Fermiophobic Higgs

1
Fermiophobic Higgs

• Drew Baden
• University of Maryland
• Dzero Collaboration
• EPS 2003

2
Fermilab Tevatron

• Run I 1992-96
• about 120 pb-1 recorded
• 1.8TeV cm energy
• 3.6ms bunch crossing
• MainRing
• Synchrotron injector for Tevatron
• In same tunnel ?
• Run II 2001-
• 1.96TeV cm energy
• 396ns bunch crossing
• MainRing pulled, Main Injector built
• 230M project
• Goal 10,000-15,000 pb-1

3
D? Detector

• Upgrades
• 2T Solenoid
• gt100k scint. fibers
• gt700k silicon strips
• Muon detector improvements
• Preshower added
• CAL, Muon, trigger electronics
• NO MAIN RING!!!

Silicon tracking out to h2
Yields
4
Run 2 Data Taking
Delivered
for Physics
5
Higgs Current Understanding

• Discovery motivation is obvious
• Higgs is a central part of the Standard Model
• But after discovery, the Higgs mass must be
  determined
• MHIGGS determines decay G, and sproduction for
  coupling to all particles
• Constraints on MHIGGS

• LEP direct search
• Mgt114GeV _at_ 95 CL

• ElectroWeakWorkingGroup
• Favors light higgs, 91GeV central value
• Mlt211 GeV 1-sided 95CL

6
What is Fermiophobic Higgs?

• Fermiophobicmeans you turn off couplings to
  fermions
• Can occur in Type-1 2-doublet Higgs models
• Type-1 one doublet couples to fermions, the
  other to bosons
• 2 CP even neutral Higgs bosons light h and
  heavy H
• mixes with scalar field with angle a
• coupling to fermions via
• mass, as usual, and
• sin(a) for H and cos(a) for h
• h is therefore fermiophobic in the limit a?p/2
• Of course we could have a fermiophobic H
  (a?0)but h is lighter so we look there

7
Fermiophobic Higgs Production

• Effect on Higgs production
• Eliminates gluon fusion
• Biggest contribution to SM Higgs production ?
• Leaving
• Associated Production
• Virtual W/Z ? onshell W/Zh
• WW fusion
• Quark lines radiate Ws, fuse to h
• ZZ fusion too small by usual EWK factor

8
Fermiophobic Higgs Decay
SM Branching Fractions

• Final states
• No bb in the final state (fermiophobic!)
• gg
• Through W triangle loop
• Dominates at low Mh
• Also WWgg vertex
• Suppressed by EM factors
• Associated Production
• Z/Wh where h ? WW/ZZ
• But h ?ZZ suppressed
• Dominant final states are
• ZWW, WWW
• Physics background from ZWW, standard EWK
  tri-linear coupling
• h ? WW dominates at high Mh
• LEP Combined Fermiophobic limit
• Mh lt 108.2 GeV _at_ 95 CL using h ? gg mode

MHlt 114.4 EWWG
LEP Higgs Working Group benchmark model
Mhlt 108.2 LHWG Note 2001-8 Hep-ex (0107035) 2001
9
Experimental Limits

• LEP Combined Fermiophobic limit
• Mh lt 108.2 GeV _at_ 95 CL using h ? gg mode
• LHWG Note 2001-8 and Hep-ex (0107035) 2001
• D?/CDF Run1 limit 78.5 / 82.0 GeV at 95 CL
• B.Abbott et al. Phys. Rev. Lett. 82, 2244 (1999 )
• F.Abe et al. Phys. Rev. D59, 092002 (1999) LEP

10
This Talk.

• So, for this talk, present status on
• W/Z ? W/Z h, h ? WW
• Look for the h ? WW
• Focus on final states with 2 Ws
• 2 Zs will be relatively suppressed (see previous
  slide)
• Search for inclusive ee-, mm-, and e?m lepton
  pairs MET
• The prompt W/Z in final state
• No requirement on any leptonic decay
• W/Zh ? W/Zgg
• Look for states with 2gs
• large MET and/or jets
• Let the theorists foot the bill as to
  interpretation
• Which particular Type etc.

11
h ? WW- ? ll-nn

• Combine ee- and e?m sample
• Dielectron sample 44pb-1
• em sample 34pb-1
• Backgrounds
• All dilepton channels have
• Small WW, Wg, ZZ, WZ, and top
• Large Wjet and QCD misidentification
• ee also has a large background from Z ? ee-
• Reduced via ee mass MET cut
• Wjet dominate after, with some ts remaining
• em Dominated by QCD and Wjet

12
Electron Sample

• Electron ID requirements
• Triggered
• IsolationEMFShower Shape
• e 85 (93) efficiency for central (endcap)
• Track match via C2(E/p and Df) and DCA
• e73 obtained using sample of Z ? ee-
• Leading electron PTgt20 GeV, 2nd electron PTgt10
  GeV
• Reduces multijet background

13
Muon Sample, Jets, and MET

• Muons
• ID from muon system
• Isolated from jets using E(cal) and tracks
• E(DRlt0.4) - E(DRlt0.1)lt2.5GeV
• SPT (in cone DRlt0.5) tracks lt 2.5 GeV
• Reject cosmics via timing requirement
• PT gt 10 GeV with central track match
• Jets
• Cut to eliminate hot towers, other pathologies
• EMF cut
• hlt2.5
• Energy corrections, cone 0.5
• MET
• Use calorimeter cells
• Correct for jet energy corrections
• Use 0.7cone jets for this

Cal corr
14
Event Cuts

• Electrons
• 2 with PTgt 20 GeV
• at least 1 with track match
• M(ee-) lt 78 GeV to reject Zs
• MET
• MET gt 25 GeV and Df(jets,MET) gt 0.5
• Dominant background is Wjets
• Spin Correlations
• W and W- have opposite spin projections
• Tendency for charged leptons to be emitted along
  same direction
• Require Df(leptons)lt2.0

15
ee- Final State

• Dominant background from Z ? ee-
• Invariant mass cut M(ee-)ltMH/2 for limit
  calculation
• 96 effecienty for MH160GeV
• MET from jet fluctuations reduced
• Transverse mass cut MTltMH20 GeV

M(ee-) before cuts
M(ee-) after electron selection and PT cut
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ee- Result

• Data after all cuts
• Monte Carlo
• Pythia 6.202 full sim/reconst.
• 0.5 min bias overlay
• Multijet backgrounds from data
• Calculated using poor quality EM object
• Efficiencies
• Backgrounds vs. Data
• largest uncertainty is in Wjets and Z(ee)

Df(ee) MC/Data Comparison
Selection optimized for MH160
17
e?m Final State and Results

• Comparison with ee- analysis
• No Z decay background
• No transverse mass cut applied
• MET cut constant MET gt 20 GeV
• Less QCD multi-jet background
• MET and PT(m) ? not aligned
• All other cuts are the same
• Efficiencies
• Uncertainty mostly from Wjets
• Results combing ee- and e?m
• Upper limit of 2-3pb _at_ 95CL
• Limited datax4 being analyzed now
• Need 10fb-1 to be sensitive up to Mhiggs160 GeV

sBr(H ?WW ? ee-/ e?m )
18
mm- Final State

• 48pb-1 analyzed
• 2 High PT isolated muons (hlt2)
• Same cuts as previous
• M(mm-), PT(m), MET, Df(MET,jet),MT, Df(mm-)
• MC samples from Pythia 6.202, full sim/reconst
• Same as for previous study
• QCD and Wjets backgrounds from data measured
• using muon isolation
• Normalized to Z? mm
• Overall signal efficiency for Mh160 GeV is 14.6
  0.6

19
mm- Result

• 1 Event remains
• 48pb-1 data
• 14.4 overall efficiency for 160 GeV Higgs
• 0.32 0.01 expected from backgrounds
• No official upper limit on sBr yet
• Will be reporting soon on combined H ? WW ?
  ee-, mm-, and e?m on 120pb-1

20
H ? gg X

• 52pb-1 analyzed
• Photon id
• EMfractiongt0.9 , Shower shape C2, isolation,
  PTgt25 GeV, charged track veto
• No jet requirements or MET cut here
• Fake photons due to
• high PT p0? gg (small opening angle)
• Drell-Yan production tracking inefficiency
• jet fluctuations mimic photon (high EMfraction)
• non-prompt QCD photons

gg mass after all cuts
21
H ? gg X Result

• Interesting to also consider TOPCOLOR
• Technicolor extension, fermiophobic except for
  top quark loops
• Assume Br(h ? gg) 1
• Starts to get interesting at 120 GeV!
• Many assumptions

22
Tevatron Higgs Working Group

• The Higgs discovery potential for Run II has been
  evaluated (using a parameterized fast detector
  simulation)
• hep-ph/0010338,
• Discovery at 3-5? can be made
• Combine all channels, data from
• both D0 and CDF
• Improve understanding of signal
• and background processes
• b-tagging, resolution of Mbb
• Advanced analysis techniques are vital
• Results of simulations consistent with SHWG
  expectations
• Significant luminosity required to discover Higgs
  at Tevatron