出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：RHIC is now confirming the discovery of the “New State of Matter”, whose properties are gradually
revealed by experimental data. It is not the free gas state, but well described by a fluid
with very small viscosity. It is now highly desired to calculate the value of the viscosity from the
fundamental theory, i.e., QCD just above the transition temperature. In this report we present our
calculation of the transport coefficient of gluon system on 243 8 lattice in the quench approximation.
Simulations are carried out in the range, 1:4 T=Tc 24. In the temperature region
slightly above the transition, where the perturbative calculation is not applicable, the shear viscosity
is smaller than typical hadron masses. The bulk viscosity is consistent with zero within the
range of error bars in 1:4 T=Tc 24. We compare our results with the perturbative calculations
in large T=Tc region. It is found that the lattice and perturbative results are consistent with each
other there. The ratio h=s is around 0:10:4 in T=Tc < 3 region and satisfies the KSS bound. In
order to estimate the contribution from high frequency part of the spectral function, we add a term,
rhigh, proposed by Aarts and Resco[3]. It is found that until the threshold mass becomes small, its
effect is quite small, and that viscosity decreases as the threshold decreses. From these studies we
think that although our result is obtained under an assumptions for the spectral function, it gives
a reasonable estimation for dr=dw at w = 0, and qualitative results will not be changed when the
accurate spectral function is obtained.
