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Tevatron Results

This presentation discusses Tevatron results on jet physics, inclusive jet production, dijet decorrelations, b-jet production, Z+jets, W and Z production, W charge asymmetry, top pair production, and top mass. It also includes examples of searches for bbh in MSSM and gluino to sbottom.

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Tevatron Results

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  1. Tevatron Results Régis Lefèvre IFAE Barcelonaon behalf of the CDF and DØCollaborations DIS 2005XIII International Workshop on Deep Inelastic Scattering April 27th – May 1st 2005, Madison, Wisconsin, U.S.A.

  2. Outline • Introduction • Tevatron, CDF & DØ • Jet Physics • Inclusive jet production, dijet  decorrelations, jet shape, b-jet production, Z+jets • EW Physics • W & Z production, W charge asymmetry, W • Top Physics • Top pair production, top mass • Examples of searches • bbh(bb) in MSSM, gluinosbottom • Conclusion  A lot more not presented here!

  3. Chicago  Booster CDF DØ Tevatron p source Main Injector (new) Fermilab

  4. Tevatron • proton-antiproton collisions • s = 1.96 TeV (Run I  1.8 TeV) • 36 bunches: 396 ns crossing time • Peak luminosity is now ~ 1032 cm-2 s-1 • Long term luminosity goal • Base 4.4 fb-1, Design 8.5 fb-1 by the end of 2009

  5. CDF and DØ • Both detectors highly upgraded • New Silicon micro-vertex tracker • New Tracking System • Upgraded muon chambers • CDF: new Plug Calorimeters, new TOF • DØ: new solenoid, new Pre-showers CDF • Both experiments taking data with good efficiency ~ 85 % • Each experiment has already collected on tape ~ 0.7 fb-1 DØ

  6. Jet Physics

  7. Jet Production with Midpoint • Inclusive jet cross section @ Tevatron • Stringent test of pQCD • Tail sensitive to new physics • PDFs at high Q2 & high x • Midpoint jet algorithm • RCONE = 0.7 / Merging fraction = 50 % • Infrared safe: no RSEP parameter introduced in theory calculation (Merging / Splitting?) • Direct comparison with NLO • QCD Hadronization / Underlying Eventcorrections small • Good data-theory agreement • Experimental uncertainty dominated by jet energy scale • Largest theoretical error from PDFs (gluon at high x)

  8. Jet Production with KT • Inclusive KT algorithm • Infrared and Collinear safe to all orders in p-QCD • No merging / splitting feature • No RSEP issue comparing to p-QCD • NLO corrected to hadron level • Good data-theory agreement

  9. D  size of jetsdij = min (P2Ti , P2Tj) · R2 / D2 KT jets vs. D

  10. Dijet  decorrelations A clean and simple way to study QCD radiative processes 12 LO inDf 12 NLO inDf Comparison with MCImpact of tuning MC generators Comparison to NLO pQCD Good agreement except at  where resummation is needed

  11. Energy Flow Inside Jets Jet shapes governed by multi-gluon emission from primary parton • Test of parton shower models • Sensitive to underlying event structure • Sensitive to quark and gluon mixture in the final state (1-)

  12. Inclusive b-jet production Important test of pQCD - Full calculations up to NLO and beyond Leading Order Next to Leading Order Flavor excitation MonteCarlo templates Flavor creation Gluon splitting

  13. Z+jets • Test of pQCD at high Q2 ( MZ) • Fundamental channel for SMand new physics processes • ZH • MCFM • NLO up to Z + 2 partons • ME-PS • Leading Order Matrix Element (Madgraph) + Parton Shower (Pythia) 1st jet in Z +  1 j 2nd jet in Z +  2 j 3rd jet in Z +  3 j

  14. EW Physics

  15. W, Z production • Test of standard Model • Require high level of understanding of the detectors • e,  and  identifications • Backgrounds W||<2 96 pb-1  Efficiencies computed on data QCD background evaluated on data

  16. W, Z cross sections W/Z cross sections • Test the SM •  often enters innon SM final states • Ability to identify  Good agreement with NLO (van Neerven)

  17. W charge asymmetry • CDF: W e (170 pb-1) • u quarks carry higher fractionof the proton momentum • W+ boosted in the proton direction • Measure Ye instead of YW • Assume SM We coupling • New constraints to PDF’s

  18. Direct measurement of W DØ: W e (177 pb-1) • Fit the transverse mass distribution in the region 100 < MT(W) < 200 GeV • 625 candidates in this range • Main systematic uncertainties • Hadronic response and resolution ~ 64 MeV • Underlying event ~ 47 MeV • EM resolution ~30 MeV

  19. Top Physics

  20. 85% 15% Top production and decay Hadronization time No top hadrons top-antitop pairs Final state given by W+ W- decays Event Classification ttlnlnbbdilepton5% ttlnqqbblepton+jets30% ttqqqqbbhadronic45% ~ one top event / 10 billion inelastic collisions Here lepton = e orm

  21. Top quark production • Sensitive to New Physics in production and decay • Increases by ~ 30 % with Run II s enhancement DØ Lepton+Jets (164 pb-1) Impact parameter tag Fit 3-4 jet bins in 1 and 2 tagged jet samples 1 tagged jet sample

  22. Top quark cross section

  23. Top quark mass Corrections to MW ~ mt2, ln(mH) CDF Dilepton (200 pb-1) weighting: assume rapidities of both ’s and calculate likelihood of observed missing ET Plot mt which maximizes WX·WY and compare to MC templates

  24. Examples of searches

  25. MSSM Higgs: bbh(bb) search Di-jet mass in  3b-tagged events •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 •Backgrounds - “QCD heavy flavor” : bbjj, ccjj, cccc, bbcc, bbbb - “QCD fakes” : jjjj - “Other” : Z(bb,cc), tt 260 pb-1 260 pb-1 No excess of events observed • Exclude significant portion of tan β down to 50 - Depending on mA and MSSM scenario

  26. Search for gluino  sbottom ~ • b1 can be very light for large tan • Expect large branching fraction • of gluino to sbottom •  Signature: 4 b-jets and missing ET Exp: 2.6 +- 0.7 Obs: 4

  27. Conclusion • Tevatron on is way to increase luminosity • Already ~ 1032 cm-2 s-1 • CDF & D0 efficiently taking very good data • Already ~ 0.7 fb-1 • Very large and very exiting Physics program • A lot more not presented here! • Preparation of the LHC • Stringent tests of pQCD and SM • Implication on PDFs • Better and better precision on mtop • Most stringent limits for some searches

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