Interaction between Noncommutative Open String and Closed-String Tachyon

TL;DR

This paper constructs a vertex operator for closed-string tachyon emission from a noncommutative open string, revealing constraints from the background B field and a coupling constant behavior similar to the zero B field case.

Contribution

It introduces a vertex operator for closed-string tachyon emission in a noncommutative open string framework, highlighting background field effects and coupling characteristics.

Findings

Vertex operator exists only under specific momentum constraints.

Coupling constant g(σ) varies as sin^2 σ, matching the B=0 case.

Constraints from the B field influence the emission process.

Abstract

We construct a vertex operator which describes an emission of the ground-state tachyon of the closed string out of the noncommutative open string. Such a vertex operator is shown to exist only when the momentum of the closed-string tachyon is subject to some constraints coming from the background $B$ field. The vertex operator has a multiplicative coupling constant $g(\sigma )$ which depends on $\sigma $ as $g(\sigma)=\sin^2 \sigma $ in $0 \le \sigma \le \pi $. This behavior is the same as in the ordinary B=0 case.