The size of the proton - closing in on the radius puzzle

TL;DR

This paper uses a dispersive framework and continued fraction analysis on recent electron-proton scattering data to precisely determine the proton's electric and magnetic radii, addressing the longstanding radius puzzle.

Contribution

It introduces a dispersive analysis combined with continued fraction methods to accurately extract proton radii from scattering data, aligning with recent muonic hydrogen results.

Findings

Proton electric radius: 0.84 fm

Proton magnetic radius: 0.86 fm

Results consistent with muonic hydrogen measurements

Abstract

We analyze the recent electron-proton scattering data from Mainz using a dispersive framework that respects the constraints from analyticity and unitarity on the nucleon structure. We also perform a continued fraction analysis of these data. We find a small electric proton charge radius, r_E^p = 0.84_{-0.01}^{+0.01} fm, consistent with the recent determination from muonic hydrogen measurements and earlier dispersive analyses. We also extract the proton magnetic radius, r_M^p = 0.86_{-0.03}^{+0.02} fm, consistent with earlier determinations based on dispersion relations.