Search for direct pair production of supersymmetric partners to the τ lepton in proton-proton collisions at s = 13 TeV

Abstract

A search is presented for ${\tau }_{}^{}$ slepton pairs produced in proton-proton collisions at a center-of-mass energy of 13 $\text{TeV}$ . The search is carried out in events containing two ${\tau }_{}^{}$ leptons in the final state, on the assumption that each ${\tau }_{}^{}$ slepton decays primarily to a ${\tau }_{}^{}$ lepton and a neutralino. Events are considered in which each ${\tau }_{}^{}$ lepton decays to one or more hadrons and a neutrino, or in which one of the ${\tau }_{}^{}$ 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 ${\text{fb}}^{-1}$ . 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 ${\tau }_{}^{}$ slepton pair production in various models for ${\tau }_{}^{}$ slepton masses between 90 and 200 $\text{GeV}$ and neutralino masses of 1, 10, and 20 $\text{GeV}$ . In the case of purely left-handed ${\tau }_{}^{}$ slepton production and decay to a ${\tau }_{}^{}$ lepton and a neutralino with a mass of 1 $\text{GeV}$ , the strongest limit is obtained for a ${\tau }_{}^{}$ slepton mass of 125 $\text{GeV}$ at a factor of 1.14 larger than the theoretical cross section.