Dilepton photoproduction on a deuteron target

TL;DR

This paper explores how measuring lepton pair production on deuterons can precisely determine the deuteron charge radius, potentially surpassing current electron scattering measurements and distinguishing between electronic and muonic values.

Contribution

It demonstrates the sensitivity of the $ ext{γ}d o l^+ l^- d$ process to the deuteron charge radius and proposes a measurement approach with high precision.

Findings

Cross section dominated by Bethe-Heitler process at small momentum transfer

A 0.1% measurement accuracy can improve deuteron charge radius precision

Potential to differentiate between electronic and muonic atomic charge radii

Abstract

We investigate the sensitivity of the cross section for lepton pair production off a deuteron target, $\gamma d \to l^+ l^- d$, to the deuteron charge radius. We show that for small momentum transfers the Bethe-Heitler process dominates, and that it is sensitive to the charge radius such that a cross section ratio measurement of about $0.1 \%$ relative accuracy could give a deuteron charge radius more accurate that the current electron scattering value and sufficiently accurate to distinguish between the electronic and muonic atomic values.