出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：The effective coupling of QCD is measured by using the gauge configurations produced by the
MILC collaboration in which the Kogut Susskind (KS) fermion is incorporated and by using
that produced by the RBC/UKQCD collaboration in which the domain wall fermion (DWF) is
incorporated. We fix the gauge to the Landau gauge and to the Coulomb gauge. The infrared
effective coupling in the Coulomb gauge agrees with the recent extraction at JLab, but that in the
Landau gauge shows infrared suppression. The suppression is expected to be due to the color
anti-symmetric ghost propagator which in the unquenched configurations has stronger infrared
singularity than the color diagonal ghost propagator. The Coulomb form factor in the infrared
depends on the kind of the fermion incorporated in the system and the temperature.
The quark has the effect of quenching randomness and the fluctuation of the color anti-symmetric
ghost propagator is reduced in the unquenched configuration, and the Kugo-Ojima parameter c is
closer to 1 in the unquenched configuration than in the quenched configuration.
