Electromagnetic proton-neutron mass difference

Abstract

We discuss the Cottingham formula and evaluate the proton-neutron electromagnetic mass difference exploiting the state-of-the-art phenomenological input. We decompose individual contributions to the mass splitting into Born, inelastic and subtraction terms. We evaluate the subtraction-function contribution from the experimental input only and the Born term accounting for the modern low-$Q^2$ data.

Comments: 5 pages, 3 figures, journal version