# Probing subnucleon scale fluctuations in ultraperipheral heavy ion collisions

## TL;DR

This paper demonstrates that incorporating subnucleon scale fluctuations, constrained by HERA data, significantly impacts the incoherent diffractive J/Ψ production cross section and transverse momentum spectra in ultraperipheral heavy ion collisions, providing new predictive insights.

## Contribution

It introduces a model for subnucleon fluctuations constrained by HERA data, revealing their significant effect on diffractive J/Ψ production in heavy ion collisions.

## Key findings

- Increased incoherent to coherent cross section ratio by a factor of about 2.
- Modified transverse momentum spectra of J/Ψ at higher momenta.
- Predictions for J/Ψ production at LHC and RHIC energies.

## Abstract

We show that introducing subnucleon scale fluctuations constrained by HERA diffractive $J/\Psi$ production data significantly affects the incoherent diffractive $J/\Psi$ production cross section in ultraperipheral heavy ion collisions. We find that the inclusion of the additional fluctuations increases the ratio of the incoherent to the coherent cross section approximately by a factor of $2$, and modifies the transverse momentum spectra of the produced $J/\Psi$ at momenta larger than the scale that corresponds to the distance scale of the subnucleonic fluctuations. We present predictions for $J/\Psi$ production in ultraperipheral heavy ion collisions at $\sqrt{s_{NN}}=5.02\,{\rm TeV}$ at the LHC and $200\,{\rm GeV}$ at RHIC.