LEP2 data to the global electroweak fit, can all these four form factors be determined and deviations from the SM be strongly constrained. Several of the recently proposed models (little Higgs, gauge bosons in extra dimensions or Higgsless models in 5D) are recognized to be 'universal' in a straightforward way after a proper definition of the effective vector boson fields. Among various applications, we show that proposed Higgsless models in 5D, when calculable, do not provide a viable description of electroweak symmetry breaking in their full range of parameters.
Spontaneous symmetry breaking and Goldstone theorem for composite states revisited
Fariborz, Amir H
2016-01-01
We discuss the well-known phenomenon of spontaneous symmetry breaking for a linear sigma model for scalar and pseudoscalar mesons based on the meson composite structure and the normalization of the quantum states. To test our formulation and validate our approach we give another proof of the Goldstone theorem and derive the corresponding mass eigenstates of the theory. We briefly describe the possible wave function of a meson that leads to the adequate mass eigenstates.
Symmetry-breaking instability in a prototypical driven granular gas.
Khain, Evgeniy; Meerson, Baruch
2002-08-01
Symmetry-breaking instability of a laterally uniform granular cluster (strip state) in a prototypical driven granular gas is investigated. The system consists of smooth hard disks in a two-dimensional box, colliding inelastically with each other and driven, at zero gravity, by a "thermal" wall. The limit of nearly elastic particle collisions is considered, and granular hydrodynamics with the Jenkins-Richman constitutive relations is employed. The hydrodynamic problem is completely described by two scaled parameters and the aspect ratio of the box. Marginal stability analysis predicts a spontaneous symmetry-breaking instability of the strip state, similar to that predicted recently for a different set of constitutive relations. If the system is big enough, the marginal stability curve becomes independent of the details of the boundary condition at the driving wall. In this regime, the density perturbation is exponentially localized at the elastic wall opposite the thermal wall. The short- and long-wavelength asymptotics of the marginal stability curves are obtained analytically in the dilute limit. The physics of the symmetry-breaking instability is discussed.
Frustrated topological symmetry breaking: Geometrical frustration and anyon condensation
Schulz, Marc D.; Burnell, Fiona J.
2016-10-01
We study the phase diagram of a topological string-net-type lattice model in the presence of geometrically frustrated interactions. These interactions drive several phase transitions that reduce the topological order, leading to a rich phase diagram including both Abelian (Z2) and non-Abelian (Ising×Ising¯ ) topologically ordered phases, as well as phases with broken translational symmetry. Interestingly, one of these phases simultaneously exhibits (Abelian) topological order and long-ranged order due to translational symmetry breaking, with nontrivial interactions between excitations in the topological order and defects in the long-ranged order. We introduce a variety of effective models, valid along certain lines in the phase diagram, which can be used to characterize both topological and symmetry-breaking order in these phases and in many cases allow us to characterize the phase transitions that separate them. We use exact diagonalization and high-order series expansion to study areas of the phase diagram where these models break down and to approximate the location of the phase boundaries.
Matter Mass Generation and Theta Vacuum Dynamical Spontaneous Symmetry Breaking
Roh, H S
2001-01-01
This work proposes a stringent concept of matter mass generation and Theta vacuum in the context of local gauge theory for the strong force under the constraint of the flat universe. The matter mass is generated as the consequence of dynamical spontaneous symmetry breaking (DSSB) of gauge symmetry and discrete symmetries, which is motivated by the parameter Theta representing the surface term. Matter mass generation introduces the typical features of constituent particle mass, dual Meissner effect, and hyperfine structure. The Theta term plays important roles on the DSSB of the gauge group and on the quantization of the matter and vacuum space. The Theta vacuum exhibits the intrinsic principal number and intrinsic angular momentum for intrinsic space quantization in analogy with the extrinsic principal number and extrinsic angular momentum for extrinsic space quantization.
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.
Effects of rotational symmetry breaking in polymer-coated nanopores
International Nuclear Information System (INIS)
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
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.
Localization and chiral symmetry in 2+1 flavor domain wall QCD
Energy Technology Data Exchange (ETDEWEB)
David J. Antonio; Kenneth C. Bowler; Peter A. Boyle; Norman H. Christ; Michael A. Clark; Saul D. Cohen; Chris Dawson; Alistair Hart; Balint Joó; Chulwoo Jung; Richard D. Kenway; Shu Li; Meifeng Lin; Robert D. Mawhinney; Christopher M. Maynard; Shigemi Ohta; Robert J. Tweedie; Azusa Yamaguchi
2008-01-01
We present results for the dependence of the residual mass of domain wall fermions (DWF) on the size of the fifth dimension and its relation to the density and localization properties of low-lying eigenvectors of the corresponding hermitian Wilson Dirac operator relevant to simulations of 2+1 flavor domain wall QCD. Using the DBW2 and Iwasaki gauge actions, we generate ensembles of configurations with a $16^3\\times 32$ space-time volume and an extent of 8 in the fifth dimension for the sea quarks. We demonstrate the existence of a regime where the degree of locality, the size of chiral symmetry breaking and the rate of topology change can be acceptable for inverse lattice spacings $a^{-1} \\ge 1.6$ GeV.
Localization and chiral symmetry in 2+1 flavor domain wall QCD
International Nuclear Information System (INIS)
We present results for the dependence of the residual mass of domain wall fermions (DWF) on the size of the fifth dimension and its relation to the density and localization properties of low-lying eigenvectors of the corresponding hermitian Wilson Dirac operator relevant to simulations of 2+1 flavor domain wall QCD. Using the DBW2 and Iwasaki gauge actions, we generate ensembles of configurations with a 163 x 32 space-time volume and an extent of 8 in the fifth dimension for the sea quarks. We demonstrate the existence of a regime where the degree of locality, the size of chiral symmetry breaking and the rate of topology change can be acceptable for inverse lattice spacings a-1 (ge) 1.6 GeV
Geng, L S; Vacas, M J Vicente
2009-01-01
We report on a recent study of the SU(3)-breaking corrections to the hyperon vector coupling $f_1(0)$ up to $\\mathcal{O}(p^4)$ in covariant baryon chiral perturbation theory with dynamical octet and decuplet contributions. The decuplet contributions are taken into account for the first time in a covariant ChPT study and are found of similar or even larger size than the octet ones. We predict positive SU(3)-breaking corrections to all the four independent $f_1(0)$'s (assuming isospin symmetry), which are consistent, within uncertainties, with the latest results from large $N_c$ fits, chiral quark models, and quenched lattice QCD calculations. We also discuss briefly the implications of our results for the extraction of $V_{us}$ from hyperon decay data.
Executive summary of the Snowmass 2001 working group (P1) ''Electroweak Symmetry Breaking''
International Nuclear Information System (INIS)
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. (orig.)
EXECUTIVE SUMMARY OF THE SNOWMASS 2001 WORKING GROUP : ELECTROWEAK SYMMETRY BREAKING.
Energy Technology Data Exchange (ETDEWEB)
CARENA,M.; GERDES,D.W.; HABER,H.E.; TURCOT,A.S.; ZERWAS,P.M.
2001-06-30
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{sup +}e{sup -} linear collider for precision measurements to clarify the underlying electroweak symmetry breaking dynamics. Finally, we note the possible roles of the {mu}{sup +} {mu}{sup -} collider and VLHC for further elucidating the physics of electroweak symmetry breaking.
Directory of Open Access Journals (Sweden)
Michiya Fujiki
2010-08-01
Full Text Available From elemental particles to human beings, matter is dissymmetric with respect to mirror symmetry. In 1860, Pasteur conjectured that biomolecular handedness— homochirality—may originate from certain inherent dissymmetric forces existing in the universe. Kipping, a pioneer of organosilicon chemistry, was interested in the handedness of sodium chlorate during his early research life. Since Kipping first synthesized several Si-Si bonded oligomers bearing phenyl groups, Si-Si bonded high polymers carrying various organic groups—polysilanes—can be prepared by sodium-mediated condensation of the corresponding organodichlorosilanes. Among these polysilanes, optically active helical polysilanes with enantiomeric pairs of organic side groups may be used for testing the mirror symmetry-breaking hypothesis by weak neutral current (WNC origin in the realm of chemistry and material science. Several theoretical studies have predicted that WNC-existing chiral molecules with stereogenic centers and/or stereogenic bonds allow for distinguishing between image and mirror image molecules. Based on several amplification mechanisms, theorists claimed that minute differences, though still very subtle, may be detectable by precise spectroscopic and physicochemical measurements if proper chiral molecular pairs were employed. The present paper reports comprehensively an inequality between six pairs of helical polysilane high polymers, presumably, detectable by (chiroptical and achiral 29Si-/13C- NMR spectra, and viscometric measurements.
Electroweak symmetry breaking without the μ2 term
Goertz, Florian
2016-07-01
We demonstrate that from a low-energy perspective a viable breaking of the electroweak symmetry, as present in nature, can be achieved without the (negative sign) μ2 mass term in the Higgs potential, thereby avoiding completely the appearance of relevant operators, featuring coefficients with a positive mass dimension, in the theory. We show that such a setup is self-consistent and not ruled out by Higgs physics. In particular, we point out that it is the lightness of the Higgs boson that allows for the electroweak symmetry to be broken dynamically via operators of D ≥4 , consistent with the power expansion. Beyond that, we entertain how this scenario might even be preferred phenomenologically compared to the ordinary mechanism of electroweak symmetry breaking, as realized in the Standard Model, and argue that it can be fully tested at the LHC. In the Appendix, we classify UV completions that could lead to such a setup, considering also the option of generating all scales dynamically.
Quantum phase transitions with parity-symmetry breaking and hysteresis
Trenkwalder, A.; Spagnolli, G.; Semeghini, G.; Coop, S.; Landini, M.; Castilho, P.; Pezzè, L.; Modugno, G.; Inguscio, M.; Smerzi, A.; Fattori, M.
2016-09-01
Symmetry-breaking quantum phase transitions play a key role in several condensed matter, cosmology and nuclear physics theoretical models. Its observation in real systems is often hampered by finite temperatures and limited control of the system parameters. In this work we report, for the first time, the experimental observation of the full quantum phase diagram across a transition where the spatial parity symmetry is broken. Our system consists of an ultracold gas with tunable attractive interactions trapped in a spatially symmetric double-well potential. At a critical value of the interaction strength, we observe a continuous quantum phase transition where the gas spontaneously localizes in one well or the other, thus breaking the underlying symmetry of the system. Furthermore, we show the robustness of the asymmetric state against controlled energy mismatch between the two wells. This is the result of hysteresis associated with an additional discontinuous quantum phase transition that we fully characterize. Our results pave the way to the study of quantum critical phenomena at finite temperature, the investigation of macroscopic quantum tunnelling of the order parameter in the hysteretic regime and the production of strongly quantum entangled states at critical points.
Spontaneous Symmetry Breaking in Presence of Electric and Magnetic Charges
Pushpa; Bisht, P. S.; Negi, O. P. S.
2011-06-01
Starting with the definition of quaternion gauge theory, we have undertaken the study of SU(2) e × SU(2) m × U(1) e × U(1) m in terms of the simultaneous existence of electric and magnetic charges along with their Yang-Mills counterparts. As such, we have developed the gauge theory in terms of four coupling constants associated with four-gauge symmetry SU(2) e × SU(2) m × U(1) e × U(1) m . Accordingly, we have made an attempt to obtain the abelian and non-Abelian gauge structures for the particles carrying simultaneously the electric and magnetic charges (namely dyons). Starting from the Lagrangian density of two SU(2)× U(1) gauge theories responsible for the existence of electric and magnetic charges, we have discussed the consistent theory of spontaneous symmetry breaking and Higgs mechanism in order to generate the masses. From the symmetry breaking, we have generated the two electromagnetic fields, the two massive vector W ± and Z 0 bosons fields and the Higgs scalar fields.
Spontaneous Symmetry Breaking in Presence of Electric and Magnetic Charges
Pushpa,; Negi, O P S
2010-01-01
Starting with the definition of quaternion gauge theory, we have undertaken the study of SU(2)_{e}\\times SU(2)_{m}\\times U(1)_{e}\\times U(1)_{m} in terms of the simultaneous existence of electric and magnetic charges along with their Yang - Mills counterparts. As such, we have developed the gauge theory in terms of four coupling constants associated with four - gauge symmetry SU(2)_{e}\\times SU(2)_{m}\\times U(1)_{e}\\times U(1)_{m}. Accordingly, we have made an attempt to obtain the abelian and non - Abelian gauge structures for the particles carrying simultaneously the electric and magnetic charges (namely dyons). Starting from the Lagrangian density of two SU(2)\\times U(1) gauge theories responsible for the existence of electric and magnetic charges, we have discussed the consistent theory of spontaneous symmetry breaking and Higgs mechanism in order to generate the masses. From the symmetry breaking, we have generated the two electromagnetic fields, the two massive vector W^{\\pm} and Z^{0} bosons fields and...
Hebeler, K.; Schwenk, A.
2014-01-01
We discuss neutron matter calculations based on chiral effective field theory interactions and their predictions for the symmetry energy, the neutron skin of 208 Pb, and for the radius of neutron stars.
Gauge Invariance and Symmetry Breaking by Topology and Energy Gap
Directory of Open Access Journals (Sweden)
Franco Strocchi
2015-10-01
Full Text Available For the description of observables and states of a quantum system, it may be convenient to use a canonical Weyl algebra of which only a subalgebra A, with a non-trivial center Z, describes observables, the other Weyl operators playing the role of intertwiners between inequivalent representations of A. In particular, this gives rise to a gauge symmetry described by the action of Z. A distinguished case is when the center of the observables arises from the fundamental group of the manifold of the positions of the quantum system. Symmetries that do not commute with the topological invariants represented by elements of Z are then spontaneously broken in each irreducible representation of the observable algebra, compatibly with an energy gap; such a breaking exhibits a mechanism radically different from Goldstone and Higgs mechanisms. This is clearly displayed by the quantum particle on a circle, the Bloch electron and the two body problem.
Matter inflation with A_4 flavour symmetry breaking
Antusch, Stefan
2013-01-01
We discuss model building in tribrid inflation, which is a framework for realising inflation in the matter sector of supersymmetric particle physics models. The inflaton is a D-flat combination of matter fields, and inflation ends by a phase transition in which some Higgs field obtains a vacuum expectation value. We first describe the general procedure for implementing tribrid inflation in realistic models of particle physics that can be applied to a wide variety of BSM particle physics models around the GUT scale. We then demonstrate how the procedure works for an explicit lepton flavour model based on an A_4 family symmetry. The model is both predictive and phenomenologically viable, and illustrates how tribrid inflation connects cosmological and particle physics parameters. In particular, it predicts a relation between the neutrino Yukawa coupling and the running of the spectral index alpha_s. We also show how topological defects from the flavour symmetry breaking can be avoided automatically.
Orbital engineering in symmetry-breaking polar heterostructures.
Disa, Ankit S; Kumah, Divine P; Malashevich, Andrei; Chen, Hanghui; Arena, Dario A; Specht, Eliot D; Ismail-Beigi, Sohrab; Walker, F J; Ahn, Charles H
2015-01-16
We experimentally demonstrate a novel approach to substantially modify orbital occupations and symmetries in electronically correlated oxides. In contrast to methods using strain or confinement, this orbital tuning is achieved by exploiting charge transfer and inversion symmetry breaking using atomically layered heterostructures. We illustrate the technique in the LaTiO_{3}-LaNiO_{3}-LaAlO_{3} system; a combination of x-ray absorption spectroscopy and ab initio theory reveals electron transfer and concomitant polar fields, resulting in a ∼50% change in the occupation of Ni d orbitals. This change is sufficiently large to remove the orbital degeneracy of bulk LaNiO_{3} and creates an electronic configuration approaching a single-band Fermi surface. Furthermore, we theoretically show that such three-component heterostructuring is robust and tunable by choice of insulator in the heterostructure, providing a general method for engineering orbital configurations and designing novel electronic systems.
Matter inflation with A4 flavour symmetry breaking
International Nuclear Information System (INIS)
We discuss model building in tribrid inflation, which is a framework for realising inflation in the matter sector of supersymmetric particle physics models. The inflaton is a D-flat combination of matter fields, and inflation ends by a phase transition in which some Higgs field obtains a vacuum expectation value. We first describe the general procedure for implementing tribrid inflation in realistic models of particle physics that can be applied to a wide variety of BSM particle physics models around the GUT scale. We then demonstrate how the procedure works for an explicit lepton flavour model based on an A4 family symmetry. The model is both predictive and phenomenologically viable, and illustrates how tribrid inflation connects cosmological and particle physics parameters. In particular, it predicts a relation between the neutrino Yukawa coupling and the running of the spectral index αs. We also show how topological defects from the flavour symmetry breaking can be avoided automatically
Crucial role of neutrinos in the electroweak symmetry breaking
Energy Technology Data Exchange (ETDEWEB)
Smetana, Adam [Institute of Experimental and Applied Physics, Czech Technical University in Prague, Horská 3a/22, 128 00 Prague 2 (Czech Republic)
2013-12-30
Not only the top-quark condensate appears to be the natural significant source of dynamical electroweak symmetry breaking. Provided the seesaw scenario, the neutrinos can have their Dirac masses large enough so that their condensates contribute significantly to the electroweak scale as well. We address the question of a phenomenological feasibility of the top-quark and neutrino condensation conspiracy against the electroweak symmetry within the simplifying two-composite-Higgs-doublet model. Mandatory is to reproduce the masses of electroweak gauge bosons, the top-quark mass and the recently observed scalar mass of 125 GeV, and to satisfy the upper limits on absolute value of active neutrino masses. To accomplish that, the number of right-handed neutrinos participating on the seesaw mechanism turns out to be rather large, O(100–1000)
Revolving D-branes and spontaneous gauge-symmetry breaking
International Nuclear Information System (INIS)
We propose a new mechanism of spontaneous gauge-symmetry breaking in the world-volume theory of revolving D-branes around a fixed point of orbifolds. In this paper, we consider a simple model of the T6/Z3 orbifold on which we put D3-branes, D7-branes, and their anti-branes. The configuration breaks supersymmetry, but the Ramond–Ramond tadpole cancellation conditions are satisfied. A set of three D3-branes at an orbifold fixed point can separate from the point, but, when they move perpendicular to the anti-D7-branes put on the fixed point, they are pulled back due to an attractive interaction between the D3- and anti-D7-branes. In order to stabilize the separation of the D3-branes at nonzero distance, we consider revolution of the D3-branes around the fixed point. Then the gauge symmetry on the D3-branes is spontaneously broken, and the rank of the gauge group is reduced. The distance can be set at will by appropriately choosing the angular momentum of the revolving D3-branes, which should be determined by the initial condition of the cosmological evolution of the D-brane configurations. The distance corresponds to the vacuum expectation values of brane moduli fields in the world-volume theory and, if it is written as M/Ms2 in terms of the string scale Ms, the scale of gauge-symmetry breaking is given by M. Angular momentum conservation of revolving D3-branes assures the stability of the scale M against Ms
Micheau, Jean-Claude; Coudret, Christophe; Cruz, José-Manuel; Buhse, Thomas
2012-10-14
A comprehensive kinetic analysis of three prototypical autocatalytic cycle models based on the absolute asymmetric Soai reaction is presented. The three models, which can give rise to amplification of enantiomeric excess and mirror-image symmetry breaking, vary by their monomeric, dimeric or trimeric order of the assumed catalytic species. Our numerical approach considered the entire chiral combinatorics of the diastereomeric interactions in the models as well as the multiplicity of coupled reversible reactions without applying fast equilibration or quasi-steady state approximations. For the simplest monomeric model, an extensive range of parameters was explored employing a random grid parameter scanning method that revealed the influence of the parameter values on the product distribution, the reaction-time, the attenuation or amplification of enantiomeric excess as well as on the presence or absence of mirror-image symmetry breaking. A symmetry breaking test was imposed on the three models showing that an increase in the catalytic oligomer size from one to three leads to a higher tolerance to poorer chiral recognition between the diastereoisomers and identifies the greater impact of the diastereoisomeric energy difference over an imperfect stereoselectivity in the catalytic step. This robustness is understood as a particular case of so-called kinetic proofreading in asymmetric autocatalysis.
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...... decreases with increasing curvature, i.e., bending is a trap for nonlinear excitations. A violation of the Vakhitov-Kolokolov stability criterion is found in the case where the instability is due to the softening of the Peierls internal mode....
Charge symmetry breaking in mirror nuclei from quarks
Tsushima, K; Thomas, A W
1999-01-01
The binding energy differences of the valence proton and neutron of the mirror nuclei, $^{15}$O -- $^{15}$N, $^{17}$F -- $^{17}$O, $^{39}$Ca -- $^{39}$K and $^{41}$Sc -- $^{41}$Ca, are calculated using the quark-meson coupling (QMC) model. The calculation involves nuclear structure and shell effects explicitly. It is shown that binding energy differences of a few hundred keV arise from the strong interaction, even after subtracting all electromagnetic corrections. The origin of these differences may be ascribed to the charge symmetry breaking effects set in the strong interaction through the u and d current quark mass difference.
Introduction to weak interaction theories with dynamical symmetry breaking
International Nuclear Information System (INIS)
A straightforward introduction to theories of the weak interactions with dynamical symmetry breaking-theories of technicolor or hypercolor is presented. The intent is to inform experimentalists, but also to goad theorists. The motivation for considering theories of this type is described. The structure that such a theory must possess, including new gauge interactions at mass scales of 1-100 TeV is then outlined. Despite their reliance on phenomena at such enormous energies, these theories contain new phenomena observable at currently accessible energies. Three such effects which are especially likely to be observed are described
Evanescent Wave-Assisted Symmetry Breaking of Gold Dipolar Nanoantennas.
Yang, Jhen-Hong; Chen, Kuo-Ping
2016-01-01
Symmetry-breaking and scattering cancellation were observed in the dark-mode resonance of dipolar gold nanoantennas (NAs) on glass substrates coupled with oblique incidence and total internal reflection. With the assistance of evanescent waves, the coupling efficiency was twice as strong when the incidence angle was larger than the critical angle. The Hamiltonian equation and absorption spectra were used to analyze the hybridization model of symmetric dipolar gold NAs. The antibonding mode could be coupled successfully by both transverse-magnetic (TM) and transverse-electric (TE) polarizations to NAs when the dimers orientation is parallel to the propagation direction of evanescent waves. PMID:27581766
Symmetry-breaking transitions in networks of nonlinear circuit elements
Energy Technology Data Exchange (ETDEWEB)
Heinrich, Martin; Dahms, Thomas; Flunkert, Valentin; Schoell, Eckehard [Institut fuer Theoretische Physik, Technische Universitaet Berlin, 10623 Berlin (Germany); Teitsworth, Stephen W, E-mail: schoell@physik.tu-berlin.d [Department of Physics, Duke University, PO Box 90305, Durham, NC 27708-0305 (United States)
2010-11-15
We investigate a nonlinear circuit consisting of N tunnel diodes in series, which shows close similarities to a semiconductor superlattice or to a neural network. Each tunnel diode is modeled by a three-variable FitzHugh-Nagumo-like system. The tunnel diodes are coupled globally through a load resistor. We find complex bifurcation scenarios with symmetry-breaking transitions that generate multiple fixed points off the synchronization manifold. We show that multiply degenerate zero-eigenvalue bifurcations occur, which lead to multistable current branches, and that these bifurcations are also degenerate with a Hopf bifurcation. These predicted scenarios of multiple branches and degenerate bifurcations are also found experimentally.
Minimal but non-minimal inflation and electroweak symmetry breaking
Marzola, Luca
2016-01-01
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 r\\^ole 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 $r \\approx 10^{-3}$, typical of Higgs-inflation models, but in contrast yields a scalar spectral index $n_s \\simeq 0.97$ which departs from the Starobinsky limit. We briefly discuss the collider phenomenology of the framework.
Stochastic model of nanomechanical electron shuttles and symmetry breaking
Zhao, Mo; Blick, Robert H.
2016-06-01
Nanomechanical electron shuttles can work as ratchets for radio-frequency rectification. We develop a full stochastic model of coupled shuttles, where the mechanical motion of nanopillars and the incoherent electronic tunneling are modeled by a Markov chain. In particular, the interaction of their randomness is taken into account, so that a linear master equation is constructed. Numerical solutions from our fast approximate method and analytical derivation reveal the symmetry breaking, which results in the direct current observed in earlier measurements [Phys. Rev. Lett. 105, 067204 (2010), 10.1103/PhysRevLett.105.067204]. Additionally, the method can facilitate device simulation of more complex designs such as shuttle arrays.
Evanescent Wave-Assisted Symmetry Breaking of Gold Dipolar Nanoantennas
Yang, Jhen-Hong; Chen, Kuo-Ping
2016-09-01
Symmetry-breaking and scattering cancellation were observed in the dark-mode resonance of dipolar gold nanoantennas (NAs) on glass substrates coupled with oblique incidence and total internal reflection. With the assistance of evanescent waves, the coupling efficiency was twice as strong when the incidence angle was larger than the critical angle. The Hamiltonian equation and absorption spectra were used to analyze the hybridization model of symmetric dipolar gold NAs. The antibonding mode could be coupled successfully by both transverse-magnetic (TM) and transverse-electric (TE) polarizations to NAs when the dimers orientation is parallel to the propagation direction of evanescent waves.
Energy Technology Data Exchange (ETDEWEB)
Alexandru, Andrei [George Washington University, Washington, DC (United States); Horváth, Ivan [University of Kentucky, Lexington, KY, USA (the speaker) (United States)
2016-01-22
The validity of recently proposed equivalence between valence spontaneous chiral symmetry breaking (vSChSB) and chiral polarization of low energy Dirac spectrum (ChP) in SU(3) gauge theory, is examined for the case of twelve mass–degenerate fundamental quark flavors. We find that the vSChSB–ChP correspondence holds for regularized systems studied. Moreover, our results suggest that vSChSB occurs in two qualitatively different circumstances: there is a quark mass m{sub c} such that for m > m{sub c} the mode condensing Dirac spectrum exhibits standard monotonically increasing density, while for m{sub ch} < m < m{sub c} the peak around zero separates from the bulk of the spectrum, with density showing a pronounced depletion at intermediate scales. Valence chiral symmetry restoration may occur at yet smaller masses m < m{sub ch}, but this has not yet been seen by overlap valence probe, leaving the m{sub ch} = 0 possibility open. The latter option could place massless N{sub f}=12 theory outside of conformal window. Anomalous behavior of overlap Dirac spectrum for m{sub ch} < m < m{sub c} is qualitatively similar to one observed previously in zero and few–flavor theories as an effect of thermal agitation.
Charge Symmetry Breaking in dd->4He{\\pi}0 with WASA-at-COSY
:,; Augustyniak, W; Bardan, W; Bashkanov, M; Bergmann, F S; Berłowski, M; Bhatt, H; Bondar, A; Büscher, M; Calén, H; Ciepał, I; Clement, H; Coderre, D; Czerwiński, E; Demmich, K; Doroshkevich, E; Engels, R; Erven, A; Erven, W; Eyrich, W; Fedorets, P; Föhl, K; Fransson, K; Goldenbaum, F; Goslawski, P; Goswami, A; Grigoryev, K; Gullström, C -O; Hanhart, C; Hauenstein, F; Heijkenskjöld, L; Hejny, V; Höistad, B; Hüsken, N; Jarczyk, L; Johansson, T; Kamys, B; Kemmerling, G; Khan, F A; Khoukaz, A; Kirillov, D A; Kistryn, S; Kleines, H; Kłos, B; Krzemień, W; Kulessa, P; Kupść, A; Kuzmin, A; Lalwani, K; Lersch, D; Lorentz, B; Magiera, A; Maier, R; Marciniewski, P; Mariański, B; Mikirtychiants, M; Morsch, H -P; Moskal, P; Ohm, H; Ozerianska, I; del Rio, E Perez; Piskunov, N M; Podkopał, P; Prasuhn, D; Pricking, A; Pszczel, D; Pysz, K; Pyszniak, A; Redmer, C F; Ritman, J; Roy, A; Rudy, Z; Sawant, S; Schadmand, S; Sefzick, T; Serdyuk, V; Shwartz, B; Siudak, R; Skorodko, T; Skurzok, M; Smyrski, J; Sopov, V; Stassen, R; Stepaniak, J; Stephan, E; Sterzenbach, G; Stockhorst, H; Ströher, H; Szczurek, A; Täschner, A; Trzciński, A; Varma, R; Wolke, M; Wrońska, A; Wüstner, P; Wurm, P; Yamamoto, A; Yurev, L; Zabierowski, J; Zieliński, M J; Zink, A; Złomańczuk, J; Żuprański, P; Żurek, M
2014-01-01
Charge symmetry breaking (CSB) observables are a suitable experimental tool to examine effects induced by quark masses on the nuclear level. Previous high precision data from TRIUMF and IUCF are currently used to develop a consistent description of CSB within the framework of chiral perturbation theory. In this work the experimental studies on the reaction dd->4He{\\pi}0 have been extended towards higher excess energies in order to provide information on the contribution of p-waves in the final state. For this, an exclusive measurement has been carried out at a beam momentum of p=1.2 GeV/c using the WASA-at-COSY facility. The total cross section amounts to sigma(tot) = (118 +- 18(stat) +- 13(sys) +- 8(ext)) pb and first data on the differential cross section are consistent with s-wave pion production.
How is chiral symmetry restored at finite density?
Tatsumi, T.; Nakano, E.
2005-01-01
Taking into account pseudoscalar as well as scalar condensates, we reexamine the chiral restoration path on the chiral manifold. We shall see both condensates coherently produce a density wave at a certain density, which delays chiral restoration as density or temperature is increased.
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.
Energy Technology Data Exchange (ETDEWEB)
Hilger, Thomas Uwe
2012-04-11
The interplay of hadron properties and their modification in an ambient nuclear medium on the one hand and spontaneous chiral symmetry breaking and its restoration on the other hand is investigated. QCD sum rules for D and B mesons embedded in cold nuclear matter are evaluated. We quantify the mass splitting of D- anti D and B- anti B mesons as a function of the nuclear matter density and investigate the impact of various condensates in linear density approximation. The analysis also includes D{sub s} and D{sup *}{sub 0} mesons. QCD sum rules for chiral partners in the open-charm meson sector are presented at nonzero baryon net density or temperature. We focus on the differences between pseudo-scalar and scalar as well as vector and axial-vector D mesons and derive the corresponding Weinberg type sum rules. Based on QCD sum rules we explore the consequences of a scenario for the ρ meson, where the chiral symmetry breaking condensates are set to zero whereas the chirally symmetric condensates remain at their vacuum values. The complementarity of mass shift and broadening is discussed. An alternative approach which utilizes coupled Dyson-Schwinger and Bethe-Salpeter equations for quark-antiquark bound states is investigated. For this purpose we analyze the analytic structure of the quark propagators in the complex plane numerically and test the possibility to widen the applicability of the method to the sector of heavy-light mesons in the scalar and pseudo-scalar channels, such as the D mesons, by varying the momentum partitioning parameter. The solutions of the Dyson-Schwinger equation in the Wigner-Weyl phase of chiral symmetry at nonzero bare quark masses are used to investigate a scenario with explicit but without dynamical chiral symmetry breaking.
International Nuclear Information System (INIS)
The interplay of hadron properties and their modification in an ambient nuclear medium on the one hand and spontaneous chiral symmetry breaking and its restoration on the other hand is investigated. QCD sum rules for D and B mesons embedded in cold nuclear matter are evaluated. We quantify the mass splitting of D- anti D and B- anti B mesons as a function of the nuclear matter density and investigate the impact of various condensates in linear density approximation. The analysis also includes Ds and D*0 mesons. QCD sum rules for chiral partners in the open-charm meson sector are presented at nonzero baryon net density or temperature. We focus on the differences between pseudo-scalar and scalar as well as vector and axial-vector D mesons and derive the corresponding Weinberg type sum rules. Based on QCD sum rules we explore the consequences of a scenario for the ρ meson, where the chiral symmetry breaking condensates are set to zero whereas the chirally symmetric condensates remain at their vacuum values. The complementarity of mass shift and broadening is discussed. An alternative approach which utilizes coupled Dyson-Schwinger and Bethe-Salpeter equations for quark-antiquark bound states is investigated. For this purpose we analyze the analytic structure of the quark propagators in the complex plane numerically and test the possibility to widen the applicability of the method to the sector of heavy-light mesons in the scalar and pseudo-scalar channels, such as the D mesons, by varying the momentum partitioning parameter. The solutions of the Dyson-Schwinger equation in the Wigner-Weyl phase of chiral symmetry at nonzero bare quark masses are used to investigate a scenario with explicit but without dynamical chiral symmetry breaking.
Tachyonic Instability and Dynamics of Spontaneous Symmetry Breaking
Felder, G; Linde, Andrei D; Felder, Gary; Kofman, Lev; Linde, Andrei
2001-01-01
Spontaneous symmetry breaking usually occurs due to the tachyonic (spinodal) instability of a scalar field near the top of its effective potential at $\\phi = 0$. Naively, one might expect the field $\\phi$ to fall from the top of the effective potential and then experience a long stage of oscillations with amplitude O(v) near the minimum of the effective potential at $\\phi = v$ until it gives its energy to particles produced during these oscillations. However, it was recently found that the tachyonic instability rapidly converts most of the potential energy V(0) into the energy of colliding classical waves of the scalar field. This conversion, which was called "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. In this paper we give a detailed description of tachyonic preheating and show that the dynamics of this process crucially depend on the shape of the effective ...
Cosmological signature change in Cartan Gravity with dynamical symmetry breaking
Magueijo, Joao; Westman, Hans; Zlosnik, T G
2013-01-01
We investigate the possibility for classical metric signature change in a straightforward generalization of the first order formulation of gravity, dubbed "Cartan gravity". The mathematical structure of this theory mimics the electroweak theory in that the basic ingredients are an $SO(1,4)$ Yang-Mills gauge field $A^{ab}_{\\phantom{ab}\\mu}$ and a symmetry breaking Higgs field $V^{a}$, with no metric or affine structure of spacetime presupposed. However, these structures can be recovered, with the predictions of General Relativity exactly reproduced, whenever the Higgs field breaking the symmetry to $SO(1,3)$ is forced to have a constant (positive) norm $V^aV_a$. This restriction is usually imposed "by hand", but in analogy with the electroweak theory we promote the gravitational Higgs field $V^a$ to a genuine dynamical field, subject to non-trivial equations of motion. Even though we limit ourselves to actions polynomial in these variables, we discover a rich phenomenology. Most notably we derive classical cos...
Bending-induced Symmetry Breaking of Lithiation in Germanium Nanowires
Energy Technology Data Exchange (ETDEWEB)
Gu, Meng; Yang, Hui; Perea, Daniel E.; Zhang, Jiguang; Zhang, Sulin; Wang, Chong M.
2014-08-01
From signal transduction of living cells to oxidation and corrosion of metals, mechanical stress intimately couples with chemical reactions, regulating these biological and physiochemical processes. The coupled effect is particularly evident in electrochemical lithiation/delithiation cycling of high-capacity electrodes, such as silicon (Si), where on one hand lithiation-generated stress mediates lithiation kinetics, and on the other electrochemical reaction rate regulates stress generation and mechanical failure of the electrodes. Here we report for the first time the evidence on the controlled lithiation in germanium nanowires (GeNWs) through external bending. Contrary to the symmetric core-shell lithiation in free-standing GeNWs, we show bending GeNWs breaks the lithiation symmetry, speeding up lithaition at the tensile side while slowing down at the compressive side of the GeNWs. The bending-induced symmetry breaking of lithiation in GeNWs is further corroborated by chemomechanical modeling. In the light of the coupled effect between lithiation kinetics and mechanical stress in the electrochemical cycling, our findings shed light on strain/stress engineering of durable high-rate electrodes and energy harvesting through mechanical motion.
Bending-induced symmetry breaking of lithiation in germanium nanowires.
Gu, Meng; Yang, Hui; Perea, Daniel E; Zhang, Ji-Guang; Zhang, Sulin; Wang, Chong-Min
2014-08-13
From signal transduction of living cells to oxidation and corrosion of metals, mechanical stress intimately couples with chemical reactions, regulating these biological and physiochemical processes. The coupled effect is particularly evident in the electrochemical lithiation/delithiation cycling of high-capacity electrodes, such as silicon (Si), where on the one hand lithiation-generated stress mediates lithiation kinetics and on the other the electrochemical reaction rate regulates stress generation and mechanical failure of the electrodes. Here we report for the first time the evidence on the controlled lithiation in germanium nanowires (GeNWs) through external bending. Contrary to the symmetric core-shell lithiation in free-standing GeNWs, we show bending the GeNWs breaks the lithiation symmetry, speeding up lithaition at the tensile side while slowing down at the compressive side of the GeNWs. The bending-induced symmetry breaking of lithiation in GeNWs is further corroborated by chemomechanical modeling. In the light of the coupled effect between lithiation kinetics and mechanical stress in the electrochemical cycling, our findings shed light on strain/stress engineering of durable high-rate electrodes and energy harvesting through mechanical motion. PMID:25025296
Parity-time symmetry breaking in magnetic systems
Galda, Alexey; Vinokur, Valerii M.
2016-07-01
The understanding of out-of-equilibrium physics, especially dynamic instabilities and dynamic phase transitions, is one of the major challenges of contemporary science, spanning the broadest wealth of research areas that range from quantum optics to living organisms. Focusing on nonequilibrium dynamics of an open dissipative spin system, we introduce a non-Hermitian Hamiltonian approach, in which non-Hermiticity reflects dissipation and deviation from equilibrium. The imaginary part of the proposed spin Hamiltonian describes the effects of Gilbert damping and applied Slonczewski spin-transfer torque. In the classical limit, our approach reproduces Landau-Lifshitz-Gilbert-Slonczewski dynamics of a large macrospin. We reveal the spin-transfer torque-driven parity-time symmetry-breaking phase transition corresponding to a transition from precessional to exponentially damped spin dynamics. Micromagnetic simulations for nanoscale ferromagnetic disks demonstrate the predicted effect. Our findings can pave the way to a general quantitative description of out-of-equilibrium phase transitions driven by spontaneous parity-time symmetry breaking.
Supersymmetry in a sector of Higgsless electroweak symmetry breaking
International Nuclear Information System (INIS)
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 mχ+∼100.. 110 GeV, the dark matter relic density points to LSP masses of around mχ∼90 GeV. At the LHC, the standard particle content of our model
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
3D toroidal physics: testing the boundaries of symmetry breaking
Spong, Don
2014-10-01
Toroidal symmetry is an important concept for plasma confinement; it allows the existence of nested flux surface MHD equilibria and conserved invariants for particle motion. However, perfect symmetry is unachievable in realistic toroidal plasma devices. For example, tokamaks have toroidal ripple due to discrete field coils, optimized stellarators do not achieve exact quasi-symmetry, the plasma itself continually seeks lower energy states through helical 3D deformations, and reactors will likely have non-uniform distributions of ferritic steel near the plasma. Also, some level of designed-in 3D magnetic field structure is now anticipated for most concepts in order to lead to a stable, steady-state fusion reactor. Such planned 3D field structures can take many forms, ranging from tokamaks with weak 3D ELM-suppression fields to stellarators with more dominant 3D field structures. There is considerable interest in the development of unified physics models for the full range of 3D effects. Ultimately, the questions of how much symmetry breaking can be tolerated and how to optimize its design must be addressed for all fusion concepts. Fortunately, significant progress is underway in theory, computation and plasma diagnostics on many issues such as magnetic surface quality, plasma screening vs. amplification of 3D perturbations, 3D transport, influence on edge pedestal structures, MHD stability effects, modification of fast ion-driven instabilities, prediction of energetic particle heat loads on plasma-facing materials, effects of 3D fields on turbulence, and magnetic coil design. A closely coupled program of simulation, experimental validation, and design optimization is required to determine what forms and amplitudes of 3D shaping and symmetry breaking will be compatible with future fusion reactors. The development of models to address 3D physics and progress in these areas will be described. This work is supported both by the US Department of Energy under Contract DE
Geomagnetic Reversals Caused by Breaking Mirror Symmetry of Core Dynamics
Petrelis, F; Dormy, E; Valet, J P
2008-01-01
The Earth's magnetic field can be geometrically described by a strong axial dipole and higher degree terms, which belong to the dipolar (even) or quadrupolar (odd) family depending on their symmetry with respect to the equatorial plane. It is established that the field has frequently (and maybe always) reversed its polarity. It has been suggested by Merrill and Mc Fadden \\cite{Merrill} that reversals occur because the fluid flow in the outer core breaks the equatorial symmetry. This results in a coupling between the dipolar and quadrupolar families. Field reversals have now been reported in several numerical simulations of dynamos and very recently for the first time in a laboratory experiment involving a Von Karman swirling flow of liquid sodium (VKS) \\cite{Berhanu}. In this experiment, reversals are observed when the velocities of the two counter rotating disks driving the flow are different, thus when a symmetry is broken. Here, we show how the interaction between the dipolar and quadrupolar modes, that re...
Spontaneous symmetry breaking in vortex systems with two repulsive lengthscales
Curran, P. J.; Desoky, W. M.; Milos̆ević, M. V.; Chaves, A.; Laloë, J.-B.; Moodera, J. S.; Bending, S. J.
2015-01-01
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. PMID:26492969
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.
Chiral symmetry and effective field theories for hadronic, nuclear and stellar matter
Holt, Jeremy W; Weise, Wolfram
2014-01-01
Chiral symmetry, first entering in nuclear physics in the 1970's for which Gerry Brown played a seminal role, has led to a stunningly successful framework for describing strongly-correlated nuclear dynamics both in finite and infinite systems. We review how the early germinal idea, conceived with the soft-pion theorems in the pre-QCD era, has evolved into a highly predictive theoretical framework for nuclear physics, aptly assessed by Steven Weinberg: "it (chiral effective field theory) allows one to show in a fairly convincing way that what they (nuclear physicists) have been doing all along... is the correct first step in a consistent approximation scheme." Our review recounts both how the theory presently fares in confronting Nature and how one can understand its extremely intricate workings in terms of the multifaceted aspects of chiral symmetry, namely, chiral perturbation theory, skyrmions, Landau Fermi-liquid theory, the Cheshire cat phenomenon, and hidden local and mended symmetries.
Inertial blob-hole symmetry breaking in magnetised plasma filaments
Kendl, Alexander
2015-01-01
Symmetry breaking between the propagation velocities of magnetised plasma filaments with large positive (blob) and negative (hole) amplitudes, as implied by a dimensional analysis scaling, is studied with global ("full-n") non-Boussinesq gyrofluid computations, which include finite inertia effects through nonlinear polarisation. Interchange blobs on a flat density background have higher inertia and propagate more slowly than holes. In the presence of a large enough density gradient, the effect is reversed: blobs accelerate down the gradient and holes are slowed in their propagation up the gradient. Drift wave blobs spread their initial vorticity rapidly into a fully developed turbulent state, whereas primary holes can remain coherent for many eddy turnover times. The results bear implications for plasma edge zonal flow evolution and tokamak scrape-off-layer transport.
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.
Lorentz Symmetry Breaking in $\\mathcal{N} =2$ Superspace
Faizal, Mir
2015-01-01
In this paper, we will study the deformation of a three dimensional theory with $\\mathcal{N} =2$ supersymmetry. This theory will be deformed by the presence of a constant vector field. This deformation will break the Lorentz symmetry. So, we will analyse this theory using $\\mathcal{N} =2$ aether superspace. The $\\mathcal{N} =2$ aether superspace will be obtained from a deformation of the usual $\\mathcal{N} =2$ superspace. This will be done by deforming the generators of the three dimensional $\\mathcal{N} =2$ supersymmetry. After analysing this deformed superalgebra, we will derive an explicit expression for the superspace propagators in this deformed superspace. Finally, we will use these propagators for performing perturbative calculations.
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...... of Scherer et al. [ Phys. Rev. Lett. 105 135302 (2010)]. It is shown that the dynamics of a spinor BEC initially prepared in an unstable Zeeman state mF=0 (|0〉) can be understood by approximating the effective trapping potential for the state |±1〉 with a cylindrical box potential. The resonances....... In addition, a detailed account of the experimental methods for the preparation and analysis of spinor quantum gases is given....
Micropropulsion and microrheology in complex fluids via symmetry breaking
Pak, On Shun; Brandt, Luca; Lauga, Eric; 10.1063/1.4758811
2013-01-01
Many biological fluids have polymeric microstructures and display non-Newtonian rheology. We take advantage of such nonlinear fluid behavior and combine it with geometrical symmetry-breaking to design a novel small-scale propeller able to move only in complex fluids. Its propulsion characteristics are explored numerically in an Oldroyd-B fluid for finite Deborah numbers while the small Deborah number limit is investigated analytically using a second-order fluid model. We then derive expressions relating the propulsion speed to the rheological properties of the complex fluid, allowing thus to infer the normal stress coefficients in the fluid from the locomotion of the propeller. Our simple mechanism can therefore be used either as a non-Newtonian micro-propeller or as a micro-rheometer.
Jumps, somersaults, and symmetry breaking in Leidenfrost drops
Chen, Simeng; Bertola, Volfango
2016-08-01
When a droplet of water impacts a heated surface, the drop may be observed to bounce. Recently is has been found that small quantities (˜100 ppm) of polymer additives such as polyethylene oxide can significantly increase the maximum bouncing height of drops. This effect has been explained in terms of the reduction of energy dissipation caused by polymer additives during the drop retraction and rebound, resulting in higher mechanical energy available for bouncing. Here we demonstrate, by comparing three types of fluids (Newtonian, shear-thinning, and viscoelastic), that the total kinetic energy carried by low-viscosity Newtonian drops during retraction is partly transformed into rotational kinetic energy rather than dissipated when compared with high-viscosity or non-Newtonian drops. We also show that non-Newtonian effects play little role in the energy distribution during drop impact, while the main effect is due to the symmetry break observed during the retraction of low-viscosity drops.
Structural topography-mediated high temperature wetting symmetry breaking
Li, Jing; Liu, Yahua; Hao, Chonglei; Li, Minfei; Chaudhury, Manoj K; Yao, Shuhuai
2015-01-01
Directed motion of liquid droplets is of considerable importance in various industrial processes. Despite extensive advances in this field of research, our understanding and the ability to control droplet dynamics at high temperature remain limited, in part due to the emergence of complex wetting states intertwined by the phase change process at the triple-phase interfaces. Here we show that two concurrent wetting states (Leidenfrost and contact boiling) can be manifested in a single droplet above its boiling point rectified by the presence of asymmetric textures. The breaking of the wetting symmetry at high temperature subsequently leads to the preferential motion towards the region with higher heat transfer coefficient. We demonstrate experimentally and analytically that the droplet vectoring is intricately dependent on the interplay between the structural topography and its imposed thermal state. Our fundamental understanding and the ability to control the droplet dynamics at high temperature represent an ...
Probing SU(2) symmetry breaking in the nucleon sea
Arash, Firooz; Tomio, Lauro
1997-02-01
Investigation of invariant cross-sections for production of K*- and overlineK*0, in the fragmentation region of the proton, in p - p and γ - p reactions, gives a direct and unambiguous probe to the symmetry breaking of the nucleon sea. Based on existing data, we clearly found a large asymmetry of the sea. Our result is in excellent agreement with NA51 measurement, signaling lack of any nuclear effect. The measurement can be carried out in a single experimental set up. The ratio K*-/overlineK*0 is equivalent to u/d, with easy access to the x-dependence of the asymmetry. The observed asymmetry from available experimental data is used to improve the valon-recombination model.
Wetting of crossed fibers: multiple steady states and symmetry breaking
Sauret, Alban; Duprat, Camille; Stone, Howard A
2014-01-01
We investigate the wetting properties of the simplest element of an array of random fibers: two rigid fibers crossing with an inclination angle and in contact with a droplet of a perfectly wetting liquid. We show experimentally that the liquid adopts different morphologies when the inclination angle is increased: a column shape, a mixed morphology state where a drop lies at the end of a column, or a drop centered at the node. An analytical model is provided that predicts the wetting length as well as the presence of a non-symmetric state in the mixed morphology regime. The model also highlights a symmetry breaking at the transition between the column state and the mixed morphology. The possibility to tune the morphology of the liquid could have important implications for drying processes.
D-term inflation after spontaneous symmetry breaking
International Nuclear Information System (INIS)
We show that one-loop quantum corrections to the potential energy density in supersymmetric hybrid inflation, outside the inflationary valley, cannot be neglected. A method is presented to calculate these one-loop corrections and they are applied to the case of D-term hybrid inflation, where a significant amount of inflation is shown to occur after spontaneous symmetry breaking. Taking this into account improves the agreement with WMAP measurements. A gauge coupling of up to 0.3 is still consistent with the CMB density perturbation. The spectral index is predicted in between 0.98 and 1.00 and the cosmic string contribution to the CMB anisotropy is sufficiently reduced
Interacting line-node semimetal and spontaneous symmetry breaking
Roy, Bitan
2016-01-01
The effects of short-range electronic interactions in a three dimensional line-node semimetal that supports linearly dispersing quasiparticles around an isolated closed loop in the Brillouin zone are discussed. Due to vanishing density of states various orderings in the bulk of the system, such as the antiferromagnet and charge-density-wave, set in for sufficiently strong onsite ($U$) and nearest-neighbor ($V$) repulsions, respectively. While onset of these two orderings from the semimetallic phase takes place through continuous quantum phase transitions, a first order transition separates two ordered phases. By contrast, topologically protected drumhead shaped surface states can undergo charge or spin orderings, depending on relative strength of $U$ and $V$, even when they are sufficiently weak. Such surface orderings as well as weak long range Coulomb interaction can be conducive to spontaneous symmetry breaking in the bulk for weaker interactions. We also discuss possible superconducting phases and interna...
Models for chiral amplification in spontaneous mirror symmetry breaking
Blanco de Torres, Celia
2014-01-01
Es un hecho empírico que hay un desequilibrio quiral absoluto (o ruptura de simetría especular) en todos los sistemas biológicos conocidos, dónde los procesos cruciales para la vida, como la replicación, implican estructuras supramoleculares que comparten el mismo signo quiral (homoquiralidad). Estas estructuras quirales son proteinas, compuestas de amino ácidos encontrados como L-enantiómeros; y polímeros de ADN y ARN y azúcares, compuestos de R-monocarbohidratos. Basándonos en el hecho de q...
Symmetry breaking and convergent extension in early chordate development.
Schiffmann, Yoram
2006-10-01
The initiation of axis, polarity, cell differentiation, and gastrulation in the very early chordate development is due to the breaking of radial symmetry. It is believed that this occurs by an external signal. We suggest instead spontaneous symmetry breaking through the agency of the Turing-Child field. Increased size or decreased diffusivity, both brought about by mitotic activity, cause the spontaneous loss of stability of the homogeneous state and the evolution of the metabolic pattern during development. The polar metabolic pattern is the cause of polar gene expression, polar morphogenesis (gastrulation), and polar mitotic activity. The Turing-Child theory explains not only the spontaneous formation of the invagination in gastrulation but also the coherent cell movement observed in convergence and extension during gastrulation and neurulation. The theory is demonstrated with respect to experimental observations on the early development of fish, amphibian, and the chick. The theory can explain a multitude of experimental details. For example, it explains the splayed polar progression of reduction in the fish blastoderm. Reduction starts on that side of the blastoderm margin, which will initiate invagination several hours later. It progresses toward the blastoderm center and somewhat laterally from this future "dorsal lip". This is precisely as predicted by a Turing-Child system in a circle. And for a fish like zebrafish with a blastoderm that is slightly oval, reduction is observed to progress along the long axis of the ellipse, which is what Turing-Child theory predicts. In general the shape and the chemical nature of the experimental patterns are the same as predicted by the Turing couple (cAMP, ATP). Embryological polarity and convergent extension are based on polar eigenfunction and saddle-shaped eigenfunction, respectively.
Energy Technology Data Exchange (ETDEWEB)
Kurkov, Maxim A. [Universidade Federal do ABC, CMCC, Santo Andre, SP (Brazil)
2016-06-15
We study effects of a rippling gravitational background on a scalar field with a double well potential, focusing on the analogy with the well known dynamics of the Kapitza's pendulum. The ripples are rendered as infinitesimal but rapidly oscillating perturbations of the scale factor. We find that the resulting dynamics crucially depends on a value of the parameter ξ in the ξRφ{sup 2} vertex. For the time-dependent perturbations of a proper form the resulting effective action is generally covariant, and at a high enough frequency at ξ < 0 and at ξ > 1/6 the effective potential has a single minimum at zero, thereby restoring spontaneously broken symmetry of the ground state. On the other side, at 0 < ξ < 1/6 spontaneous symmetry breaking emerges even when it is absent in the unperturbed case. (orig.)
Signatures of time reversal symmetry breaking in multiband superconductors
Maiti, Saurabh
Multiband superconductors serve as natural host to several possible gound states that compete with each other. At the boundaries of such competing phases, the system usually compromises and settles for `mixed' phases that can show intriguing properties like co-existence of magnetism and superconductiivty or even co-existence of different superconducting phases. The latter is particularly interesting as it can lead to non-magnetic ground states that spontaneously break Time-Reversal symmetry. While the experimental verification of such states has proved to been challenging, the theoretical investigations have provided exciting new insights into the nature of the ground state and its excitations all of which have experimental consequences of some sort. These include extrinsic properties like spontaneous currents around impurity sites, and intrinsic properties in the form of collective excitations. These collective modes bear a unique signature and should provide clear evidence for time reversal symmetry broken state. While the results are general, in light of recent Raman scattering experiments, its direct relevance to extremely hole doped Ba(1-x)K(FeAs)2 will be presented where a strong competition of s-wave and d-wave ground state is expected.
Weyl geometric gravity and "breaking" of electroweak symmetry
Scholz, Erhard
2011-01-01
A Weyl geometric scale covariant approach to gravity due to Omote, Dirac, and Utiyama (1971ff) is reconsidered. It can be extended to the electroweak sector of elementary particle fields, taking into account their basic scaling freedom. Already Cheng (1988) indicated that electroweak symmetry breaking, usually attributed to the Higgs field with a boson expected at $0.1 - 1 \\,TeV$, may be due to a coupling between Weyl geometric gravity and electroweak interactions. Weyl geometry seems to be well suited for treating questions of elementary particle physics, which relate to scale invariance and its "breaking". This setting suggests the existence of a scalar field boson at the surprisingly low energy of $\\sim 1\\, eV$. That may appear unlikely; but, as a payoff, the naturalness problem of the standard Higgs field seems to become immaterial. Moreover, the acquirement of mass arises as a result of coupling to gravity in agreement with the understanding of mass as the gravitational charge of fields. Finally, the pot...
Breaking time reversal symmetry in a circuit topological insulator
Owens, Clai; Jia, Ningyuan; Sommer, Ariel; Schuster, David; Simon, Jonathan
2014-05-01
Materials exhibiting knotted band-structures provide a unique window on interplay between topology and quantum mechanics under well-controlled conditions. The main difficulty is engineering a strong background gauge field for the electrically neutral ``particles'' that comprise such materials. In cold atom systems, the leading candidates include Raman couplings, lattice modulation, and optical flux lattices; however no scalable approach has yet been demonstrated. Meta-materials have seen substantial success, both in coupled optical waveguides, and circuit networks. Here we describe progress towards time reversal breaking in a circuit, to split up- and down- spin Chern bands. This work is essential for studies of fractional quantum hall physics, where spin-flip collisions effectively reverse the magnetic field and destroy the many-body state. We present the design of a 1D transmission line that breaks time reversal symmetry via periodic capacitance modulation. We extend this approach to a 2D geometry, realizing a Floquet topological insulator with an isolated ground Chern-band. These tools are compatible with circuit quantum electrodynamics techniques, and thus provide an exciting route to studies of topologically ordered phases of matter.
Spontaneous breaking of Lorentz symmetry for canonical gravity
Energy Technology Data Exchange (ETDEWEB)
Gielen, Steffen [Max-Planck-Institut fuer Gravitationsphysik (Albert-Einstein-Institut), Golm (Germany); Perimeter Institute for Theoretical Physics, Waterloo, Ontario (Canada); Wise, Derek [Institut fuer Theoretische Physik III, Universitaet Erlangen-Nuernberg, Erlangen (Germany)
2012-07-01
In Hamiltonian formulations of general relativity, in particular Ashtekar variables which serve as the classical starting point for loop quantum gravity, Lorentz covariance is a subtle issue which has been the focus of some debate, while at the same time being crucial with regard to possible experimental tests. After reviewing the sources of difficulty, we present a Lorentz covariant formulation in which which we generalise the notion of a foliation of spacetime usually used in the Hamiltonian formalism to a field of ''local observers'' which specify a time direction only locally. This field spontaneously breaks the local SO(3,1) symmetry down to a subgroup SO(3), in a way similar to systems in condensed matter and particle physics. The formalism is analogous to that in MacDowell-Mansouri gravity, where SO(4,1) is spontaneously broken to SO(3,1). We show that the apparent breaking of SO(3,1) to SO(3) is not in conflict with Lorentz covariance. We close by outlining other possible applications of the formalism of local observer, especially with regard to phenomenology of quantum gravity.
Energy Technology Data Exchange (ETDEWEB)
Szirmai, G.; Szirmai, E. [ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, E-08860 Castelldefels (Barcelona) (Spain); Research Institute for Solid State Physics and Optics, P.O. Box 49, H-1525 Budapest (Hungary); Zamora, A. [ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, E-08860 Castelldefels (Barcelona) (Spain); Lewenstein, M. [ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, E-08860 Castelldefels (Barcelona) (Spain); ICREA-Institucio Catalana de Recerca i Estudis Avancats, Lluis Companys 23, E-08010 Barcelona (Spain)
2011-07-15
We propose an experimentally feasible setup with ultracold alkaline-earth-metal atoms to simulate the dynamics of U(1) lattice gauge theories in 2 + 1 dimensions with a Chern-Simons term. To this end we consider the ground-state properties of spin-5/2 alkaline-earth-metal fermions in a honeycomb lattice. We use the Gutzwiller projected variational approach in the strongly repulsive regime in the case of filling 1/6. The ground state of the system is a chiral spin-liquid state with 2{pi}/3 flux per plaquette, which violates time-reversal invariance. We demonstrate that due to the breaking of time-reversal symmetry the system exhibits quantum Hall effect and chiral edge states. We relate the experimentally accessible spin fluctuations to the emerging gauge-field dynamics. We discuss also properties of the lowest energy competing orders.
Dicke superradiance, Bose-Einstein condensation of photons and spontaneous symmetry breaking
Vyas, Vivek M; Srinivasan, V
2016-01-01
It is shown that the phenomenon of Dicke superradiance essentially occurs due to spontaneous symmetry breaking. Two generalised versions of the Dicke model are studied, and compared with a model that describes photonic Bose-Einstein condensate, which was experimentally realised. In all the models, it is seen that, the occurrence of spontaneous symmetry breaking is responsible for coherent radiation emission.
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.
Lattice QCD study of partial restoration of chiral symmetry in the flux-tube
Iritani, Takumi; Hashimoto, Shoji
2014-01-01
Using the overlap-Dirac eigenmodes, we study the spatial distribution of the chiral condensate around static color sources in lattice QCD. Between the color sources, there appears a color-flux tube, which leads a linear confining potential. By measuring a local value of the chiral condensate, we show that the magnitude of the condensate is reduced inside the flux-tube for both quark-antiquark and three-quark systems. These results suggest that chiral symmetry is partially restored in the flux-tube. The reduction of the condensate is estimated to be about 20 $\\sim$ 30% at the center of the flux.
Electroweak symmetry breaking in the light of LHC
International Nuclear Information System (INIS)
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)
Spin-rotation symmetry breaking in the superconducting state of CuxBi2Se3
Matano, K.; Kriener, M.; Segawa, K.; Ando, Y.; Zheng, Guo-Qing
2016-09-01
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 further 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 conclusively obtained so far in any candidate compounds. Here, using 77Se nuclear magnetic resonance measurements, we show 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 superconductivity in this compound, but may also serve to lay a foundation for the research of topological superconductivity.
Subtraction of power counting breaking terms in chiral perturbation theory: spinless matter fields
Du, Meng-Lin; Meißner, Ulf-G
2016-01-01
When matter fields are included in chiral perturbation theory, the nonvanishing mass in the chiral limit introduces a new energy scale so that the loop diagrams including such matter field propagators spoil the usual power counting. However, the power counting breaking terms can be absorbed into counterterms in the chiral Lagrangian. In this paper, we systematically derive these terms to leading one-loop order (next-to-next-to leading order in the chiral expansion) at once by calculating the generating functional using the path integral. They are then absorbed by counterterms in the next-to-leading order Lagrangian. The method can be extended to calculating power counting breaking terms for other matter fields.
Institute of Scientific and Technical Information of China (English)
WANG Dian-Fu
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.
Chiral magnetic conductivity in an interacting lattice model of parity-breaking Weyl semimetal
Buividovich, P. V.; Puhr, M.; Valgushev, S. N.
2015-11-01
We report on the mean-field study of the chiral magnetic effect (CME) in static magnetic fields within a simple model of parity-breaking Weyl semimetal given by the lattice Wilson-Dirac Hamiltonian with constant chiral chemical potential. We consider both the mean-field renormalization of the model parameters and nontrivial corrections to the CME originating from resummed ladder diagrams with arbitrary number of loops. We find that onsite repulsive interactions affect the chiral magnetic conductivity almost exclusively through the enhancement of the renormalized chiral chemical potential. Our results suggest that nontrivial corrections to the chiral magnetic conductivity due to interfermion interactions are not relevant in practice since they only become important when the CME response is strongly suppressed by the large gap in the energy spectrum.
Spontaneous symmetry breaking in a split potential box
Shamriz, Elad; Malomed, Boris A
2016-01-01
We report results of the analysis of the spontaneous symmetry breaking (SSB) in the basic (actually, simplest) model which is capable to produce the SSB phenomenology in the one-dimensional setting. It is based on the Gross-Pitaevskii - nonlinear Schroedinger equation with the cubic self-attractive term and a double-well-potential built as an infinitely deep potential box split by a narrow (delta-functional) barrier. The barrier's strength, epsilon, is the single free parameter of the scaled form of the model. It may be implemented in atomic Bose-Einstein condensates and nonlinear optics. The SSB bifurcation of the symmetric ground state (GS) is predicted analytically in two limit cases, viz., for deep or weak splitting of the potential box by the barrier. For the generic case, a variational approximation (VA) is elaborated. The analytical findings are presented along with systematic numerical results. Stability of stationary states is studied through the calculation of eigenvalues for small perturbations, an...
Spontaneous Electro-Weak Symmetry Breaking and Cold Dark Matter
Institute of Scientific and Technical Information of China (English)
ZHU Shou-Hua
2007-01-01
In the standard model, the weak gauge bosons and fermions obtain mass after spontaneous electro-weak symmetry breaking, which is realized by one fundamental scalar field, namely the Higgs field. We study the simplest scalar cold dark matter model in which the scalar cold dark matter also obtains mass by interaction with the weakdoublet Higgs field, in the same way as those of weak gauge bosons and fermions. Our study shows that the correct cold dark matter relic abundance within 3σ uncertainty (0.093 ＜Ωdmh2 ＜ 0.129) and experimentally allowed Higgs boson mass (114.4 ≤ mh ≤ 208 GeV) constrain the scalar dark matter mass within 48 ≤ ms ≤ 78 GeV.This result is in excellent agreement with the result of de Boer et al. (50 ～ 100 GeV). Such a kind of dark matter annihilation can account for the observed gamma rays excess (10σ) at EGRET for energies above 1 GeV in comparison with the expectations from conventional Galactic models. We also investigate other phenomenological consequences of this model. For example, the Higgs boson decays dominantly into scalar cold dark matter if its mass lies within 48 ～ 64 GeV.
A pedagogical review of electroweak symmetry breaking scenarios
International Nuclear Information System (INIS)
We review different avenues of electroweak symmetry breaking explored over the years. This constitutes a timely exercise as the world's largest and the highest energy particle accelerator, namely, the Large Hadron Collider (LHC) at CERN near Geneva, has started running whose primary mission is to find the Higgs or some phenomena that mimic the effects of the Higgs, i.e. to unravel the mysteries of electroweak phase transition. In the beginning, we discuss the Standard Model Higgs mechanism. After that we review the Higgs sector of the minimal supersymmetric Standard Model. Then we take up three relatively recent ideas: little Higgs, gauge-Higgs unification and Higgsless scenarios. For the latter three cases, we first present the basic ideas and restrict our illustration to some instructive toy models to provide an intuitive feel of the underlying dynamics, and then discuss, for each of the three cases, how more realistic scenarios are constructed and how to decipher their experimental signatures. Wherever possible, we provide pedagogical details, which beginners might find useful.
Charge symmetry breaking in the A=4 hypernuclei
Gazda, Daniel
2016-01-01
Charge symmetry breaking (CSB) in the $\\Lambda$-nucleon strong interaction generates a charge dependence of $\\Lambda$ separation energies in mirror hypernuclei, which in the case of the $A=4$ mirror hypernuclei $0^+$ ground states is sizable, $\\Delta B^{J=0}_{\\Lambda}\\equiv B^{J=0}_{\\Lambda} (_{\\Lambda}^4{\\rm He})-B^{J=0}_{\\Lambda}(_{\\Lambda}^4{\\rm H})=230\\pm 90$~keV, and of opposite sign to that induced by the Coulomb repulsion in light hypernuclei. Recent {\\it ab initio} calculations of the (\\lamb{4}{H}, \\lamb{4}{He}) mirror hypernuclei $0^+_{\\rm g.s.}$ and $1^+_{\\rm exc}$ levels have demonstrated that a $\\Lambda - \\Sigma^0$ mixing CSB model due to Dalitz and von Hippel (1964) is capable of reproducing this large value of $\\Delta B^{J=0}_{\\Lambda}$. These calculations are discussed here with emphasis placed on the leading-order $\\chi$EFT hyperon-nucleon strong-interaction Bonn-J\\"{u}lich model used and the no-core shell-model calculational scheme applied. The role of one-pion exchange in producing sizable C...
Chiral doubling of heavy-light hadrons and the vector manifestation of hidden local symmetry
International Nuclear Information System (INIS)
Starting with a hidden local symmetry Lagrangian at the vector manifestation (VM) fixed point that incorporates heavy-quark symmetry and matching the bare theory to QCD, we calculate the splitting of chiral doublers of heavy-light mesons proposed by Nowak, Rho, and Zahed [M. A. Nowak, M. Rho, and I. Zahed, Phys. Rev. D 48, 4370 (1993).] and Bardeen and Hill [W. A. Bardeen and C. T. Hill, Phys. Rev. D 49, 409 (1994).]. We show, in the three-flavor chiral limit, that the splitting is directly proportional to the light-quark condensate and comes out to be ∼(1/3)mN where mN is the nucleon mass, implying that the splitting vanishes in the chiral limit at the chiral restoration point--temperature Tc, density nc, or number of flavors Nfc. The result turns out to be surprisingly simple with the vector (ρ) meson playing the crucial role in quantum corrections, pointing to the relevance of the VM to QCD in the way chiral symmetry is manifested in hadronic matter. We also make predictions on the hadronic decay processes of the excited heavy- (charm) light mesons D
Spiral Galaxies as Chiral Objects?
Capozziello, S; Capozziello, Salvatore; Lattanzi, Alessandra
2005-01-01
Spiral galaxies show axial symmetry and an intrinsic 2D-chirality. Environmental effects can influence the chirality of originally isolated stellar systems and a progressive loss of chirality can be recognised in the Hubble sequence. We point out a preferential modality for genetic galaxies as in microscopic systems like aminoacids, sugars or neutrinos. This feature could be the remnant of a primordial symmetry breaking characterizing systems at all scales.
Quantum solitons of the nonlinear sigma-model with broken chiral symmetry
Kostyuk, A P; Chepilko, N M; Okazaki, T
1995-01-01
It is proved that the quantum-mechanical consideration of global breathing of a hedgehog-like field configuration leads to the dynamically stable soliton solutions in the nonlinear sigma-model without the Skyrme term. Such solutions exist only when chiral symmetry of the model is broken.
Minimally doubled chiral fermions with C, P and T symmetry on the staggered lattice
Haegeman, Jutho
2008-01-01
Recently, the interest in local lattice actions for chiral fermions has revived, with the proposition of new local actions in which only the minimal number of doublers appear. The trigger role of graphene having a minimally doubled, chirally invariant, Dirac-like excitation spectrum can not be neglected. The challenge is to construct an action which preserves enough symmetries to be useful in lattice gauge calculations. We present a new approach to obtain local lattice actions for fermions using a reinterpretation of the staggered lattice approach of Kogut and Susskind. This interpretation is based on the similarity with the staggered lattice approach in FDTD simulations of acoustics and electromagnetism. It allows us to construct a local action for chiral fermions which has all discrete symmetries and the minimal number of fermion flavors, but which is non-Hermitian in real space. However, we argue that this will not pose a threat to the usability of the theory.
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.
Radiative Effects and Electroweak Symmetry Breaking in a Supersymmetric Preon Model
Kim, Jongbae
We construct the low energy effective theory of composite quarks, leptons, and Higgs bosons for a supersymmetric preon model and study the effects of renormalization-group based radiative corrections. The study on the evolution of scalar masses for avoiding color and charge breakings leads us to conclude that Yukawa couplings are bounded from above. The implementation of electroweak symmetry breaking requires that only the purely dynamical symmetry breaking should be needed for the model, but the combined scheme of dynamical and radiative symmetry breaking as well as the purely radiative symmetry breaking scheme be disfavored. Our analysis of (mb)/(m_τ ) including radiative effects shows that, should a discrepancy be found between the observed and the theoretical value of (mb)/(m_τ ) after experimental determination of supersymmetric particle masses, it would imply that the complete quark-lepton universality in the supersymmetric preon model does not hold either for the Yukawa couplings, or for the condensates, or for both.
Chirally Invariant Avatar in a Model of Neutrinos with Light Cone Reflection Symmetry
Chodos, Alan
2016-01-01
In previous work we developed a model of neutrinos based on a new symmetry, Light Cone Reflection (LCR), that interchanges spacelike and timelike intervals. In this paper we start with the four-dimensional model, and construct a two-dimensional avatar that obeys the same equations of motion, and preserves both the light-cone reflection symmetry and the chiral symmetry of the original theory. The avatar also contains the interaction that rendered the four-dimensional model gauge invariant. In an addendum, we make some remarks about how to determine the scalar field that enters into the definition of the LCR-covariant derivative.
Blanco, Celia; Crusats, Joaquim; El-Hachemi, Zoubir; Moyano, Albert; Hochberg, David; 10.1039/C2CP43488A
2012-01-01
We analyze limited enantioselective (LES) autocatalysis in a temperature gradient and with internal flow/recycling of hot and cold material. Microreversibility forbids broken mirror symmetry for LES in the presence of a temperature gradient alone. This symmetry can be broken however when the auto-catalysis and limited enantioselective catalysis are each localized within the regions of low and high temperature, respectively. This scheme has been recently proposed as a plausible model for spontaneous emergence of chirality in abyssal hydrothermal vents. Regions in chemical parameter space are mapped out in which the racemic state is unstable and bifurcates to chiral solutions.
Spontaneous symmetry breaking in a split potential box
Shamriz, Elad; Dror, Nir; Malomed, Boris A.
2016-08-01
We report results of an analysis of the spontaneous symmetry breaking (SSB) in a basic (actually, simplest) model that is capable of producing the SSB phenomenology in a one-dimensional setting. It is based on the Gross-Pitaevskii-nonlinear Schrödinger equation with the cubic self-attractive term and a double-well potential built as an infinitely deep potential box split by a narrow (δ functional) barrier. The barrier's strength ɛ is the single free parameter of the scaled form of the model. It may be implemented in atomic Bose-Einstein condensates and nonlinear optics. The SSB bifurcation of the symmetric ground state (g.s.) is predicted analytically in two limit cases, viz., for deep or weak splitting of the potential box by the barrier (ɛ ≫1 or ɛ ≪1 , respectively). For the generic case, a variational approximation (VA) is elaborated. The analytical findings are presented along with systematic numerical results. The stability of stationary states is studied through the calculation of eigenvalues for small perturbations and by means of direct simulations. The g.s. always undergoes the SSB bifurcation of the supercritical type, as predicted by the VA at moderate values of ɛ , although the VA fails at small ɛ , due to inapplicability of the underlying ansatz in that case. However, the latter case is correctly treated by the approximation based on a soliton ansatz. On top of the g.s., the first and second excited states are studied too. The antisymmetric mode (the first excited state) is destabilized at a critical value of its norm. The second excited state undergoes SSB bifurcation, like the g.s., but, unlike it, the bifurcation produces an unstable asymmetric mode. All unstable modes tend to spontaneously reshape into the asymmetric g.s.
Chiral Symmetry Restoration for the large-$N$ pion gas
Cortés, Santiago; Morales, John
2016-01-01
We analyze chiral restoration within the $O(N+1)/O(N)$ Non-Linear Sigma Model for large $N$ as an effective theory for low-energy QCD at finite temperature $T$. The free energy is constructed diagramatically to $O(M^3)$ in the pion mass, which allows to derive the quark condensate and the scalar susceptibility in the chiral limit. At this order, we do not have to deal with renormalization, neither from divergences from mass tadpoles nor from those of higher order loop contributions. Our results for the critical behaviour are consistent with expectations from lattice analysis and with previous works where the susceptibility is saturated by the thermal $f_0(500)$ pole.
Liquid Crystal Phases of Molecular Bananas: Polarity and Chirality as Broken Symmetries
Clark, Noel
2006-03-01
The study of the interplay of chirality and polarity has been a particularly rich theme of soft matter science since Meyer's seminal discovery that tilted smectics of chiral molecules are macroscopically polar. This event, and the subsequent realization of polar domains and high-speed electro-optic switching in chiral smectics, engaged the liquid crystal community in a worldwide pursuit of novel smectics for applications, featured by the synthesis of more than 50,000 new liquid crystal compounds, and by a consequent broad diversification of the palette of liquid crystal phases and possibilities for supermolecular ordering. A current important activity in this scenario is the study of polar order in synthetically achiral molecules, for example, in molecular bananas, which, as their shape suggests, might be expected to organize in a polar way. Indeed they do, but beyond this, almost everything learned about them has been surprising, including their persistent tendency to exhibit chirality as a spontaneously broken symmetry. I will discuss some of these new phases and phenomena, including the discovery of fluid conglomerates (Pasteur's experiment in a fluid), triclinic fluid order, chiral twist grain boundary phases of achiral molecules, chirality flipping and field-induced deracemization, ferroelectric and antiferroelectric phases with supermolecular- scale polarization modulation, and chiral thermotropic sponge phases.
Energy Technology Data Exchange (ETDEWEB)
Wang, Yuan-Sheng, E-mail: joiningnow@126.com; Li, Zhen-Yu; Zhou, Zhu-Wen; Diao, Xin-Feng
2014-01-03
Highlights: •We investigate the symmetry breaking of a dipolar Bose–Einstein condensate. •The anisotropy of dipolar interaction affects the ground state structure. •Tuning the scattering length can realize the symmetry breaking phenomena. •Increasing the barrier height can realize the symmetry breaking phenomena.
A Generalized Yang-Mills Model and Dynamical Breaking of Gauge Symmetry
Institute of Scientific and Technical Information of China (English)
WANG Dian-Fu; SONG He-Shan
2005-01-01
A generalized Yang-Mills model, which contains, besides the vector part Vμ, 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.
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.
Dynamical breaking of shift-symmetry and super-Planckian inflation
Mazumdar, Anupam; Yamaguchi, Masahide
2014-01-01
Shift-symmetry is essential to protect the flatness of the potential, even beyond the super-Planckian vacuum expectation value (VEV) for an inflaton field. The breaking of the shift-symmetry can yield potentials suitable for super-Planckian excursion of the inflaton. The aim of this paper is to illustrate that it is indeed possible to break the shift-symmetry dynamically within 4 dimensional supergravity prior to a long phase of inflation. The potential obtained for the inflaton would be akin to a natural inflationary scenario with the breaking scale M larger than the 4 dimensional Planck mass.
Chiral Symmetry and N*(1440) -> N pi pi Decay
Kamano, H; Arima, M
2004-01-01
The N*(1440) -> N pi pi decay is studied by making use of the chiral reduction formula. This formula suggests a scalar-isoscalar pion-baryon contact interaction which is absent in the recent study of Hern{\\'a}ndez et al. The contact interaction is introduced into their model, and is found to be necessary for the simultaneous description of g_{RN pi pi} and the pi-pi and pi-N invariant mass distributions.
Pleiner, Harald; Brand, Helmut R
2014-02-01
We discuss the symmetry properties as well as the dynamic behavior of various non-polar nematic liquid crystal phases with tetrahedral order. We concentrate on systems that show biaxial nematic order coexisting with octupolar (tetrahedral) order. Non-polar examples are phases with D2 and S4 symmetries, which can be characterized as biaxial nematics lacking inversion symmetry. It is this combination that allows for new features in the statics and dynamics of these phases. The D2-symmetric phase is chiral, even for achiral molecules, and shows ambidextrous chirality in all three preferred directions. The achiral S4-symmetric phase allows for ambidextrous helicity, similar to the higher-symmetric D2d-symmetric phase. Such phases are candidates for nematic phases made from banana-shaped molecules.
Multicritical Symmetry Breaking and Naturalness of Slow Nambu-Goldstone Bosons
Griffin, Tom; Horava, Petr; Yan, Ziqi
2013-01-01
We investigate spontaneous global symmetry breaking in the absence of Lorentz invariance, and study technical Naturalness of Nambu-Goldstone (NG) modes whose dispersion relation exhibits a hierarchy of multicritical phenomena with Lifshitz scaling and dynamical exponents $z>1$. For example, we find NG modes with a technically natural quadratic dispersion relation which do not break time reversal symmetry and are associated with a single broken symmetry generator, not a pair. The mechanism is protected by an enhanced `polynomial shift' symmetry in the free-field limit.
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.
On the stability of multi-scale models of dynamical symmetry breaking from holography
Faedo, Anton F; Schofield, Daniel
2013-01-01
We consider two classes of backgrounds of Type IIB supergravity obtained by wrapping D5-branes on a two-cycle inside the conifold. The field theory dual exhibits confinement and, in addition, a region in which the dynamics is walking, at least in the weak sense that the running of the coupling is anomalously slow. We introduce quenched matter in the fundamental, modelled by probe D7-branes which wrap an internal three-dimensional manifold and lie at the equator of the transverse two-sphere. In the space spanned by the remaining internal angle and the radial coordinate the branes admit two embeddings. The first one is U-shaped: the branes merge at some finite value of the radius. The second one is disconnected and extends along the entire radial direction at fixed angular separation. We interpret these two configurations as corresponding to chiral-symmetry breaking and preserving phases, respectively. We present a simple diagnostic tool to examine the classical stability of the embedding, based on the concavit...
Symmetry breaking indication for supergravity inflation in light of the Planck 2015
Energy Technology Data Exchange (ETDEWEB)
Li, Tianjun [State Key Laboratory of Theoretical Physics, and Kavli Institute for Theoretical Physics China (KITPC), Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190 (China); School of Physical Electronics, University of Electronic Science and Technology of China, Chengdu 610054 (China); Li, Zhijin [George P. and Cynthia W. Mitchell Institute for Fundamental Physics and Astronomy, Texas A& M University, College Station, TX 77843 (United States); Nanopoulos, Dimitri V. [George P. and Cynthia W. Mitchell Institute for Fundamental Physics and Astronomy, Texas A& M University, College Station, TX 77843 (United States); Astroparticle Physics Group, Houston Advanced Research Center (HARC), Mitchell Campus, Woodlands, TX 77381 (United States); Academy of Athens, Division of Natural Sciences, 28 Panepistimiou Avenue, Athens 10679 (Greece)
2015-09-01
Supergravity (SUGRA) theories with exact global U(1) symmetry or shift symmetry in Kähler potential provide natural frameworks for inflation. However, quadratic inflation is disfavoured by the new results on primordial tensor fluctuations from the Planck Collaboration. To be consistent with the new Planck data, we point out that the explicit symmetry breaking is needed, and study these two SUGRA inflation in detail. For SUGRA inflation with global U(1) symmetry, the symmetry breaking term leads to a trigonometric modulation on inflaton potential. Coefficient of the U(1) symmetry breaking term is of order 10{sup −2}, which is sufficient large to improve the inflationary predictions while its higher order corrections are negligible. Such models predict sizeable tensor fluctuations and highly agree with the Planck results. In particular, the model with a linear U(1) symmetry breaking term predicts the tensor-to-scalar ratio around r∼0.01 and running spectral index α{sub s}∼−0.004, which comfortably fit with the Planck observations. For SUGRA inflation with breaking shift symmetry, the inflaton potential is modulated by an exponential factor. The modulated linear and quadratic models are consistent with the Planck observations. In both types of models the tensor-to-scalar ratio can be of order 10{sup −2}, which will be tested by the near future observations.
Symmetry breaking indication for supergravity inflation in light of the Planck 2015
International Nuclear Information System (INIS)
Supergravity (SUGRA) theories with exact global U(1) symmetry or shift symmetry in Kähler potential provide natural frameworks for inflation. However, quadratic inflation is disfavoured by the new results on primordial tensor fluctuations from the Planck Collaboration. To be consistent with the new Planck data, we point out that the explicit symmetry breaking is needed, and study these two SUGRA inflation in detail. For SUGRA inflation with global U(1) symmetry, the symmetry breaking term leads to a trigonometric modulation on inflaton potential. Coefficient of the U(1) symmetry breaking term is of order 10−2, which is sufficient large to improve the inflationary predictions while its higher order corrections are negligible. Such models predict sizeable tensor fluctuations and highly agree with the Planck results. In particular, the model with a linear U(1) symmetry breaking term predicts the tensor-to-scalar ratio around r∼0.01 and running spectral index αs∼−0.004, which comfortably fit with the Planck observations. For SUGRA inflation with breaking shift symmetry, the inflaton potential is modulated by an exponential factor. The modulated linear and quadratic models are consistent with the Planck observations. In both types of models the tensor-to-scalar ratio can be of order 10−2, which will be tested by the near future observations
The chiral transition and U(1)_A symmetry restoration from lattice QCD using Domain Wall Fermions
Bazavov, A; Buchoff, Michael I; Cheng, Michael; Christ, N H; Ding, H -T; Gupta, Rajan; Hegde, Prasad; Jung, Chulwoo; Karsch, F; Lin, Zhongjie; Mawhinney, R D; Mukherjee, Swagato; Petreczky, P; Soltz, R A; Vranas, P M; Yin, Hantao
2012-01-01
We present results on both the restoration of the spontaneously broken chiral symmetry and the effective restoration of the anomalously broken U(1)_A symmetry in finite temperature QCD at zero chemical potential using lattice QCD. We employ domain wall fermions on lattices with fixed temporal extent N_\\tau = 8 and spatial extent N_\\sigma = 16 in a temperature range of T = 139 - 195 MeV, corresponding to lattice spacings of a \\approx 0.12 - 0.18 fm. In these calculations, we include two degenerate light quarks and a strange quark at fixed pion mass m_\\pi = 200 MeV. The strange quark mass is set near its physical value. We also present results from a second set of finite temperature gauge configurations at the same volume and temporal extent with slightly heavier pion mass. To study chiral symmetry restoration, we calculate the chiral condensate, the disconnected chiral susceptibility, and susceptibilities in several meson channels of different quantum numbers. To study U(1)_A restoration, we calculate spatial ...
Wigner–Souriau translations and Lorentz symmetry of chiral fermions
Directory of Open Access Journals (Sweden)
C. Duval
2015-03-01
Full Text Available Chiral fermions can be embedded into Souriau's massless spinning particle model by “enslaving” the spin, viewed as a gauge constraint. The latter is not invariant under Lorentz boosts; spin enslavement can be restored, however, by a Wigner–Souriau (WS translation, analogous to a compensating gauge transformation. The combined transformation is precisely the recently uncovered twisted boost, which we now extend to finite transformations. WS-translations are identified with the stability group of a motion acting on the right on the Poincaré group, whereas the natural Poincaré action corresponds to action on the left.
Symmetry Breaking of Counter-Propagating Light in a Nonlinear Resonator
Del Bino, Leonardo; Stebbings, Sarah L; Del'Haye, Pascal
2016-01-01
Light is generally expected to travel through isotropic media independent of its direction. This makes it challenging to develop non-reciprocal optical elements like optical diodes or circulators, which currently rely on magneto-optical effects and birefringent materials. Here we present measurements of non-reciprocal transmission and spontaneous symmetry breaking between counter-propagating light in dielectric microresonators. The symmetry breaking corresponds to a resonance frequency splitting that allows only one of two counter-propagating (but otherwise identical) light waves to circulate in the resonator. Equivalently, the symmetry breaking can be seen as the collapse of standing waves and transition to travelling waves within the resonator. We present theoretical calculations to show that the symmetry breaking is induced by Kerr-nonlinearity-mediated interaction between the counter-propagating light. This effect is expected to take place in any dielectric ring-resonator and might constitute one of the m...
Quantum chaos and breaking of all anti-unitary symmetries in Rydberg excitons.
Aßmann, Marc; Thewes, Johannes; Fröhlich, Dietmar; Bayer, Manfred
2016-07-01
Symmetries are the underlying principles of fundamental interactions in nature. Chaos in a quantum system may emerge from breaking these symmetries. Compared to vacuum, crystals are attractive for studying quantum chaos, as they not only break spatial isotropy, but also lead to novel quasiparticles with modified interactions. Here we study yellow Rydberg excitons in cuprous oxide which couple strongly to the vacuum light field and interact significantly with crystal phonons, leading to inversion symmetry breaking. In a magnetic field, time-reversal symmetry is also broken and the exciton states show a complex splitting pattern, resulting in quadratic level repulsion for small splittings. In contrast to atomic chaotic systems in a magnetic field, which show only a linear level repulsion, this is a signature of a system where all anti-unitary symmetries are broken simultaneously. This behaviour can otherwise be found only for the electro-weak interaction or engineered billiards. PMID:27064527
Konishi, Eiji
2016-01-01
We propose a mechanism for time reparametrization symmetry breaking in canonical gravity. We consider a model of spinor gravity, based on Sen's reformulation of canonical gravity as a spin system, with one additional long-range self-interacting massive spinor particle that is coupled to spinor gravity. The symmetry breaking is identified with the origin of the quantum mechanical non-unitary evolution. A part of our approach to deriving non-unitary time-dependent processes of wave functions fo...
Energy Technology Data Exchange (ETDEWEB)
Lim, S C [Faculty of Engineering, Multimedia University, Jalan Multimedia, Cyberjaya, 63100, Selangor Darul Ehsan (Malaysia); Teo, L P [Faculty of Information Technology, Multimedia University, Jalan Multimedia, Cyberjaya, 63100, Selangor Darul Ehsan (Malaysia)], E-mail: sclim@mmu.edu.my, E-mail: lpteo@mmu.edu.my
2008-04-11
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.
Coherent States and Spontaneous Symmetry Breaking in Light Front Scalar Field Theory
Energy Technology Data Exchange (ETDEWEB)
Vary, J.P.; /Iowa State U. /LLNL, Livermore /SLAC; Chakrabarti, D.; /Florida U.; Harindranath, A.; /Saha Inst.; Lloyd, R.; /Arkansas State U.; Martinovic, L.; /Bratislava,; Spence, J.R.; /Iowa State U.
2005-12-14
Recently developed nuclear many-body techniques provide novel results when applied to constituent quark models and to light-front scalar field theory. We show how spontaneous symmetry breaking arises and is consistent with a coherent state ansatz in a variational treatment. The kink and the kink-antikink topological features are identified and the onset of symmetry restoration is demonstrated.
$B_K$ from quenched QCD with exact chiral symmetry
Garron, N; Hölbling, C; Lellouch, L P; Rebbi, C; Garron, Nicolas; Giusti, Leonardo; Hoelbling, Christian; Lellouch, Laurent; Rebbi, Claudio
2004-01-01
We present a calculation of the standard model Delta S=2 matrix element relevant to indirect CP violation in K->pipi decays which uses Neuberger's chiral formulation of lattice fermions. The computation is performed in the quenched approximation on a 16^3x32 lattice that has a lattice spacing asim 0.1 fm. The resulting bare matrix element is renormalized non-perturbatively. Our main result is B_K^{RGI}=0.87(8)^{+2+14}_{-1-14}, where the first error is statistical, the second is systematic and the third is an estimate of the uncertainty associated with the quenched approximation and with the fact that our kaons are composed of degenerate s and d quarks with masses sim m_s/2.
Field sources in a Lorentz-symmetry breaking scenario with a single background vector
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, Av. BPS 1303, Pinheirinho, Caixa Postal 50, Itajuba, MG (Brazil); Helayel-Neto, J.A. [Centro Brasileiro de Pesquisas Fisicas, Rio de Janeiro, RJ (Brazil)
2014-06-15
This paper is devoted to an investigation of the interactions between stationary sources of the electromagnetic field, in a model which exhibits explicit Lorentz-symmetry breaking due to the presence of a single background vector. We focus on physical phenomena that emerge from this kind of breaking and which have no counterpart in Maxwell electrodynamics. (orig.)
\\pi N transition distribution amplitudes: their symmetries and constraints from chiral dynamics
Pire, Bernard; Szymanowski, Lech
2011-01-01
Baryon to meson Transition Distribution Amplitudes (TDAs) extend the concept of generalized parton distributions. Baryon to meson TDAs appear as building blocks in the colinear factorized description of amplitudes for a class of hard exclusive reactions, prominent examples of which being hard exclusive meson electroproduction off a nucleon in the backward region and baryon-antibaryon annihilation into a meson and a lepton pair. We study general properties of these objects following from the underlying symmetries of QCD. In particular, the Lorentz symmetry results in the polynomiality property of the Mellin moments in longitudinal momentum fractions. We present a detailed account of isotopic and permutation symmetry properties of nucleon to pion (\\pi N) TDAs. This restricts the number of independent leading twist \\pi N TDAs to eight functions providing description of all isotopic channels. Using chiral symmetry and the crossing relation between \\pi N TDAs and \\pi N generalized distribution amplitudes we establ...
Burgers-like equation for spontaneous breakdown of the chiral symmetry in QCD
Blaizot, Jean-Paul; Warchoł, Piotr
2013-01-01
We link the spontaneous breakdown of chiral symmetry in Euclidean QCD to the collision of spectral shock waves in the vicinity of zero eigenvalue of Dirac operator. The mechanism, originating from complex Burger's-like equation for viscid, pressureless, one-dimensional flow of eigenvalues, is similar to recently observed weak-strong coupling phase transition in large $N_c$ Yang-Mills theory. The spectral viscosity is proportional to the inverse of the size of the random matrix that replaces the Dirac operator in the universal (ergodic) regime. We obtain the exact scaling function and critical exponents of the chiral phase transition for the averaged characteristic polynomial for $N_c \\ge3$ QCD. We reinterpret our results in terms of known properties of chiral random matrix models and lattice data.
Burgers-like equation for spontaneous breakdown of the chiral symmetry in QCD
International Nuclear Information System (INIS)
We link the spontaneous breakdown of chiral symmetry in Euclidean QCD to the collision of spectral shock waves in the vicinity of zero eigenvalue of the Dirac operator. The mechanism, originating from complex Burger's-like equation for viscid, pressureless, one-dimensional flows of eigenvalues, is similar to the recently observed weak-strong coupling phase transition in large Nc Yang–Mills theory. The spectral viscosity is proportional to the inverse size of the random matrix that replaces the Dirac operator in the universal (ergodic) regime. We obtain the exact scaling function and critical exponents of the chiral phase transition for the averaged characteristic polynomial for Nc⩾3 QCD. We reinterpret our results in terms of known properties of chiral random matrix models and lattice data
SU(3)-breaking corrections to the baryon-octet magnetic moments in chiral perturbation theory
Camalich, J Martin; Geng, L S; Vacas, M J Vicente
2009-01-01
We report a calculation of the baryon magnetic moments using covariant chiral perturbation theory within the extended-on-mass-shell renormalization scheme including intermediate octet and decuplet contributions. By fitting the two available low-energy constants, we improve the Coleman-Glashow description of the data when we include the leading SU(3) breaking effects coming from the lowest-order loops. We compare with previous attempts at the same order using heavy-baryon and covariant infrared chiral perturbation theory, and discuss the source of the differences.
Chiral symmetry restoration in σ-meson production in hadronic processes
Directory of Open Access Journals (Sweden)
Kukulin V.I.
2014-06-01
Full Text Available Some puzzles about the nature and properties of the lightest scalar meson, σ or f0(500, are analyzed in the paper. We studied the σ-meson production both in N + N, N + d, etc., collisions and also in J/ψ, ψ(2S, ψ(3S, Υ(2S, etc., two-pion decays. The fundamental distinctions between the basic σ-meson parameters found in various hadronic processes can be explained most naturally by the chiral symmetry restoration in intermediate excited hadronic resonances. In the present paper we discuss some important aspects of chiral symmetry restoration in hadronic processes with interrelation to the basic features of QCD.
D7-anti-D7 bilayer: holographic dynamical symmetry breaking
Grignani, Gianluca; Kim, Namshik; Semenoff, Gordon W.
2012-01-01
We consider a holographic model of dynamical symmetry breaking in 2+1-dimenisons, where a parallel D7-anti-D7 brane pair fuse into a single object, corresponding to the U(1)XU(1)->U(1) symmetry breaking pattern. We show that the current-current correlation functions can be computed analytically and exhibit the low momentum structure that is expected when global symmetries are spontaneously broken. We also find that these correlation functions have poles attributable to infinite towers of vect...
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
International Nuclear Information System (INIS)
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.)
The Effective Kahler Potential, Metastable Vacua and R-Symmetry Breaking in O'Raifeartaigh Models
Benjamin, Shermane; Kain, Ben
2010-01-01
Much has been learned about metastable vacua and R-symmetry breaking in O'Raifeartaigh models. Such work has largely been done from the perspective of the superpotential and by including Coleman-Weinberg corrections to the scalar potential. Instead, we consider these ideas from the perspective of the one loop effective Kahler potential. We translate known ideas to this framework and construct convenient formulas for computing individual terms in the expanded effective Kahler potential. We do so for arbitrary R-charge assignments and allow for small R-symmetry violating terms so that both spontaneous and explicit R-symmetry breaking is allowed in our analysis.
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.)
Kac-Moody and Borcherds Symmetries of Six-Dimensional Chiral Supergravity
Henneaux, Marc
2015-01-01
We investigate the conjectured infinite-dimensional hidden symmetries of six-dimensional chiral supergravity coupled to two vector multiplets and two tensor multiplets, which is known to possess the $F_{4,4}$ symmetry upon dimensional reduction to three spacetime dimensions. Two things are done. (i) First, we analyze the geodesic equations on the coset space $F_{4,4}^{++}/K(F_{4,4}^{++})$ using the level decomposition associated with the subalgebra $\\mathfrak{gl}(5)\\oplus \\mathfrak{sl}(2)$ of $F_{4,4}^{++}$ and show their equivalence with the bosonic equations of motion of six-dimensional chiral supergravity up to the level where the dual graviton appears. In particular, the self-duality condition on the chiral $2$-form is automatically implemented in the sense that no dual potential appears for that $2$-form, in contradistinction with what occurs for the non chiral $p$-forms. (ii) Second, we describe the $p$-form hierarchy of the model in terms of its $V$-duality Borcherds superalgebra, of which we compute t...
Burgers-like equation for spontaneous breakdown of the chiral symmetry in QCD
Blaizot, Jean-Paul; Nowak, Maciej A.; Warchoł, Piotr
2013-01-01
We link the spontaneous breakdown of chiral symmetry in Euclidean QCD to the collision of spectral shock waves in the vicinity of zero eigenvalue of Dirac operator. The mechanism, originating from complex Burger's-like equation for viscid, pressureless, one-dimensional flow of eigenvalues, is similar to recently observed weak-strong coupling phase transition in large $N_c$ Yang-Mills theory. The spectral viscosity is proportional to the inverse of the size of the random matrix that replaces t...
Suppression and restoration of disorder-induced light localization mediated by PT-symmetry breaking
Kartashov, Yaroslav V; Konotop, Vladimir V; Vysloukh, Victor A; Huang, Guoxiang; Torner, Lluis
2016-01-01
We uncover that the breaking point of the PT-symmetry in optical waveguide arrays has a dramatic impact on light localization induced by the off-diagonal disorder. Specifically, when the gain/loss control parameter approaches a critical value at which PT-symmetry breaking occurs, a fast growth of the coupling between neighboring waveguides causes diffraction to dominate to an extent that light localization is strongly suppressed and statistically averaged width of the output pattern substantially increases. Beyond the symmetry-breaking point localization is gradually restored, although in this regime the power of localized modes grows upon propagation. The strength of localization monotonically increases with disorder at both, broken and unbroken PT-symmetry.
On The Complexity and Completeness of Static Constraints for Breaking Row and Column Symmetry
Katsirelos, George; Walsh, Toby
2010-01-01
We consider a common type of symmetry where we have a matrix of decision variables with interchangeable rows and columns. A simple and efficient method to deal with such row and column symmetry is to post symmetry breaking constraints like DOUBLELEX and SNAKELEX. We provide a number of positive and negative results on posting such symmetry breaking constraints. On the positive side, we prove that we can compute in polynomial time a unique representative of an equivalence class in a matrix model with row and column symmetry if the number of rows (or of columns) is bounded and in a number of other special cases. On the negative side, we show that whilst DOUBLELEX and SNAKELEX are often effective in practice, they can leave a large number of symmetric solutions in the worst case. In addition, we prove that propagating DOUBLELEX completely is NP-hard. Finally we consider how to break row, column and value symmetry, correcting a result in the literature about the safeness of combining different symmetry breaking c...
Infra-red fixed point structure characterising SUSY SU(5) symmetry breaking
Allanach, Benjamin C; Philipsen, O
1996-01-01
We analyze the one-loop renormalisation group equations for the parameters of the Higgs potential of a supersymmetric SU(5) model with first step of symmetry breaking involving an adjoint Higgs. In particular, we investigate the running of the parameters that decide the first step of symmetry breaking in an attempt to establish which symmetry-breaking scenarios would be most likely if the model is the effective low-energy description of some more fundamental theory. An infra-red fixed point is identified analytically. It is located at the boundary between the region of Higgs parameter space corresponding to unbroken SU(5) and the region corresponding to the breaking of SU(5) to the Standard Model, and we elaborate on its implications. We also observe that certain forms of the Higgs potential discussed at tree level in the literature are not renormalisation group invariant.
Supersymmetry and R-symmetry Breaking in Meta-stable Vacua at Finite Temperature and Density
Arai, Masato; Sasaki, Shin
2014-01-01
We study a meta-stable supersymmetry-breaking vacuum in a generalized O'Raifeartaigh model at finite temperature and chemical potentials. Fields in the generalized O'Raifeartaigh model possess different R-charges to realize R-symmetry breaking. Accordingly, at finite density and temperature, the chemical potentials have to be introduced in a non-uniform way. Based on the formulation elaborated in our previous work we study the one-loop thermal effective potential including the chemical potentials in the generalized O'Raifeartaigh model. We perform the numerical analysis and find that the R-symmetry breaking vacua, which exist at zero temperature and zero chemical potential, are destabilized for some parameter regions. In addition, we find that there are parameter regions where new R-symmetry breaking vacua are realized even at high temperature by the finite density effects.
Light meson electromagnetic form factors from three-flavor lattice QCD with exact chiral symmetry
Aoki, S; Feng, X; Hashimoto, S; Kaneko, T; Noaki, J; Onogi, T
2015-01-01
We study the chiral behavior of the electromagnetic (EM) form factors of pion and kaon in three-flavor lattice QCD. In order to make a direct comparison of the lattice data with chiral perturbation theory (ChPT), we employ the overlap quark action that has exact chiral symmetry. Gauge ensembles are generated at a lattice spacing of 0.11 fm with four pion masses ranging between M_pi \\simeq 290 MeV and 540 MeV and with a strange quark mass m_s close to its physical value. We utilize the all-to-all quark propagator technique to calculate the EM form factors with high precision. Their dependence on m_s and on the momentum transfer is studied by using the reweighting technique and the twisted boundary conditions for the quark fields, respectively. A detailed comparison with SU(2) and SU(3) ChPT reveals that the next-to-next-to-leading order terms in the chiral expansion are important to describe the chiral behavior of the form factors in the pion mass range studied in this work. We estimate the relevant low-energy...
Light meson electromagnetic form factors from three-flavor lattice QCD with exact chiral symmetry
Aoki, S.; Cossu, G.; Feng, X.; Hashimoto, S.; Kaneko, T.; Noaki, J.; Onogi, T.
2016-02-01
We study the chiral behavior of the electromagnetic (EM) form factors of pions and kaons in three-flavor lattice QCD. In order to make a direct comparison of the lattice data with chiral perturbation theory (ChPT), we employ the overlap quark action that has exact chiral symmetry. Gauge ensembles are generated at a lattice spacing of 0.11 fm with four pion masses ranging between Mπ≃290 MeV and 540 MeV and with a strange quark mass ms close to its physical value. We utilize the all-to-all quark propagator technique to calculate the EM form factors with high precision. Their dependence on ms and on the momentum transfer is studied by using the reweighting technique and the twisted boundary conditions for the quark fields, respectively. A detailed comparison with SU(2) and SU(3) ChPT reveals that the next-to-next-to-leading order terms in the chiral expansion are important to describe the chiral behavior of the form factors in the pion mass range studied in this work. We estimate the relevant low-energy constants and the charge radii, and find reasonable agreement with phenomenological and experimental results.
Emergent p-Wave Kondo Coupling in Multi-Orbital Bands with Mirror Symmetry Breaking
Rhim, Jun Won; Han, Jung Hoon
2013-10-01
Kondo effect in the periodic Anderson model is examined for situations where the conduction bands are of multi-orbital character and subject to mirror-symmetry-breaking electric field. Taking p-orbital-based model for analysis, we find that a new hybridization channel opens up between p-orbital electrons and the local moments, leading to Kondo-coupled phases with nematic, or two-fold symmetry, although the microscopic Hamiltonian has the full square symmetry. The reduced symmetry in the band structure should be readily observable in spectroscopic or transport measurements for heavy fermion system in a multilayer environment such as successfully grown recently.
Topological Insulators and Nematic Phases from Spontaneous Symmetry Breaking in
Energy Technology Data Exchange (ETDEWEB)
Sun, K.
2010-05-26
We investigate the stability of a quadratic band-crossing point (QBCP) in 2D fermionic systems. At the non-interacting level, we show that a QBCP exists and is topologically stable for a Berry flux {-+}2{pi}, if the point symmetry group has either fourfold or sixfold rotational symmetries. This putative topologically stable free-fermion QBCP is marginally unstable to arbitrarily weak shortrange repulsive interactions. We consider both spinless and spin-1/2 fermions. Four possible ordered states result: a quantum anomalous Hall phase, a quantum spin Hall phase, a nematic phase, and a nematic-spin-nematic phase.
Kondratyuk, S; Myhrer, F; Scholten, O
2004-01-01
The Adler-Weisberger and Goldberger-Miyazawa-Oehme sum rules are calculated within a relativistic, unitary and crossing symmetric dynamical model for pion-nucleon scattering using two different methods: 1) by evaluating of the scattering amplitude at the corresponding low-energy kinematics and 2) by evaluating the sum-rule integrals with the calculated total cross section. The discrepancy between the results of the two methods provides a measure of the breaking of analyticity and chiral symmetry in the model. The contribution of the $\\Delta$ resonance, including its dressing with meson loops, is discussed in some detail and found to be small.
Superfluidity and Space-Time Translation Symmetry Breaking
Wilczek, Frank
2013-01-01
I present a simple model that exhibits a temporal analogue of superconducting crystalline (LOFF) ordering. I sketch designs for minimally dissipative AC circuits, all based on time translation symmetry ($\\tau$) invariant dynamics, exploiting weak links (Josephson effects). These systems violate $\\tau$ spontaneously. I also discuss effective theories of that phenomenon, and space-time generalizations.
Li, Jiaming; Liu, Ji; de Melo, Leonardo; Joglekar, Yogesh N; Luo, Le
2016-01-01
Open physical systems with balanced loss and gain exhibit a transition, absent in their solitary counterparts, which engenders modes that exponentially decay or grow with time and thus spontaneously breaks the parity-time PT symmetry. This PT-symmetry breaking is induced by modulating the strength or the temporal profile of the loss and gain, but also occurs in a pure dissipative system without gain. It has been observed that, in classical systems with mechanical, electrical, and electromagnetic setups with static loss and gain, the PT-symmetry breaking transition leads to extraordinary behavior and functionalities. However, its observation in a quantum system is yet to be realized. Here we report on the first quantum simulation of PT-symmetry breaking transitions using ultracold Li-6 atoms. We simulate static and Floquet dissipative Hamiltonians by generating state-dependent atom loss in a noninteracting Fermi gas, and observe the PT-symmetry breaking transitions by tracking the atom number for each state. W...
Chiral phases of fundamental and adjoint quarks
Energy Technology Data Exchange (ETDEWEB)
Natale, A. A. [Centro de Ciências Naturais e Humanas, Universidade Federal do ABC 09210-170, Santo André, SP (Brazil); Instituto de Física Teórica - UNESP Rua Dr. Bento T. Ferraz, 271, Bl.II - 01140-070, São Paulo, SP (Brazil)
2016-01-22
We consider a QCD chiral symmetry breaking model where the gap equation contains an effective confining propagator and a dressed gluon propagator with a dynamically generated mass. This model is able to explain the ratios between the chiral transition and deconfinement temperatures in the case of fundamental and adjoint quarks. It also predicts the recovery of the chiral symmetry for a large number of quarks (n{sub f} ≈ 11 – 13) in agreement with lattice data.
In Search of a Pristine Signal for (Scale-)Chiral Symmetry in Nuclei
Rho, Mannque
2016-01-01
I describe the long-standing search for a "smoking-gun" signal for the manifestation of (scale-)chiral symmetry in nuclear interactions. It is prompted by Gerry Brown's last unpublished note, reproduced verbatim below, on the preeminent role of pions and vector ($\\rho$,$\\omega$) mesons in providing a simple and elegant description of strongly correlated nuclear interactions. In this note written in tribute to Gerry Brown, I first describe a case of an unambiguous signal in axial-charge transitions in nuclei and then combine his ideas with the more recent development on the role of hidden symmetries in nuclear physics. What transpires is the surprising conclusion that the Landau-Migdal fixed point interaction $G_0^\\prime$, the nuclear tensor forces and Brown-Rho scaling, all encoded in scale-invariant hidden local symmetry, as Gerry put, "run the show and make all forces equal."
Quantum structure of T-dualized models with symmetry breaking
Casteill, P Y
2000-01-01
We study the principal sigma-models defined on any group manifold GL x GR/GD with breaking of GR, and their T-dual transforms. For abritary breaking we can express the torsion and Ricci tensor of the dual model in terms of the frame geometry of the initial principal model. Using these results, we give necessary and sufficient conditions for the dual model to be torsionless and prove that the one-loop renormalizability of a given principal model is inherited by its dual partner, who shares the same beta-functions. These results are shown to hold also if the principal model is endowed with torsion. As an application we compute the beta-functions for the full Bianchi family and show that for some choices of the breaking parameters the dilaton anomaly is absent: for these choices the dual torsion vanishes. For the dualized Bianchi V model (which is torsionless for any breaking), we take advantage of its simpler structure, to study its two-loops renormalizability.
Spontaneous Breaking of Lorentz Symmetry with an antisymmetric tensor
Hernaski, Carlos A
2016-01-01
Spontaneous violation of Lorentz symmetry by the vacuum condensation of an antisymmetric $2$-tensor is considered. The coset construction for nonlinear realization of spacetime symmetries is employed to build the most general low-energy effective action for the Goldstone modes interacting with photons. We analyze the model within the context of the Standard-Model Extension and noncommutative QED. Experimental bounds for some parameters of the model are discussed, and we readdress the subtle issues of stability and causality in Lorentz non-invariant scenarios. Besides the two photon polarizations, just one Goldstone mode must be dynamical to set a sensible low-energy effective model, and the enhancement of the stability by accounting interaction terms points to a protection against observational Lorentz violation.
Breaking of forward-backward symmetry in driven systems
DEFF Research Database (Denmark)
Szolnoki, Attila; Szabó, György
1993-01-01
The dynamical pair approximation was modified to study the stationary states in a two-dimensional repulsive-lattice-gas model driven far from equilibrium by the application of an external field. This approximation distinguishes between the forward, backward, and transverse directions with respect...... to the electric field. In the present driven system, the forward-backward symmetry is broken at the level of the pair approximation. The difference between the forward and backward directions is confirmed by Monte Carlo simulations....
Maximally Generalized Yang-Mills Model and Dynamical Breaking of Gauge Symmetry
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
A maximally generalized Yang-Mills model, which contains, besides the vector part Vμ, also an axial-vector part Aμ, a scalar part S, a pseudoscalar part P, and a tensor part Tμv, 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.
PT-symmetry breaking with divergent potentials: lattice and continuum cases
Joglekar, Yogesh N; Saxena, Avadh
2014-01-01
We investigate the parity- and time-reversal ($\\mathcal{PT}$)-symmetry breaking in lattice models in the presence of long-ranged, non-hermitian, $\\mathcal{PT}$-symmetric potentials that remain finite or become divergent in the continuum limit. By scaling analysis of the fragile $\\mathcal{PT}$ threshold for an open finite lattice, we show that continuum loss-gain potentials $V_\\alpha(x)\\propto i |x|^\\alpha \\mathrm{sign}(x)$ have a positive $\\mathcal{PT}$-breaking threshold for $\\alpha>-2$, and a zero threshold for $\\alpha\\leq -2$. When $\\alpha<0$ localized states with complex (conjugate) energies in the continuum energy-band occur at higher loss-gain strengths. We investigate the signatures of $\\mathcal{PT}$-symmetry breaking in coupled waveguides, and show that the emergence of localized states dramatically shortens the relevant time-scale in the $\\mathcal{PT}$-symmetry broken region.
Chiral gap effect in curved space
Flachi, Antonino
2014-01-01
We discuss a new type of QCD phenomenon induced in curved space. In the QCD vacuum a mass gap of Dirac fermions is attributed to the spontaneous breaking of chiral symmetry. If the curvature is positive large, the chiral condensate melts but a chiral invariant mass gap can still remain, which we name the chiral gap effect in curved space. This leads to decoupling of quark deconfinement which implies a view of black holes surrounded by a first-order QCD phase transition.
Symmetry breaking in MAST plasma turbulence due to toroidal flow shear
Fox, M F J; Field, A R; Ghim, Y -c; Parra, F I; Schekochihin, A A
2016-01-01
The flow shear associated with the differential toroidal rotation of tokamak plasmas breaks an underlying symmetry of the turbulent fluctuations imposed by the up-down symmetry of the magnetic equilibrium. Using experimental Beam-Emission-Spectroscopy (BES) measurements and gyrokinetic simulations, this symmetry breaking in ion-scale turbulence in MAST is shown to manifest itself as a tilt of the spatial correlation function and a finite skew in the distribution of the fluctuating density field. The tilt is a statistical expression of the "shearing" of the turbulent structures by the mean flow. The skewness of the distribution is related to the emergence of long-lived density structures in sheared, near-marginal plasma turbulence. The extent to which these effects are pronounced is argued (with the aid of the simulations) to depend on the distance from the nonlinear stability threshold. Away from the threshold, the symmetry is effectively restored.
Unified model of fermion masses with Wilson line flavor symmetry breaking
Seidl, Gerhart
2008-01-01
We present a supersymmetric SU(5) GUT model with a discrete non-Abelian flavor symmetry that is broken by Wilson lines. The model is formulated in 4+3 dimensions compactified on a manifold S^3/Z_n. Symmetry breaking by Wilson lines is topological and allows to realize the necessary flavor symmetry breaking without a vacuum alignment mechanism. The model predicts the hierarchical pattern of charged fermion masses and quark mixing angles. Small normal hierarchical neutrino masses are generated by the type-I seesaw mechanism. The non-Abelian flavor symmetry predicts to leading order exact maximal atmospheric mixing while the solar angle emerges from quark-lepton complementarity. The resulting leptonic mixing matrix is in excellent agreement with current data and could be tested in future neutrino oscillation experiments.
Uniform trace formulae for SU(2) and SO(3) symmetry breaking
Brack, M; Tanaka, K
1999-01-01
We develop uniform approximations for the trace formula for non-integrable systems in which SU(2) symmetry is broken by a non-linear term of the Hamiltonian. As specific examples, we investigate Hénon-Heiles type potentials. Our formalism can also be applied to the breaking of SO(3) symmetry in a three-dimensional cavity with axially-symmetric quadrupole deformation.
Electroweak symmetry breaking and beyond the Standard Model physics – A review
Indian Academy of Sciences (India)
Gautam Bhattacharyya
2009-01-01
In this talk, I shall first discuss the Standard Model Higgs mechanism and then highlight some of its deficiencies making a case for the need to go beyond the Standard Model (BSM). The BSM tour will be guided by symmetry arguments. I shall pick up four specific BSM scenarios, namely, supersymmetry, little Higgs, gauge-Higgs unification, and the Higgsless approach. The discussion will be confined mainly on their electroweak symmetry breaking aspects.
Symmetry breaking and restoration for interacting scalar and gauge fields in Lifshitz type theories
Farakos, K.; Metaxas, D.
2012-05-01
We consider the one-loop effective potential at zero and finite temperature in field theories with anisotropic space-time scaling, with critical exponent z = 2, including both scalar and gauge fields. Depending on the relative strength of the coupling constants for the gauge and scalar interactions, we find that there is a symmetry breaking term induced at one loop at zero temperature and we find symmetry restoration through a first-order phase transition at high temperature.
Symmetry breaking and restoration for interacting scalar and gauge fields in Lifshitz type theories
Farakos, K
2011-01-01
We consider the one-loop effective potential at zero and finite temperature in field theories with anisotropic space-time scaling, with critical exponent $z=2$, including both scalar and gauge fields. Depending on the relative strength of the coupling constants for the gauge and scalar interactions, we find that there is a symmetry breaking term induced at one-loop at zero temperature and we find symmetry restoration through a first-order phase transition at high temperature.
Symmetry breaking and restoration for interacting scalar and gauge fields in Lifshitz type theories
Energy Technology Data Exchange (ETDEWEB)
Farakos, K., E-mail: kfarakos@central.ntua.gr [Department of Physics, National Technical University of Athens, Zografou Campus, 15780 Athens (Greece); Metaxas, D., E-mail: metaxas@central.ntua.gr [Department of Physics, National Technical University of Athens, Zografou Campus, 15780 Athens (Greece)
2012-05-01
We consider the one-loop effective potential at zero and finite temperature in field theories with anisotropic space-time scaling, with critical exponent z=2, including both scalar and gauge fields. Depending on the relative strength of the coupling constants for the gauge and scalar interactions, we find that there is a symmetry breaking term induced at one loop at zero temperature and we find symmetry restoration through a first-order phase transition at high temperature.
Alves, S. G.; Braga, F. L.; Martins, M. L.
2007-10-01
Electrochemical ferromagnetic deposits grown under a planar magnetic field exhibit a striking morphological symmetry breaking. The present paper demonstrate through two-dimensional off-lattice simulations of an extended diffusion-limited aggregation (DLA) model that the competition between magnetic dipolar interactions and electric forces can impose locally the experimentally observed angle selection in a two-dimensional extended DLA model. The long-range correlations in the orientation of dipoles interacting with the applied and dipolar fields preserve this order over a macroscopic scale. Hence, the magnetic dipolar interactions alone cannot impose the field-induced symmetry breaking observed in ferromagnetic electrochemical deposition (ECD).
Electroweak symmetry breaking and new physics at the TeV scale
Haber, Howard E; Siegrist, James L; Barklow, Timothy L
1997-01-01
This is an expanded version of the report by the Electroweak Symmetry Breaking and Beyond the Standard Model Working Group which was contributed to Particle Physics - Perspectives and Opportunities, a report of the Division of Particles and Fields Committee for Long Term Planning. One of the Working Group&s primary goals was to study the phenomenology of electroweak symmetry breaking and attempt to quantify the "physics reach" of present and future colliders. Their investigations encompassed the Standard Model - with one doublet of Higgs scalars - and approaches to physics beyond the Standard
Semiclassical treatment of symmetry breaking and bifurcations in a non-integrable potential
Koliesnik, M. V.; Krivenko-Emetov, Ya D.; Magner, A. G.; Arita, K.; Brack, M.
2015-11-01
We have derived an analytical trace formula for the level density of the Hénon-Heiles potential using the improved stationary phase method, based on extensions of Gutzwiller's semiclassical path integral approach. This trace formula has the correct limit to the standard Gutzwiller trace formula for the isolated periodic orbits far from all (critical) symmetry-breaking points. It continuously joins all critical points at which an enhancement of the semiclassical amplitudes occurs. We found a good agreement between the semiclassical and the quantum oscillating level densities for the gross shell structures and for the energy shell corrections, solving the symmetry breaking problem at small energies.
Mass Formulas Derived by Symmetry Breaking and Prediction of Masses on Heavy Flavor Hadrons
Chang, Yi-Fang
2008-01-01
The base is the Lagrangian of symmetry and its dynamical breaking or Higgs breaking. When the soliton-like solutions of the scalar field equations are substituted into the spinor field equations, in the approximation of non-relativity we derive the Morse-type potential, whose energy spectrum is the GMO mass formula and its modified accurate mass formula. According to the symmetry of s-c quarks, the heavy flavor hadrons which made of u,d and c quarks may be classified by SU(3) octet and decuplet. Then some simple mass formulas are obtained, from this we predict some masses of unknown hadrons.
Semiclassical treatment of symmetry breaking and bifurcations in a non-integrable potential
Koliesnik, M V; Magner, A G; Arita, K; Brack, M
2014-01-01
We have derived an analytical trace formula for the level density of the H\\'enon-Heiles potential using the improved stationary phase method, based on extensions of Gutzwiller's semiclassical path integral approach. This trace formula has the correct limit to the standard Gutzwiller trace formula for the isolated periodic orbits far from all (critical) symmetry-breaking points. It continuously joins all critical points at which an enhancement of the semiclassical amplitudes occurs. We found a good agreement between the semi- classical and the quantum oscillating level densities for the gross shell structures and for the energy shell corrections, solving the symmetry breaking problem at small energies.
Augmented Superfield Approach to Nilpotent Symmetries in Self-Dual Chiral Bosonic Field Theory
Srinivas, N; Malik, R P
2015-01-01
We exploit the beauty and strength of the symmetry invariant restrictions on the superfields to derive the Becchi-Rouet-Stora-Tyutin (BRST), anti-BRST and (anti-) co-BRST symmetry transformations in the case of a two (1+1)-dimensional (2D) self-dual chiral bosonic field theory within the framework of augmented superfield formalism. Our 2D ordinary theory is generalized onto a (2, 2)-dimensional supermanifold which is parameterized by the superspace variable $Z^M = (x^\\mu, \\theta, \\bar\\theta)$ where $x^\\mu$ (with $\\mu = 0, 1$) are the ordinary 2D bosonic coordinates and ($\\theta,\\, \\bar\\theta$) are a pair of Grassmannian variables with their standard relationships: $\\theta^2 = {\\bar\\theta}^2 =0, \\theta\\,\\bar\\theta + \\bar\\theta\\theta = 0$. We impose the (anti-)BRST and (anti-)co-BRST invariant restrictions on the superfields, defined on the (anti-)chiral (2, 1)-dimensional super-submanifolds of the above {\\it general} (2, 2)-dimensional supermanifold, to derive the above nilpotent symmetries. We do not exploit ...
Chiral symmetry and pi-pi scattering in the Covariant Spectator Theory
Biernat, Elmar P; Ribeiro, J E; Stadler, Alfred; Gross, Franz
2014-01-01
The pi-pi scattering amplitude calculated with a model for the quark-antiquark interaction in the framework of the Covariant Spectator Theory (CST) is shown to satisfy the Adler zero constraint imposed by chiral symmetry. The CST formalism is established in Minkowski space and our calculations are performed in momentum space. We prove that the axial-vector Ward-Takahashi identity is satisfied by our model. Then we show that, similarly to what happens within the Bethe-Salpeter formalism, application of the axial-vector Ward-Takahashi identity to the CST pi-pi scattering amplitude allows us to sum the intermediate quark-quark interactions to all orders. The Adler self-consistency zero for pi-pi scattering in the chiral limit emerges as the result for this sum.
Chiral symmetry and π -π scattering in the covariant spectator theory
Biernat, Elmar P.; Peña, M. T.; Ribeiro, J. E.; Stadler, Alfred; Gross, Franz
2014-11-01
The π -π scattering amplitude calculated with a model for the quark-antiquark interaction in the framework of the covariant spectator theory (CST) is shown to satisfy the Adler zero constraint imposed by chiral symmetry. The CST formalism is established in Minkowski space and our calculations are performed in momentum space. We prove that the axial-vector Ward-Takahashi identity is satisfied by our model. Then we show that, similar to what happens within the Bethe-Salpeter formalism, application of the axial-vector Ward-Takahashi identity to the CST π -π scattering amplitude allows us to sum the intermediate quark-quark interactions to all orders. The Adler self-consistency zero for π -π scattering in the chiral limit emerges as the result for this sum.
Strong-interaction isospin-symmetry breaking within the density functional theory
Baczyk, Pawel; Dobaczewski, Jacek; Konieczka, Maciej; Satula, Wojciech
2015-01-01
The conventional Skyrme interaction is generalized by adding zerorange charge-symmetry-breaking and charge-independence-breaking terms, and the corresponding energy density functional is derived. It is shown that the extended model accounts for experimental values of mirror and triplet displacement energies (MDEs and TDEs) in sd-shell isospin triplets with, on average, ∼ 100 keV precision using only two additional adjustable coupling constants. Moreover, the model is able to...
Loop suppressed electroweak symmetry breaking and naturally heavy superpartners
Dermisek, Radovan
2016-01-01
A model is presented in which O(10 TeV) stop masses, typically required by the Higgs boson mass in supersymmetric models, do not originate from soft supersymmetry breaking terms that would drive the Higgs mass squared parameter to large negative values but rather from the mixing with vectorlike partners. Their contribution to the Higgs mass squared parameter is reduced to threshold corrections and thus it is one loop suppressed compared to usual scenarios. New fermion and scalar partners of the top quark with O(10 TeV) masses are predicted.
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.
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.
Symmetry Breaking and Adaptation The Genetic Code of Retroviral Env Proteins
Vera, S
1996-01-01
Although several synonymous codons can encode the same aminoacid, this symmetry is generally broken in natural genetic systems. In this article, we show that the symmetry breaking can result from selective pressures due to the violation of the synonym symmetry by mutation and recombination. We conjecture that this enhances the probability to produce mutants that are well-adapted to the current environment. Evidence is found in the codon frequencies of the HIV resistant to the current immunological attack, are found with a greater frequency than their less mutable synonyms.
Supersymmetry-breaking nonlinear sigma models
Energy Technology Data Exchange (ETDEWEB)
Imai, Takumi, E-mail: imai@yukawa.kyoto-u.ac.jp [Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502 (Japan); Izawa, K.-I. [Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502 (Japan); Kavli Institute for the Physics and Mathematics of the Universe, University of Tokyo (WPI), Kashiwa 277-8583 (Japan); Nakai, Yuichiro [Department of Physics, Tohoku University, Sendai 980-8578 (Japan)
2012-10-22
We consider a novel class of constraints on chiral superfields to obtain supersymmetric nonlinear sigma models in four spacetime dimensions, which strictly combine the internal symmetry breaking with spontaneous supersymmetry breaking. The resultant massless modes can be exclusively Nambu-Goldstone bosons without their complex partners and the goldstino that is charged under the internal symmetry. The massive modes show a peculiar relation among their masses and the scales of symmetry breakings.
Chiral symmetry restoration versus deconfinement in heavy-ion collisions at high baryon density
Cassing, W.; Palmese, A.; Moreau, P.; Bratkovskaya, E. L.
2016-01-01
We study the production of strange hadrons in nucleus-nucleus collisions from 4 to 160 A GeV within the parton-hadron-string dynamics (PHSD) transport approach that is extended to incorporate essentials aspects of chiral symmetry restoration (CSR) in the hadronic sector (via the Schwinger mechanism) on top of the deconfinement phase transition as implemented in PHSD. Especially the K+/π+ and the (Λ +Σ0) /π- ratios in central Au+Au collisions are found to provide information on the relative importance of both transitions. The modeling of chiral symmetry restoration is driven by the pion-nucleon Σ term in the computation of the quark scalar condensate that serves as an order parameter for CSR and also scales approximately with the effective quark masses ms and mq. Furthermore, the nucleon scalar density ρs, which also enters the computation of , is evaluated within the nonlinear σ -ω model which is constrained by Dirac-Brueckner calculations and low-energy heavy-ion reactions. The Schwinger mechanism (for string decay) fixes the ratio of strange to light quark production in the hadronic medium. We find that above ˜80 A GeV the reaction dynamics of heavy nuclei is dominantly driven by partonic degrees of freedom such that traces of the chiral symmetry restoration are hard to identify. Our studies support the conjecture of "quarkyonic matter" in heavy-ion collisions from about 5 to 40 A GeV and provide a microscopic explanation for the maximum in the K+/π+ ratio at about 30 A GeV, which only shows up if a transition to partonic degrees of freedom is incorporated in the reaction dynamics and is discarded in the traditional hadron-string models.
Dark Matter and Neutrino Masses from Global $U(1)_{B-L}$ Symmetry Breaking
Lindner, Manfred; Schwetz, Thomas
2011-01-01
We present a scenario were neutrino masses and Dark Matter are related due to a global $U(1)_{B-L}$ symmetry. Specifically we consider neutrino mass generation via the Zee{Babu two-loop mecha- nism, augmented by a scalar singlet whose VEV breaks the global $U(1)_{B-L}$ symmetry. In order to obtain a Dark Matter candidate we introduce two Standard Model singlet fermions. They form a pseudo-Dirac particle and are stable because of a remnant $Z_2$ symmetry. Hence, in this model the stability of Dark Matter follows from the global $U(1)_{B-L}$ symmetry. We discuss the Dark Matter phenomenology of the model, and compare it to similar models based on gauged $U(1)_{B-L}$. We argue that in contrast to the gauged versions, the model based on the global symmetry does not suffer from sever constraints from Z' searches.
Symmetry-breaking in drop bouncing on curved surfaces
Liu, Yahua; Li, Jing; Yeomans, Julia M; Wang, Zuankai
2015-01-01
The impact of liquid drops on solid surfaces is ubiquitous in nature, and of practical importance in many industrial processes. A drop hitting a flat surface retains a circular symmetry throughout the impact process. Here we show that a drop impinging on Echevaria leaves exhibits asymmetric bouncing dynamics with distinct spreading and retraction along two perpendicular directions. This is a direct consequence of the cylindrical leaves which have a convex/concave architecture of size comparable to the drop. Systematic experimental investigations on mimetic surfaces and lattice Boltzmann simulations reveal that this novel phenomenon results from an asymmetric momentum and mass distribution that allows for preferential fluid pumping around the drop rim. The asymmetry of the bouncing leads to ~40% reduction in contact time.
Spontaneous Symmetry Breaking in Metal Adsorbed Graphene Sheets
Jalbout, A F
2012-01-01
Graphene has received a great deal of attention and this has more recently extended to boron nitride sheets (BNS) with a similar structure. Both have hexagonal lattices and it is only the alternation of atoms in boron nitride, which changes the symmetry structure. This difference can for example be seen in the mean field equations, which for the corners of the Brillouin Zone are Dirac equations. For the case of graphene (equal atoms) we have the equation for massless particles, while for Boron Nitride has a finite gap and is more near a Dirac equation with mass near this gap.. Carbon structures in general and in particular also graphene can adsorb electron donors, such as alkaline atoms or molecules with a dipole moment. Typically these atoms and the dipoles can only attach in the sense to donate electron density. Some results for small sheet like structures are available.
UNIVERSALITY OF PHASE TRANSITION DYNAMICS: TOPOLOGICAL DEFECTS FROM SYMMETRY BREAKING
Energy Technology Data Exchange (ETDEWEB)
Zurek, Wojciech H. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Del Campo, Adolfo [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2014-02-13
In the course of a non-equilibrium continuous phase transition, the dynamics ceases to be adiabatic in the vicinity of the critical point as a result of the critical slowing down (the divergence of the relaxation time in the neighborhood of the critical point). This enforces a local choice of the broken symmetry and can lead to the formation of topological defects. The Kibble-Zurek mechanism (KZM) was developed to describe the associated nonequilibrium dynamics and to estimate the density of defects as a function of the quench rate through the transition. During recent years, several new experiments investigating formation of defects in phase transitions induced by a quench both in classical and quantum mechanical systems were carried out. At the same time, some established results were called into question. We review and analyze the Kibble-Zurek mechanism focusing in particular on this surge of activity, and suggest possible directions for further progress.
Color Rendering Plasmonic Aluminum Substrates with Angular Symmetry Breaking.
Duempelmann, Luc; Casari, Daniele; Luu-Dinh, Angélique; Gallinet, Benjamin; Novotny, Lukas
2015-12-22
We fabricate and characterize large-area plasmonic substrates that feature asymmetric periodic nanostructures made of aluminum. Strong coupling between localized and propagating plasmon resonances leads to characteristic Fano line shapes with tunable spectral positions and widths. Distinctive colors spanning the entire visible spectrum are generated by tuning the system parameters, such as the period and the length of the aluminum structures. Moreover, the asymmetry of the aluminum structures gives rise to a strong symmetry broken color rendering effect, for which colors are observed only from one side of the surface normal. Using a combination of immersed laser interference lithography and nanoimprint lithography, our color rendering structures can be fabricated on areas many inches in size. We foresee applications in anticounterfeiting, photovoltaics, sensing, displays, and optical security. PMID:26498131
Breaking Instance-Independent Symmetries In Exact Graph Coloring
Aloul, F A; Ramani, A; Sakallah, K A; 10.1613/jair.1637
2011-01-01
Code optimization and high level synthesis can be posed as constraint satisfaction and optimization problems, such as graph coloring used in register allocation. Graph coloring is also used to model more traditional CSPs relevant to AI, such as planning, time-tabling and scheduling. Provably optimal solutions may be desirable for commercial and defense applications. Additionally, for applications such as register allocation and code optimization, naturally-occurring instances of graph coloring are often small and can be solved optimally. A recent wave of improvements in algorithms for Boolean satisfiability (SAT) and 0-1 Integer Linear Programming (ILP) suggests generic problem-reduction methods, rather than problem-specific heuristics, because (1) heuristics may be upset by new constraints, (2) heuristics tend to ignore structure, and (3) many relevant problems are provably inapproximable. Problem reductions often lead to highly symmetric SAT instances, and symmetries are known to slow down SAT solvers. In t...
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 phase transition in a lattice fermion-gauge-scalar model with U(1) gauge symmetry
International Nuclear Information System (INIS)
The chiral phase transition induced by a charged scalar field is investigated numerically in a lattice fermion-gauge-scalar model with U(1) gauge symmetry, proposed recently as a model for dynamical fermion mass generation. For very strong gauge coupling the transition is of second order and its scaling properties are very similar to those of the Nambu-Jona-Lasinio model. However, in the vicinity of the tricritical point at somewhat weaker coupling, where the transition changes the order, the scaling behavior is different. Therefore it is worthwhile to investigate the continuum limit of the model at this point. (orig.)
Chiral symmetry and pi-pi scattering in the Covariant Spectator Theory
Biernat, Elmar P.; Peña, M. T.; Ribeiro, J. E.; Stadler, Alfred; Gross, Franz
2014-01-01
The pi-pi scattering amplitude calculated with a model for the quark-antiquark interaction in the framework of the Covariant Spectator Theory (CST) is shown to satisfy the Adler zero constraint imposed by chiral symmetry. The CST formalism is established in Minkowski space and our calculations are performed in momentum space. We prove that the axial-vector Ward-Takahashi identity is satisfied by our model. Then we show that, similar to what happens within the Bethe-Salpeter formalism, applica...
Universality and Symmetry Breaking in Conformally Reduced Quantum Gravity
Bonanno, Alfio
2012-01-01
The scaling properties of quantum gravity are discussed by employing a class of proper-time regulators in the functional flow equation for the conformal factor within the formalism of the background field method. Renormalization group trajectories obtained by projecting the flow on a flat topology are more stable than those obtained from a projection on a spherical topology. In the latter case the ultraviolet flow can be characterized by a Hopf bifurcation with an ultraviolet attractive limiting cycle. Although the possibility of determining the infrared flow for an extended theory space can be severely hampered due to the conformal factor instability, we present a robust numerical approach to study the flow structure around the non-gaussian fixed point as an inverse-problem strategy. In particular it is shown the possibility of having a spontaneous breaking of the diffeomorphism invariance can be realized with non-local functionals of the volume operator.
PT Symmetry Breaking and Nonlinear Optical Isolation in Coupled Microcavities
Zhou, Xin
2016-01-01
We perform a theoretical study of nonlinear optical isolator devices based on coupled microcavities with gain and loss. Using coupled-mode theory, we derive a correspondence between the boundary of asymptotic stability in the nonlinear regime, where gain saturation is present, and the PT-breaking transition in the underlying linear system. For zero detuning and weak input intensity, the onset of optical isolation can be rigorously derived, and corresponds precisely to the PT transition point. When the couplings to the external ports are unequal, the isolation ratio exhibits an abrupt jump at the transition point, determined by the ratio of the couplings. This could be exploited to realize an actively controlled nonlinear optical isolator, in which strong optical isolation can be switched on or off using tiny variations in the inter-resonator separation.
Probing the Source of Proton Mass by"Unbreaking" Scale-Chiral Symmetry
Rho, Mannque
2016-01-01
I describe a possible scenario for the origin of proton mass in terms of Cheshire Cat, half-skyrmions, topology change and interplay between hidden chiral-scale symmetry and induced local symmetry. This differs from the standard constituent-quark scenario. As the baryonic matter density is increased toward the vector manifestation (VM) fixed-point at which the $\\rho$ mass is to vanish, the effective in-medium mass ratio $m^*_\\rho/m^*_N$ is to tend to zero proportionally to $g^*_\\rho$ where $g^*_\\rho$ is the in-medium hidden gauge coupling constant. I develop the thesis that the intricacy involved in the mass generation could be decoded from experiments at RIB accelerators and massive compact stars.
Kagome Chiral Spin Liquid as a Gauged U (1 ) Symmetry Protected Topological Phase
He, Yin-Chen; Bhattacharjee, Subhro; Pollmann, Frank; Moessner, R.
2015-12-01
While the existence of a chiral spin liquid (CSL) on a class of spin-1 /2 kagome antiferromagnets is by now well established numerically, a controlled theoretical path from the lattice model leading to a low-energy topological field theory is still lacking. This we provide via an explicit construction starting from reformulating a microscopic model for a CSL as a lattice gauge theory and deriving the low-energy form of its continuum limit. A crucial ingredient is the realization that the bosonic spinons of the gauge theory exhibit a U (1 ) symmetry protected topological (SPT) phase, which upon promoting its U (1 ) global symmetry to a local gauge structure ("gauging"), yields the CSL. We suggest that such an explicit lattice-based construction involving gauging of a SPT phase can be applied more generally to understand topological spin liquids.
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.
Origin of Symmetry Breaking and Confinement in Conducting Polymers with Ring Structures
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
A model to describe the main features of conjugated polymers with ring structures, such as polythiophene and polypyrrole, is constructed. It is shown that the origin of the symmetry breaking and confinement of a soliton and anti-soliton pair is branch hopping in the polymer rings.
Dallas, V; Alexakis, A
2013-12-01
We investigate the evolution and stability of a decaying magnetohydrodynamic Taylor-Green flow, using pseudospectral simulations with resolutions up to 2048(3). The chosen flow has been shown to result in a steep total energy spectrum with power law behavior k(-2). We study the symmetry breaking of this flow by exciting perturbations of different amplitudes. It is shown that for any finite amplitude perturbation there is a high enough Reynolds number for which the perturbation will grow enough at the peak of dissipation rate resulting in a nonlinear feedback into the flow and subsequently break the Taylor-Green symmetries. In particular, we show that symmetry breaking at large scales occurs if the amplitude of the perturbation is σ(crit)∼Re(-1) and at small scales occurs if σ(crit)∼Re(-3/2). This symmetry breaking modifies the scaling laws of the energy spectra at the peak of dissipation rate away from the k(-2) scaling and towards the classical k(-5/3) and k(-3/2) power laws.
International Nuclear Information System (INIS)
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
Charge symmetry breaking in $\\Lambda$ hypernuclei: updated HYP 2015 progress report
Gal, Avraham
2016-01-01
Ongoing progress in understanding and evaluating charge symmetry breaking in $\\Lambda$ hypernuclei is discussed in connection to recent measurements of the $_{\\Lambda}^{4}{\\rm H}(0^+_{\\rm g.s.})$ binding energy at MAMI [A1 Collaboration: PRL 114 (2015) 232501] and of the $_{\\Lambda}^{4}{\\rm He}(1^+_{\\rm exc})$ excitation energy at J-PARC [E13 Collaboration: PRL 115 (2015) 222501].
Spontaneous Symmetry Breaking in SO(3) Gauge Theory to Discrete Subgroups
Etesi, Gábor
2016-01-01
A systematical description of possible symmetry breakings in the SO(3) gauge theory and an algorithmical method to construct SU(2) or SO(3) invariant Higgs potentials in an arbitrary irreducible representation is given. We close our paper with the explicit construction of the Lagrangian of the simplest SO(3) theory violated to its subgroup A_4.
Symmetry-breaking intramolecular charge transfer in the excited state of meso-linked BODIPY dyads
Whited, Matthew T.
2012-01-01
We report the synthesis and characterization of symmetric BODIPY dyads where the chromophores are attached at the meso position, using either a phenylene bridge or direct linkage. Both molecules undergo symmetry-breaking intramolecular charge transfer in the excited state, and the directly linked dyad serves as a visible-light-absorbing analogue of 9,9′-bianthryl.
Pseudo-magnetic catalysis of the time-reversal symmetry breaking in graphene
Herbut, Igor F.
2008-01-01
Finite flux of the (time-reversal-symmetric) pseudo-magnetic field, which represents the effect of wrinkling of the graphene sheet for example, is shown to be a catalyst for spontaneous breaking of the time-reversal symmetry of Dirac fermions in two dimensions. Possible experimental consequences of this effect for graphene are discussed.
Symmetry Breaking in the Hidden-Order Phase of URu2Si2
Shibauchi, Takasada
2013-03-01
In the heavy fermion compound URu2Si2, the hidden-order transition occurs at 17.5 K, whose nature has posed a long-standing mystery. A second-order phase transition is characterized by spontaneous symmetry breaking, and thus the nature of the hidden order cannot be determined without understanding which symmetry is being broken. Our magnetic torque measurements in small pure crystals reveal the emergence of an in-plane anisotropy of the magnetic susceptibility below the transition temperature, indicating the spontaneous breaking of four-fold rotational symmetry of the tetragonal URu2Si2. In addition, our recent observation of cyclotron resonance allows the full determination of the electron-mass structure of the main Fermi-surface sheets, which implies an anomalous in-plane mass anisotropy consistent with the rotational symmetry breaking. These results impose strong constraints on the symmetry of the hidden order parameter. This work has been done in collaboration with R. Okazaki, S. Tonegawa, K. Hashimoto, K. Ikada, Y. H. Lin, H. Shishido, H. J. Shi, Y. Haga, T. D. Matsuda, E. Yamamoto, Y. Onuki, H. Ikeda, and Y. Matsuda.
Mirror-symmetry breakings in human sperm rheotaxis
Stoop, Norbert; Bukatin, Anton; Kukhtevich, Igor; Dunkel, Joern; Kantsler, Vasily
Rheotaxis, the directed response to fluid velocity gradients, has been shown to facilitate stable upstream-swimming of mammalian sperm cells along solid surfaces, suggesting a robust mechanism for long-distance navigation during fertilization. However, the dynamics by which a human sperm orients itself w.r.t. ambient flows is poorly understood. Here, we combine microfluidic experiments with mathematical modeling and 3D flagellar beat reconstruction to quantify the response of individual sperm cells in time-varying flow fields. Single-cell tracking reveals two kinematically distinct swimming states that entail opposite turning behaviors under flow reversal. We constrain an effective 2D model for the turning dynamics through systematic large-scale parameter scans, and find good quantitative agreement with experiments. We present comprehensive 3D data demonstrating the rolling dynamics of freely swimming sperm cells around their longitudinal axis. Contrary to current beliefs, this analysis uncovers ambidextrous flagellar waveforms and shows that the cell's turning direction is is not defined by the rolling direction. Instead, the different rheotactic turning behaviors are linked to a broken mirror-symmetry in the midpiece section, likely arising from a buckling instability.
Inversion symmetry breaking of atomic bound states in strong and short laser fields
Stooß, Veit; Ott, Christian; Blättermann, Alexander; Ding, Thomas; Pfeifer, Thomas
2015-01-01
In any atomic species, the spherically symmetric potential originating from the charged nucleus results in fundamental symmetry properties governing the structure of atomic states and transition rules between them. If atoms are exposed to external electric fields, these properties are modified giving rise to energy shifts such as the AC Stark-effect in varying fields and, contrary to this in a constant (DC) electric field for high enough field strengths, the breaking of the atomic symmetry which causes fundamental changes in the atom's properties. This has already been observed for atomic Rydberg states with high principal quantum numbers. Here, we report on the observation of symmetry breaking effects in Helium atoms for states with principal quantum number n=2 utilizing strong visible laser fields. These findings were enabled by temporally resolving the dynamics better than the sub-optical cycle of the applied laser field, utilizing the method of attosecond transient absorption spectroscopy (ATAS). We ident...
$SU(3)_{F}$ Gauge Family Model and New Symmetry Breaking Scale From FCNC Processes
Bao, Shou-Shan; Wu, Yue-Liang
2015-01-01
Based on the $SU(3)_{F}$ gauge family symmetry model which was proposed to explain the observed mass and mixing pattern of neutrinos, we investigate the symmetry breaking, the mixing pattern in quark and lepton sectors, and the contribution of the new gauge bosons to some flavor changing neutral currents (FCNC) processes at low energy. With the current data of the mass differences in the neutral pseudo-scalar $P^{0}-\\bar{P}^{0}$ systems, we find that the $SU(3)_{F}$ symmetry breaking scale can be as low as 300TeV and the mass of the lightest gauge boson be about $100$TeV. Other FCNC processes, such as the lepton flavor number violation process $\\mu^{-}\\rightarrow e^{-}e^{+}e^{-}$ and the semi-leptonic rare decay $K\\rightarrow \\pi \\bar{\
Radiative Symmetry Breaking in Supersymmetric $B-L$ Models with Inverse Seesaw
Khalil, Shaaban
2016-01-01
We study the radiative symmetry breaking of B-L in supersymmetric models with inverse seesaw mechanism. We show that for a wide region of parameter space the radiative corrections can drive the squared mass of the extra Higgs boson from positive initial values at the GUT scale to negative values at the TeV scale, leading to the spontaneous breaking of the B-L symmetry. We also emphasize that in this class of models, unlike the supersymmetric B-L models with type I seesaw, the right-handed sneutrino cannot get a non-zero vacuum expectation value. Therefore, B-L can be radiatively broken while R-parity remains an exact symmetry.
750 GeV messenger of dark conformal symmetry breaking
Davoudiasl, Hooman; Zhang, Cen
2016-03-01
The tentative hints for a diphoton resonance at a mass of ˜750 GeV from the ATLAS and CMS experiments at the LHC may be interpreted as first contact with a "dark" sector with a spontaneously broken conformal symmetry. The implied TeV scale of the dark sector may be motivated by the interaction strength required to accommodate a viable thermal relic dark matter (DM) candidate. We model the conformal dynamics using a Randall-Sundrum-type five-dimensional geometry whose IR boundary is identified with the dynamics of the composite dark sector, while the Standard Model (SM) matter content resides on the UV boundary, corresponding to "elementary" fields. We allow the gauge fields to reside in the five-dimensional bulk, which can be minimally chosen to be S U (3 )c×U (1 )Y. The "dark" radion is identified as the putative 750 GeV resonance. Heavy vectorlike fermions, often invoked to explain the diphoton excess, are not explicitly present in our model and are not predicted to appear in the spectrum of TeV scale states. Our minimal setup favors scalar DM of O (TeV ) mass. A generic expectation in this scenario, suggested by DM considerations, is the appearance of vector bosons at ˜ few TeV, corresponding to the gluon and hypercharge Kaluza-Klein (KK) modes that couple to UV boundary states with strengths that are suppressed uniformly compared to their SM values. Our analysis suggests that these KK modes could be within the reach of the LHC in the coming years.