1 / 44

Observing Heavy Higgs in Weak Boson Fusion with Forward Jet Tagging at the CERN CMS Experiment

Observing Heavy Higgs in Weak Boson Fusion with Forward Jet Tagging at the CERN CMS Experiment. HATICE DURAN YILDIZ DUMLUPINAR UNIVERSITY TURKEY. LHC, PRAHA CONFERENCE JULY 6-12, 2003. Outline. Standard Model & Higgs Mechanism Higgs Observation LHC-CMS experiment Weak Boson Fusion (WBF)

sopoline-abbott
Télécharger la présentation

Observing Heavy Higgs in Weak Boson Fusion with Forward Jet Tagging at the CERN CMS Experiment

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Observing Heavy Higgs in Weak Boson Fusion with Forward Jet Tagging at the CERN CMS Experiment HATICE DURAN YILDIZ DUMLUPINAR UNIVERSITY TURKEY LHC, PRAHA CONFERENCE JULY 6-12, 2003

  2. Outline • Standard Model & Higgs Mechanism • Higgs Observation • LHC-CMS experiment • Weak Boson Fusion (WBF) • Analysis of qqqqH, HWWljj qqqqH, HZZlljj qqqqH, HZZll • Results mH300 GeV

  3. : unitarity purpose Above this value, perturbation theory is not valid. Limits of the Higgs Mass : • The mass of the Higgs boson is a free parameter because of theunknowncoupling λ, but • SM gives us information about the allowed mass range, by • choosing & finite & Theoretical constraints & experimental limits : • Another hint for the mass of the H boson comes from the precision • fits to electroweak observables : • Direct experimental search at LEP2 gives the lower bound on • Higgs mass as:

  4. WW/ZZ fusion gg fusion associated WH, ZH associated

  5. BR

  6. l q  W W H q W W q q Characteristics of WBF qqqqH, HWWljj Forward Jets Centrally produced Leptons Color coherence between forward quarks

  7. Simulation of Events # Events are generated with PYTHIA (6152). # Calorimeter simulation, jet and ETmiss reconstruction with CMSJET # Jet reconstructions cone size = 0.5 for mH=600 GeV = 0.7 for mH=300 GeV # For pile-up: --> 2 min. bias events superimposed at low luminosity # We assume 90% efficiency to account for lepton reconstruction and trigger

  8. I have looked the final states of One isolated lepton Two central jets from W & Z One forward jet + one backward jet Main Backgrounds from tt events W + jets events Z + jets events We show our results; For low luminosity only For low (300 GeV) and for high mass (600 GeV) HIGGS mH = 200 & 800 GeV studied too

  9. How to isolate Higgs events? Signature, mass peak Find two vector bosons in event as H WW, ZZ Wl and Z  Z ll Z jj and W jj Reconstructed Higgs  WW or ZZ system Exploit special Kinematics  Pt(WW,ZZ)  Pt(W,Z)  Pt(l) Angular cuts Higgs Production Mode Weak Boson Fusion: Tagging jets with very high mass

  10. pTl>30 GeV SELECTION CUTS: One isolated lepton No charged track with pt>2 GeV in a cone R<0.3 around the lepton

  11. ETmiss >60 GeV for 600 GeV & no cut for 300 GeV Reconstruction of Leptonic W:  Pl is resolved from mW constraint  The smaller of the two solutions is selected

  12. PTWl>200 GeV for 600 GeV & no cut for mH=300 GeV

  13. Central jet cuts: No extra jet in Top mass veto cut: Reconstruct top mass from 3 central jets cut on

  14. Etjets > 40

  15. Large tail due • to merging jets Reconstruction of Hadronic W for 600 GeV  Start asking 2 jets, ET > 40 GeV for Wjj and reconstruct mjj • No mass reconstructed since only 1j found (36%) Reconstr. W mass in the calorimeter for events with 1 central j & for events in the tail mjj > 100 GeV. Start from the direction of harder jet (or single jet), add cells in a cone R=0.9

  16. W Reconstruction of hadronic W for mH=300 GeV Mass window cut 65 < mjj < 100 Two central jets with  jet< 2 ETjet> 40 GeV Problem of merged jets not too serious for mH=300 GeV.

  17. Cut on PTW Hadronic >200 for mH=600 GeV >100 for mH=300 GeV

  18. PtHiggs> 40 GeV

  19. S + B Signal

  20. 2.0<jet<5 ETjet>20 GeV Forward Jet Tagging One forward & one backward jet with For mH=600 GeV

  21. Cut in |forw-back|>5 Forward jet selection for mH=300 GeV Forw. jet:Take the most energetic jet with >0 not in Wjj Back. jet:Take the most energetic jet with  >0 not in Wjj Cut in | forw-back|>5 W+jets tt signal

  22. How Big!! Forward jet energies for signal and backgrounds

  23. Tagging cuts: We have also tried Efficiency for forward jet tagging

  24. Compare ? Event Selection forHWWlvjj for mH=300 GeV X 1000 Tagging jet reductions

  25. Compare ? Event Selection for HWWlvjj for mH=600 GeV X 100

  26. Event Selection for HZZlljj for mH=300 GeV

  27. Event Selection for HZZlljj for mH=600 GeV

  28. mH=300 GeV

  29. Same selection criterion used for Zlljj except Zll

  30. S+B

  31. Signal + background

  32. S / For an integrated luminosity of 30 fb-1 Expected luminosities in fb-1 for 5 discovery

  33. Signal and background for H WW / ZZ with mH=800 GeV

  34. CONCLUSIONS • If Higgs Boson exists;HWWlvjj • HZZlljj Channels via Weak Boson Fusion mechanism are potential Discovery channels at CMS experiment at CERN, LHC accelerator. • In 1 year of LHC running, CMS experiment would manifest • with mass 300-800 GeV in WBF. • The analysis,HWWllvj for mH=200 GeV is still statistically • acceptable. • Channel is MSSM is hopeless to observe any Higgs • signal.

More Related