Polarization of the $\phi$ meson in the hadronic phase with nucleon scatterings and a viscous hydrodynamic background

TL;DR

This study investigates the spin alignment of the $\,phi\,$ meson during the hadronic phase of quark-gluon plasma, incorporating nucleon scatterings and hydrodynamics, but finds these effects do not fully explain experimental observations.

Contribution

It extends previous models by including nucleon scatterings and realistic hydrodynamic backgrounds to analyze $\,phi\,$ meson polarization.

Findings

Nucleon scatterings have limited impact on $\,phi\,$ meson polarization.

The model cannot reproduce the observed out-of-plane spin alignment.

Hydrodynamic effects alone are insufficient to explain experimental data.

Abstract

We extend our previous work on the spin alignment of the $\phi$ vector meson in the hadronic phase of the Quark Gluon Plasma, by including effects of nucleon scatterings. The emission rates are calculated in a realistic hydrodynamic background simulated with the code Fluid$u$m, for different beam energies. We find that all the effects taken into account cannot explain the out-of-plane spin alignment of the $\phi$ meson observed experimentally.