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Kevin Zhang Department of Physics Syracuse University CLEO Collaboration Email: hzhang@phy.syr

First Measurements of the Exclusive Decays of Y (5S) to B (*) B (*) ( p )( p ) Final States and Improved B s * Mass Measurement. Kevin Zhang Department of Physics Syracuse University CLEO Collaboration Email: hzhang@phy.syr.edu. Outline.

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Kevin Zhang Department of Physics Syracuse University CLEO Collaboration Email: hzhang@phy.syr

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  1. First Measurements of the Exclusive Decays of Y(5S) to B(*)B(*)(p)(p) Final States and Improved Bs* Mass Measurement Kevin Zhang Department of Physics Syracuse University CLEO Collaboration Email: hzhang@phy.syr.edu BNL Seminar Kevin Zhang

  2. Outline • Part I: B(*)B(*)(p)(p) final states at the Y(5S). • Introduction and Motivation. • Bs CLEO measurements at the Y(5S). • Final states with J/Y. • Final states with D(*). • Summary. • Part II: BTeV RICH and TestBeam Results. BNL Seminar Kevin Zhang

  3. Y(5S) Introduction • The Y(5S) discovered by CLEO & CUSB in 1985. massive enough to decay into : • Knowledge of Bs production at Y(5S) essential for assessing the potential of Bsphysics at a high luminosity e+e collider (Super-B factory): hep-ex/0406071, hep-ph/0503261 • One mystery: M(5S) – M(4S) > M(4S) – M(3S). BNL Seminar Kevin Zhang

  4. Model Predictions R DR DR Energy (GeV) • The hadronic cross section in the Upsilon region is well described by the Unitarized Quark Model (UQM), which is a coupled channel model (ref: S. Ono et al, PRL55, 2938(1985)). • The UQM predicts that the Bs(*)Bs(*) production ~ 1/3 of the total Y(5S) cross section, the remaining 2/3 from ordinary B. And Y(5S) decays are dominated by B*B* and Bs*Bs*. • Other models predict a smaller Y(5S)Bs*Bs* component. BNL Seminar Kevin Zhang

  5. Motivation • Further test of UQM at the Y(5S). • Expect ~100K of Bs in CLEO Y(5S) data sample. • And about twice that in ordinary B’s (if UQM is correct). • This talk focuses on B(*)B(*)(p)(p) states. Aim to measure or set upper limits on all possible B(*)B(*)(p)(p) final states. • Along with Mbc(Bs*), can provide precise M(Bs*). (largest systematic, beam energy shift, cancels) BNL Seminar Kevin Zhang

  6. CLEO III Detector and Data Sample • Data taken using CLEO III detector at Cornell • Lint = 0.42 fb-1 • Ebeam~ M(5S)/2 = 5.434 GeV Kevin Zhang, Syracuse University

  7. Inclusive Bs Analysis (CLEO) • Evidence of Bs in Y(5S) from inclusive yields of Ds • Phys. Rev. Lett 95, 261801(2005) • This analysis exploits the • difference in Ds inclusive yields • in B and Bs decays • B(Y(5S)  DsX) = (55.05.217.8)% • B(Y(4S)  Ds X) = (22.30.75.7)% • B (Y(5S)Bs(*)Bs(*)) = (16.02.65.8)% • ~ 6 σ away from 0 statistically • Excess Ds production @Y(5S), • compared to Y(4S). is evidence • for Bs @ Y(5S). BNL Seminar Kevin Zhang

  8. Exclusive Bs Reconstruction Ebeam – Ecandidate (GeV) Mbc (Bs candidate) (GeV) Mbc (Bs candidate) (GeV) • The B reconstruction techniques used at Y(4S) are employed to reconstruct Bs from Y(5S): • Three sources of Bs produce three distinct distributions. B (Bs*Bsg) ~100% MC BNL Seminar Kevin Zhang

  9. Exclusive Bs Analyses (CLEO) Phys. Rev. Lett. 96, 022002 (2006) 10 cand. 4 cand. BNL Seminar Kevin Zhang

  10. Ordinary B mesons @ Y(5S) The center of the signal band for Bs mesons The center of the signal band for ordinary B mesons • The Y(5S) resonance can decay into 7 possible states with ordinary B mesons: MC • No chance of a mix-up. • Ordinary B decay modes • occupy a different • region on the ΔE-Mbc plane • & have distinct decay • Modes. BNL Seminar Kevin Zhang

  11. Exclusive B Meson Channels (25 in Total) D0  K+ p- D0 K+ p- p0 D0 K+ p+ p- p- D- K+ p- p- • BJ/y decays • B+J/y K+ • B0 J/y Ks • B0 J/y K+p- D decay channels • BD(*) decays • B+D0p+ • B+D0 r+ • B+D*0 p+ • B+D*0 r+ • B0D- p+ • B0D- r+ • B0D*- p+ • B0D*- r+ D*-D-p0 D*-D0p- D*0D0p0 BNL Seminar Kevin Zhang

  12. Selection Criteria (1) • Event selection: • Using hadron skim • Ntr 5 • R2<0.25 (5S), 0.4 (4S) (suppress continuum) Track selection: • 0.1<p<5.3 GeV • cos<0.95 • Hit fraction  0.5 • 2/dof<10 • D0 < 0.005m • Z0 < 0.05m PionID: | sp2 | <4 or RICH Lp-LK>-5 Muons for J/ : • One muon depth3 • The other one E<0.3 GeV Electrons for J/ : E9/E25>0.75 0.5  E/P 1.2 KaonID: • using both RICH and dE/dx info • |sK2|  3 • Combined 2 <0 BNL Seminar Kevin Zhang

  13. Selection Criteria (2) For J/ modes: • PJ/<2.6 GeV (5S), 2.0 GeV (4S) • 3.05  Mmm 3.14 GeV • 1.5  Mee 3.14 GeV • Radiated photons included for ee • J/y mass constraint, fit 2<100 • For D modes: • D0 and D± 2s mass cut • M(D*-D) require 3s cut • |Mr-775.8|<150 MeV • For r, |cosqhelicity|>0.3 and cosqhelicty >-0.7 • Require p0 P>0.4GeV in D0K-p+ p0 decay • |cosqthrust|<0.75 B+ J/K+ Y(4S) data BNL Seminar Kevin Zhang

  14. Y(5S) Signal MC Mbc vs E (B+ J/K+) BNL Seminar Kevin Zhang

  15. Testing B J/ X Reconstruction at Y(4S) Measured branching fractions agree with PDG BNL Seminar Kevin Zhang

  16. B D(*) X Expectation at Y(5S) BNL Seminar Kevin Zhang

  17. Analysis Validation B J/ X & B D(*) X in Y(4S) data ~5 fb-1 Y(4S) data 6 (4.65±0.4) ´ 10 BB Measured(black) PDG (red) 22 D modes (Measured - PDG ) 3 J/ modes BNL Seminar Kevin Zhang

  18. Mbc vs E Y(5S) Data J/ Modes B*B* BB* BB No significant backgrounds from other B decays, Bs decays or the continuum. BNL Seminar Kevin Zhang

  19. DE in Slices of MbcJ/ Modes (data) The red dash lines are MC predictions BB* BB B*B* BBpp BNL Seminar Kevin Zhang

  20. Mbc in Signal Region J/ Modes (data) BB* BB B*B* BBpp BNL Seminar Kevin Zhang

  21. B Invariant Mass J/ Modes (Data) Recall: we expected 8 ± 2 evts Cross section: s(e+e-B(*)B(*) (p)(p)) = (Y-B)/L*(ei*BFi) BNL Seminar Kevin Zhang

  22. Mbc vs E 5S data D modes Here we expect 53 ± 11 evts B*B* BB* BB BNL Seminar Kevin Zhang

  23. DE in Slices of Mbc D modes BB BB* B*B* BBpp Note different horizontal scales! BNL Seminar Kevin Zhang

  24. Mbc in Signal Region D modes B*B* BBpp BB* BB BNL Seminar Kevin Zhang

  25. B Invariant Mass D Modes (Y(5S) Data) Recall: we expected 53 ± 11 evts BNL Seminar Kevin Zhang

  26. Data J/ and D modes combined Signal region Sideband 1 Sideband 2 BNL Seminar Kevin Zhang

  27. Total DEin Slices of Mbc J/ and D modes combined BB* BB B*B* BBpp BNL Seminar Kevin Zhang

  28. B Invariant Mass J/ and D modes combined Averaged total cross section: s(e+e-B(*)B(*) (p)(p)) =0.177±0.030 nb BNL Seminar Kevin Zhang

  29. Determination of Contributing Subprocesses J/ and D modes combined Mbc sideband BNL Seminar Kevin Zhang

  30. Determination of Contributing Subprocesses J/y and D modes Fix widths Fix MB*-MB to PDG B*B* BB* BB B(*)B(*)p + BBpp Mbc in the signal region BNL Seminar Kevin Zhang

  31. Invariant Mass for B(*)B(*)p and BBpp B(*)B(*)p : Mbc[5.351, 5429] GeV BBpp : Mbc[5.351, 5429] GeV Cross-feed from B(*)B(*)p is (7~18)% Upper limits are set for BB,B(*)B(*)p and BBpp. BNL Seminar Kevin Zhang

  32. Systematics BNL Seminar Kevin Zhang

  33. Cross Section Results Evidence for B*B, B*B* is established BNL Seminar Kevin Zhang

  34. Bs* Mass Measurement • Combine Mbc(B*) with Mbc(Bs*), measureDM = M(Bs*) - M(B*) M(Bs*) = M(B*) + DM • Dominant systematic uncertainty from beam energy calibration, cancels • M(B*) = (5325±0.6) MeV (PDG) • This analysis: Mbc(B*) = (5333.1±1.3) MeV(note: beam energy shift of (6.4 ±1.3) MeV) • CLEO Bs analysis: Mbc(BS*)= (5413.6 ± 1.0 ± 3.0) MeV • From kinematic considerations: DM = DMbc + 1.6 MeV • We therefore obtain: M(BS*)= DM +M(B*)=(5411.7±1.6±0.6) MeV • Using the CDF measurement M(Bs)=(5366.01 ± 0.73 ± 0.33) MeV • M1 Mass splitting M(BS*) - M(BS) = (45.7 ± 1.7 ± 0.7) MeV M(B*) - M(B) = (45.78 ± 0.35) MeV B*B* BB* BB BNL Seminar Kevin Zhang

  35. Summary • First determination of the composition of ordinary BB final states at Y(5S). • B*B*:BB*:BB ~ 3:1:<1, consistent with UQM predictions. • Cross section measurements: • s(Y(5S)BBX) = (0.177 ± 0.030 ± 0.016) nb, • ~2/3 of the Y(5S) resonance cross-section (~rest producing Bs mesons) • s(Y(5S)B*B*) = (0.119 ± 0.023 ± 0.013) nb (dominant). • s (Y(5S)BB*) = (0.039 ± 0.015 ± 0.005) nb. • Upper limits for BB ,B(*)B(*)p and BBpp. • M(Bs*)=(5411.7 ± 1.6 ± 0.6) MeV is most precise measurement to date. • M1 Mass splitting: M(BS*) - M(BS) = (45.7 ± 1.7 ± 0.7) MeV BNL Seminar Kevin Zhang

  36. Part II: BTeV RICH and TestBeam Results BNL Seminar Kevin Zhang

  37. BTeV Rich Overview The purpose of the RICH (Ring Imaging Cherenkov detector) is to distinguish p, K, and protons from one another. Cherenkov photons are produced at "Cherenkov angle“,        cos(qCh) = 1/bn,  Liquid C5F12 (n=1.24) Gas C4F10(n=1.00138) BNL Seminar Kevin Zhang

  38. Schematic of the Testbeam Box Beam BNL Seminar Kevin Zhang

  39. In M-TEST Area Glass mirror MAPMTs Gas tank: C4F8O and Argon Beam (120 GeV p) BNL Seminar Kevin Zhang

  40. DAQ Overview 12 F-T boards mounted outside on the enclosure 12 pairs of MUX/FEH boards inside the enclosure 10 had been used in data taking. 24 50’ long cables 53 MAPMT Tubes mounted on baseboards in RICH enclosure 6 pairs of PMC/PTA cards in PCI expansion box Linux box running Pomone based DAQ 12 F-T boards BNL Seminar Kevin Zhang

  41. MAPMT Electrical Measurements HV=800 V MAPMT  Test Box shown with Optical Fiber Connected to XY Stage.The MAPMT is middle-center and is connected to a signal distribution PC board. X-Y scan BNL Seminar Kevin Zhang

  42. MAPMT Electrical Measurements (continue) Plateau Curves Column Scan results BNL Seminar Kevin Zhang

  43. Determination of HV Settings • MAPMT tubes are divided into 3 groups according to their gain and applied different HV. • Definition: two or more adjacent channels with hit form a cluster hit. • The cluster hit may not correspond to only one photon, but with this treatment one can measure plateau. • We decided to use 800/750/700 V as nominal HV. BNL Seminar Kevin Zhang

  44. Cluster Size In HV Scan Background Beam LED Pulser • There are LEDs inside enclosure to generate light pulses. This is useful to study cross talk effect. • We also took data with background (pure electronic noise and light leaks). • With 800/750/700 V setting, most of cluster hits in beam data are due to photons hitting adjacent channels. Only ~5% of total hits are due to cross-talk. BNL Seminar Kevin Zhang

  45. The Beautiful Rings Obtained • The cumulative distribution of many • Cherenkov rings on top of one • another. Each square represents a • single MAPMT cell. • The size of the box is proportional • to the number of photons detected • in that cell.  • The resolution and number of photons • per track are in good agreement with • the Monte Carlo simulation. • The results published.Nucl. Instrum. Meth. A 558,373(2006) • [physics/0505110]. BNL Seminar Kevin Zhang

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