# Charmonium spectrum and diffractive production in a light-front Hamiltonian approach

## TL;DR

This paper develops a light-front Hamiltonian approach to compute charmonium spectra and wavefunctions, applying them to predict diffractive production cross sections that align with experimental data, enhancing understanding of meson structure and gluon distributions.

## Contribution

It introduces a basis light-front quantization method with a specific interaction model to calculate charmonium properties and production cross sections, providing a new theoretical framework for heavy quarkonium studies.

## Key findings

- Cross sections agree with HERA, RHIC, and LHC data.
- Excited state production ratios are less model-dependent.
- Future measurements can refine quarkonium wavefunctions.

## Abstract

We study exclusive charmonium production in diffractive deep inelastic scattering and ultra-peripheral heavy-ion collisions within the dipole picture. The mass spectrum and light-front wavefunctions of charmonium are obtained from the basis light-front quantization approach, using the one-gluon exchange interaction plus a confining potential inspired by light-front holography. We apply these light-front wavefunctions to exclusive charmonium production. The resulting cross sections are in reasonable agreement with electron-proton collision data at HERA and ultra-peripheral nucleus collision measurements at RHIC and LHC. The charmonium cross-section has model dependence on the dipole model. We observe that the cross-section ratio of excited states to the ground state has a weaker dependence than the cross-section itself. We suggest that measurements of excited states of heavy quarkonium production in future electron-ion collision experiments will impose rigorous constraints on heavy quarkonium light-front wavefunctions, thus improving our understanding of meson structure, which eventually will help us develop a precise description of the gluon distribution function in the small-$x$ regime.