Very stringent experimental bounds exist on the amount of P and CP violation
in strong interactions. Nevertheless, the presence of non-Abelian topological
solutions and the axial anomaly make the issue of CP invariance in QCD
non-trivial ("the strong CP problem"). Even in the absence of a global P and CP
violation the fluctuations of topological charge in the QCD vacuum are expected
to play an important role in the breaking of chiral symmetry, and in the mass
spectrum and other properties of hadrons. Here I argue that topological
fluctuations in hot QCD matter can become directly observable in the presence
of a very intense external magnetic field by inducing local P- and CP- odd
effects. These local parity-violating phenomena can be described by using the
Maxwell-Chern-Simons, or axion, electrodynamics as an effective theory. Local P
and CP violation in hot QCD matter can be observed in experiment through the
"chiral magnetic effect" - the separation of electric charge along the axis of
magnetic field that is created by the colliding relativistic ions. There is a
recent evidence for the electric charge separation relative to the reaction
plane of heavy ion collisions from the STAR Collaboration at RHIC.Comment: 10 pages, 2 figures; presented at the 25th Winter Workshop on Nuclear
Dynamics, Big Sky, Montana, February 1-8, 200