83 research outputs found

### Thermodynamic Lattice Study for Preconformal Dynamics in Strongly Flavored Gauge Theory

By using the lattice Monte-Carlo simulation, we investigate the finite
temperature (T) chiral phase transition at color SU(3) gauge theories with
various species of fundamental fermions, and discuss the signal of the
(pre-)conformality at large Nf (num. of flavors.) via their comparisons. As Nf
increases, we observe stronger fermion screening effects which result from a
larger fermion multiplicity. We investigate a finite T step-scaling associated
with a uniqueness of the critical temperature (Tc) at each Nf, then the
vanishing step-scaling indicates the emergence of the conformality around Nf* =
10 - 12. Further, motivated by the functional renormalization group analyses,
we examine the Nf dependence of Tc, whose vanishing behavior indicates the
onset of conformal window around Nf* = 9 - 10.Comment: 5 pages, 5 figures, Proceedings for Extreme QCD 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

### 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

### 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 ($1/g^2$) effects for color SU($N_c$). We
find that we may have partially chiral restored medium density matter at
$N_c=3$, which would correspond to the quarkyonic matter suggested at large
$N_c$.Comment: 9 pages, 4 figure

### Schwinger-Dyson Study for Walking/Conformal Dynamics with IR Cutoffs

Motivated by recent progress on many flavor QCD on a lattice, we investigate
conformal/walking dynamics by using Schwinger-Dyson (SD) equation within an
improved ladder approximation for two-loop running coupling. By numerically
solving the SD equation, we obtain a pole mass $m_{p}$, pion decay constant
$f_{\pi}$, and investigate the chiral symmetry breaking and mass anomalous
dimension $\gamma_{m}$ in the presence of IR cutoffs $\Lambda_{\mathrm{IR}}$.
We find that the chiral symmetry breaking is suppressed \ if IR cutoff
$\Lambda_{\mathrm{IR}}$ becomes larger than the critical \ value near the
dynamical mass ($\Lambda_{\mathrm{IR}}$ $\simeq m_{D}$) In the conformal phase
the $\gamma_{m}$ is strongly suppressed by IR cutoffs for $\Lambda
_{\mathrm{IR}}$ $\simeq m_{p}$. We, then, obtain finite size hyperscaling (FSS)
relation by adapting a linearized approximation for the SD equation, and
examine the $\gamma_{m}$ The results offer valuable insight and suggestion for
analyses in lattice gauge theories.Comment: 5 pages,2 figures; Presented at Sakata Memorial KMI Workshop on
"Origin of Mass and Strong Coupling Gauge Theories" (SCGT15

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