Search for direct pair production of supersymmetric partners to the $${\uptau }_{}^{}$$τ lepton in proton–proton collisions at $$\sqrt{s}=13\,\text {TeV} $$s=13TeV

A search is presented for $${\uptau }_{}^{}$$ 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 $${\uptau }_{}^{}$$ leptons in the final state, on the assumption that each $${\uptau }_{}^{}$$ slepton decays primarily to a $${\uptau }_{}^{}$$ lepton and a neutralino. Events are considered in which each $${\uptau }_{}^{}$$ lepton decays to one or more hadrons and a neutrino, or in which one of the $${\uptau }_{}^{}$$ 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 $${\uptau }_{}^{}$$ slepton pair production in various models for $${\uptau }_{}^{}$$ 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 $${\uptau }_{}^{}$$ slepton production and decay to a $${\uptau }_{}^{}$$ lepton and a neutralino with a mass of 1$$\,\text {GeV}$$, the strongest limit is obtained for a $${\uptau }_{}^{}$$ slepton mass of 125$$\,\text {GeV}$$ at a factor of 1.14 larger than the theoretical cross section.