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Heavy Flavor Production at the Tevatron

Heavy Flavor Production at the Tevatron

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Heavy Flavor Production at the Tevatron

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  1. 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

  2. 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/yJ/y search and production upper limit See many other CDF and D0 talks for more interesting b and c results from the Tevatron! J. Pursley, Beauty 06

  3. Triggers and Data Samples D0 • 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! J. Pursley, Beauty 06

  4. Sb Motivation • Lb only established B baryon • Enough statistics at Tevatron to probe other heavy baryons • Next accessible baryons: = 3/2+(Sb*) Sb: b{qq}, 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 J. Pursley, Beauty 06

  5. Reconstructing Sb • With 1.1 fb-1, world’s 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 J. Pursley, Beauty 06

  6. Sb Search Methodology • Sb backgrounds: • Lb Hadronization + Underlying Event – Dominant! • B meson Hadronization • Combinatorial Bkg • Fix background contributions from data or PYTHIA Monte Carlo • 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 < Q< 100 MeV/c2 J. Pursley, Beauty 06

  7. Sb Observation • Observe signals consistent with lowest lying charged Sb states • With unbinned likelihood fit, measure events • And mass difference values: J. Pursley, Beauty 06

  8. 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 b Fragmentation Fractions J. Pursley, Beauty 06

  9. 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 J. Pursley, Beauty 06

  10. 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… J. Pursley, Beauty 06

  11. 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 J. Pursley, Beauty 06

  12. (1S) Production • With 160 pb-1, reconstruct (1S) → m+m- • Unresolved (2S) and (3S) signals • Previous studies at CDF limited to at √s = 1.8 TeV • Divide into three rapidity regions: J. Pursley, Beauty 06

  13. (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 J. Pursley, Beauty 06

  14. 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 J. Pursley, Beauty 06

  15. hb → J/y J/yResults • Expected 3.6 bkg events; observe 3 events • Set upper limit for production cross section: J. Pursley, Beauty 06

  16. 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… J. Pursley, Beauty 06

  17. Backup Slides J. Pursley, Beauty 06

  18. Sb Systematics J. Pursley, Beauty 06

  19. Sb Fit Likelihood Ratios J. Pursley, Beauty 06

  20. Sb Two Peak Fit J. Pursley, Beauty 06