Preparation of  b Scan Jianchun Wang Syracuse University CLEO Meeting 04/13/02

Jianchun (JC) Wang2 People Involved Basit Athar, Raja Nandakumar, Jianchun Wang Sheldon Stone, John Yelton, Steve Blusk David Kreinick, Jean Duboscq Others

04/13/02Jianchun (JC) Wang3 Motivation of  b Study See February’s talk by JC/Sheldon   b lifetime, mass precision (current: 9 MeV), absolute branching ratio  Necessary for determining Vcb via  b  c l  Provide input to hadron collider b experiments for Vcb, production rate, etc  … This is possible if the  b  b cross-section is large enough

04/13/02Jianchun (JC) Wang4 Events at  b Threshold  We hope to have 50 pb for  b  b pair production. For the study, we use MC simulated events for this portion.  The contribution from udsc is similar to that of  (4S), with decreasing of cross-section due to CM energy. We use off-resonance data here.  Most of bb events produce B mesons. We use on-4S resonance data ( subtracted by off-resonance data ) for this part, with cross-section adjusted to 200pb.

04/13/02Jianchun (JC) Wang5 Signature of  b Events  It has BB-like event shape ( we require R2<0.2 to reject continuum background).  The  c production rate is very large ( ~ 100% per  b, compared to 6.4% per B). Hence counting number of reconstructed  c is a direct tool.  The proton and lepton production rate is also high, and reconstruction efficiency is big. So requiring both proton and lepton in same event is even better.  We also count number of proton,  and hadronic event in the scan.

04/13/02Jianchun (JC) Wang6  c Decay Modes  0.27    1.3        0.27  0.8  0.26   1.3     0.27  0.8   0.3      1.0pK       0.39    0.7pK       0.8  0.39  0.26   1.0pK    0.8  0.39   0.6pK  2 ( 0.02 )   1.3pK    1  Br  Br(pK  ) Measured Eff (  ) Estimated Efficiency Br (%)Modes Not all modes will be used in scan, But most of them can be used in further study

04/13/02Jianchun (JC) Wang7 Brief Selection Criteria  Good tracks.  P/K/  : Dedx, Grand LL (combine Dedx, RICH info).  Electron: Dedx, X925, E/P, Grand LL.  Muon: Dedx, Mudepth.   : X925, Barrel, no track matching, cos  CM.  K S : Fit quality(prob>0.01), Distance(r-  ) > 2mm.   : Fit quality(prob>0.01), Distance(r-  ) > 1mm.

04/13/02Jianchun (JC) Wang8 Decay Mode pK     Scaled to 12 pb .  Sum of three sources:  b  b pair, BB pair, and udsc continuum.  About 20  c from  b can be seen. M pK  (GeV) Number of Entries / 2 MeV

04/13/02Jianchun (JC) Wang9 Decay Modes PKs and   Number of Entries / 2 MeV M pKs (GeV) M  (GeV) Two modes add 23% more to pK  mode

04/13/02Jianchun (JC) Wang10 Sum of Three Modes  S/  S+N    Background  C signal Sum pK S PK    Budsc bb B bb

04/13/02Jianchun (JC) Wang11 Proton Lepton Event  Require at least one muon or electron in the event.  With R2 < 0.2 cut.  The efficiency for  b  b event is 17%.  With 12 pb , reconstruct:  from  b  b events.  80.3 from udsc continuum.  30.1 from BB events.  S/  S+N = 7.1. XP p Number of Entries / 0.01

04/13/02Jianchun (JC) Wang12 Proton Lepton Event Number of Entries / 0.01

04/13/02Jianchun (JC) Wang13 Proposed Scan Plan  At 6  10 32, we expect 16 pb  /day.  12 pb  per point, total 27 points.  36pb  (equivalent to 3 points) at MeV.  With 6 MeV interval, scan 7 points till ~11270 MeV.  Take 1 point at the end of the scan region (11380 MeV).  By then we should have enough information to decide where to go next.  Should we find a resonance or a large cross-section point, we will stop the scan and take as much data as possible at that point.

04/13/02Jianchun (JC) Wang14 Computation Resources  We expect to have useful information in 24 hours.  David Kreinick and Jean Duboscq estimated the CPU consumption and allocate enough computers for the scan.  Methods to reduce CPU burden: tighter filter, fast RICH algorithm, …  Save PDS data on disk: ~ 64GB.  Save only “hot-store” information.

04/13/02Jianchun (JC) Wang15 Beam Condition Hello, A few minutes ago we began collecting our first collisions at 5.6 GeV. Luminosity at 268 (10**30) - not too bad for the first fill. Crate 5 on DR went thru major surgery today during access so we are still evaluating its performance. I'll let you know how things go. Dan Dan Cronin-Hennessy message (03/20/02)

04/13/02Jianchun (JC) Wang16 What’s Next? Possible things to do with  b data sample  Combine  c with a pion or rho to measure  b mass.  Inclusive semileptonic decay  b  c l X  Measure  b  b production with double reconstruced  c.  Measure  b  b production with proton lepton ( this requires good MC).  …

04/13/02Jianchun (JC) Wang17 Tuning Decay Table DECAY LAMB CHANNEL NUEB E- LAMC CHANNEL NUMB MU- LAMC CHANNEL LAMC PI- CHANNEL LAMC RHO- CHANNEL LAMC A1- CHANNEL LAMC DS- CHANNEL LAMC DS*- CHANNEL ETAC LAM CHANNEL PSI LAM CHANNEL LAMC PI+ PI- PI- CHANNEL LAM K0 PI+ PI+ PI- PI- CHANNEL P+ D0 PI- CHANNEL LAMC *DU* CHANNEL SIGC+ *DU* CHANNEL CCS1 *DU* CHANNEL P+ *DU* CHANNEL CSU1 *DU* ENDDECAY With reference to B decays, Steve adjusted the decay table. The effect to the two estimations presented here may be small. And we are checking on this.

04/13/02Jianchun (JC) Wang18 Acknowledgement We really want to thank following people for their help on the coding: Alan Magerkurth Hanna Mahlke-Krueger Hajime Muramatsu And many others we bugged

04/13/02Jianchun (JC) Wang19 Summary  The scan tools are tested and ready.  The proton-lepton method is more effective.  CPU estimation and resource reallocation is going on.  We are mostly ready for the scan.

04/13/02Jianchun (JC) Wang20 Track Selection Criteria  Dedx information valid, and 3  consistence.  Grand LL: LL(K)-LL(pi)+Nsig(K)**2 – Nsig(pi)**2  RICH valid, P(K)>0.5 Gev, P(p)> 1GeV: Grand LL < - 4  Others: (no RICH), Grand LL < -4  Number of expected hits > 0, and number of hits > half of the expected.  Number of expected hits in fit > 0, track fitted, fit not abort.  Fit helix valid, track quality valid, track fit, not abort, degreesOfFreedom > 0, D0 < 0.6cm (0.35), Z0 < 5cm.

04/13/02Jianchun (JC) Wang21 Reconstruction of  c  c  pK    Br  ~ 0.05  ~  = 5.4 MeV

04/13/02Jianchun (JC) Wang22  Missing mass calculation: (  b  X   Since P  is relatively small, and cos  is unknown, conventionally the last term is treat as 0.  In fact the resolution can be improved by giving cos  a fixed value, this is due to the boost of  b. Semi-leptonic Mode:  b  c +  

04/13/02Jianchun (JC) Wang23 None-zero cos  E CM  M  b = 140 MeV MC at generator level cos  =

04/13/02Jianchun (JC) Wang24 None-zero cos  Effect of boost is stronger with more kinetic energy. Reconstruction efficiency depends on the boost mainly due to P  >GeV requirement. cos  is fixed to of reconstructed event. E CM  2M  b (MeV)

04/13/02Jianchun (JC) Wang25 The Effect of Beam Energy E CM  2M  b (MeV)

04/13/02Jianchun (JC) Wang26 Full Reconstruction of  b  c +    b  c +    c +  pK    E CM  M  b = 20 MeV  E CM = 4.5 MeV M  c  (GeV)  = 3.1 MeV

04/13/02Jianchun (JC) Wang27 The Effect of Beam Energy Sigma of M  c  (MeV) E CM  2M  b (MeV)

04/13/02Jianchun (JC) Wang28 The Effect of Beam Energy E CM  2M  b (MeV) M  c   M  b  (MeV) Sigma of M  c  (MeV) E CM  2M  b (MeV)