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H g 4l in Full Simulation preliminary results 2

H g 4l in Full Simulation preliminary results 2. A. Khodinov * and K. Assamagan ** * State University of New York at Stony Brook ** Brookhaven National Laboratory. Data set (signal only). h g ZZ (*) m h = 130 GeV. Z (*) g e + e - Z (*) g m + m -. h g 4e 25% c h g 4 m 25%

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H g 4l in Full Simulation preliminary results 2

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  1. Hg4l in Full Simulationpreliminary results 2 A. Khodinov* and K. Assamagan** * State University of New York at Stony Brook ** Brookhaven National Laboratory

  2. Data set (signal only) hgZZ(*) mh = 130 GeV Z(*)ge+e- Z(*)gm+m- hg4e 25% chg4m25% hg2e2m 50%

  3. Framework details • Number of Events 100.000 • Generator Pythia 6.217 (6.5.0) no filters • Fully simulated with ATLSIM (6.5.0) • VDC dataset simul_000033 • geometry level dc1 (|h|< 2.7) • Reconstructed with ATHENA (7.0.2) • Job Options file RecExCommon_jobOptions.txt • Additional MC Truth Spcl_MC (F.Paige and I.Hinchliffe)

  4. Lepton Reconstruction We suppose to compare 2 alternative methods matching tracks in the Inner Detector with Muon Spectrometer. • STACO (statistical combination) MuonBox + Xkalman ( planned to be included in the ATLAS software release. When?). so currently use ONLY MuonBox Ref: Muon reconstruction with Muonbox and STACO byHassani, S.(Saclay) 2. MuID combined (already in the release) Moore + IPatRec Ref: Muon reconstruction with Moore and MuID by Biglietti M., Cataldi G. (Naples University, INFN Lecce) STACO &Muid Comb: Combination of the muon system and the inner detector tracks “MuonBox” & “MuidStandAlone” : Back tracking of the MuonBox and MOORE tracks to the interaction point

  5. Kinematical cuts as in TDR • e1+e2- or m1+m2- with pT>20 GeV (leading pair*) • e3+e4- or m3+m4- with pT>7 GeV (following pair) • 2. Calculate invariant Z mass • m12 = mZ 15GeVor ( 6 GeV) • m34 > 20GeV • Using these cuts the best result obtained was s=2.1 GeV (MUID Comb) • We show improvement since our last meeting in November • We will show results for H4e and H 2e 2m also!

  6. Additional requirements (Our own) • TRD + combinatorial treatment • Instead of taking just the 2 hardest leptons as • the leading pair, we look though all the possible • 4 lepton combinations for the leading and following • pairs but retain the combination where the leading pair • is best reconstructed (we do not require hardest pTs): • e1+e2- or m1+m2- with pT>20 GeV min(Mz-Mld) Doing the above, our best resolution improves from s=2.1 GeV to s=1.8 GeV (MUID Comb)

  7. Additional Requirements our own 2. Z-mass constraint • Assuming the 2 leading leptons come from an on-shell Z of mass m0, rescale the lepton 4-momentums such that: p  p*m0/mll Where mll is the measured (reconstructed) invariant mass of the 2 leading leptons • Do this before reconstructing the H mass • To find m0, we do this on event by event basis: convolute detector resolution with the Breit-Wigner shape for the Z: m0 = max ( Gaussian(mll, s0) * BW(mZ,GZ) ) where s0 is the detector resolution by plotting mll without the mass constraint

  8. without mass constraint s =2.9 GeV without mass constraint s =1.8 GeV mean 129.9 s 2.306 mean 130.2 s 1.618 hg4m Leading Mll cut = Mz+-15 GeV Mass constraint applied mean 130.2 s 2.564 Improvement from 2.1 GeV to 1.8 GeV with the handing of combinatorial as described

  9. Without mass constraint s IPat =2.85 GeV mean 129.9 s 1.902 mean 129.9 s 1.858 hg4e hg4e Leading Mll cut =Mz+-15 GeV mean 129.8 s 1.894 MC Isol Cut 5 GeV ET cut 15 GeV track match YES hg2e2m |h|<2.7 Norm calorimeter factor =1/0.9845

  10. Z (*) gm+m- reconstruction by MuID Comb

  11. mean 130.2 s 1.564 mean 129.8 s 2.277 hg4m Leading Mll cut = Mz+-6 GeV Mass constraint applied mean 130.2 s 2.468

  12. mean 129.9 s 1.834 mean 129.9 s 1.890 Leading Mll cut = Mz+-6 GeV Mass constraint applied mean 129.9 s 1.895 |h|<2.7 Norm calorimeter factor =1/0.9845

  13. Problem in calibration for electrons: The normalization factor of 1/0.9845 required to restore the 4 momentum of reconstructed electrons Z (*) ge+e-

  14. Summary of our results • all the new H4manalyses using Muid CB, we have the best resolution (see the Higgs Working Group meetings) • Our H2e2m results are in agreement with Wisconsin Group (see the talk • Steve Armstrong in the Higg group) • Our H4e result compare well with Wisconsin result (see the talk by Stathes Paganis : he has worked on electron calibration!)

  15. Summary and plans • MuID combined provides better resolution than MuId stand alone, so we are awaiting for STACO to implement into the analysis. • Photos + filters on h is required to simulate Brem properly (Pythia itself does not provide right Brem) and increase the statistics of ‘good’ reconstructed Higgs bosons. • Analysis tuning is planned (mostly hg4e and hg2e2m) • A look at backgrounds: electron, muon isolations • We will obtain and use the electron calibration done recent by the Wisconsin Group (see the talk by Stathes Paganis in the Higgs Working Group!)

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