Muon production in low-energy electron-nucleon and electron-nucleus scattering

TL;DR

This paper analyzes Standard-Model muon production in low-energy electron-nucleon and electron-nucleus scattering, showing these processes can overshadow signals of new physics and discussing ways to enhance the muon signal.

Contribution

It identifies Standard-Model processes that mimic lepton-flavor violation signals and evaluates their cross sections, providing insights for future experimental searches.

Findings

Standard-Model muon production cross sections are significantly larger than lepton-flavor-violating signals.

Nuclear targets can potentially enhance the muon production signal.

Standard processes can obscure beyond-Standard-Model physics in electron-nucleon scattering.

Abstract

Recently, muon production in electron-proton scattering has been suggested as a possible candidate reaction for the identification of lepton-flavor violation due to physics beyond the Standard Model. Here we point out that the Standard-Model processes $e^- p \to \mu^- p \bar{\nu}_\mu \nu_e$ and $e^- p \to e^- n \mu^+ \nu_\mu$ can cloud potential beyond-the-Standard-Model signals in electron-proton collisions. We find that Standard-Model $e p \to \mu X$ cross sections exceed those from lepton-flavor-violating operators by several orders of magnitude. We also discuss the possibility of using a nuclear target to enhance the $e p \to \mu X$ signal.