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XXXIV International Symposium on Multiparticle Dynamics

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Alberto Cruz. On behalf of the CDF collaboration. XXXIV International Symposium on Multiparticle Dynamics. Chicago . Florida. Booster. CDF. DØ. Tevatron. p sou rce. Main Injector. Fermilab. Long Term Luminosity Projection (by end FY2009). Base Goal -> 4.4 fb-1

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Presentation Transcript
slide1

Alberto Cruz

On behalf of the CDF collaboration

XXXIV International Symposium on Multiparticle Dynamics

fermilab

Chicago

Florida

Booster

CDF

Tevatron

p source

Main Injector

Fermilab
tevatron

Long Term Luminosity Projection

(by end FY2009)

Base Goal -> 4.4 fb-1

Design -> 8.5 fb-1

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)

Increasing Luminosity:

RUN IIa (2001~2005) ~1fb-1

RUN I (1992-95) ~0.1fb-1

tevatron performance
Tevatron Performance

Recent Luminosity Record of 10.3x1031 sec-1cm-2 (July 16, 2004)

cdf run ii data
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

slide6

The Jet Algorithm Allows us to “see” the partons (or at least their fingerprints) in the final hadronic state.

In proton-antiproton collisions we can occasionally have a “hard” parton-parton scattering resulting in large transverse momentum outgoing partons.

jet algorithms physics
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)
run ii midpoint algorithm
Run II -> MidPoint algorithm
  • Define a list of seeds using CAL towers with E > 1 GeV
  • Draw a cone of radius R around each seed and form “proto-jet”
  • Draw new cones around “proto-jets” and iterate until stable cones
  • Put seed in Midpoint (-) for each pair of proto-jets separated by less than 2R and iterate for stable jets
  • Merging/Splitting

T

Cross section calculable in pQCD

Arbitrary Rsep parameter still

present in pQCD calculation …

slide9

Comparison of JetClu and MidPoint for HERWIG MC

Comparison of the JetClu to MidPoint cone algorithms

Differences between MidPoint and JetClu found to be due to “ratcheting”.

JetClu  0.5-2% higher ET jets

w z g jets production introduction
W/Z/g(+jets) production: introduction
  • QCD-wise, are W/Z/g cross sections of interest?
    • Smaller subset of diagrams, different mix of initial partons
      • Below is a set of LO diagrams for W/Z and W/Z/g + 1 jet
    • Inclusive distributions are not affected by jet finding uncertainties
  • More theoretical work is needed, e.g.:
    • W inclusive: known at the level of NNLO
    • W + 1 jet: known at the level of NLO
    • W + 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)
w jet s production jetclu r 0 4
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)

Inclusive s (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

W + 1 parton +PS

W+ 2 partons

QCD corrections cover this difference.

40% higher than the RUNI result

Alpgen + Herwig

LO  large uncertainty

w jet s production jetclu r 0 41
W+ jet(s) Production (JetClu R=0.4)

ME+PS implementation tested using the Nth jet spectrum in W+Njet events.

Dijet Mass in W+2jets

1st jet in W + 1p

Energy-scale

2nd jet in W + 2p

4th

3rd

diphoton production
Diphoton Production
  • General agreement with NLO predictions

Data: 2 isolated γs in central region, ET1,2 > 14, 13 GeV

  • Testing NLO pQCD and resummation methods
  • Signature of interesting physics
    • One of main Higgs discovery channels at LHC
heavy flavour production
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

slide15

γ+heavy flavour production

γ+b-quark

γ+c-quark

Good agreement with LO pQCD

within still very large stat. errors

Validates quark flavour separation

using secondary vertex mass

summary
Summary
  • Tevatron and CDF are performing well
    • Data samples already significantly exceed those of Run I
    • On track for accumulating 4-8 fb-1 by 2009
  • Robust QCD program is underway
    • Jets, photons, W+jets, heavy flavors
      • Jet energy scale is the dominant systematics – improvements on the way
      • Heavy flavor identification is working well
    • Verifying 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
  • We don’t see any discrepancies.
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