Comments to the problem of experimental determination of the neutron-electron scattering length and its theoretical interpretation

TL;DR

This paper reviews experimental data on neutron-electron scattering length and neutron charge radius, showing consistency among measurements and comparing them with theoretical predictions, highlighting the need for improved theoretical models.

Contribution

It critically analyzes 50 years of experimental data on neutron charge radius and compares it with modern theoretical predictions, emphasizing the need for better theoretical accuracy.

Findings

Experimental estimates of <r^2> are consistent and average to -0.1178±0.0037 fm^2.

Modern theories agree with the experimental <r^2> value.

Current theoretical models lack sufficient precision in describing neutron structure.

Abstract

We discuss the experimental data on the n,e-scattering length bne and the values of mean square charge radius of the neutron <r^2> obtained from them. It is shown that the accumulated during the last 50 years most significant experimental estimates of the bne are not contradictory and lead to the average value <r^2>=-0.1178+-0.0037 fm^2. Assuming that all the authors have underestimated the errors of their measurements by a factor of 1.7, the combined fit of all available experimental data would lead to Chi^2~1 per degree of freedom. Different modern theoretical predictions of <r^2> are considered. They are found to be in a good agreement with the obtained experimental value <r^2>. However the existing theoretical description of the structure of neutron does not provide a value of <r^2> with a sufficient accuracy.