# Interference Effects in $t{\bar t}$ Production at the LHC as a Window on New Physics

## TL;DR

This paper investigates how interference effects between new scalar or pseudoscalar particles and QCD background in top quark pair production at the LHC can serve as a probe for new physics beyond the Standard Model.

## Contribution

It provides a detailed analysis of interference effects in $t\bar t$ production across various BSM models, including singlet scalars, two-Higgs doublets, and supersymmetry, with realistic detection considerations.

## Key findings

- Interference effects can significantly alter the $t\bar t$ signal shape.
- Search strategies can potentially detect or constrain new scalar resonances.
- Interference patterns depend on model parameters and can be used to distinguish BSM scenarios.

## Abstract

Many extensions of the Standard Model contain (pseudo)scalar bosons with masses in the TeV range. At hadron colliders, such particles would predominantly be produced in gluon fusion and would decay into top quark pair final sates, a signal that interferes with the large QCD background $gg \to t\bar t$. This phenomenon is of interest for searches for by the LHC experiments. Here, we consider the signal and background interference in this process and study it in various benchmark scenarios, including models with extra singlet (pseudo)scalar resonances, two-Higgs doublet models, and the minimal supersymmetric extension of the SM with parameters chosen to obtain the measured light Higgs mass (the hMSSM). We allow for the possible exchanges of beyond the SM vector-like particles as well as scalar quarks. We calculate the possible interference effects including realistic estimates of the attainable detection efficiency and mass resolution. Studies of our benchmark scenarios indicate that searches with an LHC detector could permit the observation of the $t\bar t$ final states or constrain significantly large regions of the parameter spaces of the benchmark scenarios.