Combinatorics of Boundaries in String Theory

TL;DR

This paper explores how nonperturbative effects in string theory can be understood as boundary effects on the world-sheet, especially in Dirichlet string theory, highlighting their exponential suppression related to the string coupling.

Contribution

It introduces a new formulation of Dirichlet string theory emphasizing the role of boundaries and their nonperturbative effects, which differ from previous approaches.

Findings

Boundaries in string world-sheets can encode nonperturbative effects.

Nonperturbative boundary effects are weighted by exponential factors involving the inverse string coupling.

A new perspective on Dirichlet string theory formulation is proposed.

Abstract

We investigate the possibility that stringy nonperturbative effects appear as holes in the world-sheet. We focus on the case of Dirichlet string theory, which we argue should be formulated differently than in previous work, and we find that the effects of boundaries are naturally weighted by $e^{-O(1/g_{\rm st})}$.