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Tevatron Searches for Beyond-SM Higgs

Tevatron Searches for Beyond-SM Higgs

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Tevatron Searches for Beyond-SM Higgs

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  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 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 A. Safonov (Texas A&M)

  4. MSSM Higgs Production MSSM Higgs coupling to b, t ~tanβ gluon fusion Higgs decays: • bb(~90%) • tt(~5-13%) b-quark fusion A. Safonov (Texas A&M)

  5. 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 A. Safonov (Texas A&M)

  6. 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)~90-150 GeV 260 pb-1 260 pb-1 A. Safonov (Texas A&M)

  7. CDF • 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 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=90-150 GeV) • Dominant bg: Z/g*→tt • Z/Higgs separation: mvis(ℓ,th,ET) Before Ntrk and opposite charge cuts 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 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 A. Safonov (Texas A&M)

  10. 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 A. Safonov (Texas A&M)

  11. CDF Charged MSSM Higgs • Production: • Major decay modes: • 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 t →bH+ (mH < mt-mb) A. Safonov (Texas A&M)

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

  13. CDF Charged MSSM Higgs Consistent with the SM No-mixing benchmark scenario mhmax benchmark scenario 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 A. Safonov (Texas A&M)

  15. CDF Doubly Charged Higgs 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 A. Safonov (Texas A&M)

  16. CDF Doubly Charged Higgs • 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 Muon+Tau channel is nearly done. Box not opened, but similar sensitivity 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 A. Safonov (Texas A&M)