Thermal relaxation time in chemically non-equilibrated quark-gluon plasma

The definition of thermal relaxation time is extended to chemically non-equilibrated quark-gluon plasma and the chemical non-equilibrated thermal relaxation times for partons are calculated using the non-equilibrium Debye mass as the infrared regulator. The dependence of the thermal relaxation time on the fugacity is given and the influence of the chemical non-equilibration is discussed. We find that there are threshold fugacities λg* and λq* for gluons and quarks. for λg<λg*(λq<λq*), τgNEQ/τgEQ (τqNEQ/τqEQ) decreases strongly with increasing fugacity, while for λg>λg*(λq>λq*), the ratios are almost 1. It is shown that there is also the two-stage equilibration in a chemically non-equilibrated plasma. We also discussed the effect of using the non-equilibrium Debye mass as the infrared cutoff. (orig.)