Sacha Kopp, Univ. Texas -- Austin 1 Search for CP in Rare B Decays Sacha E. Kopp, University of Texas – Austin for the CLEO Collaboration

Sacha Kopp, Univ. Texas -- Austin 2 Constraints on CKM Phase Fits to all data favor 44° <  < 75° Parodi, Roudeau, Stocci, hep-ph/ |V cd V cb | |V td V tb | * * |V ud V ub |* Constraints on  +i  from many results Newest contributions sin(2  ) (CDF),  m s > 14.5 ps -1 (LEP+CDF)   

Sacha Kopp, Univ. Texas -- Austin 3 Rare B Decays Tree decays b  u vs. b  c suppressed by |V ub | 2 /|V cb | 2 ~ 0.01 Additional |V us | 2 /|V ud | 2 ~ 0.04 for K  Expect tree dominantly b  uud. Decays b  s,d GIM-suppressed Loop diagram  (m t /m W ) 2. |V td | 2 /|V ts | 2 ~ 0.01 Expect penguins dominantly b  uus. u u s u u KK  u u s u  Tree: Penguin: d u  s u KK d u 

Sacha Kopp, Univ. Texas -- Austin 4 CP Asymmetries Measure B and B reactions described by two amplitudes:  (B  f) = | a 1 e i(  1 +  1 ) + a 2 e i(  2 +  2 ) | 2  (B  f) = | a 1 e i(  1 +  1 ) + a 2 e i(  2 +  2 ) | 2 CP asymmetry from strong and weak phase differences  sin(  1  2 )sin(  1  2 ) Depends upon comparable magnitudes as well CLEO can measure decays that are sensitive to  = arg(V ub *) B   K   , B   K   , B   K   ’

Sacha Kopp, Univ. Texas -- Austin 5 A CP Predictions Factorization model calculations (no FSI interactions) Ali, Kramer, Liu, hep-ph/ »K    » K    »K    0.01 » K   ’ »   Final state interactions may boost A CP ~ %. »He et al, Phys. Rev. Lett. 81, 5738 (1998) »Neubert, JHEP 9902, 014 (1999) »Deshpande et al., Phys. Rev. Lett. 82, 2240 (1999) New physics could boost A CP ~ %. »He et al., hep-ph/980982

Sacha Kopp, Univ. Texas -- Austin 6 R *  (1-R * )/  3/2  |  EW - cos  | Fleischer-Mannel (Phys. Rev. D57, 2752(1998))  (B   K    )  (B   K    ) Neubert-Rosner (Phys. Lett. B441, 403 (1998))  (B   K    ) 2  (B   K    )  from Decay Rates R   sin 2  CLEO: R = 1.01  0.26 Also model-dependent fit to many CLEO branching ratios of , K , ,  (Wuerthwein et al. hep-ex/ ): 84 <  < 154 (90% C.L.) 0.58  0.74  | (0.64  0.15) - cos  |

Sacha Kopp, Univ. Texas -- Austin 7 CESR Ring/CLEO Detector Total 14 fb  of e  e  collisions ~ 1/3 at  s = GeV to study continuum e  e   qq (q = u, d, s, c) ~ 2/3 at  (4S) resonance.  BB ~ 1 nb  9.7  10 6 BB pairs Symmetric collider  P B ~ 300 MeV/c CESR Phase II peak instantaneous luminosity: 8.3  cm -2 sec -1 Recorded 4.4 fb  in 1998 alone, stored 36 bunches/beam, 260 mA/beam Phase III underway now Mass (GeV/c 2 ) Rate (nb)  1998   1996   1997  Monthly Integrated Luminosity (pb -1 ) off on

Sacha Kopp, Univ. Texas -- Austin 8 B  K    /     Topology B  KB  K B  KB  K e + e -  qq P daughter ~ 2.55 – 2.85 GeV/c (higher than for b  c decays) Major background from e + e -  qq “continuum” Continuum events are “jetty” in topology P B ~ 300 MeV/c  BB events “spherical” Continuum suppression from ML fit to several kinematic and topological variables (more efficient). Continuum suppression factor of ~ 10 6, efficiency for K  /  of ~ 40%

Sacha Kopp, Univ. Texas -- Austin 9 K/  Separation (dE/dx - Expected)/  Pions Kaons  E  (GeV) KK   E resolution studied with D 0  K    (   ) mass resolutions EE EE dE/dx CLEO II25 MeV 1.7  CLEO II.V20 MeV 2.1  2.0  K  vs.  from dE/dx in drift chamber »Resol. confirmed with D *   D   , D   K    Also separation from kinematics:  E  = E  + E  - E beam CLEO data

Sacha Kopp, Univ. Texas -- Austin 10 Fit Results for B  h  h  K  K  yield is events  set to zero Restricted fit for …      K     First observation of a  mode! If remove 3  events with highest likelihood, still 3.4  significance. N(K    ) N(     )

Sacha Kopp, Univ. Texas -- Austin 11 B  K    and B     Cuts applied on  E and topological variables to make these plots. Results in ~ factor 2 loss in efficiency Can perform similar procedure to look at other distributions (  E, Fisher, etc). B Mass (GeV/c 2 )

Sacha Kopp, Univ. Texas -- Austin 12 Signal (events) #  (%) BR (  )   0.5 < KKKKKKKK    KKKKKKKK < 1.9 < 5.1 B  K , B   Summary

Sacha Kopp, Univ. Texas -- Austin 13 B , B   Signal (events) #  (%) BR (  )    3.3  B Mass (GeV/c 2 )     K   1.4 < Greater challenges from feed-across (  ) Results soon on  0  0 and  0  +. Inconsistent with non-resonant B  hhh

Sacha Kopp, Univ. Texas -- Austin 14 Look for  ’        decays Look for ,       decays B      ’K’K B Mass (GeV/c 2 ) ’K’K Fit for  ( ’ ) K and  ( ’ )  simultaneously Efficiencies ~ 2 - 9% for these modes  

Sacha Kopp, Univ. Texas -- Austin 15 Signal (events) #  BR (  ) Prediction* K’K’KKK’K’KK   9 <6.9 < K   K   K   ’ K   ’   1.6 <35 < B      Summary * Ali, Kramer, Liu, hep-ph/

Sacha Kopp, Univ. Texas -- Austin 16 CP Asymmetry Systematics B flavor tagged by high momentum track Must demonstrate reconstruction not charge dependent. Charge difference in K - N and K + N cross sections Track reconstruction difference confirmed in Monte Carlo ~ 0.002

Sacha Kopp, Univ. Texas -- Austin 17 CP Systematics (cont’d) Likelihood fits heavily dependent on tracking resolutions See no CP asymmetry in reconstructed D 0 mass -- even in tails of resolution.

Sacha Kopp, Univ. Texas -- Austin 18 dE/dx Uncertainty dE/dx used in likelihood fit Charge asymmetry checked with D 0  K   + (  0 ) decays No asymmetry observed -- even in tails of resolution Assign systematic error  0.01 (dE/dx – Expected)/ 

Sacha Kopp, Univ. Texas -- Austin 19 CP Asymmetry Results events events events events events K+K+ K0K0 K+K+ KK  + A CP % C.L.

Sacha Kopp, Univ. Texas -- Austin 20 CP from New Physics? Penguin amplitude  |V ts | Other amplitudes, CP, small in SM Some Higgs models introduce CP, possibly even if b  s  rate unaffected. »Wolfenstein & Wu, Phys. Rev. Lett. 73, 2809 (1998) »Asatrian & Ioannissian, Phys. Rev. D54, 5642 »Kagan & Neubert, Phys. Rev. D58, B Candidate Mass (GeV/c 2 ) 126  15 events

Sacha Kopp, Univ. Texas -- Austin 21 b  s  Results Upper limit on b  d exclusive penguins: BR(B  (  )  ) < Updated branching ratio results: BR(B 0  K *0  ) = (4.5  0.7  0.3)  BR(B +  K *+  ) = (3.8  0.9  0.3)  CP asymmetry from special kinematic region for best K/  identification CLEO result: A CP = 0.08  0.13 Asymmetry for inclusive b  s  (based on 3.3M BB pairs only): < A CP < 0.42 (90% C.L.) Monte Carlo

Sacha Kopp, Univ. Texas -- Austin 22 Search for b  d  Expect that B  also described by penguin amplitude  dominant top?  (B  ) |V td | 2  (B  K *  ) |V ts | 2 Updated branching ratio limits: BR(B 0  0  ) < 1.7  BR(B +  +  ) < 1.3  BR(B 0  ) < 1.0  Expect  /K*  ~ 1/50 and they look alike! = =   K*K*

Sacha Kopp, Univ. Texas -- Austin 23 Current  /K separation statistical -- we want event-by event Lower fake rates for rare modes (  ) Goal: 4   /K at p = 2.8 GeV/c with dE/dx (3.2  from RICH) Several photons per track in radiator material  trk =   /  n  Design goals of   = 14 mrad n  = 12 CLEO III RICH Detector  C = 12.8 mrad in LiF  need  trk = 4 mrad

Sacha Kopp, Univ. Texas -- Austin 24 CLEO III RICH Proximity focussing with solid radiators. LiF radiators N 2 expansion gap CH 2 /TEA photosensitive medium in MWPC Pad read-out

Sacha Kopp, Univ. Texas -- Austin 25 First Colliding Beam Data Engineering run Recorded ~ 80 pb -1 of data Peak lum. ~ 5  cm -2 s -1 Nov.16, 1999 Bhabha event

Sacha Kopp, Univ. Texas -- Austin 26 After background subtraction: »10.2  flat radiators (stat. error only) »13.2  sawtooth radiators Expect 10-20% more photons with higher gain CLEO RICH Performance Planar Sawtooth Gain ~ 2  10 4

Sacha Kopp, Univ. Texas -- Austin 27 Conclusions b  s penguins appear dominant » K  »  ( ’ ) K (*) Definitive observations of hadronic b  u decays »  »  »  First CP asymmetries consistent with zero »Based on ~ 9.7 fb-1 of data »Will be statistics limited for some time to come First exciting data from CLEOIII »RICH, Drift Chamber working very well. »Silicon installed in February. »Physics running begins April 3rd.

Sacha Kopp, Univ. Texas -- Austin 28 B      B   D      D   D   D   K      KK     A Fully- Reconstructed event Sacha Kopp, Univ. Texas -- Austin

29 Continuum Suppression (cont’d) B Mass (GeV/c 2 ) cos(  T ) »Fisher variable which utilizes  R 2 = H 2 / H 0 Fox-Wolfram moment  cos  B – angle between thrust axis and beam  Energy flow around thrust axis – 9 cones »“Beam-constrained” mass of B: M B =  E beam - |p B | 2 »Resonance masses (for , , K* modes) 2 Maximum Likelihood fit utilizes 6 different variables: »cos  T -- angle between thrust axis of B and rest of the event |cos  T | < 0.8 removes 83% of continuum backgrounds Off  (4S) data BB Monte Carlo

Sacha Kopp, Univ. Texas -- Austin 30