Search for top squark pair production in a final state with two tau leptons in proton-proton collisions at s
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Received: October 28, 2019 Accepted: January 20, 2020 Published: February 3, 2020
The CMS collaboration E-mail: [email protected] Abstract: A search for pair production of the supersymmetric partner of the top quark, √ the top squark, in proton-proton collision events at s = 13 TeV is presented in a final state containing hadronically decaying tau leptons and large missing transverse momentum. This final state is highly sensitive to high-tan β or higgsino-like scenarios in which decays of electroweak gauginos to tau leptons are dominant. The search uses a data set corresponding to an integrated luminosity of 77.2 fb−1 , which was recorded with the CMS detector during 2016 and 2017. No significant excess is observed with respect to the background prediction. Exclusion limits at 95% confidence level are presented in the top squark and lightest neutralino mass plane within the framework of simplified models, in which top squark masses up to 1100 GeV are excluded for a nearly massless neutralino. Keywords: Hadron-Hadron scattering (experiments), Supersymmetry, Top physics ArXiv ePrint: 1910.12932
Open Access, Copyright CERN, for the benefit of the CMS Collaboration. 3 Article funded by SCOAP .
https://doi.org/10.1007/JHEP02(2020)015
JHEP02(2020)015
Search for top squark pair production in a final state with two tau leptons in proton-proton collisions at √ s = 13 TeV
Contents 1
2 The CMS detector
3
3 Monte Carlo simulation
3
4 Event reconstruction
5
5 Event selection
7
6 Background estimation 6.1 Tau lepton pairs from top production 6.2 Misidentified hadronically decaying tau lepton candidates
8 8 11
7 Systematic uncertainties
13
8 Results
14
9 Summary
17
The CMS collaboration
25
1
Introduction
Supersymmetry (SUSY) [1–9] is one of the most widely studied theories of physics beyond the standard model (SM), providing solutions to various shortcomings of the SM. In SUSY models there is a bosonic superpartner for each fermion (and vice-versa), the superpartner having the same quantum numbers, other than spin, as its SM partner. The superpartners of the SM gauge and Higgs bosons (gauginos and higgsinos, respectively) mix to produce e 01 can be a dark charginos and neutralinos. The weakly interacting lightest neutralino χ matter candidate in R-parity conserving SUSY models [10]. The SUSY partners of leftand right-handed top quarks are the top squarks, et L and et R . These particles can mix with each other, resulting in physical states et 1 and et 2 , with et 1 defined to be the lighter of the two. The top squarks play an important role in stabilizing the Higgs boson mass by canceling the dominant top quark loop correction. Therefore, there is a strong motivation to perform searches for top squark production. In this study, we focus on the signal of top squark pair production in a final state with two tau leptons. This probes the part of the parameter space of the minimal supere± symmetric standard model (MSSM) in which the lightest charginos ( χ 1 ) and neutralino p
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