Masses of Heavy Quarkonium states in magnetized matter -- effects of PV mixing and (inverse) magnetic catalysis

TL;DR

This paper investigates how strong magnetic fields in nuclear matter affect the masses of heavy quarkonium states, considering effects like PV mixing and magnetic catalysis, with implications for heavy ion collision experiments.

Contribution

It introduces a chiral effective model incorporating a scalar dilaton field to study in-medium heavy quarkonium mass modifications under magnetic fields, including PV mixing and inverse magnetic catalysis effects.

Findings

Magnetic fields cause significant mass shifts in heavy quarkonia.

Dirac sea contributions enhance or reduce quark condensates depending on magnetic field strength.

PV mixing and magnetic catalysis effects are prominent at large magnetic fields.

Abstract

We study the in-medium masses of the heavy quarkonium (charmonium and bottomonium) states in isospin asymmetric nuclear matter in presence of an external magnetic field. The mass modifications of the heavy quarkonia are obtained from the medium modifications of a scalar dilaton field, $\chi$, calculated within a chiral effective model. The dilaton field is introduced in the model through a scale invariance breaking logarithmic potential, and, simulates the gluon condensates of QCD. Within the chiral effective model, the values of the dilaton field along with the scalar (isoscalar, $\sigma (\sim \langle \bar u u \rangle +\langle \bar d d \rangle)$, isoscalar $\zeta (\sim \langle \bar s s \rangle$) and isovector $\delta (\sim \langle \bar u u\rangle - \langle\bar d d \rangle)$) fields, are solved from their coupled equations of motion. These are solved accounting for the effects of the Dirac sea (DS) as well as anomalous magnetic moments (AMMs) of the nucleons. The Dirac sea contributions are observed to lead to enhancement (reduction) of the quark condensates (through $\sigma$ and $\zeta$ fields) with increase in magnetic field, an effect called the (inverse) magnetic catalysis. The magnetic field effects on the masses of the heavy quarkonia include the mixing of the pseudoscalar (spin 0) and vector (spin 1) states (PV mixing), as well as, the effects from (inverse) magnetic catalysis. These effects are observed to be significant for large values of the magnetic field. This should have observable consequences on the production of the heavy quarkonia and open heavy flavour mesons, resulting from ultra-relativistic peripheral heavy ion collision experiments, where the created magnetic field can be huge.