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Victor Pavlunin on behalf of the CLEO Collaboration DPF-2006

 +.  -. K +. K -. Y(5S) Results from CLEO. Results from four CLEO Y (5S) analyses: Exclusive B s and B Reconstruction at the Y (5S) Inclusive D s and  Production at the Y (5S). Victor Pavlunin on behalf of the CLEO Collaboration DPF-2006. References:.

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Victor Pavlunin on behalf of the CLEO Collaboration DPF-2006

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  1. + - K+ K- Y(5S) Results from CLEO Results from four CLEO Y(5S) analyses: • Exclusive Bs and B Reconstruction at the Y(5S) • Inclusive Ds and  Production at the Y(5S) Victor Pavlunin on behalf of the CLEO Collaboration DPF-2006

  2. References: Exclusive measurements: • “Observation of Bs Production at the Y(5S) Resonance”, (CLEO collaboration) PRL 96, 022002 (2006) • “Measurements of the Exclusive Decays of the Y(5S) to B Meson Final States and Improved Bs* Mass Measurement”,(CLEO Collaboration) PRL 96, 152001 (2006) Inclusive Measurements: • “Evidence for Bs(*)Bs(*) Production at the Y(5S)”, (CLEO collaboration) PRL 95, 261801 (2005).[Includes a measurement of Ds production at the Y(5S)] • “Measurement of B (Y(5S)  Bs(*)Bs(*)) Using  Mesons”, (CLEO Collaboration) hep-ex/0610035. Submitted to PRD. [Includes a measurement of  production at the Y(5S)]

  3. Y(5S) Data Samples • CLEO I (1985): 0.12 fb-1 • CLEO III (2003): 0.42 fb-1 • BELLE (2005): 1.9 fb-1 • BELLE (2006): ~20 fb-1 • BABAR has not run at the Y(5S) The topic of this talk [Note: ECM are different by several MeV for different data sets]

  4. CESR and CLEO • The CLEO experiment is located at the Cornell Electron Storage Ring (CESR) operated in the region of the Upsilon resonances for over 20 years. • In 2003, we started collecting data at the(3770). Before that, we took a short run at the Y(5S). • The CLEO detector was developed for B physics at the Y(4S). The CLEO-III configuration: • B-field: 1.5 T • Gas (drift chamber): He and C3H8 • Tracking: 93% of 4, P/P0.6% for a 1.0 GeV track • Hadron particle ID: RICH (80% of 4) and dE/dx • E/M crystal calorimeter: 93% of 4π, E/E  2.0% (4.0)% for a 1.0 GeV (100 MeV) photon • Muon prop. chambers at 3, 5 and 7 I .

  5. Introduction: Bs at the Y(5S) (1) CLEO PRL 54, 381 (1985) Y(5S) • The Y(5S) resonance was discovered by CLEO and CUSB at CESR in 1985. • The Y(5S) is massive enough to decay into the following channels: • No evidence for Bs production at the Y(5S) was found in 116 pb-1 collected in1985. • Knowledge of Bs production at the Y(5S) is important for evaluating the potential of Bsphysics at a high luminosity e+e collider (Super-B factory). Results fromCLEO III studies of Bs production are the focus of this talk.

  6. Introduction: Bs at the Y(5S) (2) Curve: UQM Data: CLEO Y(5S) ECM (GeV) • There are two papers that measure the hadronic cross section above the Y(4S) resonance: • CLEO: PRL 54, 381 (1985) • CUSB: PRL 54, 377 (1985) • The cross section above the Y(4S) is described well by the Unitarized Quark Model (S.Ono et al., Phys.Rev.D 34, 186 (1986)). • The UQ model predicts: • Y(5S)  B*B* or Bs*Bs*, • The Bs cross section is  1/3 of the Y(5S) cross section. • (e+ e-  Y(5S))  0.35 nb • Expect 150Kof Y(5S) decays in the CLEOIII 0.42 fb-1 data sample, 1/3 of that are Bs(*)Bs(*) pairs.

  7. Count hadronic events at the Y(5S) Subtract the continuum using data taken below the Y(4S) Scale by ratios of luminosities and Ecm2 Luminosity ratio is a significant source of systematic errorsince s(Y5S) ~ 0.1s(continuum) and the continuum data are taken 300 MeV below the Y(5S) Results: s[Y(5S)]=(0.301±0.002±0.039) nb Consistent with theoretical predictions Y(5S) Cross Section Measurements Ref: hep-ex/0610035

  8. Exclusive B(s) Reconstruction at the Y(5S)

  9. Overview of the Method (1) • An extension of B reconstruction technique used at the Y(4S) is employed to reconstruct Bs mesons at the Y(5S): • Continuum background suppression variables (e.g., R2 = H2/H0) • Three decay channels of the Y(5S) to Bs mesons are possible: • Decay channel 1: • Decay channel 2: • Decay channel 3: MC

  10. Overview of the Method (2) MC A signal band for Bs mesons A signal band for B mesons • The Y(5S) can decay into a variety of states with ordinary B mesons: • Large background from the continuum (e+e-  qq) : [The ON Y(4S) data are used to model B bkg in the Bs analysis] [The OFF Y(4S) and bdata are used to model the continuum bkg]

  11. Bs modes with a J/ • Search for very clean modes having very large S/B ratio: BsJ/ , J/  and J/ ’. • The J/ is reconstructed in the  and ee channels. The following channels are used for other particles:   KK,   ,   ()+-. • Expect to find few signal events, assuming branching fractions similar to those for B mesons. In the Y(5S) data, we find: 4 events in the signal box for Y(5S)  Bs* Bs*: 3 events in Bs J/ 1 event in Bs J/ The level of non-Bs background is  0.08 events at 68% CL in the Bs*Bs* signal region. The probability for 0.08 events to fluctuate to 4 events or more is PI  1.6  10-6 M(Bs*) = 5.4150  0.0018(stat) (GeV) DATA DATA

  12. A Signal Event +  - K+ K-

  13. Bs modes with a Ds(*)- B0 branching fractions: • Bs Ds(*) / with Ds modes given in the tables • MC predicts that a total of 10-14 events can be reconstructed in these channels • In the Y(5S) data we find 10 signal candidates (including background): The level of background is  1.8 events at 68% CL in the Bs*Bs* signal region. The probability for 1.8 events to fluctuate to 10 events or more is PII  1.9  10-5 M(Bs*)= 5.41290.0012(stat) (GeV) DATA DATA

  14. Results for Bs(*) Production • PI and PII are combined to obtain an overall probability for a background fluctuation [P = (PIPII)(1-ln(PIPII))]: P  8  10-10(6). • All signal events correspond to Bs*Bs* production. We set the following limits (90% CL): and • Relating Bs branching fractions to B branching fractions, we find: which is consistent with the theory (UQM): 1/3 of 0.30 - 0.35 nb of the total Y(5S) cross-section. • The mass of the Bs* meson is measured to be [for more information see: PRL 96, 022002 (2006)]

  15. B modes with J/ and D(*) • Modes B D(*)p / r and B  J/yK(*) (in total 25 modes): Data MC Mbc (GeV) E (GeV) Note the non-standard definition of E in these plots (should have the opposite sign)

  16. Results for B(*) Production (53  9) events B*B* BBpp BB* BB(*)p BB • B*B* is again dominant (consistent with models): • (B*B*)/(BBX) = (74±15±8)% • (BB*)/(BBX) = (24±9±3)% • (BB)/(BBX) < 22% at 90% CL In combination with gives consistent with theory and exper. [for more information see: PRL 96, 152001 (2006)]

  17. Inclusive Ds and Measurements at the Y(5S)

  18. Overview of the Inclusive Method measure measure • The method relies on the fact that Ds (and)mesons are produced more copiously in Bs decays compared to B decays. Main Analysis Steps: • Measure Ds yields (Ds  +, K+K-) in bins of x = |PDs|/Ebeam in the continuum, Y(4S) and Y(5S) data. • Measure B(Y(4S)  DsX) and B(Y(5S)  DsX) by subtracting properly scaled and normalized continuum yields from the Y(4S) and Y(5S) yields • Extractfs according to the equation above and account for systematic errors. Model dependent estimate: B(Bs DsX) = (92  11) % [B(Bs X) = (15  3) %]

  19. Results of the Inclusive Ds Method Y(5S) Y(4S) continuum Y(4S) Y(5S) • CLEO inclusive DS yields for x < 0.5 and R2<0.25 • The largest sources of the systematic uncertainty are • the uncertainty associated with the luminosity measurements • the uncertainty in B(Ds). [for more information see: PRL 95, 261801 (2005)]

  20. Results of the inclusive fmethod CLEO inclusive f yields for x < 0.5 and R2<0.25 Y(4S) continuum Y(5S) Y(4S) Branching Fraction Y(5S) X = |P|/Ebeam [for more information see: hep-ex/0610035

  21. Summary and Conclusions Using 0.42 fb-1 of data at the Y(5S) resonance, we obtain the following results: • First observation of BS production at the Y(5S): • ; • and limits: and • First study of B production at the Y(5S): • ; • Determination of • Estimates of Bs production using inclusive measurements of Ds and  production at the Y(5S) (model dependent): • Ds production: •  production: • Belle (using the 1.9 fb-1 sample) confirms CLEO results The Y(5S) resonance is a significant source of Bs mesons for a high luminosity e+e- collider

  22. Additional Slides

  23. Model estimate of B(BS→fX) • Use CLEO-c inclusive yields (hep-ex/0610008) for B(Do→fX) = (1.0±0.10±0.10)% B(D+→fX) = (1.0±0.10±0.20)% B(DS→fX) = (15.1±2.1±1.5)% • Demonstrate that majority of  mesons arise from B  D and B  DS   . • PredictB(BS→fX) = (14.9±2.9)% • Consult hep-ex/0610035 for details

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