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arXiv · 2008.05806

Sum rule for the Compton amplitude and implications for the proton-neutron mass difference

J. Gasser·H. Leutwyler·A. Rusetsky
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Abstract

The Cottingham formula expresses the leading contribution of the electromagnetic interaction to the proton-neutron mass difference as an integral over the forward Compton amplitude. Since quarks and gluons reggeize, the dispersive representation of this amplitude requires a subtraction. We assume that the asymptotic behaviour is dominated by Reggeon exchange. This leads to a sum rule that expresses the subtraction function in terms of measurable quantities. The evaluation of this sum rule leads to $m_{QED}^{p-n}=0.58\pm 0.16\,\mbox{MeV}$.

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J. Gasser, H. Leutwyler, A. Rusetsky. 2020-08-13. Sum rule for the Compton amplitude and implications for the proton-neutron mass difference. https://doi.org/10.1140/epjc%2Fs10052-020-08615-2

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