Illuminating the charged leptons in the proton

TL;DR

This paper proposes using QED Compton scattering in ultraperipheral proton-nucleus collisions at the LHC to constrain the charged lepton content inside the proton, which is crucial for understanding proton structure and new physics searches.

Contribution

It introduces a novel method to measure the lepton parton distribution functions inside the proton using ultraperipheral collisions at the LHC.

Findings

Cross section estimates vary with different lepton PDF models

Feasibility of experimental analysis demonstrated

Potential to constrain electron, muon, and tau content inside proton

Abstract

The description of the structure of proton is fundamental in order to describe the standard model processes at the LHC as well as for the searching of New Physics. Quantum fluctuations imply the presence of photons and leptons inside the proton, which admit a parton distribution function (PDF). Although the lepton PDFs are expected to be small, its presence opens new production mechanisms. In order to explore the lepton - induced processes at the LHC, a precise determination of the leptonic content of the proton is needed. In this paper we propose to constrain the content of charged leptons inside the proton through the study of the QED Compton scattering in ultraperipheral proton - nucleus collisions at the LHC. We estimate the total cross sections and associated distributions considering different models for the lepton PDFs and distinct lepton flavours. We demonstrate that a future experimental analysis of this process is feasible and that it can be used to constrain the content of electrons, muons and taus inside the proton.