Exclusive photoproduction ofJ/Ψ and Ψ′ mesons in proton-proton collisions

Anna Cisek,Wolfgang Schäfer,Antoni Szczurek

doi:10.1051/epjconf/20148104001

Abstract

We present results based on our new paper (1). The amplitude for the γp → Vp reaction is calculated in a pQCD kt-factorization approach. The corresponding total cross section for different unintegrated gluon distributions is calculated and compared with new HERA data for photon-proton collisions. We also compare the total cross section for γp → Vpreaction with recent data extracted by the LHCb collaboration. The amplitude for γp → Vpis used to predict cross section for exclusive photoproduction of J/ψ and ψ � mesons in proton-proton collisions. Both Dirac and Pauli electromagnetic form factors are included in the calculation and results are compared with results when only Dirac form factor is included. The effect of Pauli form factor is quantified. Absorption effects are included and their uncertainties are discussed. Different differential distributions e.g. in J/ψ(ψ � ) rapidity and transverse momentum are presented and compared with existing experimental data for the Tevatron and LHC energy.

Highlights

Several years ago in Ref.[2] the exclusive production of J/ψ meson in pp and ppcollisions was discussed including absorptive corrections and using a γp → J/ψp amplitude extracted from HERA data
The formalism exposed in detail in [4] allows to test unintegrated gluons distributions (UGDF’s)
The imaginary part of the amplitude depends on the unintegrated gluon distibution function (UGDF) F(xe f f, κ2) and on the wave function of the vector meson ψV (z, k2) and for Δ = 0 and Q2 = 0 is given by the formula [3]:

Summary

Introduction

Several years ago in Ref.[2] the exclusive production of J/ψ meson in pp and ppcollisions was discussed including absorptive corrections and using a γp → J/ψp amplitude extracted from HERA data. In [3] we discussed the exclusive production of Υ mesons, where a microscopic calculation of the γp → Υp amplitude was performed within a a kt-factorization approach. Besides the unintegrated gluon distribution, the second ingredient for the calculation is the light-cone wave function of the meson.

Results

Conclusion