QED is not endangered by the proton's size

TL;DR

This paper argues that the recent precise measurement of the proton's charge radius from muonic hydrogen does not threaten the validity of Quantum Electrodynamics (QED) or require new physics beyond the standard model.

Contribution

It provides a critical analysis showing that the discrepancy in proton radius measurements does not undermine QED or imply new physics, countering recent claims of potential anomalies.

Findings

The proton radius discrepancy does not invalidate QED.

The suggested need for new physics is unsubstantiated.

The Rydberg constant remains consistent with existing data.

Abstract

Pohl et al. have reported a very precise measurement of the Lamb-shift in muonic Hydrogen, from which they infer the radius characterizing the proton's charge distribution. The result is 5 standard deviations away from the one of the CODATA compilation of physical constants. This has been interpreted as possibly requiring a 4.9 standard-deviation modification of the Rydberg constant, to a new value that would be precise to 3.3 parts in $10^{13}$, as well as putative evidence for physics beyond the standard model. I demonstrate that these options are unsubstantiated.