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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 $λ_g^*$ and $λ_q^*$ for gluons and quarks. For λ_g < λ_g^* (λ_q < λ_q^*), τ_g^{NEQ}/τ_g^{EQ} (τ_q^{NEQ}/τ_q^{EQ}) decreases strongly with increasing fugacity, while for $λ_g > λ_g^* (λ_q>λ_q^*$), 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 Deby mass as the infrared cutoff.