# Quarkonium as relativistic bound state on the light front

## TL;DR

This paper models charmonium and bottomonium as relativistic bound states using light-front holography, incorporating a longitudinal confinement and one-gluon exchange to improve spectroscopy and compute various properties.

## Contribution

It introduces a novel light-front holographic model with longitudinal confinement and running coupling for heavy quarkonia, enhancing spectral accuracy and wave function analysis.

## Key findings

- Improved mass spectra for charmonium and bottomonium
- Accurate decay constants and radii calculations
- Detailed light-front wave functions and distributions

## Abstract

We study charmonium and bottomonium as relativistic bound states in a light-front quantized Hamiltonian formalism. The effective Hamiltonian is based on light-front holography. We use a recently proposed longitudinal confinement to complete the soft-wall holographic potential for the heavy flavors. The spin structure is generated from the one-gluon exchange interaction with a running coupling. The adoption of asymptotic freedom improves the spectroscopy compared with previous light-front results. Within this model, we compute the mass spectroscopy, decay constants and the r.m.s. radii. We also present a detailed study of the obtained light-front wave functions and use the wave functions to compute the light-cone distributions, specifically the distribution amplitudes and parton distribution functions. Overall, our model provides a reasonable description of the heavy quarkonia.