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Moriond ElectroWeak 2005, Gregorio Bernardi, Paris/FNAL, for the CDF and D Ø Collaborations

Results on Higgs Searches @Tevatron. Tevatron/ Luminosity CDF and D Ø SM Higgs Searches b-tagging / Z bb BSM Higgs Searches Summary Only Results new since last Moriond are shown, i.e no unstable H ++ , nor H  . Moriond ElectroWeak 2005, Gregorio Bernardi, Paris/FNAL,

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Moriond ElectroWeak 2005, Gregorio Bernardi, Paris/FNAL, for the CDF and D Ø Collaborations

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  1. Results on Higgs Searches @Tevatron Tevatron/ Luminosity CDF and DØ SM Higgs Searches b-tagging / Zbb BSM Higgs Searches Summary Only Results new since last Moriond are shown, i.e no unstable H++, nor H  Moriond ElectroWeak 2005, Gregorio Bernardi, Paris/FNAL, for the CDF and DØ Collaborations

  2. Tevatron Parameters Run I Run IIa Run IIb Bunches in Turn 6  6 36  36 36 36 s (TeV) 1.8 1.96 1.96 Typical L (cm-2s-1) 1.6 1030 9 1031 3 1032  Ldt (pb-1/week) 3 17 50 Bunch crossing (ns) 3500 396 396 Interactions/ crossing 2.5 2.3 8 Run IRun IIa Run IIb 0.1 fb-1 Upgrades for Run II: 2001-2009 10% energy increase: 30% higher stop integrated luminosity increase: x50 Plan (build higher antiproton stacks!) - Increase # of protons on antiproton target - Optimization of transfers, improved optics/helices - Increase p stacking/storing (mixed mode/e-cool) - Upgrade Tevatron for higher bunch intensities Since last Moriond: improvement in reliability / operating efficiency:  in stores ~120 hours/week Typical ratio of “recorded” to “delivered” luminosity is 80%-90% So far both exper. recorded ~0.8 fb-1 Results presented on ~0.2-0.3 fb-1

  3. Tevatron Run II Performance Design for 2005 Base for 2005 2005 : so far along Design 2004 2003 2002 1.1032 cm-2sec-1 0.8 fb-1 Peak luminosity is above 1.1032 cm-2sec-1 Total ~0.7 fb-1 delivered in Run II 2004 : above Design !

  4. Tevatron Long Term Luminosity Plan Currently expecting delivered luminosity to each experiment  4 - 8 fb-1 by the end of 2009 Increase in number of antiprotons  key for higher luminosity Expected peak luminosity  3.1032 cm-2sec-1 by 2007 Today

  5. The DØ Experiment in Run II LAr/U Calorimeter, fine-grained, hermetic New trackers Silicon microVTX,  Central Tracker (Scint Fibers) 2T superconducting solenoid Pre-shower detectors Upgraded muon detectors Faster readout electronics New trigger & DAQ Total of 800,000 Silicon channels 55000 Calorimeter cells 80,000 channels in the Central Fiber Tracker

  6. SM Higgs Production and Decays Excluded mH (GeV/c2) Production Decays Production cross section  in the 1.0-0.1 pb range for gg  H  in the 0.2-0.02 pb range for associated vector boson production Dominant Decays  bb for MH < 135 GeV  WW* for MH > 135 GeV Search strategy: MH <135 GeV associated production WH and ZH with Hbb decay Backgrounds: top, Wbb, Zbb… MH >135 GeV gg H production with decay to WW* Backgrounds: electroweak WW production…

  7. Experimental Limits on Higgs Mass • direct searches at LEP MH >114 GeV at 95% C.L. • precision EW fits (winter 2005) MH= 126+73-48 GeV MH  280 GeV @ 95% C.L.  Light Higgs favored LEP Tevatron provides: Precision measurements of mtop& Mw and Direct searches:  SM Higgs  non-SM Higgs

  8. Tevatron SM Higgs Search: Outlook LEP Ldt (fb-1) Updated in 2003 in the low Higgs mass region W(Z)Hln(nn,ll)bb to include  better detector understanding  optimization of analysis Tevatron Sensitivity in the mass region above LEP limit starts at ~2 fb-1 Meanwhile  optimizing analysis techniques  understanding detectors better  searching for non-SM Higgs with higher production cross sections or enhanced branching into modes with lower backgrounds

  9. SM “Heavy” Higgs: H  WW  lnln e+ n W+ n W- e- Search strategy:  2 high Pt leptons and missing Et  WW comes from spin 0 Higgs: leptons prefer to point in the same direction H Main Background: WW Production Good agreement with NLO theory: 12.0-13.5 pb Now Measured at the Tevatron by both Experiments Ohnemus, Campbell, R.K.Ellis DØ: PRL/ hep-ex/0410062

  10. Data Selection: two isolated leptons with opposite charges with pT > 20 GeV, >25 GeV, ( , l or j) , veto on jets, light (<MH/2) invariant dilepton mass *BR(H→WW)< 5.6pb For MH=160 GeV Maximum likelihood limit on the ll distributions for mH=140-180 GeV Search for H  WW* Search in 3 channels: HWW*ll with l = ee,,einclusive high pT lepton triggers: integrated luminosity 184 pb-1 (CDF), 147-177 pb-1(D0) 95% CL for the 3 channels s*BR(H→WW) < 5.7pb For MH=160 GeV D: Obs: 9 evts; Bkgnd:11.1  3.2 Signal: 0.27  0.004(mH=160 GeV) CDF: Obs: 8 evts; Bkgnd: 8.9  1 Signal: 0.17  0.02(mH=180 GeV)

  11. Search for WH  WWW* Search of high-pT isolated like-sign (LS) dilepton events in 193.5 pb-1 data. leading lepton pT,1 > 20 GeV,2nd lepton pT2 > 16 GeV, pT12=|vect.sum of 1,2| > 35 GeV. Search in the (pT,2,pT,12) plane: - 0 events found - total exp. Backgnd: 0.95 +- 0.61(stat) +- 0.18(syst) - bosophilic Higgs (110 GeV)exp. to be about 0.06 evts . (assuming same production x-section as SM Higgs) - SM Higgs (160 GeV) expected to be about 0.03 evts.

  12. Also difficult at LHC (combination of several channels) At Tevatron need to fully exploit associated productions: WH and Z (l+l- or ) H with H  bbb-tagging Understand intrumental and SM backgrounds W,Z+heavy flavor are backgrounds to leptonic WH,ZH instrumental background (QCD) is difficult for  H Here after, results for b-tagging, Z and W+ Heavy Flavor, WH, and SM Higgs prospects Low Mass (<135 GeV) Higgs Search

  13. Tagging b-quarks (B-hadrons) • Top, Higgs have b-quark jets • Leptons from B meson • Contain a B meson • Has finite life time • Travels some distance from the vertex before decaying • ~ 1mm • With charm cascade decay, about 4.2 charged tracks Vertex Tagging a B (transverse plane) B (Signed) Track Impact Parameter (dca) Decay Lengh (Lxy) Hard Scatter Several algorithms under development/improvement: 3 main categories: - Soft-lepton tagging - Impact Parameter based - Secondary Vertex reconstruction Impact Parameter Resolution dca/s(dca) Decay Length Resolution Lxy/s(Lxy)

  14. Impact Parameter (dca) Algorithms Jet Lifetime Impact Parameter Based on signed dca Significance. Light jets: same flat probability for postive & negative dca significance • Probability distributions • P(Track from PV) • Defined for each class of tracks • # of SMT Hits, pT, etc. To each jet is assigned a Probability to be a light quark: Pjet 48% b jets: probability for positive dca sign. peaks at 0. 0.5% Light Quark Fake Rate Another algo also used in D0: counting displaced tracks

  15. SVT Algorithm Secondary Vertex Tagger Reconstruct Vertices using displaced tracks ~50% Cut on Decay Length Significance S(Lxy) = Lxy/s(Lxy). 0.5% Performance on signal tt lepton+jets ~ 56% Single Top (s channel) ~ 52% Wbb ~ 52% Wj ~ 0.3% Z axis Combining the 3 Taggers, correlations already studied N.B.: in D0, b-tagging efficiency is defined w.r.t. “taggable” jets, i.e. results are slightly higher than if estimated w.r.t to all jets

  16. Secondary Vertex Algorithm 42% Performance on signal SecVtx tagger efficiency to tag jets in top quark MC samples, as obtained by multiplying the tag rate for such MC jets by the data/MC scale factors: 0.909±0.060 for the tight tagger and 0.927±0.066 for the loose tagger. The bands represent the systematic error on the data/MC scale factors. 0.5%

  17. 3 views of a high dijet mass (220 GeV) Wbb (WH) candidate ETmiss Vertex view of a low mass candidate Clean Events! Mass Reconstruction? ETmiss b-tags dijet mass (48 GeV) electron ETmiss

  18. First steps in Measuring Z bb Dijet invariant mass of 85,794 events with both jet containing a secondary vertex b-tag. Events are selected from 333 pb-1 of CDF data (dedicated trigger). Two leading jets must be back-to-back in azimuth (Delta Phi>3.0), and the event must have no other jet with ET above 10 GeV. The background shape is computed using untagged data passing the same selection. The Z->bb signal shape is computed with Pythia The 2 shapes are fit to the experimental data (blue points) Fit results are in red Fit uncertainties are stat. only.

  19. Z+heavy flavor is background to ZH Z + single b-tag Probe of b-quark PDF b PDF is important for hb and single-top production Measure s(Z+b)/s(Z+j) Many systematics cancel Selection Z in ee and mm channels (cut on mass window) 1 Jet pT>20 GeV, ||<2.5 3458 Z+jet events Z + Heavy Flavor Production

  20. Apply sec. vertex b-tag 42 events with 1 tag 8.3 from QCD background (sideband) Disentangle light, c, b contributions Use light and b-tagging efficiency from data c-tagging efficiency from MC and scaled for data/MC difference in b-tagging Nc=1.69Nb from theory Cross checks with Soft lepton tagging Impact parameter tagging 0.0240.005(stat)0.005(syst) Theory predicts 0.018 Large part of systematic error from tagging efficiency and background estimation s(Z+b)/s(Z+j) signal Sec. Vtx displacement/resolution Submitted to PRL - hep-ex/0410078

  21. Search for Wbb Production 174pb-1 sample with one electron and (dominant backgd for WH) Compared to ALPGEN,PYTHIA showering, and full detector simulation. Normalized to NLO x-section (MCFM for W+jets) Electron: pT > 20 GeV, ||<1.1 Missing ET > 25 GeV 2 Jets: pT > 20 GeV/c, ||<2.5 2540 evts (2580  630 expected)  1 tag: 76 evts (72.6  20 exp.) Data well described by simulation Total experimentalsyst. Error ~15 %

  22. Wbb / WH Search 95% CL upper limit on WH production of 9.0 - 12.2 pb for Higgs masses of 105-135 GeV Published Run II limit better than Run I  detector improvements 6 evts (4.4  1.17 expected) 95% CL upper limit of 6.6 pb on production for b with pTb > 20 GeV and >0.75 Accepted in PRL - hep-ex/0410062

  23. Search for Wbb Production 162pb-1 sample with one electron or muon and Electron or muon: pT > 20 GeV/c Missing ET > 20 GeV 2 Jets: pT > 15 GeV/c, ||<2.0 Total systematic error ~ 11% No significant peak from Higgs W+ 1b-tagged jet W+2 jet events (before b-tagging) Data well described by simulation 62 evts (66.5  9 expected) 2540 evts observed

  24. Wbb  WH SM Higgs Prospects Future improvements Extend b-tagging acceptance, efficiency Additional kinematic variables Better Mbb resolution Add bb channel 95% CL upper limit on 5.3 (4) pb @ mH=115 (150) GeV

  25. bbh(bb) Search • Search for neutral Higgs in a two-Higgs-doublet MSSM SUSY model. • 260 pb-1 sample of triple b-tagged multi-jet events. • No distinction between h or H and A SUSY-MSSM h h • Sample Selection: • - Trigger >3 jets with ET>15 GeV, • - Offline cut on ET of leading jets • optimised for each Higgs mass. • - 3 b-tagged jets or more • Background: • “QCD heavy flavor” : bbjj, ccjj, cccc, bbcc, bbbb • “QCD fakes” : jjjj • “Other” : Z(bb,cc), tt • Theory/Simulation: NLO SM Higgs production (Campbell et. al., Dawson et. Al), MSSM (Carena, Mrenna, Wagner), PYTHIA, MADGRAPH, ALPGEN Di-jet mass in  3b-tagged events 260 pb-1 No excess of events observed

  26. bbh(bb) Search Limits on signal production cross section & in the tan β vs. mA plane: 260 pb-1 Two benchmark MSSM scenarios: 260 pb-1  < 70-20 pb for mA=90-150 GeV Exclude significant portion of tan β down to 50, depending on mA and MSSM scenario: For mA=120 GeV: < 31 pb-1 @ 95%c.l., tan < 55 @ 95%c.l. (Max Mixing)

  27. Search for gg h t+t- 200 pb-1 sample from t triggers (lepton+isolated track): two t’s, one decaying into hadrons+n and the other to an e/m + 2n. Cuts on lepton pT, Z mass window. To remove light quark bkgnd: PYTHIA+ Tauola (signal simul.) 230 evts. obs. 263.630.1 exp. Limit onsxBR extracted from likelihoodfit of the “partial mass” distribution:

  28. Search for H++/H-- l + q H++ l + */Z l - H-- q l - Predicted by some beyond SM models like Left-Right Symmetric Models If short lived:  prominent signature – multiple high Pt leptons, like sign di-lepton mass peak  backgrounds: WZ, W+jets, conversions (e) If long lived (ct > 3 m):  two high ionization tracks D0 (113 pb-1) M(HL) > 118 GeV (mm) at 95% C.L. CDF (240 pb-1) M(HL) > 136 GeV (mm) at 95% C.L. Background < 10-5 MH>134GeV

  29. Summary No deviations from SM observed (yet) Higgs search is in progress:  SM Higgs  sensitivity (mH >114 GeV) starts at ~2 fb-1 (Moriond 07 ?)  non-SM Higgs  many different models tested  already see reduction in allowed phase space (Run I, LEP) Expect substantial improvements in Higgs hunting with ~0.8 fb-1 already on tapes ~8 fb-1 expected in Run II

  30. Backup

  31. Data Collection by the Experiments Typical ratio of “recorded” to “delivered” luminosity is 80%-90% As of now both exper. recorded ~0.7 fb-1 Results presented correspond to ~0.3 fb-1 Analyzed data Analyzed data

  32. Search for H gg • In the SM Higgs gg has Br~10-3 •  search for SM Higgs decaying to gamma pair is not practical at Tevatron • Many SM extensions allow enhanced gamma pair decay rate largely due to suppressed coupling to fermions •  Fermiphobic Higgs • Topcolor Higgs • Search strategy: • Look for peaks in gg mass spectrum for high Pt isolated g’s

  33. Wbb  Technicolor D rules out the m(T)=200 GeV m(T)=105 GeV combination for MV between 200 and 500 GeV CDF  x-section limits for m(T0) between 85 and 120 GeV

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