Presentation is loading. Please wait.

Presentation is loading. Please wait.

Search for SM Higgs in WW* channel at CDF

Published byNoel Job Dennis Modified over 6 years ago

Similar presentations

Presentation on theme: "Search for SM Higgs in WW* channel at CDF"— Presentation transcript:

1 Search for SM Higgs in WW* channel at CDF
Mircea Coca Duke University On behalf of the CDF Collaboration TEV4LHC Workshop Fermilab October 20-22, 2005 Mircea Coca, Tev4LHC, October 20-22, 2005

2 Mircea Coca, Tev4LHC, October 20-22, 2005
Overview SM Higgs Production and Decay Sensitivity to Non-SM Physics 4th Generation Fermion Families Di-boson Cross-Section Measurement at CDF Signal and Background for HWW 95% CL. on sxBR(HWW*) Prospects for 1/fb Looking forward “Panning for Higgs” Mircea Coca, Tev4LHC, October 20-22, 2005

3 Standard Model (SM) Higgs Production …
Higgs Production in SM Four main production mechanisms Gluon fusion dominant Higgs-strahlung also relevant at the Tevatron (x8 smaller cross-section) Mircea Coca, Tev4LHC, October 20-22, 2005

4 Mircea Coca, Tev4LHC, October 20-22, 2005
… And Higgs Decay Higgs Decay in SM MH< 135 GeV Higgs decays predominantly into bb MH>135 GeV Higgs decays mainly into WW ggHWW* Only search channel using single Higgs production through gluon fusion Maximum sensitivity for MH=160 GeV Mircea Coca, Tev4LHC, October 20-22, 2005

5 Non-SM Production: 4th Generation Models
Number of fermion generations Ng not fixed by the SM Asymptotic freedom: Ng<8 LEP data: number of light neutrinos N=2.994+/-0.012 An additional fourth generation of quarks Mass limit for the 4th generation quarks mb’>199 GeV/c2 (95% CL.) Increase gluon fusion Higgs production cross-section Higgs couples to mass X8 larger s(ggH) for GeV Higgs E. Arik-hep-ph/ Mircea Coca, Tev4LHC, October 20-22, 2005

6 Mircea Coca, Tev4LHC, October 20-22, 2005
Higgs WW final states W boson decay channels: leptonically ~ 33 % (ℓ =e,m,t) hadronically ~ 67% 3 signatures, from WW decay: Dilepton: BR= 5% Very small BR, but easily triggerable, clean Sensitive to leptonic decays of taus Might be the only signature to identify HWW at the Tevatron Single lepton+th: BR= 4% Could potentially be used at the Tevatron Single lepton+jets: BR=30% BR larger, large W+multi-jets backgrounds Previous studies concluded that there is not much hope to use this channel All-hadronic: BR=45% BR largest, hard to trigger, enormous QCD backgrounds Convention: ℓ =e,m Final state 2 leptons missing energy (neutrinos) Dileptons Mircea Coca, Tev4LHC, October 20-22, 2005

7 Signal and Backgrounds
Use PYTHIA + GEANT detector simulation 10 Higgs mass points between GeV (in 10 GeV steps) Backgrounds: Vector boson pair production WW, WZ, ZZ (estimated from PYTHIA) WW about 70% of the total background (mH=160GeV) Vector boson production Drell-Yan: Z/g*ee/mm/tt (estimated from PYTHIA) W+jets(jete/m) (estimated completely from data) W+g (ge) (estimated from MC) Smaller backgrounds tt, multijets Luminosity: We analyzed 360pb-1 of Run II data. (weighted value–different subsystem requirements). Relative backgrounds MH=160GeV Mircea Coca, Tev4LHC, October 20-22, 2005

8 Mircea Coca, Tev4LHC, October 20-22, 2005
Diboson Production WW production is the dominant background Compulsory to first measure the WW production cross-section Select a large WW sample to check Simulation modelling of the data (PYTHIA, ALPGEN), ex: Df(l,l) Trigger, lepton identification efficiencies, everything comes into the mix Still statistically limited [PRL 94, (2005)] (CDF) S/B = 2 Mircea Coca, Tev4LHC, October 20-22, 2005

9 Handles to separate WW from HWW
It is the main challenge of this analysis Exploit spin correlations Higgs is a spin 0 particle V-A structure in W decay Leptons tend to be parallel Small Df(ℓ, ℓ) Neutrinos go parallel Typically larger missing energy than WW Small di-lepton invariant mass It is important to have Higgs mass-dependent selection requirements Heavier the Higgs, better the separation of the signal from WW W- W+ e+ e- Df(ℓ, ℓ) after event selection Mircea Coca, Tev4LHC, October 20-22, 2005

10 Mircea Coca, Tev4LHC, October 20-22, 2005
Event Selection Optimized for the best a-priori 95% C.L. on sxBR(HWW) Two leptons: pT trigger, non-trigger>(20,10) GeV Muons: |h|<1.0; electrons: (|h|<1.0, |h|<2.0) Mℓℓ > 16 GeV Jet veto (signal can only have soft ISR jets) 0jet || 15<ET1jet<55 GeV || 15<ET2jet<40 GeV jets: ||<2.5 ET > ¼MH ET >50 GeV || (met, closest lep/jet)>20º Opposite sign Mℓℓ < (½*MH – 5) GeV pT1lep1+pT2lep2+ ET < MH Backgrounds rejected Mircea Coca, Tev4LHC, October 20-22, 2005

11 Mircea Coca, Tev4LHC, October 20-22, 2005
Signal Acceptance HWW acceptance; does not include BR(HWW) Cut (MH=160GeV) Efficiency (%) 2 well-identified leptons 9.14 ± 0.04 Mll > 16 GeV 96.1 ± 0.06 jet veto 88.2 ± 0.11 MET > MH/4 80.5 ± 0.14 MET>50GeV || met,l/j>20º 96.4 ± 0.07 opposite signs 98.7 ± 0.04 Mll < MH/2 – 5 GeV 98.9 ± 0.04 ptlep1+ptlep2+met < MH 97.2 ± 0.07 Systematic errors ISR (initial state radiation) % Parton distribution functions 3.0% as % Lepton ID, Track Isolation % Jet energy scale, Trigger Effic 1.0% Acceptance loss due to: - detector coverage - lepton identification Mircea Coca, Tev4LHC, October 20-22, 2005

12 Mircea Coca, Tev4LHC, October 20-22, 2005
Control Regions We did not performed a blind analysis this time Looked in some control regions/cross checks Measured Zee, mm cross-sections  used data with 2 leptons Compare the number of same-sign charge events with SM predictions Compare the SM expectations with data events with 25< missing energy<MH/4 Signal selection requires missing energy>MH/4 We found good agreement between SM and data Same-sign events, 2 leptons, jet veto CDF Run II Preliminary Mircea Coca, Tev4LHC, October 20-22, 2005

13 SM Expectation and Data
Data does not show any excess. Mircea Coca, Tev4LHC, October 20-22, 2005

14 Azimuthal angle between di-leptons
Take advantage of the difference in the HWW and WW Df(l,l) distributions Use a binned likelihood in Df, which we maximize as a function of sxBR(HWW) to set 95% C.L. limits Mircea Coca, Tev4LHC, October 20-22, 2005

15 Mircea Coca, Tev4LHC, October 20-22, 2005
95% CL on s x BR(HWW) Mircea Coca, Tev4LHC, October 20-22, 2005

16 Few kinematic distributions
Mircea Coca, Tev4LHC, October 20-22, 2005

17 HWW contribution to the Tevatron Higgs search
HWW channel is important for a MH>130 GeV SM Higgs discovery. Tune on Tom Junk’s talk for more. Mircea Coca, Tev4LHC, October 20-22, 2005

18 Potential improvements
Two main areas to focus on: Reducing WW background Find better discriminating variables Exploit any correlations between them Advanced techniques: ANN, likelihood, SVM, etc Increase the signal acceptance Loosen the lepton identification criteria Loosen the trigger lepton PT Help mainly at lower Higgs masses Involve using a different trigger Include the lepton+hadronic tau channel Include acceptance from associated VH and VV fusion HWWll: L=360 pb-1, MH=160 GeV S 0.58 B 13.78 WW: 9.8 W+g/W+j:2.5 S/√B 0.12 Exploit known/find new discriminating variables Mircea Coca, Tev4LHC, October 20-22, 2005

19 Neural Networks (Work in progress)
DR=(Df)2 + (Dh)2 Considered variables showing separation between WW and HWW: Exploit Higgs’ spin 0 Production of a heavy particle, mH Exploit different production mechanisms qqWW vs ggH Optimize on S/sqrt(B) for easy comparison with the current analysis (MH=160GeV) Find 9 discriminating variables 1.42x better S/sqrt(B) Mircea Coca, Tev4LHC, October 20-22, 2005

20 1/fb projections summary
Assume the current analysis as starting point Below are just few ways we think we can use to improve our sensitivity Potential Improvement S/sqrt(B) Using a NN                                           *  Including hadronic taus                        1.15 Include associated VH and VV fusion  1.15 Estimate performed in hep-ph/ Loose leptons                                        1.10 Overall Equivalent to ~4x more luminosity There is still potential to do better Not all these improvements might be ready for Winter conferences Mircea Coca, Tev4LHC, October 20-22, 2005

21 Mircea Coca, Tev4LHC, October 20-22, 2005
Looking forward CDF performed a benchmark search for HWW* in leptonic decays We are a factor of 12 away from the SM predictions (MH~160 GeV) Soon to become sensitive to extra fermion families Further optimizations are being worked on A lot more to learn about this channel in the next few years Could play a bigger role at the low Higgs masses than previously thought ? See Tom Junk’s plenary talk for a CDF big picture Mircea Coca, Tev4LHC, October 20-22, 2005

Download ppt "Search for SM Higgs in WW* channel at CDF"

Similar presentations

Search for Large Extra Dimensions at the Tevatron Bob Olivier, LPNHE Paris XXXVI ème Rencontre de Moriond 17 - 24 Mars 2001 1 Search for Large Extra Dimensions.

Search for Large Extra Dimensions at the Tevatron Bob Olivier, LPNHE Paris XXXVI ème Rencontre de Moriond Mars Search for Large Extra Dimensions.
Current limits (95% C.L.): LEP direct searches m H > 114.4 GeV Global fit to precision EW data (excludes direct search results) m H < 157 GeV Latest Tevatron.

Current limits (95% C.L.): LEP direct searches m H > GeV Global fit to precision EW data (excludes direct search results) m H < 157 GeV Latest Tevatron.
Search for Top Flavor Changing Neutral Current Decay t → qZ Ingyin Zaw DOE Review August 21, 2006.

Search for Top Flavor Changing Neutral Current Decay t → qZ Ingyin Zaw DOE Review August 21, 2006.
Recent Results on the Possibility of Observing a Standard Model Higgs Boson Decaying to WW (*) Majid Hashemi University of Antwerp, Belgium.

Recent Results on the Possibility of Observing a Standard Model Higgs Boson Decaying to WW (*) Majid Hashemi University of Antwerp, Belgium.
Tau dilepton channel The data sample used in this analysis comprises high-p T inclusive lepton events that contain an electron with E T >20 GeV or a muon.

Tau dilepton channel The data sample used in this analysis comprises high-p T inclusive lepton events that contain an electron with E T >20 GeV or a muon.
Higgs Searches using Vector Boson Fusion. 2 Why a “Low Mass” Higgs (1) M H

Higgs Searches using Vector Boson Fusion. 2 Why a “Low Mass” Higgs (1) M H
Recent Electroweak Results from the Tevatron Weak Interactions and Neutrinos Workshop Delphi, Greece, 6-11 June, 2005 Dhiman Chakraborty Northern Illinois.

Recent Electroweak Results from the Tevatron Weak Interactions and Neutrinos Workshop Delphi, Greece, 6-11 June, 2005 Dhiman Chakraborty Northern Illinois.
Top Physics at the Tevatron Mike Arov (Louisiana Tech University) for D0 and CDF Collaborations 1.

Top Physics at the Tevatron Mike Arov (Louisiana Tech University) for D0 and CDF Collaborations 1.
WW  e ν 14 April 2007 APS April Meeting WW/WZ production in electron-neutrino plus dijet final state at CDFAPS April Meeting 14-17 April 2007 Jacksonville,

WW  e ν 14 April 2007 APS April Meeting WW/WZ production in electron-neutrino plus dijet final state at CDFAPS April Meeting April 2007 Jacksonville,
1 Viktor Veszprémi (Purdue University, CDF Collaboration) SUSY 2005, Durham Search for the SM Higgs Boson at the CDF Experiment Search for the SM Higgs.

1 Viktor Veszprémi (Purdue University, CDF Collaboration) SUSY 2005, Durham Search for the SM Higgs Boson at the CDF Experiment Search for the SM Higgs.
Heavy charged gauge boson, W’, search at Hadron Colliders YuChul Yang (Kyungpook National University) (PPP9, NCU, Taiwan, June 04, 2011) June04, 2011,

Heavy charged gauge boson, W’, search at Hadron Colliders YuChul Yang (Kyungpook National University) (PPP9, NCU, Taiwan, June 04, 2011) June04, 2011,
1 g g s Richard E. Hughes The Ohio State University for The CDF and D0 Collaborations Low Mass SM Higgs Search at the Tevatron hunting....

1 g g s Richard E. Hughes The Ohio State University for The CDF and D0 Collaborations Low Mass SM Higgs Search at the Tevatron hunting....
W properties AT CDF J. E. Garcia INFN Pisa. Outline Corfu Summer Institute Corfu Summer Institute September 10 th 2 1.CDF detector 2.W cross section measurements.

W properties AT CDF J. E. Garcia INFN Pisa. Outline Corfu Summer Institute Corfu Summer Institute September 10 th 2 1.CDF detector 2.W cross section measurements.
1 A Preliminary Model Independent Study of the Reaction pp  qqWW  qq ℓ qq at CMS  Gianluca CERMINARA (SUMMER STUDENT)  MUON group.

1 A Preliminary Model Independent Study of the Reaction pp  qqWW  qq ℓ qq at CMS  Gianluca CERMINARA (SUMMER STUDENT)  MUON group.
L. Bellagamba, Excited fermions and other searches at HERA 1 International Conference on High Energy Physics Amsterdam 24-31 July 2002 Excited fermions.

L. Bellagamba, Excited fermions and other searches at HERA 1 International Conference on High Energy Physics Amsterdam July 2002 Excited fermions.
KIRTI RANJANDIS, Madison, Wisconsin, April 28, 20051 Top Quark Production Cross- Section at the Tevatron Collider On behalf of DØ & CDF Collaboration KIRTI.

KIRTI RANJANDIS, Madison, Wisconsin, April 28, Top Quark Production Cross- Section at the Tevatron Collider On behalf of DØ & CDF Collaboration KIRTI.
Study of the to Dilepton Channel with the Total Transverse Energy Kinematic Variable Athens, April 17 th 2003 Victoria Giakoumopoulou University of Athens,

Study of the to Dilepton Channel with the Total Transverse Energy Kinematic Variable Athens, April 17 th 2003 Victoria Giakoumopoulou University of Athens,
HERA-LHC, CERN Oct.11 2004 Preliminary study of Z+b in ATLAS /1 A preliminary study of Z+b production in ATLAS The D0 measurement of  (Z+b)/  (Z+jet)

HERA-LHC, CERN Oct Preliminary study of Z+b in ATLAS /1 A preliminary study of Z+b production in ATLAS The D0 measurement of  (Z+b)/  (Z+jet)
Alex Melnitchouk DPF conference - May 2002 1 Search for Fermiophobic Higgs in the h   Channel DPF 2002, Williamsburg Alex Melnitchouk (Brown University)

Alex Melnitchouk DPF conference - May Search for Fermiophobic Higgs in the h   Channel DPF 2002, Williamsburg Alex Melnitchouk (Brown University)
Searches for the Standard Model Higgs at the Tevatron presented by Per Jonsson Imperial College London On behalf of the CDF and DØ Collaborations Moriond.

Searches for the Standard Model Higgs at the Tevatron presented by Per Jonsson Imperial College London On behalf of the CDF and DØ Collaborations Moriond.

Similar presentations

Ads by Google