scispace - formally typeset
Search or ask a question

Showing papers on "Explicit symmetry breaking published in 1994"


Journal ArticleDOI
TL;DR: In this article, the authors review the current status of heavy-quark symmetry and its applications to weak decays of hadrons containing a single heavy quark, including a comprehensive treatment of symmetry breaking corrections.

978 citations


Journal ArticleDOI
TL;DR: It is shown that in 2+1 dimensions, a constant magnetic field is a strong cata- lyst of dynamical flavor symmetry breaking,leading to generating a fermion dy- namical mass even at the weakest attractive interaction between fermions.
Abstract: It is shown that in 2 + 1 dimensions, a constant magnetic field is a strong catalyst of dynamical flavor symmetry breaking, leading to generating a fermion dynamical mass even at the weakest attractive interaction between fermions. The effect is illustrated in the Nambu-Jona-Lasinio model in a magnetic field. The low-energy effective action in this model is derived, and the thermodynamic properties of the model are established.

427 citations


Posted Content
TL;DR: In this article, the superpotential and the coefficient of the gauge kinetic terms in supersymmetric theories have been studied and the underlying conceptual reason for the important non-renormalization theorems.
Abstract: Holomorphy of the superpotential and of the coefficient of the gauge kinetic terms in supersymmetric theories lead to powerful results. They are the underlying conceptual reason for the important non-renormalization theorems. They also enable us to study the exact non-perturbative dynamics of these theories. We find explicit realizations of known phenomena as well as new ones in four dimensional strongly coupled field theories. These shed new light on confinement and chiral symmetry breaking. This note is based on a talk delivered at the PASCOS (94) meeting at Syracuse University.

150 citations


Journal ArticleDOI
TL;DR: In this article, the two-loop β-functions for soft supersymmetry-breaking interactions in general supersymmetric gauge theories were calculated, emphasising the role of the evanescent couplings and masses that are generic to a non-supersymmetric theory.

148 citations



Journal ArticleDOI
TL;DR: In this paper, a complete symmetry group for the classical Kepler problem is presented, which acts freely and transitively on the manifold of all allowed motions of the system, and the given equations of motion are the only ordinary differential equations that remain invariant under the specified action of the group.
Abstract: A rather strong concept of symmetry is introduced in classical mechanics, in the sense that some mechanical systems can be completely characterized by the symmetry laws they obey Accordingly, a ‘‘complete symmetry group’’ realization in mechanics must be endowed with the following two features: (1) the group acts freely and transitively on the manifold of all allowed motions of the system; (2) the given equations of motion are the only ordinary differential equations that remain invariant under the specified action of the group This program is applied successfully to the classical Kepler problem, since the complete symmetry group for this particular system is here obtained The importance of this result for the quantum kinematic theory of the Kepler system is emphasized

86 citations


Journal ArticleDOI
TL;DR: In this article, the authors consider a quantum many-body system on a lattice which exhibits spontaneous symmetry breaking in its infinite-volume ground states, but in which the corresponding order operator does not commute with the Hamiltonian.
Abstract: We consider a quantum many-body system on a lattice which exhibits a spontaneous symmetry breaking in its infinite-volume ground states, but in which the corresponding order operator does not commute with the Hamiltonian. Typical examples are the Heisenberg antiferromagnet with a Neel order and the Hubbard model with a (superconducting) off-diagonal long-range order. In the corresponding finite system, the symmetry breaking is usually “obscured” by “quantum fluctuation” and one gets a symmetric ground state with a long-range order. In such a situation, Horsch and von der Linden proved that the finite system has a low-lying eigenstate whose excitation energy is not more than of orderN −1, whereN denotes the number of sites in the lattice. Here we study the situation where the broken symmetry is a continuous one. For a particular set of states (which are orthogonal to the ground state and with each other), we prove bounds for their energy expectation values. The bounds establish that there exist ever-increasing numbers of low-lying eigenstates whose excitation energies are bounded by a constant timesN −1. A crucial feature of the particular low-lying states we consider is that they can be regarded as finite-volume counterparts of the infinite-volume ground states. By forming linear combinations of these low-lying states and the (finite-volume) ground state and by taking infinite-volume limits, we construct infinite-volume ground states with explicit symmetry breaking. We conjecture that these infinite-volume ground states are ergodic, i.e., physically natural. Our general theorems not only shed light on the nature of symmetry breaking in quantum many-body systems, but also provide indispensable information for numerical approaches to these systems. We also discuss applications of our general results to a variety of interesting examples. The present paper is intended to be accessible to readers without background in mathematical approaches to quantum many-body systems.

85 citations


Journal ArticleDOI
TL;DR: In a Hamiltonian formalism, chiral symmetry for lattice fermions formulated in terms of Shockley surface states bound to a wall in an extra spatial dimension is studied to provide a natural scheme for taking quark masses to zero without requiring a precise tuning of parameters.
Abstract: In a Hamiltonian formalism we study chiral symmetry for lattice fermions formulated in terms of Shockley surface states bound to a wall in an extra spatial dimension. For hadronic physics this provides a natural scheme for taking quark masses to zero without requiring a precise tuning of parameters. We illustrate the chiral anomaly as a flow of states in this extra dimension. We discuss two alternatives for extending the picture to a chiral coupling of gauge fields to such fermions: one with a small explicit breaking of gauge symmetry and one with heavy mirror fermions.

61 citations


Journal ArticleDOI
TL;DR: In this article, it is suggested that both the Peccei-Quinn symmetry and the spontaneously broken $R$ symmetry may be the sources of the needed $\mu$ term in the minimal supersymmetric standard model provided that they are spontaneously broken at a scale $10^{10}-10^{12}$ GeV.
Abstract: We stress that a natural solution of the $\mu$ problem requires two ingredients: a symmetry that would enforce $\mu = 0$ as well as the occurence of a small breaking parameter that generates a nonzero $\mu$. It is suggested that both the Peccei-Quinn symmetry and the spontaneously broken $R$ symmetry may be the sources of the needed $\mu$ term in the minimal supersymmetric standard model provided that they are spontaneously broken at a scale $10^{10}-10^{12}$ GeV. To solve the strong CP problem with a hidden sector confining group, both of these symmetries are needed in superstring models with an anomalous $U(1)_A$.

50 citations


Journal ArticleDOI
TL;DR: Two-dimensional model equations, invariant under the symmetry operations of an infinite horizontal plane, can undergo a cellular instability to ''quasipatterns'' of eight- or 12-fold orientational order.
Abstract: Two-dimensional model equations, invariant under the symmetry operations of an infinite horizontal plane, can undergo a cellular instability to ``quasipatterns'' of eight- or 12-fold orientational order. Two different nonlinear selection mechanisms are discussed and related to recent experiments.

49 citations


Journal ArticleDOI
TL;DR: A linear time algorithm to find the axes of skew symmetry inO(n) time, where n is the number of contour points, which is especially suited to industrial applications where the degree of symmetry is often knowna priori.
Abstract: Symmetry is pervasive in both man-made objects and nature. Since symmetries project to skew symmetries, finding axes of skew symmetry is an important vision task. This paper presents a linear time algorithm for finding the axes of skew symmetry, where the degree of symmetry is known. First, we present a review and critique of current methods for finding the axes of skew symmetry. Next, we decompose the problem of finding skew symmetry into the subproblems of solving for the rotational parameter of a “shear symmetry” and recovering the shear parameter of a reflexive symmetry. Using this approach, the authors derive a direct, non-heuristic moment-based technique for finding the axes of skew symmetry. For skew symmetric figures with degree of symmetry less than five we obtain a closed-form solution. The method does not rely on continuous contours but assumes there is no occlusion and requires knowing the contour's degree of symmetry. It is the first algorithm to find the axes of skew symmetry inO(n) time, where n is the number of contour points. The method is especially suited to industrial applications where the degree of symmetry is often knowna priori. Examples of the method are presented for both real and synthetic images, and an error analysis of the method is given.

Journal ArticleDOI
TL;DR: In this paper, an alternative formulation of the symmetry breaking sector of the Standard Model as a gauged non-linear sigma model (NLSM) following the philosophy of the Chiral lagrangian approach, which is the only compatible with all the experimental and theoretical constraints.

Journal ArticleDOI
TL;DR: In this paper, the authors derive and analyze several low dimensional Hamiltonian normal forms describing system symmetry breaking in ideal hydrodynamics, which are motivated by three-dimensional instabilities of rotating columnar fluid flows with circular streamlines (such as the Burger vortex) subjected to precession, elliptical distortion or off-center displacement.

Journal ArticleDOI
TL;DR: In this article, the possibility of topological mass generation through symmetry breaking in a simple model consisting of a self-interacting (massive or massless) λφ4 scalar field on the space-time TN×Rn, n, N∈N0−TN being a general torus is investigated.
Abstract: The possibility of topological mass generation through symmetry breaking in a simple model consisting of a self‐interacting (massive or massless) λφ4 scalar field on the space–time TN×Rn, n, N∈N0−TN being a general torus—is investigated. The nonrenormalized effective potential is calculated and the specific dependences of the generated mass on the compactification lengths and on the initial mass of the field are determined. Later, in order to obtain the renormalized topologically generated mass, the analysis is restricted to n+N=4 dimensions. It is shown that if the field is massive no symmetry breaking can occur. On the contrary, when it is massless, for n=1 and n=0 and for values of the vector of compactification lengths belonging to some specific domain of RN, symmetry breaking does actually take place. Explicit values of the mass topologically generated in this way are obtained.

Journal ArticleDOI
TL;DR: In this article, the quark-loop contribution to mixing self-energy is calculated within a QCD-based model field theory in which the mesons are composite qq bound states and the dressed quark propagator, obtained from a model Dyson-Schwinger equation, is confining.


Journal ArticleDOI
TL;DR: In this paper, the E_6 GUT model of a single generation of fermions with strong 4-fermi interactions is studied and the effective potential is analyzed analytically by the help of Michel's conjecture and the result is confirmed numerically.
Abstract: Dynamical symmetry breaking is studied in an E_6 GUT model of a single generation of fermions with strong 4-fermi interactions. The effective potential is analyzed analytically by the help of Michel's conjecture and the result is confirmed numerically. We find that the E_6 symmetry is spontaneously broken either to F_4 or to Sp(8) or G_2 or SU(3), depending on which of the 4-fermi coupling constants G_27 and G_351 in the 27/351 channels is stronger. The possibilities for obtaining other type of breaking patterns are also discussed.

Book ChapterDOI
TL;DR: In this paper, the observations of the symmetry breaking effects in nuclear and particle physics and the implications of those effects are reviewed and a review of the implications for those effects can be found.
Abstract: Charge independence and charge symmetry are approximate symmetries of nature, violated by the perturbing effects of the mass difference between up and down quarks and by electromagnetic interactions. The observations of the symmetry breaking effects in nuclear and particle physics and the implications of those effects are reviewed.

Journal ArticleDOI
TL;DR: It is found that in the minimal supersymmetric SO(10) grand unified theory only one-step symmetry breaking is allowed, whether or not supersymmetry remains unbroken in an intermediate symmetry breaking.
Abstract: The vacuum conditions for preserving supersymmetry in the minimal supersymmetric SO(10) grand unified theory are constructed and studied. The mass spectrum for each symmetry-breaking chain which preserves supersymmetry is considered. It is found that in the minimal supersymmetric SO(10) grand unified theory only one-step symmetry breaking is allowed, whether or not supersymmetry remains unbroken in an intermediate symmetry breaking.

Journal ArticleDOI
TL;DR: In this paper, a theory for the statistical properties of spectra of chaotic Hamiltonian systems with approximate integrals of the motion is presented, which is determined by a random matrix ensemble that depends on a single transition parameter.
Abstract: A theory for the statistical properties of spectra of chaotic Hamiltonian systems with approximate integrals of the motion is presented. Spectral statistics are determined by a random matrix ensemble that depends on a single transition parameter, which is evaluated herein semiclassically for Hamiltonians with a symmetry-breaking perturbation. At finite fi, substantial deviations from results of canonical matrix ensembles are predicted. Application is given to a coupled quartic oscillator Hamiltonian.

Journal ArticleDOI
TL;DR: A relativistically covariant symmetry of QED is constructed, and the Noether charge generating the symmetry transformation is obtained, and it imposes a constraint on the physical states.
Abstract: We construct a relativistically covariant symmetry of QED. Previous local and nonlocal symmetries are special cases. This generalized symmetry need not be nilpotent, but nilpotency can be arranged with an auxiliary field and a certain condition. The Noether charge generating the symmetry transformation is obtained, and it imposes a constraint on the physical states.

Journal ArticleDOI
TL;DR: In this paper, the anyon approach to the t-J model is shown to predict a conventional BCS order parameter of d x 2 − y 2 + iϵd xy symmetry, with ϵ roughly 3 times the doping fraction, which is consistent with these experiments but not demonstrated by them.
Abstract: It is argued that recent Josephson junction and point-contact tunneling experiments, interpreted as intended by their authors, indicate that time0reversal symmetry breaking occurs at surfaces of cuprate superconductors. The variation among experiments and the failure of previous searches to find T violation are ascribed to disorder and effects of three-dimensionality. The anyon approach to the t-J model is shown to predict a conventional BCS order parameter of d x 2 − y 2 + iϵd xy symmetry, with ϵ roughly 3 times the doping fraction δ, which is consistent with these experiments but not demonstrated by them.



Journal ArticleDOI
TL;DR: In this paper, the existence of an infinite number of high energy symmetry structures of the closed bosonic string theory was shown by using zero-norm states in the spectrum, and the results of Das and Sathiapalan which claim the σ-model is nonperturbatively nonrenormalizable were reproduced from a stringy symmetry argument point of view.

Proceedings ArticleDOI
23 May 1994
TL;DR: A randomized protocol that constructs a maximal independent set in O(log n) expected time is presented, and also a protocol for the dining philosophers problem that schedules a job that competes with 6 other jobs in expected 0(6) time, which is optimal.
Abstract: Thw paper considers symmetry-breakhg in an aaynchronoue d~tributed network. We present and analyze a randomized protocol that constructs a maximal independent set in O(log n) expected time, and also a protocol for the dining philosophers problem that schedules a job that competes with 6 other jobs in expected 0(6) time, which is optimal. The beat previous algorithms for dining philosophers achieved only 0(62). In addition, the new protocols are 2-wait-/iwe which means that delays at a process are only dependent on processors or links at most distance two in the communication graph.

Journal ArticleDOI
TL;DR: It is pointed out that the SU(3) mass splitting of the heavy baryons essentially measure the low energy'' physics once more and that the comparison with experiment is satisfactory.
Abstract: We discuss the generalization of the Callan-Klebanov model to the case of heavy quark baryons. The light flavor group is considered to be SU(3) and the limit of heavy spin symmetry is taken. The presence of the Wess-Zumino-Witten term permits the neat development of a picture, at the collective level, of a light diquark bound to a heavy'' quark with decoupled spin degree of freedom. The consequences of SU(3) symmetry breaking are discussed in detail. We point out that the SU(3) mass splitting of the heavy baryons essentially measure the low energy'' physics once more and that the comparison with experiment is satisfactory.

Journal ArticleDOI
TL;DR: The distribution function of the local density of states is computed exactly for the Wigner-Dyson ensemble of random Hamiltonians with precise agreement with the supersymmetry theory by Efetov and Prigodin of the NMR line shape in disordered metal particles.
Abstract: The distribution function of the local density of states is computed exactly for the Wigner-Dyson ensemble of random Hamiltonians. In the absence of time-reversal symmetry, precise agreement is obtained with the supersymmetry theory by Efetov and Prigodin of the NMR line shape in disordered metal particles. Upon breaking time-reversal symmetry, the variance of the Knight shift in the smallest particles is reduced by a universal factor of 2/3.

Journal ArticleDOI
TL;DR: In this paper, the phase structure of the d = 3 Nambu-Jona-Lasinio model in curved space-time is considered to leading order in the 1/Nexpansion and in the linear curvature approximation.
Abstract: The phase structure of the d = 3 Nambu-Jona-Lasinio model in curved space-time is considered to leading order in the 1/N-expansion and in the linear curvature approximation. The possibility of a curvature-induced first order phase transition is investigated numerically. The dynamically generated fermionic mass is calculated for some values of the curvature.

Journal ArticleDOI
TL;DR: In this paper, a possible mechanism for the explanation of the doublet-triplet mass hierarchy in the grand unified theories is considered, where the Higgs doublet is automatically light since it is related by a certain SU(2)C symmetry to another doublet which after GUT symmetry breaking becomes an unphysical Higgs.