QUARK CONFINEMENT IN C-PERIODIC CYLINDERS AT TEMPERATURES ABOVE T-C

Due to the Gauss law, a single quark cannot exist in a periodic volume , while it can exist with C-periodic boundary conditions. In a C-perio dic cylinder of cross section A = LxLy and length L-z >> L-x,L-y conta ining deconfined gluons, regions of different high temperature Z(3) ph ases are aligned along the z-direction, separated by deconfined-deconf ined interfaces. In this geometry, the free energy of a single static quark diverges in proportion to L-z. Hence, paradoxically, the quark i s confined, although the temperature T is larger than T-c. At T approx imate to T-c, the confined phase coexists with the three deconfined ph ases. The deconfined-deconfined interfaces can be completely or incomp letely wet by the confined phase. The free energy of a quark behaves d ifferently in these two cases. Our results imply that deconfined-decon fined interfaces are not just Euclidean artifacts, but have observable consequences in a system of hot gluons. (C) 1997 Elsevier Science B.V .