Speaker
Description
Using a data sample of $230~pb^{−1}$ collected with the CMD-3 detector at the VEPP-2000
$e^{+}e^{−}$ collider, we selected about 43k events of the process $e^{+}e^{−} \rightarrow
p\bar{p}$ and measure its cross-section at 29 energy points. The Born cross-section of the process is given by
$$\sigma_{p\bar{p}}(s) = \frac{4\pi\alpha\beta C}{3s}\left[ |G_M(s)|^2 +
\frac{2M_p^2}{s}|G_E|^2 \right],$$
where $\sqrt{s}=2E_{beam}=E_{c.m.}$ is the center-of-mass energy, $M_p$ is the proton mass, and $\beta = \sqrt{1 - 4M_p^2/s}$, $C= y/(1-e^{-y})$, $y = \pi\alpha/\beta$ is the Sommerfeld-Gamov-Sakharov factor which takes into account Coulomb interaction of particles in the final state. From the angular distribution of produced nucleons, we obtain the ratio $|G_{E}/G_{M}|$, which is of great interest because
of the inconsistency between results obtained in the PS170 experiment at LEAR and BaBar latest measurement in the energy region almost entirely covered by this work. Additional interest in this energy range is related to an unusual behaviour of the $e^{+}e^{−} \rightarrow 3(\pi^+\pi^-)$ cross-section near the proton-antiproton threshold.
Preliminary results of the cross-section and form factor ratio measurements will be shown.
