Exclusive $\mathrm{J/}\psi$ photoproduction off protons in ultra-peripheral p-Pb collisions at $\sqrt{s_{\rm NN}}=5.02$ TeV
Phys.Rev.Lett. 113 (2014) 232504, 2014.
The ALICE collaboration

Abstract (data abstract)
CERN-LHC. We present the first measurement at the LHC of exclusive J/PSI photoproduction off protons, in ultra-peripheral proton-lead collisions at sqrt(sNN) = 5.02 TeV. Events are selected with a dimuon pair produced either in the rapidity interval, in the laboratory frame, 2.5 < YRAP < 4 (p-Pb) or -3.6 < y < -2.6 (Pb-p), and no other particles observed in the ALICE acceptance. The data set used in this analysis corresponds to an integrated luminosity of 3.9 nb^{-1} +- 3.2% (syst) for p-Pb collisions and 4.5 nb^{-1} +- 3.0% (syst) for Pb-p collisions. The measured cross sections SIGMA(GAMMA P --> J/PSI P) are 33.2 +- 2.2 (stat) +- 3.1 (syst) +- 0.7 (theo) nb in p-Pb and 284 +- 36 (stat) +27,-32 (syst) +- 26 (theo) nb in Pb-p collisions. We measure this process up to about 700 GeV in the GAMMA-P centre-of-mass, which is a factor of two larger than the highest energy studied at HERA. The cross section as a function of the GAMMA-P centre of mass, W(GAMMA P), and the differential cross section as a function of rapidity are also presented along with the product of the photon energy, K, and the photon flux, DN/DK.

Loading Data...