Locality and causality properties of light cone string field theory

Abstract

The recent discovery of a new maximally supersymmetric background for the type IIB superstring theory has revived the interest in light cone string field theory. This background is a plane wave background with the additional support of a non- trivial self dual Ramond-Ramond 5-form field strength. It can be quantised in the light cone gauge and hence it naturally fits into the framework of light cone string field theory. In this thesis we re-examine the causality and locality properties of string theory in the flat background and compare it with the recent results for string theory in this plane wave background. We formulate the causality requirement in terms of the commutativity of the string field, as it is usually done in point particle field theory. We find that the string light cone in the plane wave background shares similar properties with the string light cone in the flat background. Even more interesting is that, unlike the flat background theory, string interactions in the plane wave background do not modify the causal structure of the theory. This has interesting consequences for the choice of the 3-string vertex in the plane wave background, a topic that is still an active subject of research.