Search for direct top squark pair production in events with one lepton, jets, and missing transverse momentum at 13 TeV
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Springer
Received: December 18, 2019 Accepted: April 13, 2020 Published: May 8, 2020
The CMS collaboration E-mail: [email protected] Abstract: A search for direct top squark pair production is presented. The search is based on proton-proton collision data at a center-of-mass energy of 13 TeV recorded by the CMS experiment at the LHC during 2016, 2017, and 2018, corresponding to an integrated luminosity of 137 fb−1 . The search is carried out using events with a single isolated electron or muon, multiple jets, and large transverse momentum imbalance. The observed data are consistent with the expectations from standard model processes. Exclusions are set in the context of simplified top squark pair production models. Depending on the model, exclusion limits at 95% confidence level for top squark masses up to 1.2 TeV are set for a massless lightest supersymmetric particle, assumed to be the neutralino. For models with top squark masses of 1 TeV, neutralino masses up to 600 GeV are excluded. Keywords: Hadron-Hadron scattering (experiments), Supersymmetry, top squark ArXiv ePrint: 1912.08887
Open Access, Copyright CERN, for the benefit of the CMS Collaboration. 3 Article funded by SCOAP .
https://doi.org/10.1007/JHEP05(2020)032
JHEP05(2020)032
Search for direct top squark pair production in events with one lepton, jets, and missing transverse momentum at 13 TeV with the CMS experiment
Contents 1
2 The CMS detector
2
3 Simulated samples
3
4 Event reconstruction and search strategy 4.1 Event reconstruction 4.2 Search strategy
4 4 9
5 Background estimation 5.1 Lost-lepton background 5.2 One-lepton background 5.3 Background from events containing Z → ν ν¯
12 13 14 16
6 Systematic uncertainties
16
7 Results and interpretation
17
8 Summary
22
The CMS collaboration
30
1
Introduction
Supersymmetry (SUSY) [1–8] is an attractive extension of the standard model (SM), characterized by the presence of SUSY partners for every SM particle. These partner particles have the same quantum numbers as their SM counterparts, except for the spin, which differs by one-half unit. In models with R-parity conservation [9], the lightest supersymmetric particle (LSP) is stable, and, if neutral, could be a dark matter candidate [10]. The extended particle spectrum in SUSY scenarios allows for the cancellation of quadratic divergences arising from quantum corrections to the Higgs boson mass [11–15]. Scenarios realizing this cancellation often contain top squarks (et ), SUSY partners of the SM top quark (t), and higgsinos, SUSY partners of the SM Higgs boson, with masses near the electroweak scale. The et pair production cross section is expected to be large compared to the electroweak production of higgsinos at CERN LHC for et masses near the electroweak scale. In this paper, a search is presented for top squark pair production in final states with √ events from pp collisions at s = 13 TeV, collected between 2016 and 2018 by the CMS experiment, corresponding to an integrated luminosity of 137 fb−1 . Tw
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