Attila Mihalyi University of Wisconsin-Madison Recent results on the CKM angle a from BaBar DAFNE 2004, Frascati, Italy Attila Mihalyi University of Wisconsin-Madison 12/6/2018 Attila Mihalyi - Wisconsin

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’)=VCKM (d,s,b) Wolfenstein parametrization: Unitarity leads to: l=sinqC (Cabibbo angle) Independent parameters: l,r,h, A The angles of the triangle are related to CP–violation. 1 (r,h) b g a Measure a from CP-asymmetries in b→uud processes. B→pp, B→rp, B→rr 12/6/2018 Attila Mihalyi - Wisconsin

B-decay modes sensitive to a Time dependent asymmetry of a B-B system (h=p,r): where Decay amplitudes: T=Tree P=penguin aeff directly related to Shh Due to the presence of both tree and penguin amplitudes we have: The extraction of a is complicated by penguins! 12/6/2018 Attila Mihalyi - Wisconsin

Isospin analysis for B→pp and B→rr Two triangular (isospin) relations can be constructed from the decay amplitudes. M. Gronau, D. London, Phys. Rev. Lett., 65, 3381 (1990) d=0 if no penguins Unknowns: Decay amplitudes Observables: Branching ratios, CP asymmetries Solvable but a 4-fold ambiguity on a remains: Common base: EW penguins neglected One can set a limit on the shift from penguins, a-aeff (useful only if the B→ h0h0 BR is small): Gronau-London-Sinha-Sinha Phys. Lett. B514, 315 (2001) Y. Grossman, H. R. Quinn, Phys. Rev., D58, 017504 (1998) 12/6/2018 Attila Mihalyi - Wisconsin

Prospects of a from B0→p+p- 113 fb-1 of data Preliminary,LP03 From 81fb-1 of data, taken in 1999-2001: PRL 89 281802 (2002), PRL 91 021801 (2003) HFAG average: The B0→ p0p0 BR was recently measured at BaBar, PRL 91 241801 (2003), and also at Belle. BR comparable to B0→ p+p- and B+→ p+p0 but not large enough to measure the B0 - B0 asymmetry. Implies large penguin contributions: |a-aeff |<48o at 90% c.l. Not easy to get a from B→pp ! 12/6/2018 Attila Mihalyi - Wisconsin

Prospects of a from B→rp rp is not a CP eigenstate: Both tree and penguin processes contribute. Time dependent decay rate: S: CPV in interference between mixing and decay C: direct CPV DC, DS: parameters related to rp not being a CP eigenstate. ACP: asymmetry between r+p- and r-p+ Babar Results from 113 fb-1 with a quasi-2-body approach. (Select the r bands on the Dalitz plot) PRL 91 201802 (2003) 12/6/2018 Attila Mihalyi - Wisconsin

Lipkin, Nir, Quinn, Snyder, PRD 44, 1454,1991 rp Isospin Analysis Neutral and charged B decay amplitudes: Construct an SU(2) pentagon relationship to solve for a: Lipkin, Nir, Quinn, Snyder, PRD 44, 1454,1991 Even in the absence of penguins there’s an eightfold ambiguity on a. Analysis is complicated by penguins (aeff) and the non-CP eigenstates No model independent constraints yet on a, from B→ rp The next step is a full Dalitz analysis. (Quinn-Snyder, PRD 48, 2139, 1993) 12/6/2018 Attila Mihalyi - Wisconsin

Prospects of a from B→rr Penguin Both tree and penguin amplitudes contribute. If no penguins: With penguin contributions: Tree Using the Grossman-Quinn bound to limit Da=|a-aeff| Decay is penguin dominated. B0→r0r0 branching ratio is small compared to B+→r+r0 ! 12/6/2018 Attila Mihalyi - Wisconsin

Attila Mihalyi - Wisconsin The B→rr decay B0  + - 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: l=0 → longitudinal polarization. Pure CP even eigenstate. l=±1→ transverse polarization. Mix of CP even and odd eigenstates. The decay B0  + - has been observed at BaBar and its BR and polarization measured: (PRD 69, 031102 (2004) and hep-ex/0404029, submitted to PRL) B0  + - is an excellent candidate for measuring a: § Longitudinally saturated § Relatively large BR § Small penguin pollution § Two charged tracks in the decay for vertexing 12/6/2018 Attila Mihalyi - Wisconsin

Attila Mihalyi - Wisconsin Analysis Strategy In a simultaneous fit we measure: signal yield, polarization, Clong and Slong.. 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 p+p-p0p0 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 Gr.. (Falk, Ligeti, Nir, Quinn, Phys. Rev. D69:011502,2004) 12/6/2018 Attila Mihalyi - Wisconsin

Attila Mihalyi - Wisconsin B→rr Signal Selection B-decay: isotropic Continuum qq: jet-like Combine event shape variables into a Neural Network. Also use the r-mass and r-decay angle (helicity) to distinguish signal from background. Events with clean tags. B-mass: Missing energy: Full likelihood Background Data 12/6/2018 Attila Mihalyi - Wisconsin

Attila Mihalyi - Wisconsin 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): 12/6/2018 Attila Mihalyi - Wisconsin

Attila Mihalyi - Wisconsin Global CKM Fits More plots at: http://ckmfitter.in2p3.fr Other B→rr used in the SU(2) analysis. Can’t exclude a large a region with pp. Includes the Belle B→pp result. The B→rr system provides the most stringent constraint on a! Includes Belle 12/6/2018 Attila Mihalyi - Wisconsin

Attila Mihalyi - Wisconsin Summary No significant constraint on a from B→pp Non optimal B0→p0p0 BR (large penguins). B→ rp quasi-2-body analysis performed but no model-independent constraints on a Non-CP eigenstate and penguins not under control. B→rr provides the most stringent constraint on a. This analysis has been carried out at BaBar, and the result is (with some simple assumptions): 12/6/2018 Attila Mihalyi - Wisconsin