Unraveling the couplings of a Drell-Yan produced $Z'$ with heavy-flavor tagging

TL;DR

This paper explores how heavy-flavor tagging at the LHC can help identify the couplings of a potential $Z'$ boson produced via Drell-Yan processes, focusing on distinguishing charm and bottom quark interactions.

Contribution

It introduces a method using $c$- and $b$-tagging algorithms to determine the $Z'$ couplings in Drell-Yan production at the LHC, highlighting the potential to distinguish different quark interactions.

Findings

$b$-tagging can effectively identify $b Z'$ couplings.

Mistagging of light jets can be eliminated, but $b$-jets mistagged as $c$-jets remains a challenge.

Simultaneous searches for $c g o c Z'$ and $b g o b Z'$ can clarify $Z'$ coupling structures.

Abstract

Despite no new physics so far at the LHC, a $Z'$ boson with $m_{Z'} \sim 100$ GeV could still emerge via Drell-Yan (DY) production, $q \bar q \to Z' \to \mu^+ \mu^-$, in the next few years. To unravel the nature of the $Z'$ coupling, we utilize the $c$- and $b$-tagging algorithms developed by ATLAS and CMS to investigate $cg \to c Z'$ at 14 TeV LHC. While light-jet contamination can be eliminated, mistagged $b$-jets cannot be rejected in any of the tagging schemes we adopt. On the other hand, for nonzero $bbZ'$ coupling, far superior $b$-tagging could discover the $bg \to b Z'$ process, where again light-jet mistag can be ruled out, but mistagged $c$-jets cannot yet be excluded. Provided that DY production is discovered soon enough, we find that a simultaneous search for $c g \to c Z'$ and $b g \to b Z'$ can conclusively discern the nature of $Z'$ couplings involved.