NS Open Strings with B Field and Their Interactions with NS Closed Strings

TL;DR

This paper investigates how NS open strings interact with NS closed strings, specifically tachyons and gravitons, in the presence of a background B field on D-branes, revealing unique singularity behaviors due to boundary conditions.

Contribution

It demonstrates that B fields do not impose constraints on certain vertex operators but cause singularities linked to boundary conditions, offering new insights into string interactions.

Findings

No constraints from B field on these vertex operators.

Singularities occur at string ends due to Dirichlet boundary conditions.

Interactions depend on external momenta and boundary conditions.

Abstract

We consider interactions of a NS open string with first important states of a NS closed string, i.e., a closed-string tachyon and a graviton, where both ends of the NS open string are attached on a D-brane, and a constant background B field is lying along directions parallel to the D-brane world volume. Contrary to general expectations, there are no constraints on these vertex operators coming from the B field. However, we point out that these vertex operators have singularities at both ends of the NS open string when external momenta take some values. These kinds of singularities essentially come from the Dirichlet boundary conditions along directions transverse to the D-brane world volume.