BRST-INVARIANT APPROACH TO QUANTUM-MECHANICAL TUNNELING

A new approach with BRST invariance is suggested to cure the degenerac y problem of ill defined path integrals in the path-integral calculati on of quantum mechanical tunneling effects in which the problem arises due to the occurrence of zero modes, The Faddeev-Popov procedure is a voided and the integral over the zero mode is transformed in a systema tic way into a well defined integral over instanton positions. No spec ial procedure has to be adopted as in the Faddeev-Popov method in calc ulating the Jacobian of the transformation, The quantum mechanical tun neling for the sine-Gordon potential is used as a test of the method a nd the width of the lowest energy band is obtained in exact agreement with that of WKB calculations.