Notes
Slide Show
Outline
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CDF: Experimental Interests and Theoretical Issues.
  • Ronan McNulty
  • (University of Liverpool)
  • on behalf of the UK CDF groups:
  • Glasgow; Liverpool; Oxford; UCL.
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"Explore areas of common interest..."
  • Explore areas of common interest between theorists/phenomenologists at IPPP and experimentalists at the Tevatron.


  • Shopping list of theoretical questions and desires


  • Brief Status of collider and detector
  • Concentrate on physics measurements that UK is involved in.  (RAL status report http://hep.ph.liv.ac.uk/cdf/Liverpool/group/talks.html)
  • Highlight theoretical/phenomenological problems that we experimentalists see


  • Maybe we can compile a list of common topics and follow it up with more detailed discussions with relevant experts.
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The Tevatron
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The Tevatron
  • Run I: 120 pb-1 until 1996
  • Run II:
    • Started March 2001
    • 2    fb-1 by 2006
    • 6.5 fb-1 by 2008
  • Disappointing startup but have now exceeded Run I luminosity!


  • Peak luminosity increasing
    • Run I   best:   2.8x1031 cm-2s-1
    • Run II best:   3.5x1031 cm-2s-1
    • Run II  goal: 20  x1031 cm-2s-1


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CDF
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CDF in Run II
  • Major upgrades
    • trigger/DAQ
    • Plug calorimeters
    • Silicon tracker
    • Tracking drift chamber
  • Started March 2001
  • >100 pb-1 of good data by now


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SVT Level 2 Trigger
  • Level 2 hadronic B trigger
    • s(d0) ~ 48 mm
    • 15 ms operation
  • online primary vertex finding, tracking
  • trigger on displaced  vertices
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TOF Performance
  • TOF resolution within 10 –20% of design value (100 ps)
  • Calibration ongoing


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Physics programme at Run 2
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Production and Decay of Higgs
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Higgs: Signal and Background rates
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Higgs
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Diffractive Higgs
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Diffractive Higgs
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Electroweak: W mass and width
  • Tag W by decay to hard isolated e,m
  • Calorimetry scale set by Z, resonances (J/y)
  • Obtain m(W), G(W) from transverse mass fit


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Electroweak: m(W) errors
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DiBoson
Production
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DiBoson
Production
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Top: Production Mechanism
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Decay Mechanism
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Hadronic Mode (6 jets)
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Physics of Top
  • Is it a Standard Model Top?


  • Can it be a probe for New Physics?


  • Can it tell us about the Higgs?


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Is it a Standard Model Top
  • Does the cross-section agree with QCD?
  • Does the mass agree with SM
  • Are decays as expected?  Count e, m,t, jets, b-jets.
  • Check kinematics: pT & angular distributions
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W Polarisation, Vtb, Top Spin
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Vtb from Single Top
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New Physics
  • Probe for new physics
    • Non SM production X->tt
    • Non SM decay t->Xb
  • Resonances in tt production
    • Topcolour: qq->V->tt
    • Technicolour: qq->hT->tt
    • In some models tt condensate explains large top mass/EWSB
  • SUSY
    • stop: t->t+c0  &   t->b+l+v
    • gluino -> stop + top


  • SUSY Higgs
    • t->b + H+  => enhanced t s.
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W + Njets Background
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Inclusive Central Jet Cross Section
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SM explanation (gluon at high-x)
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RunII jet cross-section
  • Increased c/s at high Et, quite apart from luminosity increase


  • Better forward calorimeters
    • Is excess in barrel and forward (PDF) or confined to barrel (New Physics?)
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RunII: Jet cross-section
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New Physics
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b-jet + g
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Typical event
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b-jet + g
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SUSY: projected limits
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Heavy flavour physics: lifetimes
  • First measurements which CDF will perform in b sector
  • Necessary step towards oscillation
  • Best measurement of Bs0, Lb.  (Unique)


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Heavy flavour physics: lifetimes
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Exclusive lifetimes
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Bs oscillations
  • x = Dm/G



  • Currently: xs > 14.6
  • Projection for 15 fb-1:
    • 20 000 Bs decays
    • Effective tagging eff. *2 cf. Run 1
    • Sensitive to xs < 63
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B oscillations
  •  Dm     DG = f (tH, tL )
    • Separate eigenstates and measure each lifetime

  • BS ® DS+ DS-  (CP even)      Work continuing in triggering on these difficult hadronic modes (track/vertex/reconstruct)
  • BS ®  J/y f    (CP even&odd) Different angular distribution for mm allow separation of CP even and odd states
  • BS ® J/y h    (CP odd)


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"In QCD and top measurements"
  • In QCD and top measurements, as well as searches, we would like to know the original parton energy.
  • Experimentally we observe jets
  • Definition of jet


  • Energy correction scheme (how to go from jet energy to parent parton)
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Example: Problems with Top Mass Measurement
  • We see a peak on top of background
  • BUT
  • How is the peak position related to the top quark mass?
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Jet Energy Correction Scheme
  • Naively balance photon and jet in g + jet events
  • Would like to validate:



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(Aside: As if technically that isn’t bad enough….)
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Jet Algorithms
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Jet Algorithms
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