Polarized tops from new physics: signals and observables

TL;DR

This paper explores how top quark polarization measurements at the LHC can reveal new physics, proposing specific observables for different decay modes and analyzing signals from supersymmetric and same-spin partner models.

Contribution

It introduces polarization-sensitive observables for collimated top quarks in various decay modes and analyzes their effectiveness in detecting new physics signals.

Findings

Polarization observables can distinguish new physics signals from backgrounds.

Distributions for hadronic and leptonic decay modes are characterized.

Signals from stop squark decays and same-spin partner models are analyzed.

Abstract

Top quarks may be produced in large numbers in association with new physics at the LHC. The polarization of these top quarks probes the chiral structure of the new physics. We discuss several kinematic distributions which are sensitive to the polarization of single top quarks and can be used without full event reconstruction. For collimated tops we construct polarization-sensitive observables for both hadronic and leptonic decay modes and plot their distributions. We compute the observable polarization signals from top quarks produced in the on-shell cascade decay of a stop squark into a top quark and a neutralino, as well as top quarks produced in the analogous decay chain in same-spin partner models.