Search for direct pair production of supersymmetric partners to the _^ lepton in proton–proton collisions at √s=13\,TeV

A search is presented for _^ τ slepton pairs produced in proton–proton collisions at a center-of-mass energy of 13 \,TeV TeV . The search is carried out in events containing two _^ τ leptons in the final state, on the assumption that each _^ τ slepton decays primarily to a _^ τ lepton and a neutralino. Events are considered in which each _^ τ lepton decays to one or more hadrons and a neutrino, or in which one of the _^ τ leptons decays instead to an electron or a muon and two neutrinos. The data, collected with the CMS detector in 2016 and 2017, correspond to an integrated luminosity of 77.2 \,fb⁻¹ fb-1 . The observed data are consistent with the standard model background expectation. The results are used to set 95% confidence level upper limits on the cross section for _^ τ slepton pair production in various models for _^ τ slepton masses between 90 and 200 \,GeV GeV and neutralino masses of 1, 10, and 20 \,GeV GeV . In the case of purely left-handed _^ τ slepton production and decay to a _^ τ lepton and a neutralino with a mass of 1 \,GeV GeV , the strongest limit is obtained for a _^ τ slepton mass of 125 \,GeV GeV at a factor of 1.14 larger than the theoretical cross section.