1. Hggs-D meeting MPI 11/20061 Higgs Physics – Activities in Bonn/Siegen Jörn Große-Knetter ATLAS-Higgs-D Treffen München, 28.11.2006

2. Hggs-D meeting MPI 11/20062 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

3. Hggs-D meeting MPI 11/20063 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 different jet algos – eff. vs. eta and Pt matching between truth jets (hadron level) and reco jets within a ΔR Forward Jet Studies (Iris Rottländer) Cone 07 Cone 04 ● : Tower o : Topo

4. Hggs-D meeting MPI 11/20064 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) Pythia QCD Forwardjets Herwig QCD Dijets Pythia 6.3 VBF H->tautau->ll Herwig VBF H->tautau->ll Different MC Generators and Topologies

5. Hggs-D meeting MPI 11/20065 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??

6. Hggs-D meeting MPI 11/20066 Survial Probability w.r.t central jet veto Signal w/o underlying eventSignal with underlying event 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

7. Hggs-D meeting MPI 11/20067 Survial Probability w.r.t central jet veto Zjj(EW) w/o underlying eventZjj(QCD) with underlying event 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

8. Hggs-D meeting MPI 11/20068  -ID for VBF H    lh (A. Veenendaal)  from VBF Higgs decay have relatively low p T 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

9. Hggs-D meeting MPI 11/20069 Comparison tauRec/tau1P3P Find best working point: tauRec better for p T >20GeV, 1P3P for p T <20GeV Combine both algorithms? 10 GeV < p T < 20 GeVavg. over all p T

10. Hggs-D meeting MPI 11/200610  signature: tagging jets + 2 leptons + large missing transverse energy   M /M ~ 10%  dominated by E miss H    e  ATLAS 30 fb -1  expected BG ~ 5 to 10% (Scientific note) for M H > 125 GeV: side band for M H < 125 normalisation from Z-peak, shape from Z   collinear approximation Background Estimate for VBF: H    ll4n from data (M. Schmitz)

11. Hggs-D meeting MPI 11/200611 Idea: jjZ  μμ and jjZ    μμ with 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    μμ4 ν MC (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 VBF, H   : determination of bkgr. from data (M. Schmitz)

12. Hggs-D meeting MPI 11/200612 Prospects for mass determination with limited luminosity 30fb -1, only   decay 6 out of 8 fits fine 120fb -1,   decay =30fb -1,  ll decays? all fits fine

13. Hggs-D meeting MPI 11/200613 Invisible Higgs boson decays invisble Higgs decays: SUSY H  LSP LSP, ADD, Majoron,… VBF most sensitive, but how to trigger on 2 jets + missing energy?  LVL1 trigger study for jets including FCAL 95% CL exclusion with 30 fb-1 VBF result assumes trigger on jets up to = 4.9

14. Hggs-D meeting MPI 11/200614 Ongoing LVL1 Trigger Study (Guilherme Hanninger) Goal: determine efficiencies and rates for various options of trigger menues for combinations of E T miss + central jet + forward jet “plain cuts”:

15. Hggs-D meeting MPI 11/200615 Estimation of LVL1 trigger efficiencies, rates Maybe forward + central good for background rejection? Gain from using topological cuts: re-define boundaries? QCD: LVL1 output rates extremely sensitive to ETmiss topological cuts:

16. Hggs-D meeting MPI 11/200616 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 p T 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?