Search for vector-like quarks in events with two oppositely charged leptons and jets in proton-proton collisions at s = 13 Te

Abstract

A search for the pair production of heavy vector-like partners $T$ and $B$ of the top and bottom quarks has been performed by the CMS experiment at the CERN LHC using proton-proton collisions at $\sqrt{s}=13\text{Te}$ . The data sample was collected in 2016 and corresponds to an integrated luminosity of 35.9 ${\text{fb}}^{-1}$ . Final states studied for $T\overline{T}$ production include those where one of the $T$ quarks decays via $T\to tZ$ and the other via $T\to bW$ , $tZ$ , or $tH$ , where $H$ is a Higgs boson. For the $B\overline{B}$ case, final states include those where one of the $B$ quarks decays via $B\to bZ$ and the other $B\to tW$ , $bZ$ , or $bH$ . Events with two oppositely charged electrons or muons, consistent with coming from the decay of a $Z$ boson, and jets are investigated. The number of observed events is consistent with standard model background estimations. Lower limits at 95% confidence level are placed on the masses of the $T$ and $B$ quarks for a range of branching fractions. Assuming 100% branching fractions for $T\to tZ$ , and $B\to bZ$ , $T$ and $B$ quark mass values below 1280 and 1130 $\text{Ge}$ , respectively, are excluded.