Quark Confinement in C-periodic Cylinders at Temperatures above Tc ∗

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-periodic cylinder of cross section A = L x L y and length L z ≫ L x , L y containing deconfined gluons, regions of different high temperature Z Z(3) phases are aligned along the z-direction, separated by deconfined-decon-fined interfaces. In this geometry, the free energy of a single static quark diverges in proportion to L z. Hence, paradoxically, the quark is confined , although the temperature T is larger than T c. At T ≈ T c , the confined phase coexists with the three deconfined phases. The deconfined-deconfined interfaces can be completely or incompletely wet by the confined phase. The free energy of a quark behaves differently in these two cases. In contrast to claims in the literature, our results imply that deconfined-deconfined interfaces are not Euclidean artifacts, but have observable consequences in a system of hot gluons.