Search for supersymmetry in pp collisions at sqrt (s) = 13 TeV in the single-lepton final state using the sum of masses of large radius jets

Results are reported from a search for supersymmetric particles in pp collisions in the final state with a single, high $p_{\rm T}$ lepton; multiple jets, including at least one b-tagged jet; and large missing transverse momentum. The data sample corresponds to 2.1~fb$^{-1}$ recorded by the CMS experiment at $\sqrt s=13$ TeV. The search focuses on processes leading to high jet multiplicities, such as ${\rm gg}\to{\rm \tilde g\tilde g}$ with ${\rm \tilde g}\to{\rm t}{\rm \bar t}\,{\tilde\chi^0_1}$. The quantity $M_J$, defined as the sum of the masses of the large-radius jets in the event, is used in conjunction with other kinematic variables to provide discrimination between signal and backgrounds and as a key part of the background estimation method. The observed event yields in the signal regions in data are consistent with those expected for standard model backgrounds, which are estimated from control regions. Exclusion limits are obtained for the simplified model T1tttt, which corresponds to gluino pair production with decays into top quarks plus neutralinos. Gluinos with mass below 1575 GeV are excluded at 95$\%$ CL for T1tttt scenarios with low $\tilde\chi_1^0$ mass.