Searches for Non-Minimal

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Searches for Non-Minimal Higgs Bosons
Andre S. Turcot Brookhaven National
Laboratory for the DØ Experiment at Fermilab
With many thanks to A. Haas, A. Kharchilava and
G. Watts
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Outline

• A SUSY Higgs Primer
• Searching for hbb
• Doubling your fun with H
• h ? gg Pushing beyond LEP

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A SUSY Higgs Primer

• Addition of a second scalar doublet results in 5
  physical higgs bosons

h, H, A, H, H-

• Standard Model Yukawa couplings modified
• hbb sin(b - a) - tanb cos (b a)
• Hbb cos(b - a) tanb sin(b a)
• Abb tan b

• Two interesting cases arise for large tan b
• CP Even states can flip-flop playing the role of
  SM higgs
• M(A) gtgt M(Z) ? cos(b - a) ltlt 1
• M(A) M(H), Hbb coupling ? tan b
• M(A) lt M(Z) ? cos(b - a) 1
• M(A) M(h), hbb coupling ? tanb

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SUSY Higgs Production
When tan b is large two of the three Neutral
Higgs bosons will have enhanced bb couplings

CP-odd HiggsProduction
CP-even HiggsProduction
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SUSY Higgs The RunII Angle

• Much theoretical progress since RunII SUSY-Higgs
  Wkshp
• Recent work indicates that the LO cross-sections
  are an underestimate by a factor 3 (e.g.
  hep-ph/0204093)
• Better understanding of NLO effects, scale
  dependencies
• Theoretical bias towards expecting large tan ?
• b-t Yukawa unification at the GUT scale
• ? mt/mb tan ? 50
• Since cross section scales as tan2? there will be
  a huge enhancement, O(1000) for motivated values
• Leads to an interesting complementarity with LEP
  as Tevatron can probe high tan b region of
  parameter space where small sin(b - a) and/or
  kinematics preclude hA, HA, Zh ZH production at
  LEP

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Triggering on bb(h,H,A)

• Multi-Level Trigger
• Level 1 Require 3 trigger towers of 5 GeV
• Level 2 Require 3 jets of 8 GeV, HT gt 50 GeV
• Level 3 3 Jets 15 GeV, 2 of 25 GeV, primary
  vtx within SMT
• Rates at L 60E30 are 280/100/6 Hz

Done for all trigger components

• Efficiencies relative to off-line selection are
  excellent
• e.g. for M120 4 jets of 45, 35, 2x15 GeV (0.5
  cone algorithm)

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Tagging b-jets
Secondary Vertex Tag Algorithm
Extra Loose Operating Point
Light j 2
Many improvements in the works Improved
Tracking Improved Alignment Improved Algorithms
hbb
This represents only the first sketches in the
art of b-tagging
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Quadruple b-tagged event
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Search for bb(h,H,A)
Leading Backgrounds jjjj with multiple fakes bb
jj with fake (8 ccjj) Zbb and bbbb are small
Comparison of double b-tagged events with 4
jets to Monte Carlo
The ALPGEN Monte Carlo describes the multi-jet
heavy-flavor background very well. We have
measured the normalization factor of data / MC
1.140.02 (stat.)
4 jets 2 b-tags
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Search for bb(h,H,A)
Comparison of triple b-tagged events to expected
background
The background shape was extrapolated from double
b-tagged data using a tag-rate-function derived
on the full multi-jet data sample. Limits were
set on the signal production, using simulated
signal shapes, the normalized background, and the
observed data.
Excluded Signal
3 jets 3 b-tags
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Systematic Uncertainties
Systematic Errors on Acceptance ()
Dominated by JES Ongoing efforts to improve
Systematic Errors on Backgrounds
Both b-id related and statistics 8-11 depending
upon the optimized point
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Search for bb(h,H,A)
Constraints in the MSSM parameter space
Limits will continue to improve with More
data Better b-tagging Better triggers Expect new
results soon!
131 pb-1 of data
Note Complementarity with LEP
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Search for Doubly-Charged Higgs

• Many models predict the existence of Higgs bosons
  with twice the electric charge of other
  particles
• Left/Right Symmetric
• Higgs Triplet
• Little Higgs
• We search for decays of the doubly-charged Higgs
  into two like-signed muons.
• Assume a 100 branching ratio to muons when
  setting limits

Coupling depends on L/Rhandedness
Feynman diagram for the production of
doubly-charged Higgs
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Search for Doubly-Charged Higgs
Comparisons of mass and ?f distributions of the
di-muon data to Monte Carlo
Good agreement before requirment of Like Sign
muons
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Search for Doubly-Charged Higgs
Comparisons of mass and ?fdistributions of the
like-signed and isolated di-muon data to Monte
Carlo
No evidence of excess in like-sign isolated
muons 3 candidates vs 1.5 /- 0.4 expected
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Search for Doubly-Charged Higgs
Confidence Limit set as a function of
doubly-charged (left-handed) Higgs mass
Set limits on the masses of doubly-charged
Higgs bosons mHL gt 118.4 GeV mHR gt 98.2
GeV
113 pb-1
On going efforts to improve Double the data
set Include t t, WW channels
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Search for Higgs? ??

• Some models predict an enhanced branching
  fraction of Higgs bosons to two photons
• Top-color Higgs
• Fermio-phobic Higgs
• Boso-phillic at U of C

Total bkgd. QCD Other
Error on BG
Reasonable agreement with expected background

Di-photon Invariant mass
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Search for Higgs ? ??
No evidence of excess Set limits as a function of
branching ratio assuming model dependent
production cross-section
Can extend LEP Reach With current data but mass
limits will require more data Future Analyses
will benefit from improved g ID
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Conclusions
has searched for non-minimal Higgs bosons

• Data sets of 113 to 195 /pb studied
• Results on hbb, H and h ? gg
• Unfortunately with no hint of a signal
• Improvments to all channels in progress
  Attacking the key issues, b-tagging, JES
• Stay tuned for more exciting results