1. 6/2/2015Attila Mihalyi - Wisconsin1 Recent results on the CKM angle  from BaBar DAFNE 2004, Frascati, Italy Attila Mihalyi University of Wisconsin-Madison

2. 6/2/2015 Attila Mihalyi - Wisconsin 2 The CKM matrix and Unitarity Triangle The CKM mixing matrix relates the quarks in the weak interaction basis (d’,s’,b’) and the quark mass eigenstates (d,s,b): (d’,s’,b’)=V CKM (d,s,b) Wolfenstein parametrization: =sin  C (Cabibbo angle) Independent parameters: , A Unitarity leads to: 1 (,)(,)    The angles of the triangle are related to CP– violation. Measure  from CP-asymmetries in b → uud processes. B →  B →  B → 

3. 6/2/2015 Attila Mihalyi - Wisconsin 3 B-decay modes sensitive to  Time dependent asymmetry of a B-B system (h=  ): Decay amplitudes: Due to the presence of both tree and penguin amplitudes we have: The extraction of  is complicated by penguins! where  eff directly related to S hh T=Tree P=penguin

4. 6/2/2015 Attila Mihalyi - Wisconsin 4 Isospin analysis for B →  and B →  Two triangular (isospin) relations can be constructed from the decay amplitudes. M. Gronau, D. London, Phys. Rev. Lett., 65, 3381 (1990)  if no penguins One can set a limit on the shift from penguins,  -  eff (useful only if the B → h 0 h 0 BR is small): Gronau-London-Sinha-Sinha Phys. Lett. B514, 315 (2001) Y. Grossman, H. R. Quinn, Phys. Rev., D58, 017504 (1998) Unknowns: Decay amplitudes Observables: Branching ratios, CP asymmetries Solvable but a 4-fold ambiguity on  remains: Common base: EW penguins neglected

5. 6/2/2015 Attila Mihalyi - Wisconsin 5 Prospects of  from B 0 →  +  - The B 0 →  0  0 BR was recently measured at BaBar, PRL 91 241801 (2003), and also at Belle. 113 fb -1 of data Preliminary,LP03 From 81fb -1 of data, taken in 1999-2001: PRL 89 281802 (2002), PRL 91 021801 (2003) Implies large penguin contributions:  eff |   at 90% c.l. Not easy to get  from B→  BR comparable to B 0 →  +  - and B + →  +  0 but not large enough to measure the B 0 - B 0 asymmetry. HFAG average:

6. 6/2/2015 Attila Mihalyi - Wisconsin 6 Prospects of  from B →  Both tree and penguin processes contribute. Time dependent decay rate: S: CPV in interference between mixing and decay C: direct CPV  C,  S: parameters related to  not being a CP eigenstate. A CP : asymmetry between     and     Babar Results from 113 fb -1 with a quasi-2-body approach. (Select the  bands on the Dalitz plot)  is not a CP eigenstate: PRL 91 201802 (2003)

7. 6/2/2015 Attila Mihalyi - Wisconsin 7  Isospin Analysis Neutral and charged B decay amplitudes: Construct an SU(2) pentagon relationship to solve for  : Lipkin, Nir, Quinn, Snyder, PRD 44, 1454,1991 Even in the absence of penguins there’s an eightfold ambiguity on   Analysis is complicated by penguins (  eff ) and the non-CP eigenstates No model independent constraints yet on  from B →  The next step is a full Dalitz analysis. (Quinn-Snyder, PRD 48, 2139, 1993)

8. 6/2/2015 Attila Mihalyi - Wisconsin 8 Prospects of  from B →  Both tree and penguin amplitudes contribute. If no penguins:With penguin contributions: Using the Grossman-Quinn bound to limit  =|  -  eff | B 0 →     branching ratio is small compared to B + →     ! Decay is penguin dominated. Penguin Tree

9. 6/2/2015 Attila Mihalyi - Wisconsin 9 The B →  decay B 0   +  - is a VV-decay  The decay can proceed through 3 partial waves: S (L=0, CP even), P (L=1, CP odd), D( L=2, CP even) 3 helicity amplitudes: =0 → longitudinal polarization. Pure CP even eigenstate. = ±1→ transverse polarization. Mix of CP even and odd eigenstates. The decay B 0   +  - has been observed at BaBar and its BR and polarization measured: (PRD 69, 031102 (2004) and hep-ex/0404029, submitted to PRL) B 0   +  - is an excellent candidate for measuring  § Longitudinally saturated § Relatively large BR § Small penguin pollution § Two charged tracks in the decay for vertexing

10. 6/2/2015 Attila Mihalyi - Wisconsin 10 Analysis Strategy In a simultaneous fit we measure: signal yield, polarization, C long and S long.. Use a Maximum Likelihood fit to model: True-signal, Misreconstructed signal (42% long., 15% trans.), Continuum and 17 B-background modes. B-background: 209 decay modes simulated. Dominant modes: Simple assumptions  § We neglect interference with other decays to         final states (includes non-resonant contributions). § I=1 decay amplitudes are also neglected. I=1 absent due to Bose statistics but reintroduced by the finite    (Falk, Ligeti, Nir, Quinn, Phys. Rev. D69:011502,2004)

11. 6/2/2015 Attila Mihalyi - Wisconsin 11 B →   Signal Selection Also use the  -mass and  -decay angle (helicity) to distinguish signal from background. B-decay: isotropic Continuum qq: jet-like Combine event shape variables into a Neural Network. Events with clean tags. B-mass:Missing energy: Full likelihood Background Data

12. 6/2/2015 Attila Mihalyi - Wisconsin 12 Results: Babar result from 81fb -1 of data (taken between 1999-2001) Submitted to PRL hep-ex/0404029 Recent preliminary Babar result from 113fb -1 of data (presented at Moriond EW):

13. 6/2/2015 Attila Mihalyi - Wisconsin 13 Global CKM Fits More plots at: http://ckmfitter.in2p3.fr Can’t exclude a large  region with . Includes the Belle B →  result. The B →  system provides the most stringent constraint on  ! Other B →   used in the SU(2) analysis. Includes Belle

14. 6/2/2015 Attila Mihalyi - Wisconsin 14 Summary No significant constraint on  from B→   Non optimal B 0 →     BR (large penguins). B→  quasi-2-body analysis performed but no model-independent constraints on   Non-CP eigenstate and penguins not under control. B →  provides the most stringent constraint on . This analysis has been carried out at BaBar, and the result is (with some simple assumptions):