https://doi.org/10.1140/epja/i2012-12033-6
Letter
No Sommerfeld resummation factor in 
?
1
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
* e-mail: simone.pacetti@pg.infn.it
Received:
14
December
2011
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
