Presentation is loading. Please wait.

Presentation is loading. Please wait.

Leptoquark Searches at the Tevatron April 16th, 2004 XII th Deep Inelastic Scattering Workshop Štrbské Pleso, Slovakia For the CDF and DØ Collaborations.

Similar presentations


Presentation on theme: "Leptoquark Searches at the Tevatron April 16th, 2004 XII th Deep Inelastic Scattering Workshop Štrbské Pleso, Slovakia For the CDF and DØ Collaborations."— Presentation transcript:

1 Leptoquark Searches at the Tevatron April 16th, 2004 XII th Deep Inelastic Scattering Workshop Štrbské Pleso, Slovakia For the CDF and DØ Collaborations Daniel Ryan Tufts University

2 Outline ● “Re”-introduction to CDF and DØ ● Introduction to Leptoquarks at the TeVatron ● Searches for 1 st Generation Leptoquarks ● Searches for 2 nd Generation Leptoquarks ● Summary and Comparison to Run I results ● Run II Summary and Future Outlook 2 Daniel RyanSearches for Leptoquarks at the Tevatron

3 Main Injector & Recycler Tevatron Chicago   p source pp p p pp 1.96 TeV Booster CDF DØ Muon System Central Calorimeter Solenoid Plug Calorimeter Drift Chamber Silicon Microstrip Tracker Front End Electronics Pipelined Triggers / DAQ Online & Offline Software Time-of-Flight New Partly New Old CDF and DØ Run II upgrades

4 CDF ~ 200pb -1 Feb, 2002March, 2004 DØ - 175pb -1 FY '04 Projection: 230 - 310 pb -1 FY '04 Projection: 230 - 310 pb -1 CDF - 72pb -1 DØ - 104pb -1 Run I 200 100 300 400

5 Leptoquarks  Spin 0 or 1 and both have lepton and baryon numbers  Color triplet  Fractional Electric Charge  Constraints on FCNC, assume LQ's couple uniquely within a lepton/quark generation Introduction to Leptoquarks 5 Daniel RyanSearches for Leptoquarks at the Tevatron Why study leptoquarks? Some models beyond the SM (GUT's, Technicolor, composite models) assume additional symmetry between leptons and quarks. u u e e d d c c s s t t b b µ µ   e e µ µ   quarks leptons

6 Leptoquark Production at the TeVatron Production qg  LQ + LQ* gg  LQ + LQ qq  LQ + LQ  Pair produced  Independent of, coupling between LQ's and lepton/quark. *Not shown 6 Daniel RyanSearches for Leptoquarks at the Tevatron e

7 Leptoquark Production at  s = 1.96 TeV 7 Daniel RyanSearches for Leptoquarks at the Tevatron Run I Run II

8 Leptoquark Decay Each generation can decay into 3 final states:  = 1  = 0.5  = 0 8 Daniel RyanSearches for Leptoquarks at the Tevatron LQ LQ → llqq→2l+2jBR =   LQ LQ → l qq→l+MET+2jBR = 2  (1-  LQ LQ → qq→MET+2jBR = (1-   Exclusive to the Tevatron

9 9 Daniel RyanSearches for Leptoquarks at the Tevatron 1 st Generation Leptoquark Searches,  = 1, circa 2003

10 1 st Gen. LQ's – ej ej DØ Search – 175pb -1 10 Daniel RyanSearches for Leptoquarks at the Tevatron Backgrounds  Drell-Yan+2jets  Top (W  e )  QCD/Fakes Selection 2 EM clusters E T > 25 GeV (1 cluster w/ track match) 2 jets E T > 20 GeV Z veto (80 < M ee < 102) GeV First Generation Decay

11 DØ – ej ej No. Exp. 0.4 ± 0.1 Observed 0 Exclude at 95% CL M LQ <238 GeV/c 2 11 Daniel RyanSearches for Leptoquarks at the Tevatron Selection (cont.) Scalar Sum S T (eejj) > 450 GeV Signal Acceptance ~(10 - 30)%

12 12 Daniel RyanSearches for Leptoquarks at the Tevatron CDF – ej ej Luminosity203pb -1 Acceptance(32-42)% Background6.2 +3.1 - 2.5 Observed4 Exclude at 95% CL M LQ <230 GeV/c 2 CDF Selection 2 electrons (CC,CE) E T > 25 GeV 2 jets, E T (j1) > 30 GeV, E T (j2) > 15 GeV Z Veto (76 < M µµ < 110) GeV Muon/Jets: E T j1(e1) + E T j2(e2) > 85 GeV Sqrt( (E T (j 1 ) + E T (j 2 )) 2 + (P T (e 1 ) + P T (e 2 )) 2 ) > 200 GeV

13 CDF Selection 1 electron (central) E T >25 GeV MET > 35 GeV 2 jets E T > 30 GeV  Phi (MET - jet) > 10 o Sum E T (jet1,jet2) > 80 GeV M T (e,v) > 120 GeV MET/Sqrt(  E T ) > 4.5 Signal Acceptance ~(18 - 37)% 13 Daniel RyanSearches for Leptoquarks at the Tevatron Backgrounds  W+2jets  Top (W  e )  Top (dilepton + jets) 1 st Gen. LQ's – ej j CDF Search – 72pb -1

14 Luminosity72pb -1 Background1.7 ± 1.5 Observed2 Exclude at 95% CL M LQ < 166 GeV/c 2 CDF – ej j 14 Daniel RyanSearches for Leptoquarks at the Tevatron Events Expected in 72pb -1 Update in progress... Update in progress...

15 DØ Selection 1 electron (w/ em cluster – track match) E T > 35 GeV MET > 30 GeV 2 jets E T > 25 GeV  Phi (MET,jet) > 8 o S T (j1,j2,e,MET) > 330 GeV M T (e,v) > 130 GeV Signal Acceptance ~(13 - 25)% 15 Daniel RyanSearches for Leptoquarks at the Tevatron DØ Search – ej j Luminosity175pb -1 Background4.7 ± 0.8 Observed2 Exclude at 95% CL M LQ < 194 GeV/c 2

16 MET + Jets CDF Search - 191pb -1 16 Daniel RyanSearches for Leptoquarks at the Tevatron ● Flavor Independent ● 1 st time for CDF ● Channel rich with background ● Relies heavily on event topology ● Flavor Independent ● 1 st time for CDF ● Channel rich with background ● Relies heavily on event topology

17 MET + Jets 17 Daniel RyanSearches for Leptoquarks at the Tevatron CDF Selection 2-3 jets (1 st & 2 nd leading jets in central region) Require central jets w/ 4 tracks (rejects  events) Misaligned jets and MET (rejects QCD, MET from mismeasured jets) (Signal) MET > 60 GeV 80< Phi (jet1 – jet2) < 165 o Veto e, µ events Signal Acceptance ~(1 - 8)%

18 18 Daniel RyanSearches for Leptoquarks at the Tevatron Luminosity191pb -1 Background118 ± 13 Observed124 Exclude at 95% CL 78 < M LQ < 117 GeV/c 2 MET + Jets

19 CDF Combined: beta = 0.0 M LQ > 117 GeV/c 2 beta = 0.1 M LQ > 135 GeV/c 2 beta = 0.2 M LQ > 161 GeV/c 2 beta = 0.5 M LQ > 197 GeV/c 2 beta = 1.0 M LQ > 232 GeV/c 2 eejj e jj jj jj Combined Results DØ Combined: beta = 0.0 M LQ > 98 GeV/c 2 beta = 0.1 M LQ > 155 GeV/c 2 beta = 0.2 M LQ > 184 GeV/c 2 beta = 0.5 M LQ > 213 GeV/c 2 beta = 1.0 M LQ > 238 GeV/c 2 19 Daniel RyanSearches for Leptoquarks at the Tevatroneejj e jj

20 20 Daniel RyanSearches for Leptoquarks at the Tevatron 2 nd Gen. -- µ j µj CDF Search – 198pb -1 Second Generation Decay Backgrounds  Drell-Yan+2jets  Fakes  Top (W  e ) CDF Selection 2 muons with P T > 25 GeV 2 jets with E T (j1,j2) > 30,15 GeV Dimuon Mass Veto: 76 < M µµ < 110, M µµ < 15 GeV E T (j 1 ) + E T (j 2 ) > 85 GeV and P T (µ 1 ) + P T (µ 2 ) > 85 GeV Sqrt( (E T (j 1 ) + E T (j 2 )) 2 + (P T (µ 1 ) + P T (µ 2 )) 2 ) > 200 GeV

21 21 Daniel RyanSearches for Leptoquarks at the Tevatron Luminosity198pb -1 Background 3.1 ± 1.2 Observed2 Exclude at 95% CL M LQ < 241 GeV/c 2 CDF -- µj µj

22 Luminosity104pb -1 Background1.6 ± 0.5 Observed1 Exclude at 95% CL M LQ < 186 GeV/c 2 DØ -- µj µj Update in progress... Update in progress... 22 Daniel RyanSearches for Leptoquarks at the Tevatron

23 23 Daniel RyanSearches for Leptoquarks at the Tevatron 2 nd Gen. -- µj j in progress CDF Selection Muon P T >25, MET>60 GeV 2 jets, @ E T >30GeV Veto aligned (Muon, MET) and (MET,jets) E T (jet1)+E T (jet2) > 80 GeV M T (MET,Muon) > 110 GeV MET/Sqrt(  E T ) > 4.5 Backgrounds  W+2jets  Top (W  )  QCD DØ Run I Limit180 GeV CDF Run I Limit164 GeV CDF Run II 200pb -1 Sensitivity~200 GeV

24 Summary 24 Daniel RyanSearches for Leptoquarks at the Tevatron Beta I II 1225200 1/2204 0 9898 1220202 1/2182164 0 123 1 Beta I II 1225200 1/2204 0 9898 1220202 1/2182164 0 123 1 Beta I II 1.0238200 0.5213 in progress 0.0 in progressin progress 1.0230240 0.5197 in progress 0.0117117 Beta I II 1.0238200 0.5213 in progress 0.0 in progressin progress 1.0230240 0.5197 in progress 0.0117117 1 c c 3 rd generation not shown Run 1Run 2

25 Summary 25 Daniel RyanSearches for Leptoquarks at the Tevatron  CDF and DØ have updated their 1 st and 2 nd generation direct leptoquark searches using Run II data  DØ has combined results for 1 st generation (175pb -1 )  CDF has combined results for 1 st generation (72pb -1 )  No Run II updates on vector leptoquarks from either DØ or CDF.  Work to be done:  CDF and DØ investigating  jj channel and DØ investigating qq channel.  3 rd generation leptoquarks.  Vector leptoquarks for Yang-Mills and Minimal type coupling.

26 Backup Slides

27 Run I Vector Leptoquark Searches 1 st Generation Mass (GeV/c 2 ) BetaYang-Mills Minimal 1.0345290 DØ0.5337282 0.0 298 238 1.0330280 CDF0.5310265 0.0 1 st Generation Mass (GeV/c 2 ) BetaYang-Mills Minimal 1.0345290 DØ0.5337282 0.0 298 238 1.0330280 CDF0.5310265 0.0

28

29


Download ppt "Leptoquark Searches at the Tevatron April 16th, 2004 XII th Deep Inelastic Scattering Workshop Štrbské Pleso, Slovakia For the CDF and DØ Collaborations."

Similar presentations


Ads by Google