Showing papers on "Explicit symmetry breaking published in 1982"

Cosmology for Grand Unified Theories with Radiatively Induced Symmetry Breaking

Abstract: The treatment of first-order phase transitions for standard grand unified theories is shown to break down for models with radiatively induced spontaneous symmetry breaking. It is argued that proper analysis of these transitions which would take place in the early history of the universe can lead to an explanation of the cosmological homogeneity, flatness, and monopole puzzles.

Scales of chiral symmetry breaking in quantum chromodynamics

Abstract: Computer simulations indicate that the range of the force responsible for chiral symmetry breaking in quantum chromodynamics is relatively short, independent of confinement, and depends strongly on the color representation of the quarks. Chiral-symmetry restoration temperatures are obtained for quarks in either the fundamental or the adjoint representations of color SU(2). Results on higher representations support the symmetry-breaking pattern ("tumbling") suggested by Raby, Dimopoulos, and Susskind.

Symmetry of the quadratic Zeeman effect for hydrogen

Abstract: The $O(4)$ symmetry of the hydrogen-atom degeneracy is exploited to obtain an exact separation of the quadratic Zeeman interaction on the Fock hypersphere in momentum space, and hence a complete classification of levels in the weak-field limit. The separation constant includes a double-minimum potential, and levels below the top of the barrier have an approximate $O(2)\ifmmode\times\else\texttimes\fi{}O(2)$ symmetry and vibrational structure. Levels above the top of the barrier have an approximate $O(3)$ symmetry, and a structure similar to that of an oblate symmetric top. The crossover between the two types of levels becomes sharper at high $n$, and is related to two different types of collective coupling of angular momentum and the Runge-Lenz vector.

Dynamical symmetry breaking due to radiative corrections in cosmology

Abstract: Dynamical symmetry breaking in massless $\ensuremath{\lambda}{\ensuremath{\varphi}}^{4}$ theory in curved spacetime with non-conformal coupling to the curvature is investigated It is shown that in general the one-loop self-energy for such a field will involve a term of the form $R\mathrm{ln}|R{\ensuremath{\mu}}^{\ensuremath{-}2}|$, where $R$ is the scalar curvature, and $\ensuremath{\mu}$ is a mass This term can give rise to symmetry breaking Two models, the Einstein universe and a spatially flat Robertson-Walker universe with a power-law expansion, are considered where this term is the sole contribution to the one-loop self-energy In both cases a phase transition will occur at a critical value of the curvature The form of the two-loop corrections to the self-energy and the limits of validity of the one-loop approximation are discussed

Point vortex motions with a center of symmetry

Abstract: The equations of motion for point vortices are well known to preserve certain discrete symmetries of the initial state. The case of a center of symmetry is considered in detail here, since this particular instance seems to have been overlooked in the classical literature. This symmetry provides a generalization of the early studies by Grobli and Greenhill wherein several axes of symmetry are present, a case which leads to an effective one‐body problem. The center of symmetry yields an effective two‐body problem which is Hamiltonian and integrable. As an example the ‘‘double alternate ring’’ configurations, circular analogs of the vortex street introduced by Havelock, are considered. A fully nonlinear mode wherein these double rings asymptotically dissolve into freely moving vortex pairs is found analytically. The paper concludes with a discussion of the relevance of such modes to our understanding of the disintegration of vortex streets in two‐dimensional flow.

Symmetry rules for the indirect nuclear spin-spin coupling tensor revisited

Abstract: The symmetry rules of Buckingham and Love (1970), relating the number of independent components of the indirect spin-spin coupling tensor J to the symmetry of the nuclear sites, are shown to require modification if the two nuclei are exchanged by a symmetry operation. In that case, the anti-symmetric part of J does not transform as a second-rank polar tensor under symmetry operations that interchange the coupled nuclei and may be called an anti-tensor. New rules are derived and illustrated by simple molecular models.

Chiral symmetry and chiral symmetry breaking

Abstract: Lectures presented at the session on " Recent Developments in Quantum Field Theory and Statistical Mechanics " of the Les Houches Summer School of Theoretical Physics August 1982 *Nork supported by the

Spontaneous symmetry breaking and the local freeze-out in Tl 2 + -doped K H 2 As O 4

Abstract: The slowing down of the local order-parameter fluctuations and the spontaneous dynamic symmetry breaking at a defect site in an order-disorder hydrogen-bonded system---describable by an Ising model in a transverse-field Hamiltonian---has been evaluated and shown to depend on the range of the forces with which the defect couples to the host lattice. The spontaneous symmetry breaking observed far above ${T}_{c}$ in the EPR spectra of defect centers in K${\mathrm{H}}_{2}$As${\mathrm{O}}_{4}$-type crystals is shown to be compatible with such a local slowing down and "pseudo-freeze-out" around defects which couple to the surrounding pseudospins via short-range forces which are significantly stronger than the interaction forces in the undisturbed lattice. No such freeze-out occurs for the ${\mathrm{Tl}}^{2+}$ ions which are coupled to the surrounding pseudospins via long-range forces.

A remark on the goldstone theorem in statistical mechanics

Abstract: The Goldstone theorem in any dimension and the absence of symmetry breaking in two dimensions result from a simple use of the Bogoliubov inequality. In particular, the rate of clustering of particle correlation functions in a 3-dimensional classical crystal is necessarily than slower or equal to ¦x¦-1.

Parisi solutions for the anisotropic spin glass problem

Abstract: A Heisenberg spin glass with local uniaxial anisotropy is studied at mean field level in terms of a Parisi symmetry breaking scheme. It is shown that replica symmetry breaking leads to important modifications to the replica symmetric expressions for the susceptibilities chi T, chi L which signal the transitions in this system.

Symmetry breaking a la Parisi in the n-component SK model of a spin glass

Abstract: The m-component SK model of a spin glass is studied in the presence of a magnetic field H. Below the Gabay-Toulouse line, corresponding to the freezing of the transverse components, the replica symmetry is broken a la Parisi. Near Tc=1 analytic expressions for the free energy, the longitudinal (q1) and transverse (qT) order parameters are derived. Different behaviours are found in 'strong' (H2>>(1-T)3) and 'weak' (H2

Selection rules for symmetry breaking and symmetry restoration in continuous transitions

Abstract: Using Landau's phenomenological theory as a framework, Subduction and Chain Subduction Criteria are discussed as methods for obtaining directly selection rules for symmetry breaking. For symmetry restoration Induction and Chain Induction criteria give selection rules. Minimal symmetry breaking and minimal symmetry restoration are related to satisfaction of Chain Subduction and Induction Criteria.

Does chiral symmetry breaking cause the Nucleon-Delta mass difference?

Abstract: We critically review recent calculations of the Nucleon-Delta mass splitting in the QCD sum rule approach. Some calculations indicate aN-Δ mass splitting already to zeroth order QCD, i.e., only due to the chiral symmetry breaking quark condensate. We show that there is no indication of a mass splitting to zeroth order if optimal interpolating fields are used for theN and Δ, where optimal fields are those for which the continuum contribution is minimal.