Observation of induced Chern-Simons term in P- and T-violating superconductors

We show in this letter that P- and T-odd terms of the electromagnetic poten tials (P; parity, Tt time reversal) are induced and lead an unusual phenome non in P- and T-violating superconductors discovered recently. The Ginzburg -Landau action includes this term in a gauge invariant manner. The coeffici ent of the term is nearly topological invariant with a small correction and equals to the fine structure constant approximately. The unusual 'Hall eff ect' without external magnetic field could be observed by a SQUID. (C) 1999 Published by Elsevier Science B.V. All rights reserved.