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Tag Jets in Vector Boson Fusion

This presentation by Bruce Mellado from the University of Wisconsin-Madison, delivered at the HERA and LHC Workshop on March 27, 2004, discusses the production mechanisms of the Standard Model Higgs via Vector Boson Fusion (VBF) and associated processes such as gg→H and qq→qqH. It highlights the challenges and experimental issues faced in searching for low and intermediate mass Higgs bosons, emphasizing forward jet tagging efficiency and the potential of using neural networks for improved detection. The ongoing studies and relevance of these findings to MSSM parameter space are also addressed.

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Tag Jets in Vector Boson Fusion

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  1. Tag Jets in Vector Boson Fusion Bruce Mellado University of Wisconsin-Madison HERA and LHC Workshop, 27/03/04

  2. VBF gg  H Associated SM Higgs at LHC • Production: • Direct • gg  H • Dominant • Large background at masses close to LEP limit • qq qqH (VBF) • Distinct final state • Associated • ttH, WH, ZH • Small cross-section Bruce Mellado, HERA-LHC Workshop, 27/03/04

  3. Jet Jet Forward jets f h Higgs Decay Low Mass Higgs via VBF • Wisconsin Phenomenology Institute (D.Rainwater, D.Zeppenfeld et al.): • Two high PT jets with large Dhseparation • Strong discovery potential for low Higgs mass • Helps measuring couplings • Invisible Higgs decays • Feasibility studies • CMS Note 2003/033 • ATLAS SN-ATLAS-2003-024 • Updates in progress Bruce Mellado, HERA-LHC Workshop, 27/03/04

  4. High Lumi Central Forward Low Lumi Major Experimental Issues • Major experimental issues addressed with a full detector simulation (Geant3) • Tagging forward jets: • Efficiencies critical • Full simulation used • Double tag efficiency ~50% • Central jet veto: • Pile up effects introduce fake central jets • Effect small at low luminosity • Serious concern at high luminosity • Very sensitive to underlying effect • Detailed studies underway Bruce Mellado, HERA-LHC Workshop, 27/03/04

  5. Low Mass Higgs via VBF • H->WW*->ll,lqq. Strongest in 125<MH<190 GeV • Main background: • tt EW WWjj • W + 4 jets • H->->ll,lh (+ptmiss). Strong around LEP limit • Main background • QCD and EW Zjj • H->. Contributes around LEP limit • Main background • Real and fake non-resonant  Bruce Mellado, HERA-LHC Workshop, 27/03/04

  6. Intermediate Mass Higgs via VBF • Used for first time HWWll and HZZllqq associated with two hard jets for intermediate masses (2MZ<MH<500 GeV) • By using kinematic fits obtain (M/M2.5%) with HZZllqq • Discovery confirmation and direct measurement of couplings ratio ATLAS Preliminary Bruce Mellado, HERA-LHC Workshop, 27/03/04

  7. Sensitivity to low mass SM Higgs dominated by VBF • VBF studies extended to intermediate masses ATLAS Preliminary Bruce Mellado, HERA-LHC Workshop, 27/03/04

  8. MSSM Higgs Discovery Potential One Experiment 10 fb-1 (With VBF) Two Experiments 10 fb-1 (No VBF) Bruce Mellado, HERA-LHC Workshop, 27/03/04

  9. Summary • Searches associated with two hard jets dominate sensitivity for low mass Higgs • With Neural nets and likelihood techniques may reach 5 effect for MH>115 GeV with one experiment and 10 fb-1 assuming expected detector performance • ATLAS has extended these searches to 2MZ<MH<500 GeV • With these searches one experiment may cover all MSSM parameter space with 10 fb-1 • Forward jet tagging efficiency crucial and understanding of central jet veto - crucial issues • Sensitive to underlying event. Studies with a full detector simulation underway Bruce Mellado, HERA-LHC Workshop, 27/03/04

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