B s suppressed decays at CDF

1. Bs suppressed decays at CDF bcc d decays (tree+penguin) First observation and Branching Ratio measurement BsJ/y Ksand BsJ/y K*(892) bs penguin decays: First polarization measurement in Bsff Prospects Marco Rescigno INFN/Roma On behalf of CDF collab.

2. CDF & Tevatron • Up to 8 fb-1 logged 3-6 fb-1 analysis shown today • Flexible Triggering on dimuon BsJ/yK(*), or displaced tracks Bsff • Large (R~1.4m) tracking chamber combined with silicon vertex detector provides excellent pT and impact parameter resolution • spT/pT = 0.1% pT  sM = 15-20 MeV/c2 • Decay length resolution sL=30 um • Key elements for background reduction! BsJ/K(*)(5.9 fb-1) • Delivered • Acquired Bsff(2.9fb-1) M.Rescigno - HQL 2010

3. Bs Production at Tevatron BsJ/yf BsDsp • In the past decade unique opportunity to study Bs mesons at Tevatron: • Usable b x-section ~ 6 ub (pT>6 |y|<1) • b-quark fragmentation to Bs mesons fs/fd=0.269 ±0.033 • World largest fully reconstructed Bs samples CDF PRD 75, 012010 2007 CDF Phys. Rev. D77, 072003 (2008) • Possibility to observe and study rare (next talk) or suppressed decays (BR~10-5): • B(s)h+h’-, charmless Bsff, Cabibbo suppressed B(s)D(s)K • New observation of Cabibbo suppressed Bs->J/ K(*) M.Rescigno - HQL 2010

4. BsJ/yK(*)- Introduction • Same tree and penguin amplitudes in Bd J/yKs and BsJ/yKs • Different CKM factors: Ad= T + O(l2)P  As= O(l)T + O(l)P • Greater sensitivity to penguin in Bs decays • Opportunity to constrain penguins from Bs rate and CP violation • Th. error on sin2b to a fraction of a degree • CP even final state  determine lifetime of the heavy state if no CPV • The same apply to BsJ/yK* vs BsJ/yf • Improving knowledge of penguin contribution reduces the “large” theory uncertainty on the Bs mixing phase fs probed with high experimental accuracy in BsJ/yf De Bruyn, Fleisher, Koppenburg (2010) Faller, Fleisher, Mannel (2008) M.Rescigno - HQL 2010

5. BsJ/yK(*) – Common Issues BsJ/yKs here • BsJ/yKs: construct multivariate classifier (NN) with vertexing and kinematic discriminating variables trained using sideband data and signal MC • BsJ/yK*:optimize rectangular cuts • Maximize f.o.m. S/[1.5*√(B)] • i.e. maximize sensitivity for either finding evidence (at 3 s) or excluding at the same CL a given signal sideband • Reconstruct J/m+m-, Ksp+p- [decay length> 5 mm], K*(892)Kp [ |mKp - mK*|< 50 MeV/c2 ] • With loose vertexing requirement Bd signal very clear/clean already • Need to reduce background to try and observe suppressed Bs decays M.Rescigno - HQL 2010

6. BsJ/yKs • Sig. Model (3 Gaussians) MC inspired: • Width of core Gaussians determined from the Bd data peak • Bs signal shape assumed identical with mass fixed at the Bd peak + PDG MBs-MBd • Peaking background from Lb reflection reduced by cutting on decay angle in Ks frame:cosqpmin> -0.75 • N(BdJ/yKs )= 5954 ± 79 • N(BsJ/yKs )= 64 ± 14 • Significance 7.2 s from Dc2 w.r.t. null hypothesis M.Rescigno - HQL 2010

7. BsJ/yK*(892) • N(BdJ/yK*)= 9530 ± 110 • N(BsJ/yK*)= 151 ± 25 • Significance 8.0 s from Dc2 w.r.t. null hypothesis • Sig. Model (3 Gaussians) MC inspired: • Width of core Gaussians determined from the Bd data peak • Bs signal shape assumed identical with mass fixed at the Bd peak + PDG MBs-MBd • Peaking background from BsJ/f estimated from MC M.Rescigno - HQL 2010

8. Results • First observation of new Bs decay modes CDF public note 10240 • Using fs/fd=0.269±0.033 • [from CDF fs/(fd+fu)*BR(Dsfp) and PDG 2010 for BR(Dsfp) ] • O(l2) as expected; from PDG 2010 for Bd BR: In agreement with U-spin counterparts BR(BsJ/yK*)~2*BR(BdJ/yr)= 5.4±0.8 10-5 BR(BsJ/yKs)~ 2*BR(BdJ/yp0)= 4.1±0.5 10-5 M.Rescigno - HQL 2010

9. Bsff at CDF CDF Phys. Rev. Letters 95 031801 (2005) • bs penguin dominated decay • With 2.9 fb-1 of data perform: • Improved BR measurement • Measurement of polarization amplitudes • First experimental data on charmless BsVector–Vector : insight into the so called “polarization puzzle” • Powerful probe for new physics in Bs mixing or in penguin decays via indirect CP violation  null SM prediction (not for today) • Thanks to the CDF displaced track trigger : • First evidence in just 180 pb-1 of Run II data (2004)with 8 events CDF public note 10064 CDF public note 10120 M.Rescigno - HQL 2010

10. Bsff[K+K-][K+K-] Signal • Take |m(KK)-mf(1020)|<15 MeV/c2 • BdfK* reflection ~ 3%, no other peaking background from simulation of Bs or Lb decays • Use BsJ/yf with the same trigger selection to normalize the BR and as a control sample for polarization measurement M.Rescigno - HQL 2010

11. Branching Ratio Bsff • CDF main result: • Syst. dominated by polarization uncertainties (will be reduced) • Use BR(BsJ/yf) = [13.5 ±4.6 ]·10-2 • updated from PDG using more recent fs/fd for absolute branching ratio: Consistent with both QCDF and pQCD (large uncertainties): M.Rescigno - HQL 2010

12. Bsff Polarization In BVV decays 3 decay product relative angular momentum states possible: 3 independent decay amplitudes Best decomposed in a longitudinal and two transverse polarization amplitudes A0,A//(CP even), A(CP odd) Naïve expectation: |A0|>>|A//|~|A| V-A nature of weak interaction and conservation helicity in qcd Experimentally violated in penguin decays: subleading contribution (penguin annihilation) [e.g. A. L. Kagan, Phys. Lett. B 601, 151 (2004); Beneke Nucl.Phys. B774:64-101,2007] Final State Interaction (FSI) [P. Colangelo, et al., Phys. Lett. B 597, 291 (2004) + many others] New Physics ? • Bsff Can help resolve the puzzle: • if PA is the reason can predict polarization in other modes e.g. Bsff[A.Datta, et al. Eur.Phys.J.C60:279-284,2009 ] M.Rescigno - HQL 2010

13. Bsff Polarization OBSERVABLES • Measure polarization amplitudes from untagged time-integrated differential decays rate as a function of kaon decay angles (1,2) and the angle between the two decay planes (f) Assume SM mixing phase: fBsff=0 Take GL and GH from PDG M.Rescigno - HQL 2010

14. BsJ/yf Control Sample • Analysis performed in transversity basis • Assume no CP violation: fs = 0 • Angular acceptance determined from simulation as in the Bs → ΦΦ case • Compared to CDF measurement from di-muon trigger with 1.7 fb-1 [PRL 100, 121803 (2008)] • and DØ measurement with 2.8 fb-1 [Phys.Rev.Lett.102:032001,2009] 1700 1700 Bs DØ DØ NO BIAS ! Phys.Rev.Lett.102:032001,2009 M.Rescigno - HQL 2010

15. Bsff Polarization Fit • Unbinned maximum likelihood fit to mass and decay angles: • 295 candidates S/B ~ 3/1 • Acceptance correction from simulation • Background modeled on sideband (polynomials) and fitted in the whole mass range • Non resonant contribution uncertainty from MC simulation M.Rescigno - HQL 2010

16. Bsff Polarization Exp vs Theory PRD 76 (2007) • Agreement with QCDF prediction favor polarization puzzle explanation via penguin-annihilation over FSI Datta et. al. compare longitudinal fraction via ratio of BR with BdfK* Beneke, Cheng (QCDf) and Ali (pQCD) all reproduce BdfK* observables M.Rescigno - HQL 2010

17. Conclusions • CDF accessing the largest samples of B(s) decays • Charting the largely unexplored Bs territory: • Observation and BR of BsJ/yKs • Observation and BR of BsJ/yK*(892) • First polarization amplitudes measurement for Bsff • Tevatron excellent performances will allow at least doubling available statistics with respect to that used here by 2011 • New interesting results to come M.Rescigno - HQL 2010

18. BACKUP

19. BsJ/yK(*) – Systematics M.Rescigno - HQL 2010

20. Bsff Polarization (formulae) Untagged + fV=0 M.Rescigno - HQL 2010

21. Bsff - Systematics M.Rescigno - HQL 2010

22. Angular Acceptance & Background M.Rescigno - HQL 2010