Search for the Higgs Boson Using High-pT Isolated Like-Sign Dil Events in 1.96-TeV Proton-Antiproton Collisions
- Univ. of Tsukuba (Japan)
Our physics objective is to search for the neutral on using events containing a like-sign dilepton pair in the following reaction: q$$\bar{q}$$ → W± H → W± W*W* → ℓ±ℓ± + X. The relevant Higgs boson mass region is above 160 GeV/c2 for the Standard Model Higgs boson where the branching fraction of H → W*W* supersedes that of H → b$$\bar{b}$$. The search for this signature in the region at low mass (less than 135 GeV/c2) is, however, still important because we need to investigate various Higgs boson couplings as an essential test to convince that signals are attributed to the Higgs boson production. This channel also covers the case beyond the Standard Model that the Higgs boson couples only to the gauge bosons, which is referred to as the bosophilic or fermiophobic Higgs boson. The corresponding mass region suitable to our signature is above 110 GeV/c2 where the branching fraction of H → γγ is overtaken by this channel. On the experimental side, the like-sign dilepton event is one of the cleanest signature in hadron collisions. This analysis exploiting such a distinctive signature is therefore expected to have a high potential of the sensitivity for the search of the Higgs boson. The data were collected with the CDF II detector between March 2002 and September 2003, corresponding to an integrated luminosity of 193.5 pb-1. At off-line, the central region (|η| < 1.1) is considered for the lepton detection. We require at least one electron with ET > 20 GeV or muon with pT > 20 GeV/c which is considered to be responsible for firing the corresponding trigger, and at least one other electron with E{sub T} > 6 GeV or muon with pT > 6 GeV/c. The leptons are required to be isolated in terms of the calorimeter cone-isolation with a cone size of R = 0.4. We require that the isolation is less than 2 GeV for each lepton. For the events with like-sign two or more leptons that pass our selection above, we apply a cosmic-ray veto, dilepton mass cut (Mℓℓ > 12 GeV/c2), and a Z-decay removal to clean up the sample. We also explicitly require that the leptons must be consistent with coming from the same vertex, which is an important requirement for multi-lepton signatures especially in a high-luminosity situation. The selection cuts identifies high-pT, isolated leptons with almost ''standard'' identification criteria. We observed 45 like-sign dilepton events in data.
- Research Organization:
- Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC02-76CH03000
- OSTI ID:
- 878941
- Report Number(s):
- FERMILAB-THESIS-2005-36; TRN: US0605002
- Country of Publication:
- United States
- Language:
- English
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