Superstring 'ending' on super-D9-brane: a supersymmetric action functional for the coupled brane system

TL;DR

This paper develops a supersymmetric action functional for the interaction between a superstring and a super-D9-brane in type IIB string theory, revealing conditions for endpoint interactions and describing various coupled system phases.

Contribution

It introduces a novel supersymmetric action functional for the coupled superstring and super-D9-brane system, including restrictions on gauge field interactions and phase descriptions.

Findings

Interaction requires restrictions on gauge field strength at string endpoints.

Without restrictions, equations reduce to free superstring or super-D9-brane.

Different phases of the coupled system are characterized.

Abstract

A supersymmetric action functional describing the interaction of the fundamental superstring with the D=10, type IIB Dirichlet super-9-brane is presented. A set of supersymmetric equations for the coupled system is obtained from the action principle. It is found that the interaction of the string endpoints with the super-D9-brane gauge field requires some restrictions for the image of the gauge field strength. When those restrictions are not imposed, the equations imply the absence of the endpoints, and the equations coincide either with the ones of the free super-D9-brane or with the ones for the free closed type IIB superstring. Different phases of the coupled system are described. A generalization to an arbitrary system of intersecting branes is discussed.