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Higgs & EWSB session LCWS06 8-13 marchHiggs self couplingP. Gay 1 Higgs self coupling at e + e - Linear Collider Higgs self coupling at e + e - Linear Collider P. Gay & Ph. Gris LPC Univ. B. Pascal -IN2P3
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Higgs & EWSB session LCWS06 8-13 marchHiggs self couplingP. Gay 2 Introduction Standard Model Higgs doublet ( ) Higgs potential behaves as the direct measurement of hhh and indirect measurement from m h sign of NP Goal Reconstruction of the Higgs potential Experimental establishment of the Higgs mechanism Benchmark for detector optimisation Deviation between
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Higgs & EWSB session LCWS06 8-13 marchHiggs self couplingP. Gay 3 Standard Model
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Higgs & EWSB session LCWS06 8-13 marchHiggs self couplingP. Gay 4 Detector simulation
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Higgs & EWSB session LCWS06 8-13 marchHiggs self couplingP. Gay 5 Processes @ 800 GeV CIRCE/ TESLA Expected signal for 500fb-1 is ~92 events Generated w/ WHIZARD Impact of the beamstrahlung No beamstrahlung Beamstrahlung and complete M h =120 GeV/c 2
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Higgs & EWSB session LCWS06 8-13 marchHiggs self couplingP. Gay 6 Selections Selection in two branches Evis < 500 GeVEvis > 500 GeV 4 jets 6 jets Preselection signal background
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Higgs & EWSB session LCWS06 8-13 marchHiggs self couplingP. Gay 7 “hhZ”-Selection “hhZ”-Selection Background signal g hhh contribution
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Higgs & EWSB session LCWS06 8-13 marchHiggs self couplingP. Gay 8 B-tagging For each event a b-tagging per jet is performed Based on impact parameter information per track, combined per jet, to form a probability Calibration is performed with the integral of the negative part of the distribution and yields the probability that the track is coming from a light quark Impact parameters and jet multiplicity are combined in a multivariable estimator NB: better estimator may be achieved with 3D view Not sensible to the boost (only transverse information used) Calibration has been done at 500GEV No beamstrahlung Beamstrahlung and complete
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Higgs & EWSB session LCWS06 8-13 marchHiggs self couplingP. Gay 9 “hhZ”-Selection signal Background g hhh contribution No b-like jet 4 b-like jet
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Higgs & EWSB session LCWS06 8-13 marchHiggs self couplingP. Gay 10 “hhZ”-Selection signal Background g hhh contribution
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Higgs & EWSB session LCWS06 8-13 marchHiggs self couplingP. Gay 11 “hhZ”-Selection signal Background+signal g hhh contribution
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Higgs & EWSB session LCWS06 8-13 marchHiggs self couplingP. Gay 12 “ hh”-Selection
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Higgs & EWSB session LCWS06 8-13 marchHiggs self couplingP. Gay 13 “ hh”-Selection angle measured in the cme of the pair between the higgs direction and the boost axis signal Background+signal g hhh contribution
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Higgs & EWSB session LCWS06 8-13 marchHiggs self couplingP. Gay 14 Numbers hhZ-selectionvvhh-sel.Total ProcesslooseTight tth 17.362.62- ttZ 10.141.81- tt 98.0-- hZ 16.1-1.41 eeZZ 0.43-- ZZ 0.07-0.49 ZZ 8.15-0.37 tt 0.04-- ZZZ 2.741.03- WWZ 0.28-- Backg 153.5.462.277.73 signal 34.422.08.4930.5 Eff. (%) 42.6%30.2%37.3%33% 2.54.22.6 4.93 for 500 fb -1
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Higgs & EWSB session LCWS06 8-13 marchHiggs self couplingP. Gay 15 Interpretation Counting event only hhZ channel (6jets) hh channel (4jets) for 2 ab -1 ProcesshhZ sel.vvhh-sel. Backg 21.89.1 signal 88.034. Eff. (%) 30.2%37.3% 8.25.2 ‘ hh’ ‘hhZ’ Combination and likelihood g hhh / g 0
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Higgs & EWSB session LCWS06 8-13 marchHiggs self couplingP. Gay 16 hhZ @ 500 GeV Main steps (similar to 800 GeV) 3 selections
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Higgs & EWSB session LCWS06 8-13 marchHiggs self couplingP. Gay 17 hhZ @ 500 GeV HHZ Cme=500Gev M h =120 Gev/C 2 Full polarised beams for 2 ab -1 ProcesshhZ sel. Backg 105.6 signal 124 Eff. (%) 36% 8.1 NN>0.5 likelihood NN>0.5
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Higgs & EWSB session LCWS06 8-13 marchHiggs self couplingP. Gay 18 Higgs self coupling: a benchmark for detector Any improvements done on the the detector will save data taking Impact of the Pflow resolution (fast simulation) 40%->30% move from 4.5 to 2 years data taking
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Higgs & EWSB session LCWS06 8-13 marchHiggs self couplingP. Gay 19 Events clustered in 4 jets Beamstrahlung included Full simulation LDC concept framework MOKKA w/ HCAL sensitive material scintillator Particle Flow Algorithm : Wolf in MARLIN RECO
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Higgs & EWSB session LCWS06 8-13 marchHiggs self couplingP. Gay 20 hhZ @ 500 GeV Event Display LDC
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Higgs & EWSB session LCWS06 8-13 marchHiggs self couplingP. Gay 21 Full simulation Background M34 (masse du Higgs) 20 Nbins entre 80 et 150 pour le background PLOT Background Signal
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Higgs & EWSB session LCWS06 8-13 marchHiggs self couplingP. Gay 22 Full simulation and Reconstruction Reconstruction of is of importance Photons are ~20% of jet energy Motsly coming from Challenge for calorimeters Low energy photons Example of improvement with constraint on ° mass
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Higgs & EWSB session LCWS06 8-13 marchHiggs self couplingP. Gay 23 Plots given for 10fb-1 “fast simulation” “full simulation” 25 ab-1 simulated Full vs Fast simulation Background Signal
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Higgs & EWSB session LCWS06 8-13 marchHiggs self couplingP. Gay 24 Summary @ 500 GeV, selection of the events 6 jets have been performed to hhZ final state. @ 800 GeV, selections of the events with 4 and 6 jets have been performed to respectively cover hh and hhZ final states Beamstralhung & ISR has been taken in account Realistic Fast simulation of the detector has been used At center of mass energy of 500 GeV, hhZ process leads to combination of hhZ and vvhh channel, at center of mass energy of 800 GeV, leads to With 2 ab -1 Full simulation is on the way
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