Effective string picture for confining gauge theories at finite temperature

We study the ''effective string picture'' of confinement, deriving theoretical predictions for the interquark potential at finite temperature. At low temperatures, the leading string correction to the linear confining potential between a heavy quark-antiquark pair is the ''Luescher term''. Assuming a Nambu-Goto effective string action, subleading contributions can be worked out in an analytical way. We also discuss the contribution given by a possible ''boundary term'' in the effective action, and compare these predictions with high precision results from simulations of lattice Z2 gauge theory in three dimensions, obtained with an algorithm that exploits the duality of the Z2 gauge model with the Ising spin model. (orig.)