Lepton pair production in muon-nucleus scattering

TL;DR

This paper investigates lepton pair production in muon-nucleus scattering to assess its impact as a background in the MUonE experiment, using a detailed Monte Carlo simulation to improve the understanding of this process.

Contribution

It provides a detailed numerical study of lepton pair production as a background in muon-electron scattering experiments, implementing a fully differential Monte Carlo generator without angular approximations.

Findings

Lepton pair production can significantly affect MUonE measurements.

The MESMER generator accurately models the process with no angular approximations.

Results help refine background estimates for muon-electron scattering experiments.

Abstract

The MUonE experiment aims at providing a novel determination of the leading hadronic contribution to the muon anomalous magnetic moment through the study of elastic muon-electron scattering. Since the initial-state electrons are bound in a low-$Z$ atomic target, the interaction between the incoming muons and the nuclei is expected to be the main source of experimental background. In this article, we study the production of a real lepton pair from the muon-nucleus scattering, discussing its numerical impact in the MUonE kinematic configuration. The process is described as a scattering of a muon in an external Coulomb field with the addition of a form factor to describe the nuclear charge distribution. The calculation is implemented in the fully differential Monte Carlo event generator MESMER, without introducing any approximation on the angular variables.