Proton decay in four dimensional superstring models

Abstract

In this paper, we discuss the contraints that emerge from baryon nonconserving processes in theSU(4)×O(4) andSU(5)×U(1) models derived in the fermionic formulation of the four dimensional superstring. We examine dimension five baryon violating operators arising a) from Higgs exchange diagrams, and b) from non-renormalisable terms which arise from the exchange of massive string states. Both kinds of the above operators put non-trivial constraints on the matter field assignments and on the vevs of various singlet fields of the string models under consideration.