1. Tevatron Searches for Beyond-SM Higgs
Alexei Safonov
(Texas A&M University)
For CDF & D0 Collaborations

2. Higgs Standard Model Higgs:
Higgs mechanism generates particles masses
Single physical scalar H, coupling ~mf
Higgs is unavoidable in most extensions of SM
Supersymmetry:
Radiative EWSB (mh<135 GeV)
Several Higgses: h, H, H+/-, A
Possible non-universality in coupling
Production enhancement likely
Little(st) Higgs:
Three-scale model
Light Higgs h
Also A,H,H+/-,H++/-- …
Compared to the zoo of SUSY final states and complicated phenomenology, Higgs is an “easy” target for searches
~tanb
Higgs is mentioned in the title of my talk. What makes it so special in searches for new physics? Let’s recall some basics.
What’s interesting about Higgs is that whatever that new physics is, it is very hard to not have a Higgs boson there
Thus Higgs is what I would call a convenient target: we know it got to be out there and we know what it looks like.
Moriond-QCD, March 21,2006
A. Safonov (Texas A&M)

3. Higgs Searches at the Tevatron
In this talk:
Neutral Higgs Searches
Multi-b final state (SUSY)
Di-tau final state
Charged Higgs
Analysis of top decay branching ratios
Doubly Charged Higgs (LR-sym. models)
Lepton Flavor Violation involving 3rd generation
Moriond-QCD, March 21,2006
A. Safonov (Texas A&M)

4. MSSM Higgs Production MSSM Higgs coupling to b, t ~tan β Higgs decays:
bb (~90%)
tt (~5-13%)
gluon fusion
b-quark fusion
Moriond-QCD, March 21,2006
A. Safonov (Texas A&M)

5. MSSM Higgs+b(b)→bbb(b)DØ
MSSM Higgs+b(b)→bbb(b)
Look for associated production with b(b) (suppress multi-jet bg)
Require >=3 b-tagged jets (sec. vtx)
Form invariant mass of the two highest-ET jets – binned fit
Data sample: ~260 pb-1
260 pb-1
b-tag rate estimated from data
Acceptance ~0.3-1% (mA=90-150)
Major syst uncertainties:
b-tagging (15%)
JES/resolution (9%),
signal simulation (5%)
trigger (9%)
luminosity (6.5%)
Bg estimation (3%)
260 pb-1
Moriond-QCD, March 21,2006
A. Safonov (Texas A&M)

6. MSSM Higgs+b(b)→bbb(b)DØ
MSSM Higgs+b(b)→bbb(b)
No evidence of signal
Interpretation of the results: mhmax and no-mixing scenarios with μ<0
The search is sensitive down to tanβ~50-55 for m(A)~ GeV
260 pb-1
260 pb-1
Moriond-QCD, March 21,2006
A. Safonov (Texas A&M)

7. CDF Neutral MSSM Higgs→tt Event selection
Leptonic tau (tℓ : t→ℓnn; ℓ=e,m)
Hadronic tau (th : t→hadrons n)
Opposite charge of tℓ ,th , bg supression cuts
Acceptance ~1-2% (mA= GeV)
Dominant bg: Z/g*→tt
Z/Higgs separation: mvis(ℓ,th,ET)
Before Ntrk and
opposite charge cuts
Reconstruction of th:
Cone algorithm
Energy from trks and p0’s
Isolation veto (trk, p0)
Hadronic system:
mhad< 1.8 GeV
Ntrk = 1,3 ; charge = ±1
Moriond-QCD, March 21,2006
A. Safonov (Texas A&M)

8. CDF Neutral MSSM Higgs→tt
Observed 487 ev, expect 496± 5.4(stat) ± 27.7(sys) ± 24.8(lum)
Dominant systematic uncertainties:
Particle ID: th (3.5%), e (1.3%), m (4.6%)
Jet→t mis-ID estimate (20%)  3% on total bg
PDF’s (5.7%)
Luminosity measurement (6%)
Set limits by performing likelihood fit of mvis(ℓ,th,ET) distribution
Example fit for
mA=140 GeV
Moriond-QCD, March 21,2006
A. Safonov (Texas A&M)

9. CDF Neutral MSSM Higgs→tt
Interpret the results in mhmax and no-mixing scenarios with m<0 and m>0
bb and tt Higgs decay channels are complementary
Projections are based on the current analyses techniques
A lot of improvements in the works
Moriond-QCD, March 21,2006
A. Safonov (Texas A&M)

10. DØ Neutral MSSM Higgs→tt Fresh off the press D0 result:
Include e+thad,m+thad, e+m
NN for tau ID: 3 types of had taus
Fit invariant mass distribution and set limit
Combine with the result in bbb(b) channel
No signal, set limit
Lots more data to come
Taus become really important
Moriond-QCD, March 21,2006
A. Safonov (Texas A&M)

11. CDF Charged MSSM Higgs Major decay modes: Production:
H+→t+n
H+→cs
H+→t*b→W+bb
H+→W+h→W+bb
BR’s depend on:
tan β, m(H+)
Differ from W+ BR’s
Production:
t →bH+ (mH < mt-mb)
Moriond-QCD, March 21,2006
A. Safonov (Texas A&M)

12. CDF Charged MSSM Higgs Look at four tt final states: di-lepton + jets
lepton + jets (=1 b-tag)
lepton + jets (≥ 2 b-tags)
lepton + tau + jets
Check consistency of the final states with SM expectation
Interpret for several MSSM scenarios, tan β, and mH
Lint = 192 pb-1
Moriond-QCD, March 21,2006
A. Safonov (Texas A&M)

13. CDF Charged MSSM Higgs Consistent with the SM
Final state
bg events
SM exp
data
2ℓ + jets
2.7±0.7 11 13
ℓ+ jets (1b)
20.3±2.5 54 49
ℓ + jets (≥2b)
0.94±0.17 10 8
ℓ + t + jets
1.3±0.2 2
Consistent
with the SM
No-mixing benchmark scenario
mhmax benchmark scenario
Moriond-QCD, March 21,2006
A. Safonov (Texas A&M)

14. CDF Doubly Charged Higgs
Little Higgs and L/R symmetric models (incl. SUSY)
Elegant solution for massive neutrinos via see-saw mechanism
H++ can be light
vR ~ 1010 GeV, mH±± ~ 100 GeV
DY-like H++ pair production
Constrained by the r parameter
s(m = 100 GeV) = 120 fb
(1000 times less than Ztt)
Published results in e/mu channels supersede LEP
Tau decays: start with e/mu+tau final states
H++ Lower Mass Limit e m t
133
---
115
136 99
Moriond-QCD, March 21,2006
A. Safonov (Texas A&M)

15. CDF Doubly Charged Higgs Selection: Two event categories: Backgrounds:
Zee removal not yet applied
Selection:
Electron pT>20 GeV
Tau pT>15 GeV
LTC w/ seed track pT>7 GeV
Two event categories:
3p channel: e+tau+LTC
4p channel: e+tau+LTC+LTC
Backgrounds:
Z/g*(ee)+jets (most difficult)
ZZ, WZ
QCD (easy to remove)
Others less significant
HT>190 GeV
Note the similarity with a tri-lepton search
Moriond-QCD, March 21,2006
A. Safonov (Texas A&M)

16. CDF Doubly Charged Higgs H++ Lower Mass Limit e m t 133 --- 115 136 99
Open the signal box:
No events found
Expected ~0.3 events
No discovery, but can set an exclusion limit
mH++>115 GeV – new CDF result
H++ Lower Mass Limit e m t
133
---
115
136 99
H++ Lower Mass Limit e m t
133
---
115
136 ?? 99
Muon+Tau channel is nearly done. Box not opened, but similar sensitivity
Moriond-QCD, March 21,2006
A. Safonov (Texas A&M)

17. Summary and Outlook The Higgs boson is being hunted at the Tevatron
Various scenarios and Higgs species
D0 and CDF are competing, will soon start combining results
Taus are in the game at both CDF and D0
Very important for Higgs in SUSY
May well turn out to be very useful for SM Higgs
No smoking gun with the analyzed data, but already 2-5 times more data on tape
With some luck, you may hear from us before LHC
Major improvements are better triggers, better identification efficiency and better background rejection
Moriond-QCD, March 21,2006
A. Safonov (Texas A&M)