Search for physics beyond the standard model in top quark production with additional leptons in the context of effective field theory

TL;DR

This study searches for signs of physics beyond the standard model in top quark production with extra leptons using CMS data, employing effective field theory to constrain new physics effects without observing significant deviations.

Contribution

It introduces a comprehensive EFT-based analysis of top quark events with additional leptons, setting limits on 26 EFT operators using LHC Run 2 data.

Findings

No significant deviation from the standard model observed.

Constraints placed on 26 EFT Wilson coefficients.

Methodology incorporates event-level reweighting for EFT effects.

Abstract

A search for new physics in top quark production with additional final-state leptons is performed using data collected by the CMS experiment in proton-proton collisions at $\sqrt{s}$ = 13 TeV at the LHC during 2016-2018. The data set corresponds to an integrated luminosity of 138 fb$^{-1}$. Using the framework of effective field theory (EFT), potential new physics effects are parametrized in terms of 26 dimension-six EFT operators. The impacts of EFT operators are incorporated through the event-level reweighting of Monte Carlo simulations, which allows for detector-level predictions. The events are divided into several categories based on lepton multiplicity, total lepton charge, jet multiplicity, and b-tagged jet multiplicity. Kinematic variables corresponding to the transverse momentum ($p_\mathrm{T}$) of the leading pair of leptons and/or jets as well as the $p_\mathrm{T}$ of on-shell Z bosons are used to extract the 95% confidence intervals of the 26 Wilson coefficients corresponding to these EFT operators. No significant deviation with respect to the standard model prediction is found.