Search for pair production of a new quark that decays to a Z boson and a bottom quark with the ATLAS detector

Abstract

A search is reported for the pair production of a new quark, b_s14, with at least one b_s14 decaying to a Z boson and a bottom quark. The data, corresponding to 2.0 fb^-1 of integrated luminosity, were collected from pp collisions at sqrt(s) = 7 TeV with the ATLAS detector at the CERN Large Hadron Collider. Using events with a b-tagged jet and a Z boson reconstructed from opposite-charge electrons, the mass distribution of large transverse momentum b_s14 candidates is tested for an enhancement. No evidence for a b_s14 signal is detected in the observed mass distribution, resulting in the exclusion at 95% confidence level of b_s14 quarks with masses m_{b_s14} < 400 GeV that decay entirely via b_s14 to Z_s16b. In the case of a vector-like singlet b_s14 mixing solely with the third Standard Model generation, masses m_{b_s14} < 358 GeV are excluded.