A study of e+e- -> p anti-p using initial state radiation with BABAR

TL;DR

This study measures the proton-antiproton production cross section and form factors in electron-positron collisions using initial state radiation at BABAR, providing new insights into baryon structure and charmonium decays.

Contribution

It presents the first detailed measurement of the e+e- -> p anti-p cross section and form factor ratio over a broad mass range using initial state radiation at BABAR.

Findings

|G_E/G_M| is significantly larger than 1 below 3 GeV/c^2

Measured J/psi -> p anti-p and psi(2S) -> p anti-p branching fractions

Set upper limit on Y(4260) -> p anti-p production

Abstract

The e+e- -> p anti-p cross section is determined over a range of p anti-p masses, from threshold to 4.5 GeV/c^2, by studying the e+e- -> p anti-p gamma process. The data set corresponds to an integrated luminosity of 232 fb^-1, collected with the BABAR detector at the PEP-II storage ring, at an e+e- center-of-mass energy of 10.6 GeV. The mass dependence of the ratio of electric and magnetic form factors, |G_E/G_M|, is measured for p anti-p masses below 3 GeV/c^2; its value is found to be significantly larger than 1 for masses up to 2.2 GeV/c^2. We also measure J/psi -> p anti-p and psi(2S) -> p anti-p branching fractions and set an upper limit on Y(4260) -> p anti-p production and decay.