Third Zemach Moment of the Proton

TL;DR

This paper calculates the third Zemach moment of the proton using high-precision electron scattering data, showing it cannot account for the proton radius discrepancy observed in muonic hydrogen measurements.

Contribution

It provides a new calculation of the third Zemach moment based on experimental form factor data, challenging recent claims that it could explain the proton radius puzzle.

Findings

Existing data exclude a large third Zemach moment

The calculated moment cannot resolve the proton radius discrepancy

Contradicts recent claims suggesting a larger Zemach moment

Abstract

Modern electron scattering experiments have determined the proton electric form factor, G_{Ep}(Q^2), to high precision. We utilize this data, represented by the different form factor parametrizations, to compute the third Zemach moment of the proton charge distribution. We find that existing data rule out a value of the third Zemach moment large enough to explain the current puzzle with the proton charge radius determined from the Lamb shift in muonic hydrogen. This is in contrast with the recent claim of De Rujula [arXiv:1008.3861].