Parity violation in hot QCD: Why it can happen, and how to look for it

The arguments for the possibility of violation of P and CP symmetries of strong interactions at finite temperature are presented. A new way of observing these effects in heavy ion collisions is proposed—it is shown that parity violation should manifest itself in the asymmetry between positive and negative pions with respect to the reaction plane. Basing on topological considerations, we derive a lower bound on the magnitude of the expected asymmetry, which may appear within the reach of the current and/or future heavy ion experiments.