Unravelling an Extra Neutral Gauge Boson at the LHC using Third Generation Fermions

TL;DR

This paper explores how measurements of third generation fermion final states at the LHC can help identify the properties and underlying models of hypothetical Z' bosons, especially those with non-universal couplings.

Contribution

It introduces a method using ratios of cross sections and asymmetries involving third generation fermions to distinguish between different Z' models with non-universal couplings.

Findings

Ratios of cross sections can differentiate Z' models.

Forward-backward asymmetries provide additional model insights.

Updated discovery limits for Z' bosons at the LHC.

Abstract

We study the potential to use measurements of extra neutral gauge bosons (Z') properties in pp collisions at the Large Hadron Collider to unravel the underlying physics. We focus on the usefulness of third generation final states (tau, b, t) in distinguishing between models with non-universal Z'-fermion couplings. We present an update of discovery limits of Z's including the 2010-2011 LHC run and include models with non-universal couplings. We show how ratios of sigma(pp -> Z' -> ttbar), sigma(pp -> Z' -> bbbar), and sigma(pp -> Z' -> tau^+tau^-) to sigma(pp -> Z' -> mu^+mu^-) can be used to distinguish between models and measure parameters of the models. Of specific interest are models with preferential couplings, such as models with generation dependent couplings. We also find that forward-backward asymmetry measurements with third generation fermions in the final state could provide important input to understanding the nature of the Z'. Understanding detector resolution and efficiencies will be crucial for extracting results.