$Z_b(10610)$ in a hadronic medium

TL;DR

This study examines the abundance of the $Z_b(10610)$ particle in a hot hadron gas post-heavy ion collisions, finding its multiplicity remains largely unchanged during the hadron phase.

Contribution

It provides a detailed calculation of $Z_b$ production and absorption cross sections using effective Lagrangians and demonstrates the stability of $Z_b$ abundance during the hadron phase.

Findings

$Z_b$ multiplicity is not significantly affected by production and absorption reactions.

The number of $Z_b$ particles remains constant during the hadron phase.

The results suggest $Z_b$ abundance is set during earlier collision stages.

Abstract

In this work we investigate the $Z_b (10610)$ (called simply $Z_b$) abundance in the hot hadron gas produced in the late stage of heavy ion collisions. We use effective Lagrangians to calculate the thermally averaged cross sections of $Z_b $ production in processes such as $B^{(*)} + \bar{B}^{(*)} \to \pi + Z_b (10610)$ and also of its absorption in the corresponding inverse processes. We then solve the rate equation to follow the time evolution of the $Z_b$ multiplicity, and the results remarkably suggest that this quantity is not significantly affected by the considered reactions. The number of $Z_b$'s produced at the end of the quark-gluon plasma phase remains constant during the hadron phase.