arXiv subjects

Yusuke Taniguchi

Publications and source records attributed to Yusuke Taniguchi.

58 records · Page 4Linked to original sources

arXiv1998

Perturbative Renormalization Factors of Bilinear Quark Operators for Improved Gluon and Quark Actions in Lattice QCD

We calculate one-loop renormalization factors of bilinear quark operators for gluon action including six-link loops and $O(a)$-improved quark action in the limit of massless quark. We find that finite parts of one-loop coefficients of renormalization factors diminish monotonically as either of the coefficients $c_1$ or $c_2+c_3$ of the six-link terms are decreased below zero. Detailed numerical results are given, for general values of the clover coefficient, for the tree-level improved gluon action in the Symanzik approach $(c_1=-1/12, c_2=c_3=0)$ and for the choices suggested by Wilson $(c_1=-0.252, c_2=0, c_3=-0.17)$ and by Iwasaki $(c_1=-0.331, c_2=c_3=0$ and $c_1=-0.27, c_2+c_3=-0.04)$ from renormalization-group analyses. Compared with the case of the standard plaquette gluon action, finite parts of one-loop coefficients are reduced by 10--20% for the Symanzik action, and approximately by a factor two for the renormalization-group improved gluon actions.

hep-lat↗

arXiv1995

Chiral Symmetry Restoration at Finite Temperature and Chemical Potential in the Improved Ladder Approximation

The chiral symmetry of QCD is studied at finite temperature and chemical potential using the Schwinger-Dyson equation in the improved ladder approximation. We calculate three order parameters; the vacuum expectation value of the quark bilinear operator, the pion decay constant and the quark mass gap. We have a second order phase transition at the temperature $T_c=169$ MeV along the zero chemical potential line, and a first order phase transition at the chemical potential $μ_c=598$ MeV along the zero temperature line. We also calculate the critical exponents of the three order parameters.

hep-ph↗

arXiv1995

Color Confinement in Perturbation Theory from a Topological Model,

Color confinement by the mechanism of Kugo and Ojima can treat confinement of any quantized color carrying fields including dynamical quarks. However, the non-perturbative condition for this confinement has been known to be satisfied only in the pure-gauge model (PGM), which is a topological model without physical degrees of freedom. Here we analyze the Yang-Mills theory by adding physical degrees of freedom as perturbation to PGM. We find that quarks and gluons are indeed confined in this perturbation theory.

hep-th↗

arXiv1994

Finite Temperature Deconfining Transition in the BRST Formalism

We present a toy model study of the high temperature deconfining transition in Yang-Mills theory as a breakdown of the confinement condition proposed by Kugo and Ojima. Our toy model is a kind of topological field theory obtained from the Yang-Mills theory by taking the limit of vanishing gauge coupling constant $g_{\rm YM}\to 0$, and therefore the gauge field $A_μ$ is constrained to the pure-gauge configuration $A_μ=g^{\dagger}\partial_μg$. At zero temperature this model has been known to satisfy the confinement condition of Kugo and Ojima which requires the absence of the massless Nambu-Goldstone-like mode coupled to the BRST-exact color current. In the finite temperature case based on the real-time formalism, our model in 3+1 dimensions is reduced, by the Parisi-Sourlas mechanism, to the ``sum'' of chiral models in 1+1 dimensions with various boundary conditions of the group element $g(t,x)$ at the ends of the time contour. We analyze the effective potential of the $SU(2)$ model and find that the deconfining transition in fact occurs due to the contribution of the sectors with non-periodic boundary conditions.

hep-th↗