Rotational Brownian motion and heavy quark polarization in QCD medium

TL;DR

This paper analyzes the rotational Brownian motion of heavy quarks in QCD medium, deriving polarization expressions, comparing with experimental data, and proposing polarization as a signature of initial magnetic fields in heavy-ion collisions.

Contribution

It provides analytical formulas for heavy quark polarization in QCD medium and links polarization behavior to initial magnetic fields in heavy-ion collisions.

Findings

Agreement with ALICE data for D*+ meson polarization

Predictions for open charm baryon polarization

Transverse momentum dependence as magnetic field signature

Abstract

We consider the rotational Brownian motion of heavy quark in QCD medium and provide analytical results for polarization of open heavy-flavor hadrons. We calculate expressions for vector and tensor polarization, corresponding to baryon spin polarization and vector meson spin alignment, respectively. Assuming that heavy quarks are initially fully spin polarized along the direction of magnetic field, we compare our results with recent experimental data from ALICE collaboration for $D^{*+}$ meson and provide predictions for spin polarization of open charm baryons. We propose that the transverse momentum dependence of heavy quark polarization may serve as a distinctive signature of the intense initial magnetic field generated in off-central relativistic heavy-ion collisions.