2 research outputs found
Viscosities of Hot Gluon -- A Lattice QCD Study --
We present transport coefficients (shear viscosity, , and bulk
viscosity, ) for the gluon system obtained by the lattice QCD. This is
an indispensable calculation towards the understanding of ``New State of
Matter'' observed in RHIC. We study the temperature regions of RHIC () and much higher ones up to . In RHIC regions,
the ratio of shear viscosity to entropy density, , is around , and satisfies the KSS bound. At high temperature, becomes two
or three oder of magnitude larger. Our calculation has two limitations: (i) the
use of the quench approximation, i.e., without quark pair creation-annihilation
effects on vacuum, and (ii) the use of an ansatz for the spectral function. The
first point has been well studied in calculations of the spectroscopy and the
phase-transition behavior. To investigate the second point, we compare our
results with perturbative calculations in high -regions, and also check the
effects of the modification of the spectral function on the viscosity.Comment: 4 pages, 2 figures, contribution to Proceedings of Quark Matter 2005,
Budapest, Aug 4-