11/2/2006BNL Seminar Kevin Zhang1 First Measurements of the Exclusive Decays of Y (5S) to B () B () (  )(  ) Final States and Improved B s * Mass Measurement.

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Presentation transcript:

11/2/2006BNL Seminar Kevin Zhang1 First Measurements of the Exclusive Decays of Y (5S) to B (*) B (*) (  )(  ) Final States and Improved B s * Mass Measurement Kevin Zhang Department of Physics Syracuse University CLEO Collaboration

11/2/2006BNL Seminar Kevin Zhang2 Outline  Part I: B (*) B (*) (  )(  ) final states at the Y (5S).  Introduction and Motivation.  B s CLEO measurements at the Y (5S).  Final states with J/ .  Final states with D (*).  Summary.  Part II: BTeV RICH and TestBeam Results.

11/2/2006BNL Seminar Kevin Zhang3 The Y (5S) discovered by CLEO & CUSB in massive enough to decay into : Knowledge of B s production at Y (5S) essential for assessing the potential of B s physics at a high luminosity e + e collider (Super-B factory): hep-ex/ , hep-ph/ One mystery: M(5S) – M(4S) > M(4S) – M(3S). Y (5S) Introduction

11/2/2006BNL Seminar Kevin Zhang4 Model Predictions 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 B s ( * ) B s ( * ) 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 B s *B s *. Other models predict a smaller Y (5S)  B s *B s * component. Energy (GeV) RR RR R

11/2/2006BNL Seminar Kevin Zhang5 Motivation Further test of UQM at the Y (5S). –Expect ~100K of B s in CLEO Y (5S) data sample. –And about twice that in ordinary B’s (if UQM is correct). This talk focuses on B (*) B (*) (  )(  ) states. Aim to measure or set upper limits on all possible B (*) B (*) (  )(  ) final states. Along with M bc (B s *), can provide precise M(B s * ). (largest systematic, beam energy shift, cancels)

April 25, 2006Kevin Zhang, Syracuse University 6 CLEO III Detector and Data Sample Data taken using CLEO III detector at Cornell L int = 0.42 fb -1 E beam ~ M  (5S) /2 = GeV

11/2/2006BNL Seminar Kevin Zhang7 This analysis exploits the difference in D s inclusive yields in B and B s decays B ( Y (5S)  B s ( * ) B s ( * ) ) = (16.0  2.6  5.8)% ~ 6 σ away from 0 statistically Excess D s Y (5S), compared to Y (4S). is evidence for Y (5S). B( Y (5S)  D s X) = (55.0  5.2  17.8)% B( Y (4S)  D s X) = ( 22.3  0.7  5.7 )% Evidence of B s in Y (5S) from inclusive yields of D s Phys. Rev. Lett 95, (2005) Inclusive B s Analysis (CLEO)

11/2/2006BNL Seminar Kevin Zhang8 The B reconstruction techniques used at Y (4S) are employed to reconstruct B s from Y (5S): Three sources of B s produce three distinct distributions. Exclusive B s Reconstruction M bc (B s candidate) (GeV) E beam – E candidate (GeV) B (B s *  B s  ) ~100% MC

11/2/2006BNL Seminar Kevin Zhang9 Exclusive B s Analyses (CLEO) 4 cand. 10 cand. Phys. Rev. Lett. 96, (2006)

11/2/2006BNL Seminar Kevin Zhang10 Ordinary B Y (5S) The Y (5S) resonance can decay into 7 possible states with ordinary B mesons: The center of the signal band for ordinary B mesons The center of the signal band for B s 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.

11/2/2006BNL Seminar Kevin Zhang11 Exclusive B Meson Channels (25 in Total) B  J/  decays –     J/  K + –B 0  J/  K s –B 0  J/  K +  -  B  D (*) decays     D 0  +     D 0  +     D* 0  +     D* 0  +     D -  +     D -  +     D* -  +     D* -  + D 0  K +   D 0  K +     D 0  K +       D -  K +     D* -  D    D* -  D    D* 0  D    D decay channels

11/2/2006BNL Seminar Kevin Zhang12 Event selection: 1. Using hadron skim 2. N tr 5 3. R 2 <0.25 (5S), 0.4 (4S) (suppress continuum) Selection Criteria (1) Track selection: 1.0.1<p<5.3 GeV 2.cos< Hit fraction   2 /dof<10 5.D0 < 0.005m 6.Z0 < 0.05m KaonID: 1. using both RICH and dE/dx info 2. | K 2 |  3 3. Combined  2 <0 PionID: |   2 | <4 or RICH L  -L K >-5 Muons for J/  : 1. One muon depth3 2. The other one E<0.3 GeV Electrons for J/  : 1. E9/E25>  E/P 1.2

11/2/2006BNL Seminar Kevin Zhang13 For J/  modes: P J/  <2.6 GeV (5S), 2.0 GeV (4S) 3.05  M    3.14 GeV 1.5  M ee  3.14 GeV Radiated photons included for ee J/  mass constraint, fit  2<100 For D modes:  D 0 and D ± 2  mass cut  M (D*-D) require 3  cut  |M  |<150 MeV  For , |cos  helicity |>0.3 and cos  helicty >-0.7  Require  0 P>0.4GeV in D 0  K -     decay  |cos  thrust |<0.75 Selection Criteria (2) Y(4S) data B +  J/  K +

11/2/2006BNL Seminar Kevin Zhang14 Y (5S) Signal MC M bc vs  E (B +  J/  K + )

11/2/2006BNL Seminar Kevin Zhang15 Testing B  J/  X Reconstruction at Y (4S) Number of events expected on Y (5S) channelsDecay modesProduct BF (10 -3 )Rec Eff (%) events expected      J/  K + J/   ee and  1.00 ± ± B 0  J/  K s J/   ee and  0.29 ± ± B 0  J/  K *0 J/   ee and  0.87 ± ± (1.31±0.27)x10 5 resonance events (Phys. Rev. Lett 95, (2005)) Total: 8±2 B Branching Fractions on Y (4S) (~5 fb -1 ) ModeRec eff (%) N rec Product BF PDG (10 -3 ) SourceBF from 4S Data(10 -3 ) statistic error only B +  J/  K ± ± ± 0.04 BELL ±0.06 B 0  J/  K s 41.9±1.765±80.29 ± 0.02 BELL ±0.03 B 0  J/  K *0 28.9±0.6223± ± 0.05 BELL ±0.08 Measured branching fractions agree with PDG

11/2/2006BNL Seminar Kevin Zhang16 B  D (*) X Expectation at Y (5S) channelsDecay modesProduct BF (10 -3 )Rec Eff (%) Events expected D0 +D0 + D 0  K +   0.19 ± ± D 0  K +     0.65 ± ± D 0  K +       0.37 ± ±    D 0  + D 0  K +   0.51 ± ± D 0  K +     1.74 ± ± D 0  K +       1.0 ± ±    D* 0  + D 0  K +   0.11 ± ± D 0  K +     0.37 ± ± D 0  K +       0.21 ± ±    D* 0  + D 0  K +   0.23 ± ± D 0  K +     0.79 ± ± D 0  K +       0.46 ± ±     D -  + D -  K +     0.25 ± ±     D -  + D -  K +     0.71 ± ±     D* -  + D 0  K +   0.17 ± ± D 0  K +     0.60 ± ± D 0  K +       0.34 ± ± D -  K +     0.19 ± ±     D* -  + D 0  K +   ± ± D 0  K +     0.15 ± ± D 0  K +       0.09 ± ± D -  K +     0.08 ± ± Total: 53±11

11/2/2006BNL Seminar Kevin Zhang17 Analysis Validation B  J/  X & B  D (*) X in Y (4S) data 22 D modes 3 J/ modes Measured(black) PDG (red) (Measured - PDG ) 6 ~5 fb -1 Y(4S) data (4.65  0.4)  10 BB

11/2/2006BNL Seminar Kevin Zhang18 M bc vs  E Y (5S) Data J/  Modes B*B* BB* BB No significant backgrounds from other B decays, B s decays or the continuum.

11/2/2006BNL Seminar Kevin Zhang19  E in Slices of M bc J/  Modes (data) The red dash lines are MC predictions BB BB* B*B* BB 

11/2/2006BNL Seminar Kevin Zhang20 M bc in Signal Region J/  Modes (data) BB BB* B*B* BB 

11/2/2006BNL Seminar Kevin Zhang21 Cross section:  e + e -  B (*) B (*)  = (Y-B)/L*( i *BF i ) B Invariant Mass J/  Modes (Data) Recall: we expected 8 ± 2 evts

11/2/2006BNL Seminar Kevin Zhang22 M bc vs  E 5S data D modes Here we expect 53 ± 11 evts B*B* BB* BB

11/2/2006BNL Seminar Kevin Zhang23  E in Slices of M bc BBBB* B*B* BB  D modes Note different horizontal scales!

11/2/2006BNL Seminar Kevin Zhang24 M bc in Signal Region BB BB* B*B* BB  D modes

11/2/2006BNL Seminar Kevin Zhang25 Recall: we expected 53 ± 11 evts B Invariant Mass D Modes ( Y (5S) Data)

11/2/2006BNL Seminar Kevin Zhang26 Data J/  and D modes combined Signal region Sideband 1 Sideband 2

11/2/2006BNL Seminar Kevin Zhang27 Total  E in Slices of M bc BB BB* B*B* BB  J/  and D modes combined

11/2/2006BNL Seminar Kevin Zhang28 B Invariant Mass Averaged total cross section:  e + e -  B (*) B (*)  =0.177±0.030 nb J/  and D modes combined

11/2/2006BNL Seminar Kevin Zhang29 Determination of Contributing Subprocesses M bc sideband J/  and D modes combined

11/2/2006BNL Seminar Kevin Zhang30 Determination of Contributing Subprocesses BB BB* B*B* J/  and D modes Fix widths Fix M B* -M B to PDG B (*) B (*)  BB  M bc in the signal region

11/2/2006BNL Seminar Kevin Zhang31 Invariant Mass for B (*) B (*)  and  B (*) B (*)  M bc [5.351, 5429] GeV BB  M bc  [5.351, 5429] GeV Cross-feed from B (*) B (*)  is (7~18)% Upper limits are set for BB,B (*) B (*)  and BB.

11/2/2006BNL Seminar Kevin Zhang32 Systematics Source B (*) B (*)   BB  BB *  B *  B (*) B (*)   BB   Recon. Eff.6.3 Input BFs3.0 Background Fitting Technique Multiple Candidates 3.1 Luminosity2.0 total

11/2/2006BNL Seminar Kevin Zhang33 Cross Section Results Y(5S)  YieldSignificance (  ) Cross-Section (nb)  tot BB<7.5 at 90% CL-<0.038 at 90% CL<0.22 BB * 10.3± ±0.015± ±0.09±0.03 B*B*B*B* 31.4± ±0.023± ±0.13±0.08 B (*) B (*)  <13.9 at 90% CL-<0.064 at 90% CL<0.29 BB  <6.4 at 90% CL-<0.029 at 90% CL<0.15 Total53.2± ±0.030±0.016 Evidence for B*B, B*B* is established

11/2/2006BNL Seminar Kevin Zhang34 B s * Mass Measurement Combine M bc (B*) with M bc (Bs*), measure  M = M(B s *) - M(B*) M(B s * ) = M(B*) +  M –Dominant systematic uncertainty from beam energy calibration, cancels –M(B*) = (5325±0.6) MeV (PDG) This analysis: M bc (B*) = (5333.1±1.3) MeV (note: beam energy shift of (6.4 ±1.3) MeV) CLEO B s analysis: M bc (B S *) = ( ± 1.0 ± 3.0) MeV From kinematic considerations:  M =  M bc MeV We therefore obtain: M(B S *) =  M +M(B*) =(5411.7±1.6±0.6) MeV Using the CDF measurement M(B s )=( ± 0.73 ± 0.33) MeV M1 Mass splitting M(B S *) - M(B S ) = (45.7 ± 1.7 ± 0.7) MeV M(B*) - M(B) = (45.78 ± 0.35) MeV BB BB* B*B*

11/2/2006BNL Seminar Kevin Zhang35 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: –  ( Y (5S)  BBX) = (0.177 ± ± 0.016) nb,  of the Y(5S) resonance cross-section (~rest producing B s mesons) –  ( Y (5S)  B * B * ) = (0.119 ± ± 0.013) nb (dominant). –  ( Y (5S)  BB * ) = (0.039 ± ± 0.005) nb. –Upper limits for BB,B (*) B (*)  and BB . M(B s *)=( ± 1.6 ± 0.6) MeV is most precise measurement to date. M1 Mass splitting: M(B S *) - M(B S ) = (45.7 ± 1.7 ± 0.7) MeV Summary

11/2/2006BNL Seminar Kevin Zhang36 Part II: BTeV RICH and TestBeam Results

11/2/2006BNL Seminar Kevin Zhang37 BTeV Rich Overview The purpose of the RICH (Ring Imaging Cherenkov detector) is to distinguish , K, and protons from one another. Cherenkov photons are produced at "Cherenkov angle“, cos(  Ch ) = 1/  n, Liquid C 5 F 12 (n=1.24) Gas C 4 F 10 (n= )

11/2/2006BNL Seminar Kevin Zhang38 Schematic of the Testbeam Box Beam

11/2/2006BNL Seminar Kevin Zhang39 In M-TEST Area MAPMTs Beam (120 GeV p) Glass mirror Gas tank: C 4 F 8 O and Argon

11/2/2006BNL Seminar Kevin Zhang40 53 MAPMT Tubes mounted on baseboards in RICH enclosure 12 pairs of MUX/FEH boards inside the enclosure 10 had been used in data taking. 12 F-T boards mounted outside on the enclosure 24 50’ long cables 12 F-T boards 6 pairs of PMC/PTA cards in PCI expansion box Linux box running Pomone based DAQ DAQ Overview

11/2/2006BNL Seminar Kevin Zhang41 MAPMT Electrical Measurements 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 HV=800 V

11/2/2006BNL Seminar Kevin Zhang42 MAPMT Electrical Measurements (continue) Column Scan results Plateau Curves

11/2/2006BNL Seminar Kevin Zhang43 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.

11/2/2006BNL Seminar Kevin Zhang44 Cluster Size In HV Scan Beam Background 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.

11/2/2006BNL Seminar Kevin Zhang45 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/ ].