Proton radius from electron-proton scattering and chiral perturbation theory

TL;DR

This paper estimates the proton charge radius by fitting low-$Q^2$ electron-proton scattering data using chiral perturbation theory, resulting in a value that bridges previous muonic and atomic measurements.

Contribution

It introduces a novel method of fixing higher moments to chiral perturbation theory predictions in the radius extraction process.

Findings

Proton radius estimated as 0.857(11) fm.

Result lies between muonic hydrogen and CODATA values.

Method provides a new approach to radius determination.

Abstract

We determine the root-mean-square proton charge radius, $R_{\rm p}$, from a fit to low-$Q^2$ electron-proton elastic scattering cross section data with the higher moments fixed (within uncertainties) to the values predicted by chiral perturbation theory. We obtain $R_{\rm p}=0.857(11)$ fm. This number falls between the value obtained from muonic hydrogen analyses and the CODATA value (based upon atomic hydrogen spectroscopy and electron-proton scattering determinations).