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Higgs and new particle searches at Tevatron

Higgs and new particle searches at Tevatron. Yukihiro Kato Kinki University (behalf of CDF collaboration). Contents. Higgs SUSY Technicolor High mass particles (b’). This talk includes the new results since summer 2006. Tevatron. D0. CDF. Tevatron. Integrated luminosity is 2.4fb -1.

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Higgs and new particle searches at Tevatron

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  1. Higgs and new particle searches at Tevatron Yukihiro Kato Kinki University (behalf of CDF collaboration) KEKPH07

  2. Contents • Higgs • SUSY • Technicolor • High mass particles (b’) This talk includes the new results since summer 2006 KEKPH07

  3. Tevatron D0 CDF Tevatron Integrated luminosity is 2.4fb-1 Peak luminosity record 2.89 ×1032 cm-2s (Feb 25, 2007) Tevatron delivered 165pb-1 in Jan. 2007 Main injector KEKPH07

  4. CDF • CDF has collected over 2 fb-1 data at Feb. 2007 • 653pb-1 delivered in FY06, 82% to tape (~5% trigger, ~5% beam conditions ) • General purpose detectors • Precision tracking with silicon vertex detector • Good particle identification (K, p) KEKPH07

  5. On going analyses of the exotic physics at CDF • Higgs: SM Higgs, non-SM Higgs • SUSY • High mass particles: Z’, W’, RS gravitons, b’ • Leptoquarks: 1st, 2nd, 3rd generation • Technicolor: Techni-rho • Others: Diphoton+x, large extra dimension, lepton+photon+x KEKPH07

  6. Search for Higgs ・ SM channels: WH → lνbb,jjbb ZH → ννbb,llbb, jjbb H → WW WH → WWW ・ Extended Models H → tt • bbH → bbbb • H → gg • H+hf → W+hfhf → W+gggg Low mass Higgs High mass Higgs KEKPH07

  7. WH → lνbb Event selection ・ Identified e/μ, pT > 20GeV ・ Two jets: ET > 15 GeV, |η| < 2.0 ・ At least one b-tagged jet (>2 tag, 1 tag w/ NN tag) ・ Missing ET > 20 GeV Data sample: 955 pb-1 Dominant backgrounds ・ W backgrounds: Wbb, Wcc, Wqq (false b-tag) ・ Top backgrounds: single top, tt ・ Multi-jet (non W-QCD) KEKPH07

  8. WH → lνbb Result Upper limit on Higgs mass from 110 GeV/c2 to 150 GeV/c2 New result with 955 pb-1 KEKPH07

  9. ZH→ννbb Event selection ・ Two jets, ET>60, 20 GeV ・ Lepton veto ・ Missing ET > 70 GeV, cut on direction with two jets ・ 1 or 2 b-tags (single/double tag sample) Dominant backgrounds ・ Multi-jet (QCD) ・ W/Z + heavy flavor ・ Top ・ Diboson ・ Mistag Data sample: 973 pb-1 Number of expected event after the cuts KEKPH07

  10. ZH→ννbb Sliding dijet mass cut for limit setting 95% C.L. upper limit with respect to the SM cross-sections KEKPH07

  11. H → W+W- → lνlν Good sensitivity of the “high-mass” region (mH > 150GeV) gg → H It’s large! σ(gg →H0) = 431fb @ Mh=160 GeV Br(H0→WW) = 90% @ Mh=160 GeV • Detector signature: • Two opposite-sign leptons • Missing transverse energy Same final state Vector Boson fusion KEKPH07

  12. H → W+W- → lνlν Summary of event selection vs. mH • Dominant backgrounds: • Diboson (WW, WZ, ZZ) • Drell-Yan • Wγ • tt Event selection: • Isolated leptons with opposite charge: pT(1) > 20 GeV, pT(2) > 10 GeV • 16 GeV < Mll < MH/2 – 5 GeV • # of jet cuts • Missing ET > MH/4 • Higgs mass dependent event cuts: • Relations between pT(1), pT(2), missing ET Data sample: 1fb-1 KEKPH07

  13. H → W+W- → lνlν Look in Δφ(l1, l2) distributions A statistically significant contribution of the Higgs signal is not observed ( Histograms include the signal and B.G.) Set a 95% C.L limit KEKPH07

  14. MSSM Higgs →ττ MSSM ⇒SUSY with minimal Higgs content Requires two higgs field doublets H±; A (CP-odd); h, H (CP-even) • At tree level defined by mAandtanb = vu/vd • A couplings to b, t enhanced by ～tanb • For large tanb, one of the h/H is SM-like and low mass (m<135 GeV), the other almost mass-degenerate with A, similar couplings In the following f is used to denote any of A, h, H Dominant A decays: bb (～85－95%), tt (～5－15%) bb: larger BR, but need associated b-jets search for Higgs →tt KEKPH07

  15. MSSM Higgs →ττ Signatures are determined by the decay modes of t Used in this search • Z/g*→ee • Z/g*→mm • Misidentified jet as thad (w+jets, multi-jets) • Diboson • Top pair production Dominant backgrounds KEKPH07

  16. MSSM Higgs →ττ Data sample (992pb-1) : • tethad, tmthad from lepton plus track trigger (one e/m and isolated track pT>5GeV/c) • tetm from di-lepton trigger Event selection hadronic t decay 3-prong = (3p) 1-prong = (1p) • Good isolation lepton with pTl > 10GeV/c • thad-ID: ETcl>9 GeV, pT(thad) > 15(1p), 20(3p) GeV/c, Mhad <1.8(1p), 2.2(3p) GeV, isolation(track, p) • Df(t1,t2)>0.5 rad • Diboson, tt, W+jets suppression Transverse momentum balance between t1, t2, missing ET • Soft QCD suppression • ・ te/mthad: |pThad|+|ETe(pTm)|+|mis.ET| > 55 GeV: (3p) • |pThad|+|ETe(pTm)|+|mis.ET| > 45(50)GeV: (1p)tmthad(tethad) ・tetm: |ETe|+|pTm| > 30 GeV KEKPH07

  17. MSSM Higgs →ττ Backgrounds and observed events mvis distribution mvis = invariant mass of the visible t decay products and missing ET No signal evidence for mA = 90 – 250 GeV/c2 mA = 160 GeV/c2 KEKPH07

  18. MSSM Higgs →ττ Results Observed and expected limits at 95% CL Excluded region in tan b vs mA KEKPH07

  19. Search for SUSY • Squarks and Gluinos • Charginos + Neutralinos: like-sign dilepton, trilepton • R-parity violation: multi-lepton, stop, sneutrino • GMSB: long-lived neutralinos (decays to photon and gravitino) • Rare decays and stable particles: Bs and Bd →mm, long-lived particles KEKPH07

  20. Chargino – Neutralino production Multi-lepton (trilepton, like-sign dilepton) is a strong tool! KEKPH07

  21. Chargino – Neutralino production • Trilepton • isolated three e/m, isolated two e/m and one track pTl1, pTl2, pTl3,trk (GeV/c) = (20,8,5), (20,5,5), (15,5,4), (5,5,5) • missing ET > 15 GeV • reject Mass window: Mll < 20 GeV/c2, 76< Mll< 106 GeV/c2 • Dominant backgrounds – dibosons, Drell-Yan+conversion Event selection and backgrounds low-pT high-pT • Like-sign dilepton • Pair of same charge e/m • isolated two e/m with ET(pT) > 20 GeV, 10 GeV • Missing ET > 15 GeV • Z veto ( 66 < Mll < 116 GeV/c2) • Dominant backgrounds – Drell-Yan, diboson, W/Z+1jet KEKPH07

  22. Chargino – Neutralino production Results of event selections trilepton # of observed events are consistent with SM expectations Like-sign dilepton KEKPH07

  23. Chargino – Neutralino production SUSY scenarios for this analyses (1) mSUGRA:five free parameters (M0, M1/2, A0, tanb, sign(m)), parameters: M0 = 60 GeV/c2, A0 = 0, tanb = 3, m>0, 162 < M1/2 < 230 GeV/c2 (2) MSSM with no slepton mixing: keep mSUGRA relations with slepton mixing off (diagonal terms of the mixing matrix to zero in Softsusy). → enhances the BR of to e/m parameters: (3) MSSM with W/Z decay:keep the relation in below in the MSSM framework. parameters: Acceptance of high-pT sample KEKPH07

  24. Chargino – Neutralino production The excluded cross section limit vs. chargino mass mSUGRA MSSM with W/Z decay no slepton mixing KEKPH07

  25. Neutralino can be have a long life(free parameter). The lightest neutralino is NLSP. LSP is gravitino. NLSP decays to photons and missing ET(gravitino). GMSB (Gauge Mediated Supersymmetry Breaking models) Feynman diagram for GMSB processes The arrival time is different from prompt g and decay g Compare arrival time of photons in the g+missing ET+jets events Monte Carlo simulation KEKPH07

  26. Data sample: 570pb-1 Dominant backgrounds • Collision photon: W→en, g+jet+fake missing ET, 2jets+fake missing ET, jets fake g • Non-collision photon: cosmic rays, beam effect • Selection criteria • g-ID: ET > 30 GeV, |h|<1.1 • Missing ET > 40 GeV • Jet ET > 35 GeV • Df(missing ET, jet) > 1.0 • 2.0 < tarrival < 10ns • Cosmic rejection • Collision fiducial Observed : 2 events # of backgrounds: 1.3±0.7 KEKPH07

  27. The expected and observed 95% C.L. cross section limit The exclude region in the neutralino lifetime and mass space KEKPH07

  28. Technicolor Technicolor model: ・ New interaction to induce spontaneous symmetry breaking of the gauge theory. ・ At Tevatron energy, new particle (ρT) could be produced. Search for W+2jet (b-tag) signature ・ isolated e/μ with ET(pT) > 20 GeV ・ missing ET > 25 GeV ・ two jets with ET > 20GeV, |η| < 2.0 ・ b-tag: one tag with NN, double tag w/o NN Data sample: 955 pb-1 KEKPH07

  29. Technicolor Dataset agree with B.G. 1 tag w/ NN 2 tag w/o NN Backgrounds: ・ W/Z + heavy flavors ・ tt production ・ diboson production ・ Non-W QCD ・ mistag KEKPH07

  30. b’b’ → bZbZ → bllbqq Event selection ・ At least one pair of e/μ with pT>20 GeV ・ Z mass window 81 < Mll< 101 GeV ・ # of jets (with ET>30 GeV, |η| <2) ≧ 3 Search for new particle decaying to Z0 →b’ quark may have a large branching ratio to bZ0 Target range of b’ 150 < mb’ < 350 GeV Backgrounds: ・ Z0 + jets ・ Diboson (WZ, ZZ) + jets ・ tt + jets ・ QCD multi-jet Data sample: 1055 pb-1 KEKPH07

  31. b’b’ → bZbZ → bllbqq Data compared to the Z0+jets B.G (J30T = scalar sum of ET’s of all jets) No significant excess Set cross section limit mb’ > 270 GeV ( BR(b’→ bZ0) = 100 % ) KEKPH07

  32. summary • Tevatron and CDF are working well. • CDF has collected the over 2fb-1 data • CDF has been exploring the new phenomena using ~ 1fb-1 data. • Please expect the interesting results of the new particles searches at summer conference. KEKPH07

  33. Backup slides KEKPH07

  34. By A. Anastassov KEKPH07

  35. Expected 95% C.L limits Run same likelihood procedure using “pseudoexperiments” • Replace Nobs in each channel with a Poisson fluctuated value with mean equal to the total expected background. • Replace the kinematic distribution with one randomly constructed from the above Poisson number, and the total background distribution. • Replace the Gaussian constrained background values in the likelihood function with a Gaussian fluctuated value with mean equal to that background value. The error are left the same. • Repeat many times. KEKPH07

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