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Higgs Physics – Activities in Bonn/Siegen

Higgs Physics – Activities in Bonn/Siegen. Jörn Große-Knetter ATLAS-Higgs-D Treffen München, 28.11.2006. Outline. VBF Fusion: forward jet tagging central jet veto: NLO with SHERPA, different underlying event / PS models tau tagging Zjj background estimate for H   from data

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Higgs Physics – Activities in Bonn/Siegen

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  1. Higgs Physics – Activities in Bonn/Siegen Jörn Große-Knetter ATLAS-Higgs-D Treffen München, 28.11.2006 Hggs-D meeting MPI 11/2006

  2. Outline • VBF Fusion: • forward jet tagging • central jet veto: NLO with SHERPA, different underlying event / PS models • tau tagging • Zjj background estimate for Hfrom data • W+jets background studies (M. Rast, not shown here) • LVL1 trigger studies for Hinvisible • Other non-VBF studies not shown here • Plans/potential for collaboration Hggs-D meeting MPI 11/2006

  3. Forward Jet Studies(Iris Rottländer) comparison of different jet algorithms (cone, KT with diff. par‘s), different generators (PYTHIA/HERWIG) and processes (dijet/VBF)  efficiencies, fake rates, out of jet corrections matching between truth jets (hadron level) and reco jets within a ΔR different jet algos – eff. vs. eta and Pt Cone 07 Cone 04 ●:Tower o: Topo Hggs-D meeting MPI 11/2006

  4. Different MC Generators and Topologies Pythia QCD Forwardjets Herwig QCD Dijets Pythia 6.3 VBF H->tautau->ll Herwig VBF H->tautau->ll • Jets from hard process found easier than jets from shower • Forward region: jets from VBF found easier than jets from QCD • Maybe slight dependence on generator (shower & fragmentation model) Hggs-D meeting MPI 11/2006

  5. Central Jet Veto, NLO(Talea Köchling) • Goal: study effects of NLO on sensitivity esp. jet veto with SHERPA • Def.: 1st and 2nd jet  tagging jets, 3rd jet  apply veto Signal: 3rd jet properties (including underlying event) momentum: SHERPA3j>PYTHIA>SHERPA2JEt>HERWIG rapidity: SHERPA agree well, HERWIG slightly wider, PYTHIA?? Hggs-D meeting MPI 11/2006

  6. Survial Probability w.r.t central jet veto Signal w/o underlying event Signal with underlying event Veto jets with Pt > x GeV) Veto jets with Pt > x GeV) • SHERPA H+2j and H+3j agree well  „NLO“ effect seems small? • signficant difference among different MC generators • reason not yet understood Hggs-D meeting MPI 11/2006

  7. Survial Probability w.r.t central jet veto Zjj(EW) w/o underlying event Zjj(QCD) with underlying event Veto jets with Pt > x GeV) Veto jets with Pt > x GeV) • SHERPA H+2j and H+3j agree well only for EW process • signficant difference in QCD process • reason not yet understood Hggs-D meeting MPI 11/2006

  8. -ID for VBF Hlh(A. Veenendaal) •  from VBF Higgs decay have relatively low pT • Check performance of ID of hadronic decays for this channel – tauRec and 1P3P • Look for best discrimination method against Wlepton + jets background • Own production (CSC not ready)  low MC statistics Hggs-D meeting MPI 11/2006

  9. Comparison tauRec/tau1P3P avg. over all pT 10 GeV < pT < 20 GeV • Find best working point: tauRec better for pT>20GeV, 1P3P for pT<20GeV • Combine both algorithms? Hggs-D meeting MPI 11/2006

  10. VBF, H: determination of bkgr. from data (M. Schmitz) • Idea:jjZμμandjjZμμwith identical topology • muons are MIPS  same energy deposition in calorimeters (checked!) • only difference: momentum spectra of muons • Method:select Z  μμ events • „randomise“ μ-momenta according to Z   μμ4νMC (works!) • apply „usual“ selection and mass reconstruction shape of background can be extracted precisely from data itself towards mass determination: - subtract BG prediction - Gaussian fit  mass Hggs-D meeting MPI 11/2006

  11. Prospects for mass determination with limited luminosity 30fb-1, only  mm decay 6 out of 8 fits fine 120fb-1,  mm decay =30fb-1, ll decays? all fits fine Hggs-D meeting MPI 11/2006

  12. Invisible Higgs boson decays invisble Higgs decays: SUSY HLSP LSP, ADD, Majoron,… 95% CL exclusion with 30 fb-1 VBF result assumes trigger on jets up to h = 4.9 VBF most sensitive, but how to trigger on 2 jets + missing energy?  LVL1 trigger study for jets including FCAL Hggs-D meeting MPI 11/2006

  13. Ongoing LVL1 Trigger Study(Guilherme Hanninger) Goal: determine efficiencies and rates for various options of trigger menues for combinations of ET miss + central jet + forward jet “plain cuts”: Hggs-D meeting MPI 11/2006

  14. Estimation of LVL1 trigger efficiencies, rates topological cuts: • Maybe forward + central good for background rejection? • Gain from using topological cuts: re-define boundaries? • QCD: LVL1 output rates extremely sensitive to ETmiss Hggs-D meeting MPI 11/2006

  15. Plans, collaboration options • Tools: • Forward jet tagging: • Continue jet efficiency, jet energy scale studies • Effects of pile-up, underlying event • Tau ID: • Check other background to VBF Higgs sample • Look for improvement in the few-10GeV pT region, revise LLH/NN with Higgs and its backgrd. samples • Analysis: • Study central jet veto • tune cuts to be less sensitive to MC models • Continue SHERPA studies • Continue invisible Higgs trigger studies: LV2, EF ? • Continue Zjj background studies: e-channel • Background studies (e.g. W+jets bg.) • Start HWW analysis? Hggs-D meeting MPI 11/2006

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