Search for supersymmetry in events with tau leptons and missing transverse momentum in proton-proton collisions at sqrt(s)=13 TeV

A search for supersymmetry is performed using events with $\tau$ leptons in the final state with 13 TeV data recorded in 2016, corresponding to an integrated luminosity of $35.9~\mathrm{fb}^{-1}$. Models of direct $\widetilde{\tau}$-pair production, where each $\widetilde{\tau}$ is expected to decay to a $\tau$ lepton and the lightest supersymmetric particle, the $\widetilde{\chi}^{0}_1$, as well as neutralino-chargino and chargino pair production with decays to $\tau$ leptons are investigated. Several exclusive search regions are defined to maximize the sensitivity to various new physics topologies, based on final states with one hadronically decaying $\tau$ lepton and an electron or muon from the decay of the second $\tau$, as well as final states with one electron and one muon from the decay of the $\tau$ leptons. The data are consistent with the standard model expectation, and $95\%$ CL limits are set for several scenarios. For neutralino-chargino production with mass-degenerate chargino ($\widetilde{\chi}^{\pm}_1$) or neutralino ($\widetilde{\chi}^{0}_2$), exclusion limits on the $\widetilde{\chi}^{\pm}_1$ and $\widetilde{\chi}^{0}_2$ masses can reach up to $560~\mathrm{GeV}$, depending on the masses of the intermediate $\widetilde{\tau}$ and the $\widetilde{\chi}^{0}_1$. The upper limit on cross section times the square of the branching fraction for direct $\widetilde{\tau}$-pair production is set to be $0.66~\mathrm{pb}$ for a $\widetilde{\tau}$ mass of $90~\mathrm{GeV}$ and a $\widetilde{\chi}^{0}_1$ mass of $1~\mathrm{GeV}$.