Photoproduction of $J/\psi$ and $Upsilon$ states in exclusive and proton-dissociative diffractive events

Abstract

The amplitude for γ p → V p, where V is a J/ψ or ϒ ground state or excited vector meson, is calculated in a pQCD k T -factorization approach. We use this amplitude to predict the cross section for exclusive photoproduction of J/ψ, ψ ′ , ϒ mesons in proton-proton collisions. Calculations are performed for a variety of unintegrated gluon distributions, and we compare our results to LHCb data. Here we especially focus on the possibilty of constraining saturation effects. Compared to earlier calculations we include both Dirac and Pauli electromagnetic form factors. We discuss the role of the QQ light-cone wave functions for differential distributions for ratios such as σ (ψ ′ )/σ (J/ψ). Absorption effects are always taken into account.

Central production of ρ0 in pp collisions with single proton diffractive dissociation at the LHC

“…Also from the theory point of view these breakup reactions have rarely been studied. In [7,8] the electromagnetic dissociation was estimated to be of the order of 10% (for excited states M X < 2 GeV) of the exclusive cross section for J/ψ production. Here we wish to make first estimates in the case of diffractive proton excitation for ρ 0 production.…”