EPS July 2003 1

Fermiophobic Higgs

Drew Baden

University of Maryland

Dzero Collaboration

EPS 2003

EPS July 2003 2

Fermilab Tevatron• Run I 1992-96

– about 120 pb-1 recorded– 1.8TeV cm energy– 3.6s 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

Main Injector(new)

Tevatron

DØCDF

Chicago

p source

Booster

EPS July 2003 3

D Detector• Upgrades:

– 2T Solenoid

– >100k scint. fibers

– >700k silicon strips

– Muon detector improvements

– Preshower added

– CAL, Muon, trigger electronics

– NO MAIN RING!!!

New Solenoid, Tracking SystemSi, SciFi,Preshowers

Shielding

Forward Mini-drift chambers

Forward ScintillatorCentral Scintillator

+ New Electronics, Trig, DAQSilicon tracking out to ~2

Yields

EPS July 2003 4

Run 2 Data Taking

Del

iver

ed

for P

hysic

s

Run I total

EPS July 2003 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 , and production for coupling to all particles

• Constraints on MHIGGSLEP direct search– M>114GeV @ 95% CL

ElectroWeakWorkingGroup– Favors light higgs, 91GeV central value– M<211 GeV 1-sided 95%CL

EPS July 2003 6

What is Fermiophobic Higgs?

• Fermiophobic…means 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 • coupling to fermions via

– mass, as usual, and– sin() for H and cos() for h

• h is therefore “fermiophobic” in the limit →/2– Of course we could have a “fermiophobic” H (→0)…but h is

lighter so we look there…

EPS July 2003 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/Z+h

• WW fusion – Quark lines radiate W’s, fuse to

h– ZZ fusion too small by usual

EWK factor

th

h

W*/Z* W/Z

hW+

W-

EPS July 2003 8

wh

Fermiophobic Higgs Decay• Final states:

– No bb in the final state (fermiophobic!)–

• Through W triangle loop

• Dominates at low Mh

• Also WWvertex– Suppressed by EM factors

– Associated Production:• Z/W+h 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 < 108.2 GeV @ 95% CL using h →

mode

MH< 114.4

EWWG

LEP Higgs Working Group benchmark model

SM Branching Fractions

wh

Mh< 108.2

LHWG Note 2001-8

Hep-ex (0107035) 2001

EPS July 2003 9

Experimental Limits

• LEP Combined Fermiophobic limit– Mh < 108.2 GeV @ 95% CL using h → 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

EPS July 2003 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 W’s» 2 Z’s will be relatively suppressed (see previous slide)

– Search for inclusive ee, , and e± lepton pairs + MET

• The “prompt” W/Z in final state…– No requirement on any leptonic decay

– W/Z*h → W/Z• Look for states with 2s

– large MET and/or jets

– Let the theorists foot the bill as to interpretation• Which particular “Type” etc.

EPS July 2003 11

h → WW → ll

• Combine ee and e± sample: – Dielectron sample: 44pb-1 – e sample: 34pb-1

• Backgrounds– All dilepton channels have

• Small: WW, W, ZZ, WZ, and top• Large: W+jet and QCD misidentification

– ee also has a large background from Z → ee

• Reduced via ee mass MET cut• W+jet dominate after, with some ’s remaining

– e Dominated by QCD and W+jet

EPS July 2003 12

Electron Sample• Electron ID requirements

– Triggered– Isolation+EMF+Shower

Shape• = 85% (93%) efficiency

for central (endcap)– Track match via 2(E/p and

) and DCA – =73% obtained using

sample of Z → ee

– Leading electron PT>20 GeV, 2nd electron PT>10 GeV

• Reduces multijet background

Z sample

MC

EPS July 2003 13

Muon Sample, Jets, and MET• Muons:

– ID from muon system– Isolated from jets using E(cal) and tracks

• E(R<0.4) E(R<0.1)<2.5GeV• PT (in cone R<0.5) tracks < 2.5 GeV

– Reject cosmics via timing requirement– PT > 10 GeV with central track match

• Jets:– Cut to eliminate hot towers, other pathologies– EMF cut– ||<2.5– Energy corrections, cone 0.5

• MET– Use calorimeter cells– Correct for jet energy corrections

• Use 0.7cone jets for this

MET

Iso()

Cal corr

1.0

EPS July 2003 14

Event Cuts• Electrons

– 2 with PT> 20 GeV– at least 1 with track match– M(ee) < 78 GeV to reject Z’s

• MET– MET > 25 GeV and

(jets,MET) > 0.5

• Dominant background is W+jets

• Spin Correlations– W and W have opposite spin

projections• Tendency for charged

leptons to be emitted along same direction

– Require (leptons)<2.0

(ll)

Higgs WW Top QCD

Z→ee Z→ W+jets W+

EPS July 2003 15

ee Final State• Dominant background from Z → ee

– Invariant mass cut M(e+e-)<MH/2 for limit calculation

• 96% effecienty for MH=160GeV

– MET from jet fluctuations reduced

• Transverse mass cut MT<MH+20 GeV

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

EPS July 2003 16

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 W+jets and Z(ee)

MH(GeV) 120 140 160 180

ID, pt>20 2753 2753 2753 2753

M(e+e-)<MH/2 262 378 598 1617

MET > 20 11 27 37 52

More MET cuts 1 16 25 38

(ee)<2.0 0 2 2 4

(ee) MC/Data Comparison

120 140 160 180

8.1 ± 0.4%

10.6 ± 0.4%

16.2 ± 0.5%

14.4 ± 0.5%

TOP WW W+ W+jet Z() Z(ee) QCD SUM Data

120 0.10 0.13 0 0 ± 1.1 0 0 ± 0.9 0.7 0.7±1.4 0

140 0.08 0.21 0 0 ± 1.1 0 0 ± 0.9 0.7 1.0±1.4 2

160 0.07 0.27 0.01 0 ± 1.1 0 0 ± 0.9 0.7 1.3±1.4 2

180 0.08 0.27 0.02 0 ± 1.1 0 0 ± 0.9 1.4 2.6±1.4 4 Selection optimized for MH=160

EPS July 2003 17

e± Final State and Results• Comparison with e+e- analysis

– No Z decay background• No transverse mass cut

applied• MET cut constant: MET > 20

GeV– Less QCD multi-jet background– MET and PT() → not aligned– All other cuts are the same– Efficiencies:

– Uncertainty mostly from W+jets

• Results combing ee and e± – Upper limit of 2-3pb @ 95%CL

• Limited data…x4 being analyzed now

• Need ~10fb-1 to be sensitive up to Mhiggs=160 GeV

M Higgs 120 140 160 180

Efficiency 4.5 ± 0.3%

8.6 ± 0.4%

11.7 ± 0.5%

10.9 ± 0.5%

TOP WW W+ W+jet Z() QCD SUM Data

160 0.13 0.18 0.06 0 ± 1.5 0 0.4 0.9± 1.5 1

Br(

H →

WW

→ e

+e- /

e±

)

EPS July 2003 18

Final State• 48pb-1 analyzed

• 2 High PT isolated muons (||<2)

• Same cuts as previous– M(), PT(), MET,

(MET,jet),MT, ()

• MC samples from Pythia 6.202, full sim/reconst– Same as for previous study

– QCD and W+jets backgrounds from data measured

• using muon isolation

– Normalized to Z→ – Overall signal efficiency for Mh=160

GeV is 14.6 ± 0.6%

M() PT()

MET (jet,MET)

() MT

EPS July 2003 19

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 Br yet…– Will be reporting soon on combined H → WW → ee, , and e± on 120pb-1

TOP Z() WW W+jet Z() QCD SUM Data

Events 0.11 0 0.20± 0.01

0 0 0 0.32±0.01

1

EPS July 2003 20

H → + X• 52pb-1 analyzed• Photon id:

– EMfraction>0.9 , Shower shape 2, isolation, PT>25 GeV, charged track veto

• No jet requirements or MET cut here

• “Fake” photons due to– high PT 0→ (small opening

angle)– Drell-Yan production + tracking

inefficiency– jet fluctuations mimic photon

(high EMfraction)– non-prompt QCD photons

mass after all cuts

EPS July 2003 21

H → + X Result• Interesting to also consider TOPCOLOR

– Technicolor extension, fermiophobic except for top quark loops

– Assume Br(h → ) = 1

– Starts to get interesting at 120 GeV!

• Many assumptions…

Central Photons

EPS July 2003 22

• 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

Tevatron Higgs Working Group

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