Exclusive coherent production of heavy vector mesons in nucleus-nucleus collisions at energies available at the CERN Large Hadron Collider

Abstract

Heavy nuclei at collider energies are a source of high energy Weizsäcker-Williams photons.This photon flux may be utilized to study high energy photon-nucleus interactions. Here we concentrate on the coherent diffractive production of heavy vector mesons on nuclear targets and show how it probes the unintegrated glue of the nucleus in the saturation domain. We present predictions for rapidity distributions of exclusive coherent J/Ψ and Υ mesons which can be measured by the ALICE experiment at the LHC.

Accessing transverse nucleon and gluon distributions in heavy nuclei using coherent vector meson photoproduction at high energies in ion ultraperipheral collisions

“…In the J/ψ case, this mechanism can be contrasted with predictions of other approaches available in the literature. In the k t -factorization approach [43], the unintegrated nuclear gluon distribution receives contributions from multiple scattering of both quark-antiquark (so-called Glauber regime) and quark-antiquark-gluon dipoles on a nucleus, which determine the initial condition for the nonlinear evolution equation. Note that the successful description of the proton diffractive structure functions measured in ep DIS at HERA requires both quark-antiquark and quark-antiquark-gluon dipoles in the color dipole formalism; it provides a connection to our leading twist approach, where the nuclear gluon shadowing is determined by the gluon diffractive parton distribution of the proton.…”

Coherent photoproduction ofψandΥmesons in ultraperipheralpPb and PbPb collisions at the CERN Large Hadron Collider atAdeluyi1, Nguyen2 2013Phys. Rev. C231200View full textAdd to dashboardCite

“…Effects of gluon shadowing are investigated and potentials for constraining nuclear gluon modifications are discussed. On the theory front it has been extensively studied at various energies and for different collision systems (see for instance [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]). Diverse approaches ranging from models based on perturbative Quantum Chromodynamics (pQCD) to Color Dipole models and k T factorization have been used to study coherent and incoherent photoproduction of heavy mesons.…”

Photoproduction of J/ψin Pb–Pb and p–Pb collisions at the LHC with the ALICE detector

“…The measured cross section in the forward and in the central rapidity regions has been compared to five recent theoretical calculations [11][12][13][14][15]. The comparison is shown in Figure 2a [10].…”

“…GM [12] is based on the color dipole model, where the scattering amplitude depends on the nuclear profile and the dipole nucleon cross section, which is taken from the IIM model which incorporates saturation. The CSS [15] model uses a Glauber approach and the color dipole nucleon amplitude based on the unintegrated gluon distribution of the proton. The AB models [14] use the LO pQCD amplitude scaled to fit γp → J/ψ + p data.…”