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Production of the exclusive $γγ\rightarrow J/ψ+γ$ process in proton-proton ultraperipheral collisions

Meng-Kun Jia, Xiao-Bo Jin, Kui-Yong Liu, Guang-Zhi Xu

TL;DR

This paper investigates exclusive $\gamma\gamma \to J/\psi + \gamma$ production in proton-proton ultraperipheral collisions at $\sqrt{s_{NN}}=14~\text{TeV}$. Using NRQCD with a color-singlet mechanism, it computes the short-distance coefficients at NLO in $\alpha_s$ with photon fluxes derived from the proton's electric-dipole form factor (EDFF) that explicitly depend on the impact parameter $b$. The study reports LO and NLO cross sections of $\sigma_{\rm LO}=155~\text{fb}$ and $\sigma_{\rm NLO}=107.5$–$130~\text{fb}$, corresponding to a $K$-factor of about $0.64$–$0.82$ and highlighting a moderate $\alpha_s$-driven suppression; it also shows that including the no-inelastic survival probability lowers cross sections relative to unit survival models. The results indicate that HL-LHC could yield up to roughly $10^3$ signal events per year after incorporating $J/\psi \to \mu^+\mu^-$ decays, enabling precision studies of heavy-quarkonium production and charm-quark hadronization in pp UPCs. The work underlines the importance of an explicit $b$-dependent flux treatment and motivates further NNLO refinements to reduce theoretical uncertainties and guide future experiments with forward detectors.

Abstract

In this work, we present a next-to-leading-order (NLO) study of $J/ψ+ γ$ production via photon-photon fusion in proton-proton ultraperipheral collisions (UPCs) at $\sqrt{s_{NN}} = 14$ TeV. The calculation is performed within the nonrelativistic Quantum Chromodynamics (NRQCD) framework, where we employ photon parton distribution functions derived from the proton's electric-dipole form factor (EDFF) and explicitly retain their dependence on the impact parameter $b$. Our calculation yields cross sections of $155$ fb at leading order and between $107.5$ fb and $130$ fb at NLO in $α_s$, demonstrating a moderate but manageable $α_s$ suppression. Despite this reduction, the process retains a sufficiently large cross section to be observable in future high-luminosity measurements.

Production of the exclusive $γγ\rightarrow J/ψ+γ$ process in proton-proton ultraperipheral collisions

TL;DR

This paper investigates exclusive production in proton-proton ultraperipheral collisions at . Using NRQCD with a color-singlet mechanism, it computes the short-distance coefficients at NLO in with photon fluxes derived from the proton's electric-dipole form factor (EDFF) that explicitly depend on the impact parameter . The study reports LO and NLO cross sections of and –, corresponding to a -factor of about – and highlighting a moderate -driven suppression; it also shows that including the no-inelastic survival probability lowers cross sections relative to unit survival models. The results indicate that HL-LHC could yield up to roughly signal events per year after incorporating decays, enabling precision studies of heavy-quarkonium production and charm-quark hadronization in pp UPCs. The work underlines the importance of an explicit -dependent flux treatment and motivates further NNLO refinements to reduce theoretical uncertainties and guide future experiments with forward detectors.

Abstract

In this work, we present a next-to-leading-order (NLO) study of production via photon-photon fusion in proton-proton ultraperipheral collisions (UPCs) at TeV. The calculation is performed within the nonrelativistic Quantum Chromodynamics (NRQCD) framework, where we employ photon parton distribution functions derived from the proton's electric-dipole form factor (EDFF) and explicitly retain their dependence on the impact parameter . Our calculation yields cross sections of fb at leading order and between fb and fb at NLO in , demonstrating a moderate but manageable suppression. Despite this reduction, the process retains a sufficiently large cross section to be observable in future high-luminosity measurements.

Paper Structure

This paper contains 4 sections, 9 equations, 2 figures, 1 table.

Table of Contents

  1. Introduction
  2. THEORETICAL FRAMEWORK
  3. Numerical Results and Discussion
  4. Conclusion

Figures (2)

  • Figure 1: (Color online) The differential cross sections $d\sigma / dp_T$ [fb/GeV] in different rapidity ranges at $\sqrt{S_{NN}}=14~\text{TeV}$. The dashed line represents the LO results. The shaded band corresponds to the NLO results, and the band is obtained by varying the scale between $\mu_r/2$ and $2\mu_r$. The solid line in the band indicates the central value with the renormalization scale set to $\mu_r = \sqrt{x_1x_2s}$.
  • Figure 2: (Color online) The differential cross sections $d\sigma / dy$ [fb] at $\sqrt{S_{NN}}=14~\text{TeV}$. The dashed line represents the LO results. The shaded band corresponds to the NLO results, and the band is obtained by varying the scale between $\mu_r/2$ and $2\mu_r$. The solid line in the band indicates the central value with the renormalization scale set to $\mu_r = \sqrt{x_1x_2s}$.