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Diffractive photoproduction of radially excited psi(2S) mesons in photon-Pomeron reactions in PbPb collisions at the CERN LHC

M. B. Gay Ducati, M. T. Griep, M. V. T. Machado

TL;DR

This paper investigates the exclusive photoproduction of radially excited psi(2S) mesons in PbPb collisions at the LHC using the light-cone dipole formalism. It analyzes both coherent and incoherent gamma-A interactions, incorporating the IIM dipole cross section and nuclear gluon shadowing via RG models, to assess how saturation and shadowing shape the psi(2S) cross sections. The study provides predictions for 2.76 TeV PbPb and outlines expected ratios to psi(1S), comparing with ALICE data to constrain the nuclear gluon distribution. The results indicate substantial sensitivity to shadowing, with coherent cross sections offering clear signals of saturation effects and nuclear modifications in heavy-ion environments.

Abstract

In this work we investigate the photoproduction of radially excited vector mesons off nuclei in heavy ion relativistic collisions. In particular, we analyze the exclusive photoproduction of psi(2S) off nuclei, evaluating the coherent and the incoherent contributions to that process. The theoretical framework used in the present analysis is the light-cone dipole formalism and predictions are done for PbPb collisions at the CERN-LHC energy of 2.76 TeV. The theoretical uncertainties are analyzed and comparison is also done to the recent ALICE Collaboration data for the psi(1S) state photoproduction.

Diffractive photoproduction of radially excited psi(2S) mesons in photon-Pomeron reactions in PbPb collisions at the CERN LHC

TL;DR

This paper investigates the exclusive photoproduction of radially excited psi(2S) mesons in PbPb collisions at the LHC using the light-cone dipole formalism. It analyzes both coherent and incoherent gamma-A interactions, incorporating the IIM dipole cross section and nuclear gluon shadowing via RG models, to assess how saturation and shadowing shape the psi(2S) cross sections. The study provides predictions for 2.76 TeV PbPb and outlines expected ratios to psi(1S), comparing with ALICE data to constrain the nuclear gluon distribution. The results indicate substantial sensitivity to shadowing, with coherent cross sections offering clear signals of saturation effects and nuclear modifications in heavy-ion environments.

Abstract

In this work we investigate the photoproduction of radially excited vector mesons off nuclei in heavy ion relativistic collisions. In particular, we analyze the exclusive photoproduction of psi(2S) off nuclei, evaluating the coherent and the incoherent contributions to that process. The theoretical framework used in the present analysis is the light-cone dipole formalism and predictions are done for PbPb collisions at the CERN-LHC energy of 2.76 TeV. The theoretical uncertainties are analyzed and comparison is also done to the recent ALICE Collaboration data for the psi(1S) state photoproduction.

Paper Structure

This paper contains 4 sections, 9 equations, 3 figures.

Table of Contents

  1. Introduction
  2. Photon-pomeron process in relativistic nucleus-nucleus collisions
  3. Results and discussions
  4. Summary

Figures (3)

  • Figure 1: (Color online) The rapidity distribution of coherent $\psi(1S)$ meson photoproduction at $\sqrt{s}=2.76$ TeV in PbPb collisions at the LHC. The theoretical curves stand for color dipole formalism using $R_G=1$ (dot-dashed curve) and two scenarios for the nuclear gluon distribution (solid and long-dashed curves, see text). Data from ALICE collaboration ALICE1ALICE2.
  • Figure 2: (Color online) The rapidity distribution of coherent $\psi(2S)$ meson photoproduction at $\sqrt{s}=2.76$ TeV in PbPb collisions at the LHC. The theoretical curves follow the same notation as in the previous figure.
  • Figure 3: (Color online) The rapidity distribution of incoherent $\psi(1S)$ (solid line) and $\psi(2S)$ (dashed line) meson photoproduction at $\sqrt{s}=2.76$ TeV in PbPb collisions at the LHC. Data from ALICE collaboration ALICE2.