1. XXXIV International Symposium on Multiparticle Dynamics Alberto Cruz On behalf of the CDF collaboration

2. Main Injector Tevatron DØCDF Chicago   p source Booster Fermilab Florida

3. Tevatron proton-antiproton collisions Main injector (150 GeV proton storage ring) antiproton recycler (commissioning) Electron cooling this year Operational on June’05 40% increase in Luminosity 36 bunches (396 ns crossing time) Long Term Luminosity Projection (by end FY2009) Base Goal -> 4.4 fb-1 Design -> 8.5 fb-1 Increasing Luminosity: RUN I (1992-95) ~0.1fb -1 RUN IIa (2001~2005) ~1fb -1

4. Tevatron Performance Recent Luminosity Record of 10.3x10 31 sec -1 cm -2 (July 16, 2004)

5. CDF Run II Data CDF Efficiency > 80% DAQ runs with 5% to 10% dead time Rest coming from very careful operation of detector’s HV due to machine losses (…to preserve silicon & trackers…) CDF -> ~450 pb -1 on tape

6. In proton-antiproton collisions we can occasionally have a “hard” parton-parton scattering resulting in large transverse momentum outgoing partons. The Jet Algorithm Allows us to “see” the partons (or at least their fingerprints) in the final hadronic state.

7. Jet algorithms & physics Final state partons are revealed through collimated flows of hadrons called jets Measurements are performed at hadron level & theory is parton level (hadron  parton transition will depend on parton shower modeling) Precise jet search algorithms necessary to compare with theory and to define hard physics Natural choice is to use a cone-based algorithm in  -  space (invariant under longitudinal boost)

8. Run II -> MidPoint algorithm 1.Define a list of seeds using CAL towers with E > 1 GeV 2.Draw a cone of radius R around each seed and form “proto-jet” 3.Draw new cones around “proto-jets” and iterate until stable cones 4.Put seed in Midpoint (  -  ) for each pair of proto-jets separated by less than 2R and iterate for stable jets 5.Merging/Splitting Cross section calculable in pQCD T Arbitrary Rsep parameter still present in pQCD calculation …

9. Comparison of JetClu and MidPoint for HERWIG MC Differences between MidPoint and JetClu found to be due to “ratcheting”. JetClu  0.5-2% higher E T jets Comparison of the JetClu to MidPoint cone algorithms

10. W/Z/  +jets) production: introduction QCD-wise, are W/Z/  cross sections of interest? èSmaller subset of diagrams, different mix of initial partons  Below is a set of LO diagrams for W/Z and W/Z/  + 1 jet èInclusive distributions are not affected by jet finding uncertainties lMore theoretical work is needed, e.g.: èW inclusive: known at the level of NNLO èW + 1 jet: known at the level of NLO èW + 2, 3, 4 jets:known at the level of LO  (MCFM does proved W + 2 jets at NLO, it just isn’t an event generator)

11. W+jet(s) Production (JetClu R=0.4) Background to top and Higgs Physics Stringent test of pQCD predictions Test Ground for ME+PS techniques (Special matching  MLM, CKKW to avoid double counting on ME+PS interface) Alpgen + Herwig LO  large uncertainty W + 1 parton +PS W+ 2 partons 40% higher than the RUNI result QCD corrections cover this difference. Inclusive  (nb) Run I (1.8 TeV): LO: 1.76 NLO:2.41 NNLO:2.50 CDF I:2.38  0.24 Run II (1.96 TeV): LO: 1.94 NLO:2.64 NNLO:2.73 CDF II: 2.64  0.18

12. W+ jet(s) Production (JetClu R=0.4) 1 st jet in W + 1p 2 nd jet in W + 2p 3 rd 4 th ME+PS implementation tested using the N th jet spectrum in W+N jet events. Dijet Mass in W+2jets Energy-scale

13. Diphoton Production Testing NLO pQCD and resummation methods Signature of interesting physics –One of main Higgs discovery channels at LHC Data: 2 isolated γs in central region, E T 1,2 > 14, 13 GeV General agreement with NLO predictions

14. γ +heavy flavour production Probes heavy-quark PDFs b/c-quark tag based on displaced vertices Secondary vertex mass discriminates flavour MC templates for b/c & (uds) used to extract b/c fraction in data

15. γ +heavy flavour production Good agreement with LO pQCD within still very large stat. errors Validates quark flavour separation using secondary vertex mass γ +b-quark γ +c-quark

16. Summary Tevatron and CDF are performing well èData samples already significantly exceed those of Run I èOn track for accumulating 4-8 fb -1 by 2009 lRobust QCD program is underway èJets, photons, W+jets, heavy flavors  Jet energy scale is the dominant systematics – improvements on the way  Heavy flavor identification is working well èVerifying and tuning tools: NLO calculations, Monte Carlo generators, resummation techniques, combining ME with PS  NLO does well for hard aspects  LO + Pythia give reasonable description of W+n jets lWe don’t see any discrepancies.