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arXiv · 1406.4579

Electromagnetic Contribution to the Proton-Neutron Mass Splitting

A. W. Thomas·X. G. Wang·R. D. Young
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Abstract

We study the electromagnetic contribution to the proton-neutron mass splitting by combining lattice simulations and the modified Cottingham sum rule of Walker-Loud, Carlson and Miller. This analysis yields an estimate of the isovector nucleon magnetic polarizability as a function of pion mass. The physical value, obtained by chiral extrapolation to the physical pion mass, is $β_{p-n}=(-1.12 \pm 0.40)\times 10^{-4}\ \mathrm{fm}^3$, which is in agreement with the empirical result, albeit with a somewhat smaller error. As a result, we find $δM^γ_{p-n}=1.04 \pm 0.11\ \mathrm{MeV}$, which represents a significant improvement in precision.

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A. W. Thomas, X. G. Wang, R. D. Young. 2014-06-18. Electromagnetic Contribution to the Proton-Neutron Mass Splitting. https://doi.org/10.1103/physrevc.91.015209

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