Exclusive J/ψ and ψ(2S) production in pp collisions at √s = 7 TeV

Abstract

Exclusive J/ψ and ψ(2S) vector meson production has been observed in the dimuon channel using the LHCb detector. The cross-section times branching fractions to two muons with pseudorapidities between 2.0 and 4.5 are measured to be σpp→J/ψ(→μ+ μ -)(2.0 < ημ± < 4.5) = 307 ±21 ±36 pb σpp→ψ (2S)( →μ+ μ -))(2.0 < ημ± < 4.5) = 7.8 ±1.3 ±1.0 pb where the first uncertainties are statistical and the second are systematic. The measurements are found to be in good agreement with results from previous experiments and theoretical predictions. The J/ψ photoproduction cross-section has been measured as a function of the photon-proton centre-of-mass energy. The results are consistent with measurements obtained at HERA and confirm a similar power law behaviour for the photoproduction cross-section. © CERN 2013 On behalf of the LHCb Collaboration.