Cottingham formula for the electromagnetic self-energy contribution to M_p - M_n
arXiv:1210.7777
Abstract
We provide an update of the determination of the electromagnetic self-energy contribution to M_p - M_n based upon Cottingham's Formula. A technical oversight in the literature is uncovered: the application of the Cottingham Formula requires the use of a subtracted dispersion integral; an argument to evade the subtraction function was presented; the argument was based on false assumptions about the scaling violations of the parton model, a point first mentioned by J. C. Collins. We elucidate this point and utilize low-energy effective theory to relate the unknown subtraction function to the nucleon isovector magnetic polarizability. This allows us to provide the first reliable determination of dM = 1.30(03)(47) MeV [1].
arXiv commentProceedings of The 30th International Symposium on Lattice Field Theory, June 24-29, 2012, Cairns, Australia
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