Thomas-Fermi approximation for gauge theories

An effective field approximation, similar to the atomic Thomas-Fermi approach, is proposed for studying non-Abelian gauge theories which includes finite-volume effects. As applications of the formalism the equation of state for an SU(2) gauge theory with massless fermions is obtained. The extensions to realistic situations are briefly discussed. {copyright} {ital 1997} {ital The American Physical Society}