EPJ Web Conf.
Volume 218, 2019The 11th International Workshop on e+e− Collisions from Phi to Psi (PhiPsi 2017)
|Number of page(s)||6|
|Section||Baryon Form Factors and Proton Radius|
|Published online||18 October 2019|
Nucleon form factors at threshold
Budker Institute of Nuclear Physics, Novosibirsk, Russia
* e-mail: A.I.Milstein@inp.nsk.su
** This work is supported in part by the Russian Science Foundation (project 14-50-00580)
Published online: 18 October 2019
The pp¯invariant mass spectra in the processes e+e−→ pp¯, e+e−→ nn¯, J/ψ → pp¯ω, J/ψ → pp¯ρ, and J/ψ → pp¯γ close to the pp¯is discussed. The optical potentials for NN¯pair in the superposition of S and D waves (due to tensor forces) at spin unity of the pair, as well as for NN¯pair in the S wave at spin zero of the pair, are proposed. The parameters of the potentials are obtained by fitting the cross sections of NN¯scattering together with the pp¯invariant mass spectra in e+e−→ pp¯annihilation and J/ψ decays. Good agreement with the available experimental data is achieved. Using our potential and the Green’s function approach we also describe the cross section of e+ e−→ 6π and the η’π+ π− invariant mass spectrum in the decay J/ψ → γη’π+π− in the energy region near the NN¯threshold.
© The Authors, published by EDP Sciences, 2019
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