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Radiative and electroweak penguin processes in exclusive B decays

Radiative and electroweak penguin processes in exclusive B decays. Dmytro Kovalskyi University of California, Santa Barbara BaBar Collaboration. Topics covered in this talk. RUN1-4 – 209 fb -1. BK(*)l + l  B l + l . RUN1-5 – 316 fb -1. B B.

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Radiative and electroweak penguin processes in exclusive B decays

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  1. Radiative and electroweak penguin processes in exclusive B decays Dmytro Kovalskyi University of California, Santa Barbara BaBar Collaboration ICHEP 2006

  2. Topics covered in this talk RUN1-4 – 209 fb-1 • BK(*)l+l • B l+l RUN1-5 – 316 fb-1 • B • B • FCNC – a well known method to look for new physics • bd and bd ll - new testing ground for Standard Model ICHEP 2006

  3. Extraction of |Vtd/Vts| with B() decays Form factor ratio 1/ = 1.17±0.09hep-ph/0603232 Annihilation amplitude corrections R = 0.1±0.1 • Use SU(3) to relate B() to BK* • Get |Vtd/Vts| with B() SU(3) breaking corrections: A.Ali, A.Parhomenko hep-ph/0105302 pre-ICHEP2006 results 2005 Belle observation of B() - first “direct” measurement of|Vtd/Vts| ICHEP 2006

  4. Extracting signal in B() Major challenge – enormous background from • Reconstructed decays: • B+, ++0 • B0, 0 • B, 0 Background Signal • Signal-background separation: • 0 and  photon veto and photon isolation • particle identification • event shape • event content • kinematical constraints • Maximum likelihood fit (E, mES, Neural Net, helicity) • BD used to validate signal NN PDF • BK* control sample and background ee - photon systematics ICHEP 2006

  5. We do see B B++ B00 ICHEP 2006

  6. BaBar estimate of |Vtd/Vts| BR(B→(ρ/ω)γ)/BR(B→K*γ) BaBar ICHEP 2006 Belle 2005 B-Factories average CDF measurement (mS) CKM fitter code w/o Δms Combined fit result: Global CKM fit excluding ms and B() ICHEP 2006

  7. B l+l- Terra Incognita Standard Model prediction: Last measurement by Mark II (1990): Big Bang • Expected improvement is ~ 104 – 105 • |Vtd/Vts|2 suppressed with respect to BKll, which has been seen already • Electroweak penguin and box amplitudes are not well constrained, so surprises are possible. Today Mark II ICHEP 2006

  8. B l+l- no signal found withStandard Model just around the corner ICHEP 2006

  9. Different ways to probe new physics in BK(*)l+l Electroweak penguins with substantial signal yield • well established signal • large number of observables to test SM • branching fractions • decay rate asymmetries • angular distributions • CP violation BK*ll (57 events) BKll (46 events) ICHEP 2006

  10. Forward-backward asymmetry and K* polarization Theoretical curves AFB – forward-backward asymmetry of the helicity angle of l+l- system FL – longitudinal component of polarization Experimental results ICHEP 2006

  11. Branching ratios, CP asymmetries ICHEP 2006

  12. Conclusion • BaBar confirms Belle observation of B(), finds first evidence for B++ and provides the most precise measurement of the decay rate: • Based on this information we estimate: • New search for B l+limproves the previous upper limit measured by Mark II by about 4 orders of magnitude: • Significant signal yield in BK(*)l+l decays allows to measure the forward-backward asymmetry of l+l- system, which provide a way to probe for new physics contribution in radiative and electroweak penguin decays ICHEP 2006

  13. BACK UP SLIDES ICHEP 2006

  14. The CKM matrix ICHEP 2006

  15. BaBar Detector Electromagnetic Calorimeter 1.5 T solenoid e+ (3.1 GeV) Cerenkov Detector (DIRC) e-(9 GeV) Drift Chamber Silicon Vertex Tracker Instrumented Flux Return ICHEP 2006

  16. Improvements in backgroundsuppression • Improvements •  and  veto: mass resolution vs energy dependence and photon conversion (~10% less background) • New Neural Net: B flight significance, B flavor tagging, correlations etc (~30% less background) ICHEP 2006

  17. B/K l+l details ICHEP 2006

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