Search for new particles decaying into top quark-antiquark pairs in proton-proton collisions at $\sqrt{s}$ = 13 TeV

TL;DR

This paper reports a comprehensive search for new particles decaying into top quark-antiquark pairs using 13 TeV proton-proton collision data, setting new limits on various theoretical models.

Contribution

It provides the most stringent limits to date on several models predicting new particles decaying to top quark pairs, using a large dataset from the CMS detector.

Findings

Excluded Z' bosons up to 7.4 TeV depending on width

Excluded Kaluza-Klein gluons up to 5.5 TeV

Set limits on Higgs boson coupling modifiers in 2HDM

Abstract

A search for new particles decaying to top quark-antiquark pairs is performed using proton-proton collision data at a centre-of-mass energy of 13 TeV. The data set recorded with the CMS detector between 2016 and 2018 is used, corresponding to an integrated luminosity of 138 fb$^{-1}$. Final states with 0, 1, and 2 leptons are analyzed, covering all decay modes of the top quark-antiquark pairs. Heavy Z' bosons with relative widths of 1, 10, and 30% are excluded for masses in the ranges 0.4$-$4.8, 0.4$-$6.2, and 0.4$-$7.4 TeV, respectively. A Kaluza$-$Klein gluon in the Randall$-$Sundrum model and a dark-matter mediator are excluded for masses between 0.5$-$5.5 and 1.0$-$4.2 TeV, respectively. These results set the most stringent limits to date for the considered models in the $\mathrm{t\bar{t}}$ final state. In addition, in the two-Higgs-doublet models, upper limits are set on the coupling strength modifier for scalar and pseudoscalar Higgs bosons with relative widths of 2.5, 10, and 25% in the mass range of 0.5$-$1.0 TeV.