Stretched Strings in Noncommutative Field Theory

TL;DR

This paper investigates IR/UV mixing in noncommutative field theories by analyzing one-loop open string amplitudes with an external B-field, revealing that IR/UV effects originate from intermediate stretched open strings.

Contribution

It provides a detailed string theory derivation showing IR/UV mixing as a consequence of intermediate stretched strings, clarifying its origin at the string level.

Findings

IR/UV mixing is linked to intermediate stretched strings.

The effect is a pure open string phenomenon.

The analysis isolates the IR/UV behavior at the string theory level.

Abstract

Motivated by recent discussions of IR/UV mixing in noncommutative field theories, we perform a detailed analysis of the non-planar amplitudes of the bosonic open string in the presence of an external B-field at the one-loop level. We carefully isolate, at the string theory level, the contribution which is responsible for the IR/UV behavior in the field theory limit. We show that it is a pure open string effect by deriving it from the factorization of the one-loop amplitude into the disk amplitudes of intermediate open string insertions. We suggest that it is natural to understand IR/UV mixing as the creation of intermediate ``stretched strings''.