RevModPhys.84.1477】Tests of the standard electroweak model at the energy frontier

Limits from the d0 analysis the systematic

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Unformatted text preview: ection in the D0 VH ! ET bb search. 6 efficiency. These sources have an uncertainty of roughly 5% for each. 4.  þ jets and  þ jets final states The searches described earlier for the processes WH ! ‘bb and ZH ! ‘‘bb required ‘ ¼ e, , but corresponding channels exist with ‘ ¼  leptons in the final state. In addition, BðH ! Þ % 7% in the SM, the most important mode after H ! bb. D0 (Abazov et al., 2009k) published searches for Higgs production in the modes VH ! bb ! h  and " VH ! jj !  h jj, pp ! VVjj ! Hjj ! jj !  h jj, and gg ! Hjj ! jj !  h jj using a data sample corresponding to 1:0 fbÀ1 . Here h represents a  decay to hadrons. The primary signal contribution to the bb final state comes from WH ! bb, but roughly 7% of the final signal acceptance comes from ZH ! bb in which one  is not identified. The identified  is required to decay to hadrons (Abazov et al., 2009d). Candidate events are initially selected using a trigger requiring a high pT jet and large ET . The offline selection requires a hadronic  decay, with a 6 minimum transverse energy from 12 to 20 GeV=c, with the range depending on which of two decay topologies the  lepton is reconstructed. The topologies correspond roughly to single charged-hadron  lepton decays (type 1) and single charged-hadron with multiple neutral-hadron decays (type 2). In addition to the  lepton candidate, the basic offline selection requires ET > 30 GeV, the presence of at least two 6 3 candidate b jets with pT > 20 GeV=c and jj < 2:5, jets with pT ðGeV=cÞ, and a veto of events with a high-pT electron or muon to keep orthogonality with the other 6 searches. Events are also required to pass Áð6ET ; T T Þ < =2, HT < 200 GeV, 50 < MJJ < 200 GeV=c2 , and Áð; ET Þ < 0:02ð À 2Þð6ET À 30Þ þ 2. In addition, for 6 events with type 2 tau decay, the transverse mass of the  ~ ~ must satisfy M < 80 GeV=c2 . and ET 6 T The jj final-state search has signal contributions from a " variety of processes: ZH ! bb, ZH ! qqbb (in which " H ! , VBF pp ! VVjj ! Hjj ! jj !  h jj, and gluon fusion gg ! Hjj ! jj !  h jj). Unlike other low mass channels, some of these processes have no b quarks in the decay chain. Consequently, no b-jet identification is required for this search. One of the  leptons is Rev. Mod. Phys., Vol. 84, No. 4, October–December 2012 bb jj 0:5 Æ 0:0 10:9 Æ 0:3 <0:2 0:4 Æ 0:0 9:5 Æ 0:1 0:7 Æ 0:0 1:3 Æ 0:1 23:3 Æ 0:4 13 0.216 W þ lf W þ hf Z þ lf Z þ hf " tt Diboson Multijet Total Data Signal 5:1 Æ 0:3 0:9 Æ 0:1 43:8 Æ 0:6 10:1 Æ 0:7 2:8 Æ 0:0 2:1 Æ 0:2 6:5 Æ 2:8 71:2 Æ 3:0 58 0.293 required to decay to hadrons, and the other  lepton is required to decay to a muon. Here three topologies are used. Two of these are the same as in the bb search, and the third corresponds roughly to  lepton decays to three charged hadrons. Cand...
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This document was uploaded on 09/28/2013.

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