Contrary to the reaction ˉpp → 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 ˉpp mass 2m, in the reaction ˉpd → e+e-n the value of M can take values near or below the ˉpp mass. In the antiproton-deuteron electromagnetic annihilation, this allows to access the proton electromagnetic form factors in the timelike region of q2 near the ˉpp threshold. We estimate the cross-section dσˉpd→e+e-n/dM for an antiproton beam momentum of 1.5 GeV/c. We find that near the ˉpp 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 ˉpd → e+e-n in the context of the PANDA project.
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