lepton and a , should be correlated with the mass difference between the and . A large value of is thus common in signal events for models with larger masses and relatively rare in SM background events.

The SR definitions for the [$\tauh\tauh$]{}analysis, shown in Table \[tab:sr\], are based on a cut-and-count analysis of the sample satisfying the baseline selections. The regions are defined through criteria imposed on , [$\Sigma\mT$]{}, and the number of reconstructed jets in an event, [$N_{\text{j}}$]{}. The [$\Sigma\mT$]{}and distributions of events in the [$\tauh\tauh$]{}final state surviving the baseline selections are shown in Fig. \[fig:srvariables\_tautau\]. The distributions obtained for 2016 and 2017 data are combined. Separate sets of simulated events are used to model signal and background events in 2016 and 2017 data using the methods described in Section \[sec:evtreco\]. In all distributions, the last bin includes overflow events. After applying a minimum requirement of $\mTii>25\GeV$ in all SRs, we subdivide events into low (25–50) and high (${>}50\GeV$) regions, to improve the sensitivity to lower and higher mass signals, respectively. For each region, the [$\Sigma\mT$]{}distribution is exploited to provide sensitivity for a large range of mass signals. We define three bins in [$\Sigma\mT$]{}: 200–250, 250–300, and $>$300. 