# Gluo-dissociation of Heavy Quarkonium in the Quark-Gluon Plasma Revisited

## TL;DR

This paper revisits the calculation of heavy quarkonium gluo-dissociation in quark-gluon plasma by including both electric and magnetic dipole transitions, revealing the magnetic contribution's significance near the threshold.

## Contribution

It introduces the chromo-magnetic dipole ($M_1$) transition mechanism into the calculation, showing its importance alongside the electric dipole ($E_1$) in quarkonium dissociation rates.

## Key findings

- $M_1$ contribution is significant near threshold, especially for $J/\psi$.
- Including $M_1$ increases the dissociation rate by 10-25%.
- Results align with previous $E_1$ calculations but extend understanding of magnetic effects.

## Abstract

Using an effective Hamiltonian derived from the QCD multipole expansion, we calculate the cross sections of gluo-dissociation of heavy quarkonia in the quark-gluon plasma, by including both the chromo-electric dipole ($E_1$) as well as the chromo-magnetic dipole ($M_1$) transition mechanisms. While the former allows to reproduce the results from operator-product-expansion calculations in the Coulomb approximation, the latter as a novel contribution is shown to be significant at low energies close to the threshold. Using thus obtained cross sections, we further carry out a full calculation of the gluo-dissociation rates for various charmonia and bottomonia within a non-relativitic in-medium potential model. The $M_1$ contribution turns out to be most prominent for the $J/\psi$ and accounts for $\sim 10\%-25\%$ of the total ($E1+M1$) dissociation rate at temperatures close to the transition temperature.