T-duality in the string theory effective action with a string source

TL;DR

This paper demonstrates that T-duality symmetry remains valid in the low-energy effective action of string theory even when a classical fundamental string source is present.

Contribution

It explicitly shows T-duality invariance in the effective action with a classical string source, extending previous results to include sources.

Findings

T-duality holds with string sources included

Explicit transformation properties derived

Supports consistency of string theory with sources

Abstract

We consider the T-duality transformations of the low-energy quantum string theory effective action in the presence of classical fundamental string source and demonstrate explicitly that T-duality still holds.