Remarks on the proton charge radius

TL;DR

This paper calculates the proton charge radius using dispersion relations and electromagnetic form factors, highlighting the sensitivity to experimental data and the need for more precise measurements to resolve discrepancies.

Contribution

It introduces a dispersion relation-based calculation of the proton charge radius and discusses its sensitivity to experimental data at small momentum transfer.

Findings

Calculated proton charge radius slightly larger than Lamb shift measurements.

Result sensitivity to small-momentum transfer data.

Emphasizes need for more accurate experimental data.

Abstract

Proton charge radius is calculated from the electromagnetic form factor of proton parameterized by the dispersion relation. The calculated charge radius is a little larger than that obtained by the Lamb shift of the $\mu$ mesic atom. As the result is sensitive to the experimental data of proton electric form factor at small momentum transfer, more accurate data are required to draw conclusion if the result of the nucleon form factor is different or not from that obtained Pohl et al.