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Latest results on b-spectroscopy from CDF

Latest results on b-spectroscopy from CDF. Elena Vataga (Univ. of New Mexico, USA) On behalf of the CDF Collaboration CERN - October 31, 2006. Why B spectroscopy?. We are not looking for New Physics (but may find subtle discrepancy…)

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Latest results on b-spectroscopy from CDF

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  1. Latest results on b-spectroscopy from CDF Elena Vataga (Univ. of New Mexico, USA) On behalf of the CDF Collaboration CERN - October 31, 2006

  2. Why B spectroscopy? • We are not looking for New Physics (but may find subtle discrepancy…) • Standard Model is extraordinary. Deserves thorough elucidation. • B-quark discovered in 1977. Wealth of b-mesons is found. Only one b-baryon well established so far. • Effective theories derived from QCD needed for dynamical understanding: HQET • mc,mb,mt> LQCD >> mu, md, ms  Heavy Quark Symmetry • HQET extensively tested for Qq systems; interesting to check predictions for Qqq systems E.Vataga - Latest results on b-spectroscopy from CDF

  3. What’s new? • Observation of orbitally excited Bs** mesons • Observation and mass measurement of Bc J/ψ • Search for b  J/ψ J/ψ • Observation of new beauty baryons b(*) E.Vataga - Latest results on b-spectroscopy from CDF

  4. Tools

  5. Tevatron today results: first fb-1 • Excellent performance of Tevatron in last years • Record Instantaneous luminosity > 2x1032 cm-2 s-1 • Now: delivered ∫Ldt=1.8 fb-1 • Good for b-physicson tape ∫Ldt=1.3 fb-1 E.Vataga - Latest results on b-spectroscopy from CDF

  6. The CDF II detector 96 layer drift chamber 44< r <132 cm, |z|<155 cm |η| ≤ 1.0, 30k channels  coverage || ≤ 1 84% in  silicon layers: 90 cm long, |η| ≤ 2.0 r00 = 1.31.6 cm Trigger: 3 levels 25000 / 300 / 100 Hz L1: COT tracks L2: silicon tracks dead time < 5% Resolution: pT~0.15% pT vertex r- ~ 30 μm ; r-z ~ 80 μm J/ψ mass ~14 MeV/c2 E.Vataga - Latest results on b-spectroscopy from CDF

  7. b b g g b g q b b b b b q g g g q q Flavor Excitation Flavor Creation (gluon fusion) Flavor Creation (annihilation) Gluon Splitting B physics @ Tevatron Compared to e+e- experiments on U(4S) or Z0 • Pro: • pp → bb x-section is >1000 times larger (~10 mb ) • All species of b-hadrons: not just B/B0, also Bs0, Bc, Lb0 • Contro: • QCD background ×103larger than (bb) • multiple interactions, large combinatorics. • Collision rate ~1.7 MHz  tape writing limit ~100 Hz b b g g g q b b b b g g q b g b q q Flavor creation (annihilation) Flavor creation (gluon fusion) Flavor excitation Gluon splitting E.Vataga - Latest results on b-spectroscopy from CDF

  8. B physics @ CDF: triggers are crucial BR~10-5 visible with just trigger confirmation ! Trigger configurations: • Di-muon • Lepton plus displaced track • 2 displaced tracks Bhh ~ 42 TB in BCHARM trigger! Secondary Vertex Trigger (SVT) is unique to CDF! First of its kind to trigger on fully hadronic b/c decays E.Vataga - Latest results on b-spectroscopy from CDF

  9. Bs and Lb mass measurements 220 pb -1 PRL 96, 202001 2006 better precision than the current world overage! E.Vataga - Latest results on b-spectroscopy from CDF

  10. 1fb -1 Lb Lifetime • Measured with fully reconstructed Lbg J/yL0 decay • 542 Lb candidates • World best t(Lb) measurement ! E.Vataga - Latest results on b-spectroscopy from CDF

  11. Lb Lifetime vs theory As precise as previous world average 3.1  different though! World Average (without this result) NLO (C.Tarantino et al., hep-ph/0203089) CDF New Result E.Vataga - Latest results on b-spectroscopy from CDF

  12. Observation of orbitally excited (L=1) Bs** mesons E.Vataga - Latest results on b-spectroscopy from CDF

  13. Orbitally Excited BsJ Mesons • B*+B+, where  is undetected • Shift of possible Bs2*, Bs1 peaks by M(B*+ - B+) = 45.78 MeV/c2 (see PDG) • Two channels: B+J/ψK, B+D E.Vataga - Latest results on b-spectroscopy from CDF

  14. B+ sample: ~58 000! Use Neural Network to optimize both B+ and Bs** E.Vataga - Latest results on b-spectroscopy from CDF

  15. Orbitally Excited Bs-mesons Bs2* Bs1 Two signals: • B*s2 already seen by OPAL, DELPHI and DØ • Bs1  first observation! E.Vataga - Latest results on b-spectroscopy from CDF

  16. Discovery of Bs1 • N (B*s2) = 94.8  23.4(stat) • N (Bs1) = 36.4  9.0(stat) P-value from Toy MC ~ 210-7 Greater than 5 s ! E.Vataga - Latest results on b-spectroscopy from CDF

  17. Observation of Bc J/yp and mass measurement of Bc E.Vataga - Latest results on b-spectroscopy from CDF

  18. _ b c Bc± J/ψ ± u d p • Bc is not produced at B factories • Observed in semileptonic mode • Full reconstruction allows for precise mass measurement • New analysis • Tune selection on B+ J/y K+ • After approval, “open box”. • Wait for significant excess • Measure properties of the Bc b c c c Bc J/y Bc: change K to a p E.Vataga - Latest results on b-spectroscopy from CDF

  19. _ b c Bc± J/ψ ± Challenges theoretical predictions theories N(Bc) = 45.29.4, S/B = 7.5 • m(Bc) = 6276.5  4.0 (stat) 2.7(syst) MeV/c2 E.Vataga - Latest results on b-spectroscopy from CDF

  20. Search for b  J/ψ J/ψ E.Vataga - Latest results on b-spectroscopy from CDF

  21. _ b b Introduction _ • Spin-singlet bb bound state • s(pp hbX ) ~ mb level at Tevatron energy scale • Large uncertainty on decay branching fraction: • BR(hbJ/J/mmmm) ~10-7  -5 The Bottomonium system _ E.Vataga - Latest results on b-spectroscopy from CDF

  22. Search for bJ/J/ • Exclusive search from CDF RunI and LEP • Inclusive search from CLEO ( (nS)-> hbg ; hb-> hbg) • No significant evidence yet. Run I history (80 pb-1): • 7 events observed/ 1.8 backgr. (2.2 s) • Upper limit 18 pb E.Vataga - Latest results on b-spectroscopy from CDF

  23. Results • Expected 3.6 bkg events; observe 3 events • Set upper limit for production cross section E.Vataga - Latest results on b-spectroscopy from CDF

  24. Observation of new beauty baryons b(*) http://www.fnal.gov/pub/presspass/press_releases/sigma-b-baryon.html E.Vataga - Latest results on b-spectroscopy from CDF

  25. Bottom Baryon States with B=1,C=0,JP = 1/2+, 3/2+ Mass predictions from hep-ph/9406359 E.Vataga - Latest results on b-spectroscopy from CDF

  26. Predictions on b-(*)/b+(*) properties • NRQCD, HQET • Potential models • 1/Nc expansions • Lattice QCD calculations Strong decay with  emission: b b  E.Vataga - Latest results on b-spectroscopy from CDF

  27. Methodology Decay chain: b -()→b0 - b0→ c+- c+→ p K -+ Trigger tracks  soft track from Primary Vertex 1-trk vertex E.Vataga - Latest results on b-spectroscopy from CDF

  28. Strategy Optimize Lb yield Blind Sb signal region Check for possible reflections from other B decays Optimize Sb selection (MC) Evaluate different background contributions Estimate detector resolution for Sb (MC) Understanding of background is crucial! OPEN THE BOX Measure b yields and Masses Set the limit E.Vataga - Latest results on b-spectroscopy from CDF

  29. Discriminating variable • Search for narrow resonances in • Q = m(b)- m(b)- m() • Blinded region 0.03<Q<0.10 GeV/c2 • Work with 2 distributions ( expect m(b- )> m(b+) ) • Same Charge (SC): b-() →b0 - → c+- - ( + c.c ) • Opposite charge (OC): b+() →b0 + → c+- + ( + c.c ) Remove b resolution 5.787<m(b)<5.857 GeV/c2 b-(bdd) and anti-b- b+(buu) and anti-b+ Two  have same/opposite charge E.Vataga - Latest results on b-spectroscopy from CDF

  30. Expected background E.Vataga - Latest results on b-spectroscopy from CDF

  31. Largest in the World! b sample Reflections Combinatorial background Signal region:[5.565, 5.670] E.Vataga - Latest results on b-spectroscopy from CDF

  32. Cut are optimized with signal region blinded. Signal is taken from PYTHIA Background is taken from the sidebands. Optimization is done maximizing FOM (S)/B No cut on pT () b optimization cross-check on D*D0, included in systematic E.Vataga - Latest results on b-spectroscopy from CDF

  33. Background Composition replaced E.Vataga - Latest results on b-spectroscopy from CDF

  34. Corrections to MC samples • PYTHIA bb • Do not expect perfect description for b-baryons – experimental data are limited • Needs reweighting • PT(b) • PT(soft ) • Included in systematic E.Vataga - Latest results on b-spectroscopy from CDF

  35. Fitting background Combinatorial B mesons b HA+UE alternative fit shapes in systematics E.Vataga - Latest results on b-spectroscopy from CDF

  36. E.Vataga - Latest results on b-spectroscopy from CDF

  37. Detector resolution and signal width • Estimated detector resolution from MC generating signal with 0 natural width ~ 2 MeV/c2 • Cross-check on D* D0 (MC) • (b) is predicted by HQET: • Dominated by natural width Width grows with Q hep-ph/9406359 E.Vataga - Latest results on b-spectroscopy from CDF

  38. Sum of Background Fits • Smooth background shape in signal window • Fixed fit parameters before opening the box E.Vataga - Latest results on b-spectroscopy from CDF

  39. Unblinded Q distribution Significant excess in both distributions! • Naïve S/(S+B) ~ 9 s E.Vataga - Latest results on b-spectroscopy from CDF

  40. Simultaneous unbinned NLL fit for both b-(*)/b+(*) distributions Background frozen 4 peaks: Breit-Wigner  Gaussians (b) = function (Q) 7 Floating parameters: Num of events in 4 peaks: N (b) Q(b-) and Q (b+) Common parameter Q(b*)-Q(b) Fitting the signal E.Vataga - Latest results on b-spectroscopy from CDF

  41. Fit: values and errors E.Vataga - Latest results on b-spectroscopy from CDF

  42. Signal significance • Naïve: 9s • P-value calculation: > 5s (not enough Toy MC) • Evaluate Likelihood Ratio for different hypothesis: 4 peaks are 2.6 1019 more likely then no peak at all • Background fluctuation is statistically excluded • Hypothesis with 4 peaks in the most favorable E.Vataga - Latest results on b-spectroscopy from CDF

  43. Summary • We observe four b resonant states 240 events in total • The significance of the signal > 5 • The signal is consistent with the lowest lying b() states • We measure Q values: E.Vataga - Latest results on b-spectroscopy from CDF

  44. Plans • Increase statistics by • b0→ c+-from different triggers (~1000) • b0→ J/ψL0 (~ 500) • b0→ c+ 3 • Measure m = M(b*) – M(b) for “+” and “–” separately • Measure widths E.Vataga - Latest results on b-spectroscopy from CDF

  45. Conclusions • CDF makes fundamental contributions in b-spectroscopy • Performing the world most precise measurements of b Bc Bs B+ B0masses • Discovering new particles: • b() →b • Bs1 →B*K • Bc J/ψ  • Setting new limits: • b  J/ψ J/ψ • And all these with only THE FIRST fb-1 ! E.Vataga - Latest results on b-spectroscopy from CDF

  46. E.Vataga - Latest results on b-spectroscopy from CDF

  47. BACKUP E.Vataga - Latest results on b-spectroscopy from CDF

  48. b() masses • Using m(b) = 5619.7±1.2(stat) ±1.2(syst) E.Vataga - Latest results on b-spectroscopy from CDF

  49. Systematic Errors

  50. Sb Motivation • Lb only established B baryon • Enough statistics at Tevatron to probe other heavy baryons • Next accessible baryons: Sb: b{qq}, q = u,d; = 3/2+(Sb*) 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 E.Vataga - Latest results on b-spectroscopy from CDF

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