$J/\psi$ Production by Magnetic Excitation of $\eta_c$

TL;DR

This paper calculates the probability of $J/$ meson production via magnetic excitation of $$ in heavy ion collisions, revealing a small but significant transition probability and polarization aligned with the magnetic field.

Contribution

It introduces a novel calculation of $J/$ production through magnetic excitation using both heavy quark effective theory and chiral perturbation theory.

Findings

Transition probability is approximately 2 x 10^{-4}.

Produced $J/$ polarization aligns with magnetic field direction.

Magnetic excitation provides a new mechanism for charmonium production.

Abstract

We compute the probability of $J/\psi$ production from the interaction between $\eta_c$ and the strong magnetic field generated in relativistic heavy ion collisions. The computation is first carried out in the heavy quark effective model, in which the M1 radiative transition is considered. Then we investigate the transition in the framework of non-relativistic heavy hadron chiral perturbation theory and show that the polarization of $J/\psi$ produced by this process is parallel to the direction of magnetic field and thus perpendicular to the reaction plane. The transition probability obtained in both approaches is of order $2\times 10^{-4}$.