Measurement of the neutron charge radius and the role of its constituents

The neutron is a cornerstone in our depiction of the visible universe. Despite the neutron zero-net electric charge, the asymmetric distribution of the positively- (up) and negatively-charged (down) quarks, a result of the complex quark-gluon dynamics, lead to a negative value for its squared charge radius, rn2. The precise measurement of the neutron's charge radius thus emerges as an essential part of unraveling its structure. Here we report on a rn2 measurement, based on the extraction of the neutron electric form factor, GEn, at low four-momentum transfer squared (Q(2)) by exploiting the long known connection between the N ->Delta quadrupole transitions and the neutron electric form factor. Our result, rn2=-0.1100.008 (fm2), addresses long standing unresolved discrepancies in the rn2 determination. The dynamics of the strong nuclear force can be viewed through the precise picture of the neutron's constituent distributions that result into the non-zero rn2 value. The charge radius of nucleons provides information about their structure. Here the authors present a method, based values of neutron electric form factors, to determine the charge radius of the neutron and provide information on improving the uncertainty of neutron charge radius measurements

Automated summary

The neutron, despite its zero-net electric charge, has a negative squared charge radius due to the asymmetric distribution of quarks. The precise measurement of its charge radius is crucial in understanding its structure. This study presents a new method for determining the charge radius of the neutron based on values of neutron electric form factors.