23,370 research outputs found
Spontaneous Breaking of Flavor Symmetry and Parity in the Nambu-Jona-Lasinio Model with Wilson Fermions
We study the lattice \njl~model with two flavors of Wilson fermions in the
large limit, where is the number of `colors'. For large values of the
four-fermion coupling we find a phase in which both, flavor symmetry and
parity, are spontaneously broken. In accordance with general expectations there
are three massless pions on the phase boundary, but only two of them remain
massless inside the broken phase. This is analogous to earlier results obtained
in lattice QCD, indicating that this behavior is a very general feature of the
Wilson term.Comment: 7 pages, 4 figures, LATEX, tared and uuencode
Finite-Temperature Phase Structure of Lattice QCD with the Wilson Quark Action for Two and Four Flavors
We present further analyses of the finite-temperature phase structure of
lattice QCD with the Wilson quark action based on spontaneous breakdown of
parity-flavor symmetry. Results are reported on (i) an explicit demonstration
of spontaneous breakdown of parity-flavor symmetry beyond the critical line,
(ii) phase structure and order of chiral transition for the case of
flavors, and (iii) approach toward the continuum limit.Comment: Poster presented at LATTICE96(finite temperature); 4 pages, Latex,
uses espcrc2 and epsf, seven ps figures include
Chiral perturbation theory with Wilson-type fermions including effects: degenerate case
We have derived the quark mass dependence of , and
, using the chiral perturbation theory which includes the effect
associated with the explicit chiral symmetry breaking of the Wilson-type
fermions, in the case of the degenerate quarks. Distinct features of
the results are (1) the additive renormalization for the mass parameter
in the Lagrangian, (2) corrections to the chiral log ()
term, (3) the existence of more singular term, , generated by
contributions, and (4) the existence of both and terms
in the quark mass from the axial Ward-Takahashi identity, . By
fitting the mass dependence of and , obtained by the
CP-PACS collaboration for full QCD simulations, we have found that the
data are consistently described by the derived formulae. Resumming the most
singular terms , we have also derived the modified formulae, which
show a better control over the next-to-leading order correction.Comment: 21 pages, 4 figures (10 eps files), Revtex4, some discussions and
references added, the final version to appear in PR
Two-dimensional Gross-Neveu Model with Wilson Fermion Action at Finite Temperature and Density
We analytically investigate the 2-dimensional Gross-Neveu model at finite
temperature and density using Wilson fermion action. The relation between the
phase structure on the lattice and that in the continuum is clarified.Comment: LATTICE98(hightemp), 3 pages, 3 eps figure
Ginsparg-Wilson Dirac operator in the monopole backgrounds on the fuzzy 2-sphere
In the previous papers, we studied the 't Hooft-Polyakov (TP) monopole
configurations in the U(2) gauge theory on the fuzzy 2-sphere,and showed that
they have nonzero topological charge in the formalism based on the
Ginsparg-Wilson (GW) relation. In this paper, we will show an index theorem in
the TP monopole background, which is defined in the projected space, and
provide a meaning of the projection operator. We also extend the index theorem
to general configurations which do not satisfy the equation of motion, and show
that the configuration space can be classified into the topological sectors. We
further calculate the spectrum of the GW Dirac operator in the TP monopole
backgrounds, and consider the index theorem in these cases.Comment: Latex2e, 37 pages, 3 figure
Passing through the `chiral limit' in quenched QCD with Wilson fermions
We investigate the limit of vanishing quark mass in quenched lattice QCD with
unimproved Wilson fermions at . Exploiting the correlations of
propagators at different time slices we extract pion masses extremely close to
the `chiral limit', despite the presence of `exceptional configurations'. With
this at hand, the existence of quenched chiral logarithms can be demonstrated,
provided, finite size effects are small. With reference to the phase diagram
proposed by Aoki also the range is investigated. The width
of a potential parity-flavor violating phase can, if at all, hardly be
resolved.Comment: LATTICE98(spectrum
Two-dimensional Lattice Gross-Neveu Model with Wilson Fermion Action at Finite Temperature and Chemical Potential
We investigate the phase structure of the two-dimensional lattice Gross-Neveu
model formulated with the Wilson fermion action to leading order of 1/N
expansion. Structural change of the parity-broken phase under the influence of
finite temperature and chemical potential is studied. The connection between
the lattice phase structure and the chiral phase transition of the continuum
theory is clarified.Comment: 42 pages, 20 EPS figures, using REVTe
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