Casimir effects in superstring theories

Abstract

Compactification of the space in superstring theories is studied by calculating the one-loop effective potential provided that the supersymmetry is softly broken by some mechanism. The Casimir energy of closed string modes is shown to compactify the ten-dimensional Minkowski space M 10 into a stable M d ×T 10− d (1⩽ d<10) with a i= α′ R i =1 , where α′ and R i are the Regge slope and the ith radius of the torus T 10− d , respectively. In the SST-I model, although the closed string (gravity) sector decouples from the open string (Yang-Mills) sector in α′ → 0 limit, the former functions as an initiator as well as a stabilizer of the compactification.