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arXiv · 1609.06722

On the pi pi continuum in the nucleon form factors and the proton radius puzzle

M. Hoferichter·B. Kubis·J. Ruiz de Elvira·H. -W. Hammer·U. -G. Meißner
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Abstract

We present an improved determination of the $\pi\pi$ continuum contribution to the isovector spectral functions of the nucleon electromagnetic form factors. Our analysis includes the most up-to-date results for the $\pi\pi\to\bar N N$ partial waves extracted from Roy-Steiner equations, consistent input for the pion vector form factor, and a thorough discussion of isospin-violating effects and uncertainty estimates. As an application, we consider the $\pi\pi$ contribution to the isovector electric and magnetic radii by means of sum rules, which, in combination with the accurately known neutron electric radius, are found to slightly prefer a small proton charge radius.

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M. Hoferichter, B. Kubis, J. Ruiz de Elvira, H. -W. Hammer, U. -G. Meißner. 2016-09-21. On the pi pi continuum in the nucleon form factors and the proton radius puzzle. https://doi.org/10.1140/epja/i2016-16331-7

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