Nucleon form factors and final state radiative corrections to $e^{+}{e}^{-}\to \overline{p}p\gamma$

New parametrizations for the electric and the magnetic form factors of a proton and neutron are presented. The proton form factors describe well the recent measurements by the BABAR Collaboration and earlier ones of the ratio of the form factors in a spacelike region. The neutron form factors are consistent with earlier measurements of neutron pair production and ratio of the form factors in the spacelike region. These form factors are implemented into the generator phokhara, which simulates the reactions $e^{+}{e}^{-}\to \overline{p}p\gamma$ and $e^{+}{e}^{-}\to \overline{n}n\gamma$. The influence of final state radiation is investigated.

Figure 1

The experimental data compared to the model fits results.

Figure 2

The experimental data compared to the model fits results.

Figure 3

The experimental data compared to the model fits results. Ratio of the electric and magnetic proton form factors in spacelike (upper plot) and timelike (lower plot) regions.

Figure 4

The experimental data compared to the model fits results. Neutron-antineutron production cross section (upper plot) and ratio of the electric and magnetic neutron form factors in the spacelike region (lower plot).

Figure 5

The experimental data [36] compared to the model fit results. The data points and fit results are overlaid for most cases. On the horizontal axis, the entry number from Table IV of [36] is given.

Figure 6

Relative difference between $Q^2$ distributions calculated at NLO with and without FSR radiative corrections and between complete FSR corrections and FSR corrections where only the Coulomb factor is included.

Figure 7

Relative difference between $Q^2$ distributions calculated at NLO with and without FSR radiative corrections and between complete FSR corrections and FSR corrections where only the Coulomb factor is included.

Figure 8

The cross section of the reaction $e^{+}{e}^{-}\to \overline{p}p$ with ISR at next-to-next-to-leading-order corrections included is compared to the same cross section where, in addition, FSR Coulomb corrections were added.