Antiproton-nucleus electromagnetic annihilation as a way to access the proton timelike form factors
Abstract
Contrary to the reaction pbar + 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 (pbar p) mass, in the reaction pbar + d --> n e+ e- the value of M can take values near or below the (pbar p) mass. In the antiproton-deuteron electromagnetic annihilation, this allows to access the proton electromagnetic form factors in the time-like region of q^2 near the (pbar p) threshold. We estimate the cross section dsigma(pbar +d --> e+ e- n)/dM for an antiproton beam momentum of 1.5 GeV/c. We find that near the (pbar p) threshold this cross section is about 1 pb/MeV. The case of heavy nuclei target is also discussed. Elements of experimental feasibility are presented for the process pbar + d --> n e+ e- in the context of the Panda project.
Keywords
Cite
@article{arxiv.0909.0186,
title = {Antiproton-nucleus electromagnetic annihilation as a way to access the proton timelike form factors},
author = {H. Fonvieille and V. Karmanov},
journal= {arXiv preprint arXiv:0909.0186},
year = {2009}
}
Comments
14 pages, 11 figures. submitted to EPJA