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Extraction of proton form factors in the timelike region from unpolarized e+e- --> p pbar events

A. Bianconi·B. Pasquini·M. Radici
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Abstract

We have performed numerical simulations of the unpolarized e+e- --> p pbar process in kinematic conditions under discussion for a possible upgrade of the existing DAFNE facility. By fitting the cross section angular distribution with a typical Born expression, we can extract information on the ratio |G_E/G_M| of the proton electromagnetic form factors in the timelike region within a 5-10% uncertainty. We have explored also non-Born contributions to the cross section by introducing a further component in the angular fit, which is related to two-photon exchange diagrams. We show that these corrections can be identified if larger than 5% of the Born contribution, and if relative phases of the complex form factors do not produce severe cancellations.

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A. Bianconi, B. Pasquini, M. Radici. 2006-06-29. Extraction of proton form factors in the timelike region from unpolarized e+e- --> p pbar events. https://doi.org/10.1103/physrevd.74.034009

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