https://doi.org/10.1140/epja/i2009-10884-4
Regular Article - Theoretical Physics
Antiproton-nucleus electromagnetic annihilation as a way to access the proton timelike form factors
1
Laboratoire de Physique Corpusculaire, Université Blaise Pascal, IN2P3, 63177, Aubière Cedex, France
2
Lebedev Physical Institute, Leninsky Prospekt 53, 119991, Moscow, Russia
* e-mail: helene@clermont.in2p3.fr
Received:
1
September
2009
Accepted:
1
October
2009
Published online:
20
October
2009
Contrary to the reaction 
p
e
+
e
- with a high-momentum incident antiproton on a free target proton at rest, in which the invariant mass M of the e
+
e
- pair is necessarily much larger than the
p mass 2m , in the reaction
d
e
+
e
-
n the value of M can take values near or below the
p mass. In the antiproton-deuteron electromagnetic annihilation, this allows to access the proton electromagnetic form factors in the timelike region of q2 near the
p threshold. We estimate the cross-section 
for an antiproton beam momentum of 1.5GeV/c. We find that near the
p threshold this cross-section is about 1pb/MeV. The case of heavy-nuclei target is also discussed. Elements of experimental feasibility are presented for the process
d
e
+
e
-
n in the context of the 
ANDA project.
PACS: 25.43.+t Antiproton-induced reactions – / 14.20.Dh Protons and neutrons – / 13.40.Gp Electromagnetic form factors –
© SIF, Springer-Verlag Berlin Heidelberg, 2009
