No Sommerfeld resummation factor in ?
Museo Storico della Fisica e Centro Studi e Ricerche “E. Fermi”, Rome, Italy
2 INFN, Laboratori Nazionali di Frascati, Frascati, Italy
3 INFN and Dipartimento di Fisica, Università di Perugia, Perugia, Italy
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Revised: 27 January 2012
Accepted: 28 February 2012
Published online: 20 March 2012
The Sommerfeld rescattering formula is compared to the 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.
© SIF, Springer-Verlag Berlin Heidelberg, 2012