1 / 20

Dr. Richard St. Denis Glasgow University On behalf of the CDF and D0 Collaborations

Dr. Richard St. Denis Glasgow University On behalf of the CDF and D0 Collaborations Moriond 2010 Electroweak, La Thuile, Italy March 6-March 13, 2010. Tevatron Results on SM Higgs Search in the High Mass Region. Outline. Search Foundation and Higgs detection modes

clodia
Download Presentation

Dr. Richard St. Denis Glasgow University On behalf of the CDF and D0 Collaborations

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Dr. Richard St. Denis Glasgow University On behalf of the CDF and D0 Collaborations Moriond 2010 Electroweak, La Thuile, Italy March 6-March 13, 2010 Tevatron Results on SM Higgs Search in the High Mass Region Outline • Search Foundation and Higgs detection modes • CDF and D0 detection methods in High Mass • Results, implications, next steps

  2. Higher Physics Reach Dms=17.77 ± 0.10 ± 0.07 Single Top Susy Higgs M M w t WZ New hadronic ZZ WW,WZ,ZZ Top (t) Top(ttbar) WZ Bottom Jets Build on mountain of measurements

  3. Low Mass High Mass SM Higgs Production and Decay • Trigger: 1 High Pt e or m • Focus on Decays: WW → ee, em, mm, et, mt + n’s • Separate channels by dileptons (D0), Njets (CDF) • Event Selection: High Pt Leptons, Missing ET Gluon Fusion (dominates) Associated production Vector Boson Fusion

  4. ww Df ll Df ll Z/g HWW Production Features nm g • High Pt Leptons not back to back • Spin 0 Higgs correlates spins of leptons: charged leptons (low Df ll), two neutrinos (High MET) tend to be closely aligned with one another. W+ m+ H0 W- g e- ne Backgrounds

  5. High Pt e,m Isolation Met,Mll Lo <2Jet Hi 0jet 1Jet >1Jet WW Df,DR,Ht… H M ll Discr. Ana (CDF) Wg H Wg t H B t H H Z/g WW Z/g H Z/g H t t WW WW WW Z/g H H Heavy Flavor WW DrellYan WW/Wg/top H-Enhanced H

  6. Dileptons,Iso pt>15,10GeV/c Met>20,30 GeV/c2 Discr: Dfll Mll Z/g Z/g Z/g ee WW Z/g em Z/g Z/g Z/g mm

  7. WW Hx10 Expect 35 Signal Events Z/g Bkg Uncertainty does not wash out signal

  8. CDF 5.3 fb-1 Expect 32 Signal Events →Total W/D0: 67 WW 0J tt >1 J Hx10 Fit Background Search H 1J 0,1 J, Mll<16 Hx15 WW New

  9. Control Region: Determine systematics, measure background rates → Proper W+jet fake modelling • Mtl >20 GeV • MET < 20 GeV • Dfl,MET <.5 WW→etnn,mtnn z→tt Sum track pt in tcone • Control Region New Channel for CDF • Mtt: invariant mass W+jet (fake t) t property eth mth Expected Signal:1.8

  10. Same sign Dileptons(CDF/D0), Trileptons(CDF) No Rate? Too Low? No! New l+ W+ nl • Same Sign dileptons: • WH: W(jj)W*(ln)W(ln), • ll(l) nnn • ZH: Z(jj)llnn,W(jj)ll(l) nn,… • Trileptons: • WH:lllnnn • ZH:Z(ll)W(qq)W(l) n W+ q q H0 l- l- W+ H0 W- q W- nl nl l+ l+ W+ q q q nl q q Z0 Different Channel Different Systematics No Channel Left Behind Z0 l-

  11. Same Sign Dilepton S:2.2 S:0.5 S:0.7 WH ZH S:0.6 3.6fb-1 Hx10 Different Background(WZ) New Trileptons Hx10 New S:0.41 No Bkg: Linear gain with Lumi

  12. arXiv: 1001.4468 CDF 4.8 fb-1 V. M. Abazov et al. (DØ Collaboration), Phys. Rev. Lett. 104, 061804 (2010). @165: Expected 1.20 @165: Expected 1.36 Observed 1.29 Observed 1.55 T. Aaltonen et al. (CDF Collaboration), Phys. Rev. Lett. 104, 061803 (2010). arXiv:1001.4481 SM Sensitivity: 159-169 GeV/c2! + SM Exclusion: 162-166 GeV/c2! arXiv: 1001.4162. T. Aaltonen et al., (CDF and DØ Collaborations), Phys. Rev. Lett. 104, 061802 (2010).

  13. New Improvements Over Publication • 4.8→5.3 fb-1: 5% better • Optimized e- selection • Add Trileptons, Low Mll ,VH, VBF for 0 Jet • All together: 15% better! • Improvements continue (t modes add a few %)

  14. Next:Extend sensitivity 146-183 136-190

  15. Summary • “No channel too small” strategy successful: different, backgrounds, systematics, S/B and many channels. • Combined Tevatron results exclude the Standard Model Higgs at 95% CL for 162≤ MH ≤ 166 GeV/c2. • Updated CDF results: sensitivity close to 95% CL exclusion for MH=160-165 GeV/c2. • The High mass sensitivity will be expanded: 2xCDF gives 146-183 GeV/c2 if no improvements, 136-190 GeV/c2 with improvements. • Both experiments have 8 fb-1 delivered! • These are remarkable times. Rapid changes in data collected and analysis continue.

  16. Backup

  17. D0 and CDF Detectors • Silicon Tracking • Open drift Cell Tracker • ScintillatorCalo. |h|<3.2 • Muon coverage |h|<1.5 • Silicon Tracking • Fibre Tracker • L ArCalo. |h|<4 • Muon: |h|<2 Resultsfor 5.3-5.4 fb-1

  18. score var1 NN 0 1 var2 var n ET SET mll Elep1 Elep2 ETsig ETjet1 DRleptons Dfleptons Df ET lep or jet ETjet2 Njets Data HWW WW DY Wg WZ ZZ t t fakes Neural network method • Various versions. Current: • Apply preselection (eg ET to remove Drell-Yan) • Train on {all backgrounds / WW} against Higgs mH=110,120…160…200 { possibly separate ee,em,mm } x10 BackgroundHiggs • Pass signal/all backgrounds through net • Form templates Most recent CDF “combined ME/NN” analysis also uses ME LRs as NN input variables NN 0 1  Pass templates and data to fitter

  19. CDF Published Limits D0 Published Limits CDF+D0 Published limits

  20. CDF limits for March 2010

More Related