Soft photon bremsstrahlung at next-to-leading power

TL;DR

This paper investigates soft photon bremsstrahlung at next-to-leading power, proposing analytic formulas for the differential cross-section relevant for future experimental measurements and discussing loop corrections to Low's theorem.

Contribution

It introduces a new analytic approach for soft photon emission at NLP, adapting techniques from soft gluon resummation for practical numerical use.

Findings

Derived a formula for the differential cross-section with shifted kinematics.

Analyzed the impact of loop corrections to Low's theorem.

Discussed implications for future experimental measurements.

Abstract

The emission of soft radiation provides a fundamental probe of the consistency of the underlying quantum field theory. Correspondingly, the measurement of the soft photon bremsstrahlung, such as the one proposed with the planned future upgrade of the ALICE experiment at the LHC, is of great interest. In this letter we explore the possibility to implement analytic techniques that have been recently developed for soft gluon resummation at Next-to-Leading-Power (NLP) in the context of the soft photon spectrum. We provide a formula for the differential cross-section with shifted kinematics that is particularly suitable for numerical implementations. We also discuss the impact of loop corrections to Low's theorem due to radiative jet functions.