1,161 research outputs found
Quarkyonic matter in lattice QCD at strong coupling
We study the phase diagram of quark matter at finite temperature and density
in the strong coupling lattice QCD with one species of unrooted staggered
fermions including finite coupling () effects for color SU(). We
find that we may have partially chiral restored medium density matter at
, which would correspond to the quarkyonic matter suggested at large
.Comment: 9 pages, 4 figure
Another mean field treatment in the strong coupling limit of lattice QCD
We discuss the QCD phase diagram in the strong coupling limit of lattice QCD
by using a new type of mean field coming from the next-to-leading order of the
large dimensional expansion. The QCD phase diagram in the strong coupling limit
recently obtained by using the monomer-dimer-polymer (MDP) algorithm has some
differences in the phase boundary shape from that in the mean field results. As
one of the origin to explain the difference, we consider another type of
auxiliary field, which corresponds to the point-splitting mesonic composite.
Fermion determinant with this mean field under the anti-periodic boundary
condition gives rise to a term which interpolates the effective potentials in
the previously proposed zero and finite temperature mean field treatments.
While the shift of the transition temperature at zero chemical potential is in
the desirable direction and the phase boundary shape is improved, we find that
the effects are too large to be compatible with the MDP simulation results.Comment: Talk given at 28th International Symposium on Lattice Field Theory
(Lattice 2010), Villasimius, Sardinia, Italy, 14-19 June, 201
Chiral and deconfinement transitions in strong coupling lattice QCD with finite coupling and Polyakov loop effects
We investigate chiral and deconfinement transitions in the framework of the
strong coupling lattice QCD for color SU(3) with one species of unrooted
staggered fermion at finite temperature and quark chemical potential. We take
account of the leading order Polyakov loop terms as well as the
next-to-next-to-leading order (1/g^4) fermionic terms of the strong coupling
expansion in the effective action. We investigate the Polyakov loop effects by
comparing two approximation schemes, a Haar measure method (no fluctuation from
the mean field) and a Weiss mean-field method (with fluctuations). The
effective potential is obtained in both cases, and we analytically clarify the
Polyakov loop contributions to the effective potential. The Polyakov loop is
found to suppress the chiral condensate and to reduce the chiral transition
temperature at mu=0, and the chiral transition temperature roughly reproduces
the Monte Carlo results at beta=2N_c/g^2 \lesssim 4. The deconfinement
transition is found to be the crossover and first order for light (am_0
\lesssim 4 at beta=4) and heavy quark masses, respectively.Comment: 13 pages, 15 figures. v2; More dicussions added, figures improved,
and typos correcte
Effective Potential in the Strong-coupling Lattice QCD with Next-to-Next-to-Leading Order Effects
We derive an analytic expression of the effective potential at finite
temperature (T) and chemical potential (mu) in the strong-coupling lattice QCD
for color SU(3) including next-to-next-to-leading order (NNLO) effects in the
strong coupling expansion. NNLO effective action terms are systematically
evaluated in the leading order of the large dimensional (1/d) expansion, and
are found to come from some types of connected two plaquette configurations. We
apply the extended Hubbard-Stratonovich transformation and a gluonic dressed
fermion technique to the effective action, and obtain the effective potential
as a function of T, mu, and two order parameters; chiral condensate and a
vector potential field. The next-to-leading order (NLO) and NNLO effects result
in modifications of the wave function renormalization factor, quark mass and
chemical potential. We find that T_{c,mu=0} and mu_{c,T=0} are similar to the
NLO results, whereas the position of the critical point is sensitive to NNLO
corrections.Comment: 27 pages, 10 figures. v2; More dicussions added, figures improved,
and typos correcte
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