1 / 23

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:.

marly
Download Presentation

Victor Pavlunin on behalf of the CLEO Collaboration DPF-2006

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  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

More Related