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No Sommerfeld resummation factor in $e^ + e^ - \to p\bar p$ ?

Abstract

The Sommerfeld rescattering formula is compared to the $e^ + e^ - \to p\bar p$ BABAR data at threshold and above. While there is the expected Coulomb enhancement at threshold, two unexpected outcomes have been found: the modulus of the proton form factor is normalized to one at threshold, i.e. |G p (4M p 2 )| = 1, as a pointlike fermion, and, moreover, data show that the resummation factor in the Sommerfeld formula is not needed. Other e + e → baryon-antibaryon cross-sections show similar behavior near threshold.

This article is published with open access at Springerlink.com
Communicated by J. Bijnens