Determining the Quantum Numbers of Simplified Models in $t\bar{t}X$ production at the LHC

TL;DR

This paper investigates how the LHC can determine the spin and parity of a new light resonance X coupling to third-generation quarks via the t-tbar-X channel, using differential distributions to distinguish scalar, pseudoscalar, and vector cases.

Contribution

It introduces methods to probe the quantum numbers of a new resonance in simplified models through kinematic variables and differential distributions in the t-tbar-X production channel.

Findings

Differential distributions can effectively discriminate scalar from pseudoscalar and vector resonances.

The semi-leptonic channel provides promising sensitivity for quantum number determination.

The study enhances understanding of how to characterize new particles at the LHC.

Abstract

Simplified models provide an avenue for characterising and exploring New Physics for large classes of UV theories. In this article we study the ability of the LHC to probe the spin and parity quantum numbers of a new light resonance $X$ which couples predominantly to the third generation quarks in a variety of simplified models through the $t\bar t X$ channel. After evaluating the LHC discovery potential for $X$, we suggest several kinematic variables sensitive to the spin and CP properties of the new resonance. We show how an analysis exploiting differential distributions in the semi-leptonic channel can discriminate among various possibilities. We find that the potential to discriminate a scalar from a pseudoscalar or (axial) vector to be particularly promising.