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Experimental situation of the sin2β measurement in hadronic penguin modes

Experimental situation of the sin2β measurement in hadronic penguin modes. Alfio Lazzaro Università degli Studi and INFN, Milano Workshop on New Physics with SuperB @ University of Warwick 14th-17th April 2009. Overview. Time Dependent CP violation asymmetry and CKM angle β measurements

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Experimental situation of the sin2β measurement in hadronic penguin modes

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  1. Experimental situation of the sin2β measurement in hadronic penguin modes Alfio Lazzaro Università degli Studi and INFN, Milano Workshop on New Physics with SuperB @ University of Warwick 14th-17th April 2009

  2. Overview • Time Dependent CP violation asymmetry and CKM angle β measurements • New Physics effects in b → s penguin amplitudes • Measurements from the beginning of B-Factories to the latest updates (historical prospect) • Measurement results from HFAG webpage. Refer to them for specific references • Conclusion Alfio Lazzaro

  3. Time-Dependent CP-Asymmetry • Time-dependent (TD) decay rate asymmetry for coherent B mesons to final state f • Cf related to direct CP • Sf related to CP asymmetry in interference between mixing and decay Physics observables Cf = − Af Alfio Lazzaro

  4. β measurements β = ϕ1 • In case of of tree dominated decays, such as • β is CKM phase related to CP Violation in the Standard model (SM) CKM Alfio Lazzaro

  5. TD in b → s penguin modes • Alternative measurement of • Contributions from suppressed diagrams with different weak phase produce deviation • well constrained from charmonium decays • Theoretical constraints on Tree diagram suppressed Loop (“penguin”) diagram dominant Alfio Lazzaro

  6. Standard Model Effects • In SM expected small and mode dependent • Some predictions give unsigned intervals • Deviation from SM expectation if large is found • Deviation in single modes f From J. Hirschauer talk @ ICHEP08 Alfio Lazzaro

  7. New Physics Effects • Penguins modes are sensitive to New Physics (NP) contribution: new heavy particles in the loop could give large value of ΔS, not explained by the SM (Buchalla et al., JHEP 0509,074(2005) • Clear NP effect is large deviation is found in single modes Alfio Lazzaro

  8. BaBar-PEPII @ SLAC Belle-KEKB @ KEK More than 1 billion of BB pairs Alfio Lazzaro

  9. BB Time Evolution Fully reconstructed B: signal Partial reconstructed B: identify his flavor using a tagging algorithm Alfio Lazzaro

  10. Analysis Method • Maximum likelihood fits to extract the signal parameters • Based on Quasi-two-body (Q2B) or Dalitz plot analyses (for 3 body decays KKK0 and ππK0) • parameters Sf and Cffrom a ML fit on Δt variable • Dalitz plot analysis allows to extract directly the several TD parameters for the Q2B resonances and to resolve the trigonometric ambiguity in the measurement of β • Reconstructed several sub-decays for each mode in order to increase the statistics (e.g. K0 in K0S and K0L,K0S in neutral and charged pions) Alfio Lazzaro

  11. Winter 2003: 3 modes studied !! !! Q2B analysis Excluding ϕ mass region. Main contribution so systematic due to CP content of the final state No Direct CP Alfio Lazzaro

  12. 2003: details @ 89 106BB pairs @ 85 106BB pairs Average does not consider theoretical uncertainties and correlated systematic errors!!! Alfio Lazzaro

  13. 2003: details @ 89 106BB pairs @ 85 106BB pairs @ 120 106BB pairs @ 152 106BB pairs Average does not consider theoretical uncertainties and correlated systematic errors!!! Alfio Lazzaro

  14. New modes in Summer 2004 Q2B analyses (S wafe contribution considered in the systematics) Added K0L mode (opposite CP eigenvalue of K0S) Quasi 2-body analyses with * Q2B analysis, excluding ϕ mass region * * Alfio Lazzaro

  15. 2006: CP violation observation BaBar: TD Dalitz plot analysis of K+K﹣K0 Belle: Q2B analysis CP Violation observation!!! Q2B analysis BaBar & Belle: Q2B analysis for BaBar: Dalitz plot & Q2B Q2B analysis, excluding ϕ mass region Alfio Lazzaro

  16. η´K0 mode (last update) Alfio Lazzaro 2500 signal events 1900 signal events

  17. Last Updates (2008): S Good agreement between the two experiments TD Dalitz plot analysis of K+K﹣K0 Same error as 2003 charmonium measurement TD Dalitz plot analysis of π+π﹣K0S TD Dalitz plot analysis of K+K﹣K0 & π+π﹣K0S Large Error Last mode added to the penguin “family” (angular analysis) Alfio Lazzaro

  18. Last Updates (2008): C Agreement between the two experiments Alfio Lazzaro

  19. Last Updates (2008): Averages Good agreement with SM expectation Alfio Lazzaro

  20. Conclusion • Impressive achievements in time-dependent analysis for penguin modes • Many modes studied • Complex analyses, with several improvements over the years • Measurements still statistically limited • Results in agreement with SM expectations • We experienced several fluctuations in the past years • Lesson 1: more and more data needed • More updates from Babar, using final dataset, and Belle expected in the future, but not enough (I think) to find something new • Lesson 2: more and more data needed Alfio Lazzaro

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