Heavy Flavor Production at the Tevatron

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Heavy Flavor Production at the Tevatron

• Jennifer Pursley
• The Johns Hopkins University
• on behalf of the CDF and D0 Collaborations

Beauty 2006 - University of Oxford, UK September
25-29, 2006
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Focus of this talk

• BRAND NEW RESULT! Sb() search
• B hadron relative fragmentation fractions
• B cross section using B ? J/y K
• (1S) production cross section
• hb? J/y J/y search and production upper limit

See many other CDF and D0 talks for more
interesting b and c results from the Tevatron!
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Triggers and Data Samples

• Analyses use between 160 pb-1 and 1.1 fb-1 of
  data
• Trigger paths used by these analyses
• Di-Muon (J/y) CDF D0
• Displaced track lepton (e, m) CDF
• 2 track trigger CDF
• Skipping all detector and Tevatron review!

D0
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Sb Motivation

• Lb only established B baryon
• Enough statistics at Tevatron to probe other
  heavy baryons
• Next accessible baryons

3/2(Sb)
Sb bqq, q u,d JP SQ sqq
1/2 (Sb)

• HQET extensively tested for Qq systems
  interesting to check predictions for Qqq systems
• Baryon spectroscopy also tests Lattice QCD and
  potential quark models

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Reconstructing Sb

• With 1.1 fb-1, worlds largest sample of Lb
  3000
• Use 2 track trigger to reconstruct

Lb Mass Plot

• Sb decays at primary vertex
• Combine Lb with a prompt track to make a Sb
  candidate

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Sb Search Methodology

• Separate Sb- and Sb
• ( c.c.)
• ( c.c.)
• Search for resonances in mass difference
  Q m(Lbp) - m(Lb) mp
• Use reconstructed Lb mass ? remove Lb mass
  systematic error
• Unbiased optimization
• Optimize Sb cuts with Sb signal region blinded
  30 lt Q lt 100 MeV/c2

• Sb backgrounds
• Lb Hadronization Underlying Event Dominant!
• B meson Hadronization
• Combinatorial Bkg
• Fix background contributions from data or PYTHIA
  Monte Carlo

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Sb Observation

• Observe signals consistent with lowest lying
  charged Sb states
• With unbinned likelihood fit, measure events
• And mass difference values

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b Fragmentation Fractions

• Measure flavor dependence of fragmentation
  process for b quarks (non-perturbative)
• Reconstruct semi-leptonic decays of B 0, B -,
  Bs0, and Lb0 in 360 pb-1 of data
• l D 0, l D , l D , l Ds, l Lc
• Use Particle ID likelihood cuts (important for
  Lc signal)
• Determine sample comp. from charm hadron BRs
• Indirect semi-lep decays and excited B hadrons
  explicitly included

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Fragmentation Fraction Results

• fu, fd, fs, fL probability to result in B -, B
  0, Bs0, Lb0
• Use B hadron transverse momentum (pT) threshold
  of 7 GeV/c
• Agrees with world average of fragmentation
  fraction of B - relative to B 0
• fLb differs from LEP by 2.2s

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B Production Cross Section

• Using 740 pb-1 of data, reconstruct B ? J/y K

• 8197 239 B mesons total
• Divide in 5 bins of pT and measure differential
  cross section as a function of pT, in units of
  nb/GeV/c
• Integrated cross section for pT 25 GeV/c
  21.7 3.7 nb

To be submitted to PRD very soon
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Total B Production Cross Section

• Combined stat syst errors
• Agrees with previous Tevatron measurements
• 1.8 TeV cross section increased by 10
• Also within the range of FONLL theoretical
  predictions with
• fu 0.389
• CTEQ6M fits to parton distribution functions

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(1S) Production

• With 160 pb-1, reconstruct (1S) ? mm-
• Unresolved (2S) and (3S) signals
• Previous studies at CDF limited to
  at vs 1.8 TeV
• Divide into three rapidity regions

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(1S) Diff. Cross Section
Phys. Rev. Lett. 94, 232001 (2005)

• Little variation between rapidity regions
• Also consistent with previous CDF measurement
• Allows a more precise determination of parameters
  of bottomonium production models

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Search for hb ? J/y J/y

• Spin-singlet bb bound state hb yet to be observed
• s(pp ? hb X) mb at Tevatron energy scale
• Look for hb decay into J/y J/y in 1.1 fb-1
• Large uncertainty in expected BR
• Expect between 0.2 and 20 events with both J/y
  decaying to m m-
• Reconstruct as 3m track

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hb ? J/y J/y Results

• Expected 3.6 bkg events observe 3 events
• Set upper limit for production cross section

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Summary

• First observation of lowest lying charged Sb
  states!
• With m(Lb) 5619.7 1.2 (stat) 1.2 (syst)
  MeV/c2,
• Precision measurements of b production properties
• b fragmentation fractions
• (1S) and B production cross sections
• Upper limit on hb ? J/y J/y production
• More results on the way

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Backup Slides
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Sb Systematics
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Sb Fit Likelihood Ratios
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Sb Two Peak Fit