EPJ Web of Conferences 95, 01015 (2015)
https://doi.org/10.1051/epjconf/20159501015

Proton electromagnetic form factors: present status and future perspectives at PANDA

¹ CEA, IRFU, SPhN, Saclay, 91191 Gif-sur-Yvette Cedex, France
² CNRS/IN2P3, Institut de Physique Nucléaire, UMR 8608, 91406 Orsay, France

^a e-mail: etomasi@cea.fr

Published online: 29 May 2015

Abstract

Data and models on electromagnetic proton form factors are reviewed, highlighting the contribution foreseen by the PANDA collaboration. Electromagnetic hadron form factors contain essential information on the internal structure of hadrons. Precise and surprising data have been obtained at electron accelerators, applying the polarization method in electron-proton elastic scattering. At electron-positron colliders, using initial state radiation, BABAR measured proton time-like form factors in a wide time-like kinematical region and the BESIII collaboration will measure very precisely proton and neutron form factors in the threshold region. In the next future an antiproton beam with momentum up to 15 GeV/c will be available at FAIR (Darmstadt). Measurements of the reaction p̅ + p → e⁺ + e⁻ by the PANDA collaboration will contribute to the individual determination of electric and magnetic form factors in the time-like region of momentum transfer squared, as well as to their first determination in the unphysical region (below the kinematical threshold), through the reaction p̅ + p → e⁺ + e⁻ + π⁰. From the discussion on feasibility studies at PANDA, we focus on the consequences of such measurements in view of an unified description of form factors in the full kinematical region. We present models which have the necessary analytical requirements and apply to the data in the whole kinematical region.