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b  s g Exclusive D ecays

b  s g Exclusive D ecays. Akimasa Ishikawa (Tohoku University). Evidence for bs g. CLEO found an evidence for b s g process using exclusive BK*(892) g decays in 1993 with only 1.38fb -1 data on Y(4S). More than 20 years has passed from the evidence and now…. Now we are here.

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b  s g Exclusive D ecays

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  1. bsg Exclusive Decays Akimasa Ishikawa (Tohoku University)

  2. Evidence for bsg • CLEO found an evidence for bsg process using exclusive BK*(892)g decays in 1993 with only 1.38fb-1 data on Y(4S). More than 20 years has passed from the evidence and now….

  3. Now we are here • Now we (Babar and Belle) have more than 800 times larger data of 1144fb-1 (433fb-1+711fb-1) on Y(4S) than data with which CLEO found an evidence for bsg. • Further, LHCb collected 3fb-1 at 7TeV and 8TeV at pp collisions. • sbb = 7.7mb for pTbb> 5GeV and 2.5 < h < 4.0 at 7TeV Copious numbers of B hadrons are available.

  4. Ideal tool to search for new physics • Exclusive bsg decays can be used to measure • Branching fraction (BF) • Fragmentation of Xs • Direct CP Violation (ACP) • To Search for New phase • Time dependent CP Violation (SCP) • For B0fCPg modes • to search for right handed current/new phase • CPV is suppressed by O(ms/mb) • Isospin Violation (D0+ or AI) • Spectator dependent operator • Up-Down Asymmetry (AUD) • For BK1gKppg • To search for right handed current • New physics makes |AUD| value smaller than the SM • Photon Polarization from conversion (no groups measure yet) • To search for right handed current

  5. Observed Exclusive Decays • Now we observed • BK*(892)gin 1993 • BK2*(1430)g in 2000 • BKfg in 2004 • BKhg in 2005 • BK1(1270)gin 2005 • BpLgin 2007 • BKh’g in 2010 Only 40% are exclusively known!

  6. Direct CPV • In the SM, bsg process is dominated by single EW penguin diagram, and further weak phase in Vts is suppressed by O(l2), so direct CPV in bsg is small. • E.g. ACP(BK*(892)g) = -0.6±0.4% • If new physics contribution to bsg has sizable amplitude and weak (+strong) phase, direct CPV could appear. • Is the difference of direct CPV btw B0 and B+ interesting/sensitive NP also for exclusive decays? • Benzke, Lee, Neuber and Paz propose it for inclusive decays as a sensitive probe for new physics. • Matsumori, Sanda, Keum

  7. Direct CPV in BK*(892)g • LHCb reported ACP with 1fb-1 • Only with K*0K+p- • W.A. consistent with nullasymmetry predicted in the SM • -0.6±0.4 % • exp error 3times larger than theo • LHCb 1fb-1 3fb-1 • Belle 78fb-1 711fb-1 • Matsumori, Sanda, Keum

  8. Isospin Violation • Isospin Violation can be calculated in the SM. • +5.0 ~ +10 % • +2.7±0.8 % • If new physics has isospin breaking contributions, such as spectator dependent diagrams, D0- could be deviated from the SM value • Even sign of Isospin Violation flips • Kagan, Neubert • Matsumori, Sanda, Keum

  9. Isospin Violation in BK*(892)g • Babar and Belle measured isospin violation • thanks to high reconstruction efficiency for Ks and p0 involved modes at e+e- machine • Consistent with SM Predictions • +5.0 ~ +10 % • +2.7±0.8 % • Kagan, Neubert • Matsumori, Sanda, Keum

  10. Time dependent CPV • In the SM, photon emitted from b is predominantly left handed. Time dependent CPV in BfCPg is small due to small interference • If new physics has right handed current, time dependent CPV emerges by interference. • Gluon emission bsggprocesses make SSM larger than naive calculation?? Atwood, Gronau, Soni Atwood, Gershon, Hazumi,Soni SSM ~ O(0.1) Grinstein, Grossman, Ligeti, Pirjol Grinstein, Pirjol Matsumori, Sanda Ball, Zwicky

  11. Preliminary Time Dependent CPV in BKhg 711fb-1 • Recently Belle reported measurement of time dependent CPV in BKhg with full data • Measured values are out of physical boundary but consistent with null CPV. SM prediction

  12. Summary of time dependent CP Violation • Four decay modes are used to search for time dependentCPV. • fCP = Ksp0(K*0), Ksh, Ksr, Ksf • All are consistent with null with stat errors.

  13. Up Down Asymmetry Gronau, Grossman, Pirjol, Ryd • Polarization of photon can be extracted from the BK1g(Kpp)gprocess by measuring up down asymmetry (photon polarization from K1 polarization). • Angle q btw photon and normal vector to K1 decay plane. • Interference btw rK and K*p generates imaginary part. •  modes involving p0 gives larger AUD • Need theoretical calculation of the amplitudes

  14. Up Down Asymmetry in BKppg • LHCb observed AUD with 3fb-1 in BK+p-p+g • With 13876±153 signal events • Measure AUD with 4 bins of MKpp • No resonance separation • 5.2s significance from null polarization • No interpretation to photon polarization yet

  15. bdg Exclusive Decays Given title is bsg exclusive decays but I would add bdg

  16. bdg Decays • The bdg is suppressed by Vtd • About 30 times smaller than bsg( |Vtd/Vts|2 ) • Need very good PID detector and EM Calorimeter • The observables to search for NP are the same as the bsg but NP contribution could be different. • Branching fraction (BF) • Direct CP Violation (ACP) • Time dependent CP Violation (SCP) • IsospinViolation (Dr) • Up-Down Asymmetry (AUD) • Photon Polarization from conversion (no groups measure yet)

  17. Observation of bdg • Belle had observed bdg process using exclusive B(r, w)g with 357fb-1 data in 2006

  18. |Vtd/Vts|, ACP and Dr • |Vtd/Vts| can be measured from the ratio of BF of B (r,w)g and BK*g • Consistent with the SM • Direct CPV in Br+gconsistent with null • DrIsospin Violation large? • 2~3sdeviation • + 4 +14 -7 % • - 10±6 % • - 5.4±3.9 % if f3 = 60deg • - 4.6±7 % Ali, Lunghi Lyon, Zwicky Ball, Jones, Zwicky Beneke, Feldmann, Seidel

  19. Time Dependent CPV in B0r0g • Only Belle had measured time dependent CPV in B0r0g • 48±14signal events are used for fits. • Though signal yield is smaller than B0Ksp0g, fraction of events used for time dependent fit is larger thanks to easier vertex reconstruction with r0p+p- • The results are consistent with null asymmetry

  20. Summary • Many studies of bsg are performed in more than 20 years to search for new physics. • No hint of new physics yet. • New window bdg was opened since2006. • A hint in Isospin Asymmetry?? • Some analyses in bsgand all analyses in bdgare still statistical error dominant • Need higher luminosity experiments •  Belle II and LHCbupgrade • Some theoretical predictions are different btw groups. • Isospin violation • Time dependent CPV • Hope the predictions improved in coming several years.

  21. backup

  22. CCP = - ACP

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