Centrality dependence and isospin effect on $\Wpm$ and $\Zn$ productions in nucleus-nucleus collisions at $\sNN=5.02$~TeV

TL;DR

This study investigates how collision centrality and isospin influence W and Z boson production in lead-lead collisions at 5.02 TeV, using a cascade model to compare with experimental data and predict new phenomena.

Contribution

It provides the first detailed analysis of isospin effects on W boson charge asymmetry and reproduces Z boson production data, offering new insights into initial collision conditions.

Findings

ALICE data on Z production are well reproduced.

An isospin effect on W charge asymmetry is observed.

Predictions for W boson production in Pb-Pb collisions are provided.

Abstract

In this paper, the centrality dependent $\Zn$ and $\Wpm$ production and the isospin effect in $\Wpm$ production are investigated with a parton and hadron cascade model PACIAE in Pb--Pb collisions at $\sNN=5.02$~TeV. ALICE data of $\Zn$ production in Pb--Pb collisions at $\sNN=5.02$~TeV are found to be reproduced fairly well. The prediction on $\Wpm$ production in the same collision system is given as well. An interesting isospin effect is observed in exploring the charge asymmetry between $\Wp$ and $\Wm$ as a function of the asymmetry between number of valence $u$- and $d$-quarks varied from small to large collision systems at center-of-mass energy 5.02 TeV. The results serve as a important benchmarks for understanding the initial conditions of heavy-ion collisions.