Broadening of particle distributions in electron- and (anti)neutrino-nucleus scattering from QED interactions

TL;DR

This paper investigates how QED interactions within the nucleus cause broadening of lepton distributions, affecting the interpretation of electron and neutrino scattering data by accounting for multiple photon re-scattering effects.

Contribution

It provides a quantitative analysis of Glauber photon-mediated re-scattering effects on lepton momentum broadening inside nuclei, a novel application of in-medium QED effects.

Findings

Lepton transverse momentum inside the nucleus is increased by about 10 MeV.

QED effects significantly deflect electron tracks and suppress scattering cross sections.

Neutrino scattering effects are notable only at kinematic endpoints.

Abstract

Proper interpretation of past, current, and future data on lepton-nucleus reactions requires a clear separation between quantum electrodynamics (QED) and strong interaction effects inside the nucleus. First studies of QED in-medium lepton dynamics have set a theoretical framework to derive electron-nucleus and (anti)neutrino-nucleus cross-section corrections. We employ this approach to quantitatively compute the effects of Glauber photon-mediated multiple re-scattering within the nuclear medium. We find that the relativistic charged lepton acquires momentum of order $10~\mathrm{MeV}$ transverse to its direction of propagation inside the nucleus. This broadening sizably deflects expected electron tracks and suppresses scattering cross sections. Precise extraction of the nucleon and nuclear structure by electron and muon probes should, thus, take the QED nuclear medium angular redistribution of particles into account. Our results further show that the associated effects in (anti)neutrino-nucleus scattering with measured final-lepton energy are significant only at the kinematical endpoints.