non-sm higgs searches at the tevatron
DESCRIPTION
Non-SM Higgs Searches at the TeVatron. Andy Hocker Fermi National Accelerator Laboratory for the CDF and D0 Collaborations ICHEP 2006. What we’re looking for. Minimal supersymmetric SM Higgs bosons The neutrals: h 0 , H 0 , A 0 ( = 0 ) The charged: H ± - PowerPoint PPT PresentationTRANSCRIPT
Non-SM Higgs Searches at the TeVatron
Non-SM Higgs Searches at the TeVatron
Andy HockerFermi National Accelerator Laboratory
for the CDF and D0 CollaborationsICHEP 2006
28-JUL-2006 A. Hocker, ICHEP '06, Moscow 2
What we’re looking forWhat we’re looking for
• Minimal supersymmetric SM Higgs bosons The neutrals: h0, H0, A0 ( = 0) The charged: H±
• Doubly-charged Higgs bosons (H±±) Part of Higgs triplet (0, H±, H±±) Appear in L-R symmetric SM extensions Can be light (~100 GeV), decay leptonically
• Extremely low backgrounds
• Fermiophobic Higgs bosons (0) Can appear in “Type III” 2HDM Fermion couplings suppressed, boson enhanced Distinct signature of decays via W triangles …but no new results here…
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MSSM 0 at the TeVatronMSSM 0 at the TeVatron
•Large tan (favored by LEP2 data) enhances couplings to b-quarks,
•Most of 0 BR covered by bb (~90%),
•Production:
•Main modes are
•gg, bb0 (0bb hopeless, but not 0)
•Associated production with b’s (both decays observable)
28-JUL-2006 A. Hocker, ICHEP '06, Moscow 4
Experimental toolkitExperimental toolkit
• Bottom-quark tagging Exploit long lifetime of B
hadrons Requires precision tracking (Si
microstrip detectors) with as much forward reach as possible
• Tau ID Hadronic decays
• Isolated, narrow jets• Requires good tracking/EM
calorimetry for charged/neutral pion reconstruction
Leptonic decays• Requires good EM cal, muon
detector coverage Large samples of Z’s/jets used
to study efficiencies/fake rates
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CDF and D0 in Run IICDF and D0 in Run II
Some highlights
Si detectors (D0 just got some
more!)
Good central tracking
Forward muon systems
Trigger/DAQ
CDF: forward calorimeter
Data samples
Over 1 fb-1 in the can
Det/acc resumed operations in June, running
well
Results here range from 200-
350 pb-1
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Searches for b0, bb0 (0bb)Searches for b0, bb0 (0bb)
• Start from large multijet trigger sample
• Require at least 3 jets w/ displaced secondary vertex
• Form invariant mass of two leading b-jets, look for ≈bump Shape and normalization of
bgd determined from doubly-tagged data
260 pb-1
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b0, bb0 resultsb0, bb0 results
• 95% CL upper limit on xsec vs. mA
• Compare w/ predicted xsec for canonical MSSM benchmarks
• Exclusions placed in mA, tan plane
260 pb-1
28-JUL-2006 A. Hocker, ICHEP '06, Moscow 8
Searches for 0Searches for 0
• Select ehad, had, and (at D0) e events
• Partially reconstruct Higgs via
mvis p1
vis p 2
vis p T
28-JUL-2006 A. Hocker, ICHEP '06, Moscow 9
0 results (comb. w/ bb)0 results (comb. w/ bb)
Includes bbb(b) searches --- these are your “take-home” plots for the TeVatron
28-JUL-2006 A. Hocker, ICHEP '06, Moscow 10
Just in from D0!Just in from D0!
• New search for (b)b0(b)b Less signal + less
background = competitive limit
Will be fruitful to combine
• Updated search for (b)bbb 0.9 fb-1
New NN b-tagger Still no signal, but ever-
tighter limits Too new for a nice mA-tan
plot
28-JUL-2006 A. Hocker, ICHEP '06, Moscow 11
Charged Higgs in top decaysCharged Higgs in top decays
• Normally, ttWbWb Well-def’d final states
• If H± light enough, can replace one or both W’s
• BR(t Hb) and H± decays depend on tan , mH (at tree level) H± H± cs H± t*b H± W0
• Alters mix of tt final states
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Indirect search for tH±bIndirect search for tH±b
• Look at event yield in 4 tt final states: lljj ljj ljjbj ljjbb
• Find joint prob to observe Ndata given expected yield for given mH, tan , etc.
• Determine exclusion areas in mH vs. “X” plane
28-JUL-2006 A. Hocker, ICHEP '06, Moscow 13
Charged Higgs ResultsCharged Higgs Results
Indirect search from 200 pb-1 of tt in four final states
mH/tan exclusions for “no-mix” benchmark
Other benchmarks explored as well
Radiative SUSY corrections included!
New direct search for tHbb
Look for anomalous production of ttlbj (almost pure tt)
4 expected from ttWbWb, 6 observed
Limits on BR(t->Hb) assuming BR(H±) = 1
28-JUL-2006 A. Hocker, ICHEP '06, Moscow 14
Searches forH±±e, Searches forH±±e,
• Same-sign lhad has significant background H±± pair-produced, so require additional (loose) leptons
• Counting experiment < 1 SM event expected, zero observed
CDF H++ Lower Mass Limit
e e 133 --- ---
115 136 ---
114 112 ??“stable” 134
28-JUL-2006 A. Hocker, ICHEP '06, Moscow 15
ConclusionsConclusions
• The MSSM provides the TeVatron with a real shot at a Higgs discovery Light h0, decent xsec Decays to b,
• Null results for 0 searches put the squeeze on the MSSM from the large tan side
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BackupperyBackuppery
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Evidence/discoveryEvidence/discovery
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Searches forH±±ee, e, Searches forH±±ee, e,
• Same-sign dilepton search in 3 sigma mass windows
• Low backgrounds (limit ee search to > 100 GeV)
No candidates, lower limits from 89-136 GeV set
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Searches for quasi-stable H±±Searches for quasi-stable H±±
• H±± particles that do not decay in the detector Look like highly-ionizing “muons” Large dE/dx in tracking chamber Basically, zero background… and zero observed
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Searches for fermiophobic h0 Searches for fermiophobic h0
Look for peaks in diphoton mass distribtution
Current results not competitive with LEP, but will be soon!