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

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

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

4. 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 α S = 0.118 CTEQ6L is the set used. Variables were changed to CMS Software variable format Ntuples are about to be ready

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

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

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

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

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

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

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

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

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

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

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

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

17. 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: P T, ΔR, η … m vis is an important value to distinguish the signal and background channels (value is much smaller for the signal).

18. F. Duru, CMS HCAL Meeting, Fermilab 18 Future plans (cont.) Use χ 2 test to obtain quantitative bounds on the Higgs boson self-coupling Plotting Δλ HHH [(λ-λ SM )/ λ SM ] versus different Higgs boson masses will make possible to see upper and lower limits.

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