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Exclusive Semileptonic b u   Decays at CLEO

Exclusive Semileptonic b u   Decays at CLEO. Sheldon Stone Syracuse University. Introduction. Improved measurements of B o  p -  +  & r -  +  branching ratios and q 2 dependences Measurement of B +    +  & evidence for B +  ’  + 

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Exclusive Semileptonic b u   Decays at CLEO

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  1. Exclusive Semileptonic buDecays at CLEO Sheldon Stone Syracuse University

  2. Introduction • Improved measurements of Bo p-+ & r-+ branching ratios and q2 dependences • Measurement of B+ + & evidence for B+ ’+ • Analysis Uses Neutrino Reconstruction • Extension of CLEO II/II.5 Analysis (PRD 68, 072003) by adding CLEO III data, 60% more data, total of ~14 fb-1 CKM Workshop, Dec. 12-16, 2006

  3. Formalism in Pseudoscalar Decay • q2=(pBm-pPm)2, kP is the P momentum in the B rest frame CKM Workshop, Dec. 12-16, 2006

  4. Formalism in Vector Decay • qWL is the  between the +direction in the W rest frame & the W direction in the B rest frame • q2=(pBm-pVm)2, kV is the V momentum in the B rest frame CKM Workshop, Dec. 12-16, 2006

  5. Neutrino Reconstruction pn Resolution • Estimate n 4-vector using pmiss  pCM-pvisible & Emiss  ECM-Evisible • Require in general net charge of 0, (in 0- modes also use ±1) • Require MM2 ~0 (MM2/2Emiss <0.5 GeV) • Require Spherical events • Identify e+ or m+ with pl>1 GeV/c (reject events with >1 lepton) • Form DE=Ehad+El-En-Ebeam & • Mhln2=Ebeam2-(phad+pl+pn)2 s~0.1 GeV/c p GeV/c CKM Workshop, Dec. 12-16, 2006

  6. Measurement Technique B • Vector state sensitive to cosqWL • Binning • B in q2 & cosWL bins drastically reduces model dependence of branching ratio determination • B in q2 bins • B in all phase space • B’  in all phase space Ratio Cos<0 / Cos>0 Ball04, Mel, UKQCD, ISGW2 q2 GeV2 CKM Workshop, Dec. 12-16, 2006

  7. Expectations from Simulation • Use binned log likelihood method simultaneously in all modes and bins • Use isospin constraints & efficiency matrix Backgrounds peak here Signal peaks here CKM Workshop, Dec. 12-16, 2006

  8. BXu  other B Signal , 0 XFeed Continuum (absolutely normalized) ±0 XFeed BXc   ,  XFeed Fake Lepton (absolutely normalized, very small) (very small) Fit Components Signals Backgrounds Data Events/7.5MeV/c2 Mhlv GeV/c2 CKM Workshop, Dec. 12-16, 2006

  9. Results from Fit (Summed) • Mhln Distribution -0.15< <0.25 GeV •  Distribution 5.265< Mhln < 5.28 GeV h p+, po r+, ro, wo h Events/7.5MeV/c2 Mhlv GeV/c2 Mhlv GeV/c2 Mhlv GeV/c2 Mhlv GeV/c2 Events/100MeV/c2 CKM Workshop, Dec. 12-16, 2006 GeV GeV GeV GeV

  10. Systematic Errors Largest Source Of Systematic Uncertainty CKM Workshop, Dec. 12-16, 2006

  11. Results B(B)= (1.370.150.120.01)10-4 B(Br)= (2.930.370.390.04)10-4 coswl>0 coswl<0 B10-4/GeV2 B10-4/GeV2 HPQCD 04 Prediction Ball 04 Prediction q2 GeV2 q2 GeV2 B(B++)= (0.440.230.110.00)x10-4, <1.0110-4 @90% cl B(B++)= (2.660.800.570.04)x10-4, 3s effect G(B++)/G(B++)>2.5 @90% cl Theory without color singlet has B(B++)=0.4x10-4, B(B++)=0.2x10-4, inconsistent with data CKM Workshop, Dec. 12-16, 2006

  12. B(B) • B • Comparisons • Competitive with B • factories due to • higher efficiencies at • symmetric machine CKM Workshop, Dec. 12-16, 2006

  13. B Comparisons B(B) CKM Workshop, Dec. 12-16, 2006

  14. Measurement of |Vub| • We use our measurement for B for q2 > 16 GeV2 • And recent results from unquenched lattice calculation: HPQCD collaboration (Gulez, et al, PRD 73, 074502, 2006). CLEO (2006): BABAR (2006): BELLE (2006): Note that the theoretical error dominates CKM Workshop, Dec. 12-16, 2006

  15. Preliminary Conclusions • Using n reconstruction CLEO measured Branching ratios for B→(, , ’)n & an upper limit for B→n • B(B)= (1.37  0.150.12 0.01)10-4 • B(B)= (2.93  0.37  0.39 0.04)  10-4 • B(B ’)= (2.66  0.80  0.57  0.04)  10-4 “3 s evidence for” • B(B) < 1.0110-4 @ 90% C.L. • Extracted |Vub| using  q2>16 GeV2 and HPQCD prediction: CKM Workshop, Dec. 12-16, 2006

  16. A Tribute to Bernie Gittelman • 1932-Nov. 25, 2006 • A hero of flavor physics • Pioneered e- storage rings at SLAC • First to measure B semileptonic decays • Led CLEO II project CKM Workshop, Dec. 12-16, 2006

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