Lepton pair production in ultra-peripheral collisions

TL;DR

This paper derives a comprehensive formula for lepton pair production in ultra-peripheral collisions using classical field approximation, connecting it with existing EPA and TMD frameworks, and confirms consistency with experimental data.

Contribution

It introduces a general cross section formula that incorporates corrections beyond EPA and links with TMD factorization, advancing theoretical understanding.

Findings

Derived a general cross section formula in classical field approximation.

Connected the formula with EPA and TMD frameworks.

Numerical results agree with experimental data.

Abstract

The lepton pair production in ultra-peripheral collisions (UPC) is studied in the classical field approximation. We derive a general form of the cross section in terms of photon distributions which depend on the transverse momentum and coordinate based on the wave packet form of nuclear wave functions. Such a general form of the cross section in the classical field approximation contains the results of the generalized equivalent photon approximation (EPA) as well as the corrections beyond EPA in the Born approximation. By rewriting the general form of the cross section in light-cone coordinates, we find a good connection with the transverse momentum dependent distribution (TMD) factorization formalism in the Born approximation. Our numerical results are consistent with current experimental data.