A Study of $e^{+} e^{-} \to p \bar{p}$ using initial state radiation with BABAR

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.

Note:

23 pages, 22 postscript figues, submitted to Phys. Rev. D Report-no: BABAR-PUB-05/050, SLAC-PUB-11587

13.66.Bc
13.25.Gv
13.40.Gp
14.20.Dh
electron positron: colliding beams
electron positron: annihilation
radiation: initial-state interaction
p: pair production
angular distribution
p: form factor

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