luminosity of 77.2.

Events with two leptons are used. We consider both hadronic and leptonic decay modes of the lepton, in which it decays to one or more hadrons and a neutrino, or to an electron or muon and two neutrinos, respectively. Independent analyses are carried out in the final states with two hadronically decaying leptons ([$\tauh\tauh$]{}) and with one and an electron or a muon ([$\ell\tauh$]{}, where $\ell = \Pe$ or ). The presence of missing transverse momentum, which can originate from stable neutralinos as well as neutrinos from lepton decays, provides an important source of discriminating power between signal and background.

We have introduced several improvements with respect to the analysis presented in Ref. [@Sirunyan:2018vig] that are applied to both 2016 and 2017 data. We make use of dedicated machine learning techniques to enhance the search sensitivity. These include the incorporation of an improved selection method that makes use of a deep neural network (DNN) for the [$\tauh\tauh$]{}analysis, and of a boosted decision tree (BDT) for event selection in the [$\ell\tauh$]{}analyses. Improvements have also been made to the background-estimation techniques and to the search region (SR) definitions. The incorporation of these enhancements is expected to improve the search 