Top Quark Polarization As A Probe of Models with Extra Gauge Bosons

TL;DR

This paper explores how measuring top quark polarization from decays of hypothetical heavy gauge bosons can reveal the nature of their couplings, aiding in distinguishing different models of new physics beyond the standard model.

Contribution

It demonstrates a method to determine the handedness of couplings of new gauge bosons using top quark polarization measurements from their decay products.

Findings

Decays of W' and Z' bosons into third-generation fermions can reveal coupling handedness.

Top quark decay preserves spin information, enabling polarization analysis.

Method helps discriminate among various new physics models.

Abstract

New heavy gauge bosons exist in many models of new physics beyond the standard model of particle physics. Discovery of these W^\prime and Z^\prime resonances and the establishment of their spins, couplings, and other quantum numbers would shed light on the gauge structure of the new physics. The measurement of the polarization of the SM fermions from the gauge boson decays would decipher the handedness of the coupling of the new states, an important relic of the primordial new physics symmetry. Since the top quark decays promptly, its decay preserves spin information. We show how decays of new gauge bosons into third generation fermions (W^\prime \to tb, Z^\prime\to t\bar{t}) can be used to determine the handedness of the couplings of the new states and to discriminate among various new physics models.