4,249 research outputs found
Finite Temperature QCD Interfaces Out of Equilibrium
The properties of interfaces in non-equilibrium situations are studied by
constructing a density matrix with a space-dependent temperature. The
temperature gradient gives rise to new terms in the equation for the order
parameter. Surface terms induced in effective actions by abrupt temperature
changes provide a natural theoretical framework for understanding the occurence
of both continuous and discontinuous behavior in the order parameter. Monte
Carlo simulation of pure QCD shows both kinds of interfacial behavior.
Perturbation theory predicts a universal profile in the high temperature phase,
which can be tested by Monte Carlo simulation.Comment: 3 pages, contribution to Lattice '94 conference, self-extracting
(revised only to include heplat number in line below
Book Review: Apologia Pro Beata Maria Virgine: John Henry Newman’s Defence of the Virgin Mary in Catholic Doctrine and Piety
Book Review: No abstract available
New Phases of SU(3) and SU(4) at Finite Temperature
The addition of an adjoint Polyakov loop term to the action of a pure gauge
theory at finite temperature leads to new phases of SU(N) gauge theories. For
SU(3), a new phase is found which breaks Z(3) symmetry in a novel way; for
SU(4), the new phase exhibits spontaneous symmetry breaking of Z(4) to Z(2),
representing a partially confined phase in which quarks are confined, but
diquarks are not. The overall phase structure and thermodynamics is consistent
with a theoretical model of the effective potential for the Polyakov loop based
on perturbation theory.Comment: 18 pages, 17 figures, RevTeX
Center Symmetry and Abelian Projection at Finite Temperature
At finite temperature, there is an apparent conflict between Abelian
projection and critical universality. For example, should the deconfinement
transition of an SU(2) gauge theory projected to U(1) lie in the Z(2)
universality class of the parent SU(2) theory or in the U(1) universality
class? I prove that the projected theory lies in the universality class of the
parent gauge theory. The mechanism is shown to be non-local terms in the
projected effective action involving Polyakov loops. I connect this to the
recent work by Dunne et al. on the deconfinement transition in the 2+1
dimensional Georgi-Glashow model.Comment: 3 pages, no figures, Lattice 2002 conference contribution,
Lattice2002(topology
PT symmetry and large-N models
Recently developed methods for PT-symmetric models can be applied to
quantum-mechanical matrix and vector models. In matrix models, the calculation
of all singlet wave functions can be reduced to the solution a one-dimensional
PT-symmetric model. The large-N limit of a wide class of matrix models exists,
and properties of the lowest-lying singlet state can be computed using WKB. For
models with cubic and quartic interactions, the ground state energy appears to
show rapid convergence to the large-N limit. For the special case of a quartic
model, we find explicitly an isospectral Hermitian matrix model. The Hermitian
form for a vector model with O(N) symmetry can also be found, and shows many
unusual features. The effective potential obtained in the large-N limit of the
Hermitian form is shown to be identical to the form obtained from the original
PT-symmetric model using familiar constraint field methods. The analogous
constraint field prescription in four dimensions suggests that PT-symmetric
scalar field theories are asymptotically free.Comment: 15 pages, to be published in J. Phys. A special issue on Pseudo
Hermitian Hamiltonians in Quantum Physic
Phase diagrams of SU(N) gauge theories with fermions in various representations
We minimize the one-loop effective potential for SU(N) gauge theories
including fermions with finite mass in the fundamental (F), adjoint (Adj),
symmetric (S), and antisymmetric (AS) representations. We calculate the phase
diagram on S^1 x R^3 as a function of the length of the compact dimension,
beta, and the fermion mass, m. We consider the effect of periodic boundary
conditions [PBC(+)] on fermions as well as antiperiodic boundary conditions
[ABC(-)]. The use of PBC(+) produces a rich phase structure. These phases are
distinguished by the eigenvalues of the Polyakov loop P. Minimization of the
effective potential for QCD(AS/S,+) results in a phase where | Im Tr P | is
maximized, resulting in charge conjugation (C) symmetry breaking for all N and
all values of (m beta), however, the partition function is the same up to
O(1/N) corrections as when ABC are applied. Therefore, regarding orientifold
planar equivalence, we argue that in the one-loop approximation C-breaking in
QCD(AS/S,+) resulting from the application of PBC to fermions does not
invalidate the large N equivalence with QCD(Adj,-). Similarly, with respect to
orbifold planar equivalence, breaking of Z(2) interchange symmetry resulting
from application of PBC to bifundamental (BF) representation fermions does not
invalidate equivalence with QCD(Adj,-) in the one-loop perturbative limit
because the partition functions of QCD(BF,-) and QCD(BF,+) are the same. Of
particular interest as well is the case of adjoint fermions where for Nf > 1
Majorana flavour confinement is obtained for sufficiently small (m beta), and
deconfinement for sufficiently large (m beta). For N >= 3 these two phases are
separated by one or more additional phases, some of which can be characterized
as partially-confining phases.Comment: 39 pages, 26 figures, JHEP3; references added, small corrections mad
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