Abstract

A search for the electroweak production of supersymmetric particles in proton-proton collisions at a center-of-mass energy of 13 TeV is presented in final states with a τ lepton pair. Both hadronic and leptonic decay modes are considered for the τ leptons. Scenarios involving the direct pair production of τ sleptons, or their indirect production via the decays of charginos and neutralinos, are investigated. The data correspond to an integrated luminosity of 35.9 fb−1 collected with the CMS detector in 2016. The observed number of events is consistent with the standard model background expectation. The results are interpreted as upper limits on the cross section for τ slepton pair production in different scenarios. The strongest limits are observed in the scenario of a purely left-handed low mass τ slepton decaying to a nearly massless neutralino. Exclusion limits are also set in the context of simplified models of chargino-neutralino and chargino pair production with decays to τ leptons, and range up to 710 and 630 GeV, respectively.

Highlights

  • Background estimationThe dominant background sources for this search are DY+jets, W+jets, quantum chromodynamics (QCD) multijet, tt, and diboson processes

  • A search for the electroweak production of supersymmetric particles in protonproton collisions at a center-of-mass energy of 13 TeV is presented in final states with a τ lepton pair

  • For the τhτh final state, the dominant background consists of QCD multijet and W+jets processes, where one or more of the τh candidates originates from a parton and is misidentified as a prompt τh

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Summary

The CMS detector

The central feature of the CMS apparatus is a superconducting solenoid of 6 m internal diameter, providing a magnetic field of 3.8 T. Forward calorimeters extend the pseudorapidity (η) coverage provided by the barrel and endcap detectors. Events of interest are selected using a twotiered trigger system [48]. The first level, composed of custom hardware processors, uses information from the calorimeters and muon detectors to select events at a rate of around 100 kHz within a time interval of less than 4 μs. The second level, known as the high-level trigger, consists of a farm of processors running a version of the full event reconstruction software optimized for fast processing, and reduces the event rate to around 1 kHz before data storage. A more detailed description of the CMS detector, together with a definition of the coordinate system used and the relevant kinematic variables, can be found in ref. [49]

Event reconstruction and simulated samples
Event selection
Background estimation
Estimation in the τhτh final state
Estimation in the eτh and μτh final states
Estimation in the eμ final state
Estimation of other backgrounds
Systematic uncertainties
Results and interpretation
Right-handed scenario
Summary

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