Search for top squark pair production using dilepton final states in pp collision data collected at $\sqrt{s} =$ 13 TeV

TL;DR

This paper reports a search for top squark pairs in proton-proton collision data at 13 TeV using the CMS detector, setting new mass exclusion limits based on various decay scenarios with no significant signal observed.

Contribution

It introduces a comprehensive search strategy for top squarks in dilepton final states and provides the most stringent mass limits to date for several decay channels.

Findings

No significant excess over background observed.

Exclusion limits on top squark masses up to 1.4 TeV.

Exclusion limits on neutralino masses up to 900 GeV.

Abstract

A search is presented for supersymmetric partners of the top quark (top squarks) in final states with two oppositely charged leptons (electrons or muons), jets identified as originating from b quarks, and missing transverse momentum. The search uses data from proton-proton collisions at $\sqrt{s} =$ 13 TeV collected with the CMS detector, corresponding to an integrated luminosity of 137 fb$^{-1}$. Hypothetical signal events are efficiently separated from the dominant top quark pair production background with requirements on the significance of the missing transverse momentum and on transverse mass variables. No significant deviation is observed from the expected background. Exclusion limits are set in the context of simplified supersymmetric models with pair-produced lightest top squarks. For top squarks decaying exclusively to a top quark and a lightest neutralino, lower limits are placed at 95% confidence level on the masses of the top squark and the neutralino up to 925 and 450 GeV, respectively. If the decay proceeds via an intermediate chargino, the corresponding lower limits on the mass of the lightest top squark are set up to 850 GeV for neutralino masses below 420 GeV. For top squarks undergoing a cascade decay through charginos and sleptons, the mass limits reach up to 1.4 TeV and 900 GeV respectively for the top squark and the lightest neutralino.