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HIGGS’ SELF COUPLING λ

HIGGS’ SELF COUPLING λ. F. Duru, M. H. Reno. The University of Iowa. Higgs self-coupling. To understand the shape of the Higgs potential Higgs Potential: V H = - λ ν 2 ( Ф † Ф ) + λ ( Ф † Ф ) 2 where ν =((2) 1/2 G F ) -1/2 and Ф is the Higgs field

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HIGGS’ SELF COUPLING λ

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  1. HIGGS’ SELF COUPLING λ F. Duru, M. H. Reno The University of Iowa F. Duru, CMS HCAL Meeting, Fermilab

  2. Higgs self-coupling • To understand the shape of the Higgs potential • Higgs Potential: VH = -λν2(Ф†Ф) + λ (Ф†Ф)2 where ν=((2)1/2 GF)-1/2 and Ф is the Higgs field • λ = λSM= mH2/2ν2 λ is per se a free parameter • The strength of λ affects the production rate of Higgs pairs in SM. F. Duru, CMS HCAL Meeting, Fermilab

  3. SM Channel: g g  HH • Dominant Higgs pair production mechanism : gluon-gluon fusion mH < 140GeV H  mH > 140 GeV H  W+ W- “Our” signal channel: g g HHW+W-W+W-(l± v j j) (l± v j j) 150 GeV < mH < 200 GeV (So far, mH = 180 GeV) F. Duru, CMS HCAL Meeting, Fermilab

  4. “The Code” • Code (U. Baur’s) we use to generate events is a Fortran 90 and Fortran 77 combination • CTEQ4 PDFs were replaced by CTEQ6 PDFs αS= 0.118 CTEQ6L is the set used. • Variables were changed to CMS Software variable format • Ntuples are about to be ready F. Duru, CMS HCAL Meeting, Fermilab

  5. Generated Event Plots Higgs’ masses were set at 180 GeV Plots are consistent with the set value. F. Duru, CMS HCAL Meeting, Fermilab

  6. Generator Level W’s Reconstructed W masses from generator information: Peaks around 80 GeV. F. Duru, CMS HCAL Meeting, Fermilab

  7. Generated Higgs Bosons Differential cross section vs Higgs boson’s Pt. Mean at 112.7 GeV. F. Duru, CMS HCAL Meeting, Fermilab

  8. Pt & m Mean: 310.1 GeV Mean: 381.3 GeV F. Duru, CMS HCAL Meeting, Fermilab

  9. Rjl max, Rjj max, Rjl min, Rjj min F. Duru, CMS HCAL Meeting, Fermilab

  10. Pt j max, Pt j min, Pt miss F. Duru, CMS HCAL Meeting, Fermilab

  11. Backgrounds Largest contribution: W± W+ W- j j Other backgrounds: 1 top quark decays leptonically, the other one hadronically W Z j j j j  W+ b W- b- j where 1 b quark decays semileptonically W W j j j j F. Duru, CMS HCAL Meeting, Fermilab

  12. Background cross sections (fb) U. Baur et al. (2002) For 180 GeV mH, √s = 14 TeV: HH : 0.18 W± W+ W- j j : 0.40 : 0.22 W Z j j j j : 0.15 : 0.08 : 0.05 W W j j j j : 0.005 : 0.002 Pileup ~ 0.03 F. Duru, CMS HCAL Meeting, Fermilab

  13. Backgrounds • All the background channels are being produced with Alpgen Cuts: pT(j) > 15 GeV pT(l) > 15 GeV dR(jj) > 0.6 dR(ll) > 0.2 |η | < 3.0 • Interfaced with cmkin F. Duru, CMS HCAL Meeting, Fermilab

  14. WWWjj W+ Plots F. Duru, CMS HCAL Meeting, Fermilab

  15. W- plots F. Duru, CMS HCAL Meeting, Fermilab

  16. MET F. Duru, CMS HCAL Meeting, Fermilab

  17. Future plans • These events will be put in CMS detector software: OSCAR + ORCA • We will apply necessary cuts: PT, ΔR, η … • mvis is an important value to distinguish the signal and background channels (value is much smaller for the signal). F. Duru, CMS HCAL Meeting, Fermilab

  18. Future plans (cont.) • Use χ2 test to obtain quantitative bounds on the Higgs boson self-coupling • Plotting ΔλHHH [(λ-λSM)/ λSM] versus different Higgs boson masses will make possible to see upper and lower limits. F. Duru, CMS HCAL Meeting, Fermilab

  19. λ bound F. Duru, CMS HCAL Meeting, Fermilab

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