2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/112474We discuss the shear viscosity of the quark matter by using the Kubo-Mori formula. It is found that the shear viscosity is expressed in terms of the quark spectral function. If the spectral function is approximated by a modified Bright-Wigner type, the viscosity decreases as the width of the spectral function increases. We also discuss dependence of the shear viscosity on the temperature and the density.4pages, 4figuresHigh Energy Physics - Phenomenologytext