Search for vector-like T or B quark pairs in leptonic final states in 36 fb$^{-1}$ of proton-proton collisions at $\sqrt{s}$ = 13 TeV

A search is presented for pair production of heavy vector-like T or B quarks in proton-proton collisions at $\sqrt{s} = 13~\mathrm{TeV}$. The search uses a data sample corresponding to an integrated luminosity of $35.9~\mathrm{fb}^{-1}$, collected with the CMS detector at the CERN LHC in 2016. Pair production of T quarks would result in a wide range of final states, since vector-like T quarks of charge $2e/3$ are predicted to decay to bW, tZ, and tH. Likewise, vector-like B quarks are predicted to decay to tW, bZ, and bH. This search is performed in three channels corresponding to final states with a single lepton, two leptons with the same electric charge sign, and at least three leptons. This search excludes T quark masses below 1140--1300 GeV and B quark masses below 910--1240 GeV for various branching fraction combinations, extending the reach of previous CMS searches by 200--600 GeV. These are the strongest exclusion limits to date for T quarks with $\mathcal{B}(\mathrm{bW}) < 0.6$ and B quarks with $\mathcal{B}(\mathrm{tW}) < 0.6$.