Measurements of the angles of the Unitarity Triangle at B A B AR Measurements of the angles of the Unitarity Triangle at B A B AR PHENO06 Madison,15-18 May 2006 PHENO06 Madison,15-18 May 2006 On behalf of the BaBar Collaboration Francesco Polci Universita’ degli Studi di Roma “La Sapienza” & INFN Roma Francesco Polci Universita’ degli Studi di Roma “La Sapienza” & INFN Roma

Unitarity of V CKM Unitarity Triangle The CKM matrix and the Unitarity Triangle The Standard Model explains the CP violation through the matrix V CKM 1 Francesco Polci UT Angles Measurements at BaBar

2 Improving  measurement Francesco Polci UT Angles Measurements at BaBar BABAR [PRL95, (2005),232M BB] Up to now the best channel for  determination is: 68% 90%

Measuring  in b → uud transitions Penguin contribution cannot be neglected (see which is pure penguin). That is why what we measure is  eff ! 3 Francesco Polci UT Angles Measurements at BaBar is measured analyzing the decays: Recently a proposal of determination of penguin effect in from SU(3) related decay, which should reduce the theoretical error on  ( hep-ph/ ). An isospin analysis allows to estimate the penguin contribution.

The decays B              are related by SU(2), thus we have isospin relations between amplitudes A +-, A +0, A 00  states can have I = 2 or 0, but gluonic penguins only contribute to I = 0 (  I = ½ rule). But  +  0 is pure I = 2, so only tree amplitude  |A +0 | = |A -0 | Gronau and London, Phys. Rev. Lett. 65, 3381 (1990) 4 Francesco Polci UT Angles Measurements at BaBar The  isospin analysis ~100% longitudinally polarized: New measurement of      NEW

DD 9.2  5 Francesco Polci UT Angles Measurements at BaBar New approaches:  from a 1 ? NEW Search for B 0 → a 1 (1260) +   B 0 → a 1 (1260) +   Interesting by itself since: - Little is known about the a 1 - Can test of factorization Signal has been observed! –Background to  –(in principle) sensitive to  hep-ex/

6 Francesco Polci UT Angles Measurements at BaBar Status of   = ( – 9 ) 0 (direct measurement, HFAG)  = (91.9 ± 5.5) 0 (indirect UTfit prediction from the other UT bounds) Up to now, if we combine all world measurements ( BaBar+Belle ), we can determine the Standard Model solution for  like this:

7 Francesco Polci UT Angles Measurements at BaBar Measurements of  BABAR [PRL94, (2005),227M BB] But B→J/  K S is the cleanest mode! Both theoretically: and experimentally (large branching ratio and clean signature). Charmonium: Charm (and charmonium):Penguin dominated: Many modes to measure  :

The color-suppressed tree has same weak phase as J/  K S. The b →d penguin has a different weak (and strong) phase respect to the tree. Penguin pollution causes deviations in the values of C and S parameters respect to J/  K s. Also a way for a model independent constraint on the penguin dilution within charmonium modes. 8 Francesco Polci UT Angles Measurements at BaBar The b→d penguin pollution UPDATE hep-ex/

New Physics could contribute in the loop. They are small effects, here more easily detectable since Tree is missing or negligible. Look for  sin2  ≠ 0 in many modes:  sin   sin2  9 Francesco Polci UT Angles Measurements at BaBar The b→s penguins: sin2  eff Theory prefers Examples of QCD factorization: Beneke - PL B620, 143 (2005) Cheng,chua,soni - PRD72, (2005) Experimental: J/  mode Experimental: penguin modes

Complicated analysis since: –f 0 /  overlap, BB background –Color-suppressed tree, but  sin2  expected to be small B0B0 B0B0 Asymmetry 10 Francesco Polci UT Angles Measurements at BaBar New results for sin2  eff  in b→s penguins Other searches: : first measurement ! UPDATE NEW hep-ex/

It is a penguin Allows to interpret and to put a bound on its  S. 11 Francesco Polci UT Angles Measurements at BaBar  :other searches Search for Searches for Can reduce theoretical uncertainty of Color Suppressed tree amplitudes for  ’ K s decays in SU(3)- based analysis [Gronau,Rosner,Zupan PLB596,107(2004)] Search for Confirmed from Belle. No signal for (unexpected). NEW hep-ex/ hep-ex/

12 Francesco Polci UT Angles Measurements at BaBar Measurements of  BABAR [PRL95, (2005),227M BB] Best method to  determination:

If common final state to D 0 and D 0 _ suppressed favored A(b→u) A(b→c) interference strong phase weak phase Critical parameter: (only2ambiguities) Three methods: D 0  CP modes(GLW) D 0 to common flavor state (ADS) D 0 Dalitz (GGSZ) 13 Francesco Polci UT Angles Measurements at BaBar  from DK decays

4 observables (A CP+-,R CP+- ) for three unknown (r B, ,  B ): New from BaBar: added D 0  K S , K S  131 CP+ 148 CP- 14 Francesco Polci UT Angles Measurements at BaBar Some issues: B → D  background D 0 CP have small BRs 8 ambiguities New results for the GLW Method NEW hep-ex/

V cb V * ud u,c,t V * ub V cd Favored Suppressed Interference and B 0 mixing To consider tag-side CP violation, fit for: a = 2r sin(2  ) cos (  ) c= cos(2  ) [2r sin(  )+2r’sin(  ’)] b = 2r’ sin(2  ) cos (  ’) Extract result from a, c lep and: 15 Francesco Polci UT Angles Measurements at BaBar sin(2  ) from B→D (*)  + 30% theoretical error on r (Due to use of SU(3) simmetry and W-exchange neglection) r(D  )= ± r(D *  )= ± r(D  )= ± % CL 68% CL Frequentist confidence level Small CP asymmetry (r~0.02)! |sin(2  +  )| > % C.L.) |sin(2  +  )| > % C.L.) UPDATE hep-ex/

6 sigma 5 sigma Decays proceeding through W-exchange diagrams. Allows a more precise estimation of the theoretical error on r from SU(3)-related decays D s (*)  But D s K smaller than before, so smaller r D  and less sensitivity! B 0 →D s *  and B 0 → D s * K observations. 16 Francesco Polci UT Angles Measurements at BaBar First observations for hep-ex/ NEW

V cb V ub r < 17 Francesco Polci UT Angles Measurements at BaBar Charge correlation allows to tag the B 0 : You can distinguish V ub from V cb and measure r! But no V ub observed… sin(2  ) from B 0 →D (*)0 K (*)0 NEW hep-ex/

18 Francesco Polci UT Angles Measurements at BaBar Two other approaches for  Unfortunately, didn’t find b  u ! - Strong phase difference accessed through Dalitz plot, so 8-fold  2-fold ambiguity. B  DK  - b  ucs decay includes color-allowed diagrams, so (possibly) large CP -violating effects. - Self-tagging. - First step: search for the ( b  u ) SU(3)- related decays D s (*) a 0(2) - Due to form-factor suppression in B  a 0(2) X, favored and suppressed amplitudes become comparable. B  D (*) a 0(2) NEW hep-ex/ hep-ex/ Again, V ub component is missing!

19 Francesco Polci UT Angles Measurements at BaBar Status of   = (65 ± 20) o &  = (-115 ± 20) o Combining all direct world measurements ( BaBar+Belle ):

Angles measurements are still being performed at BaBar both updating old results to the full available dataset and exploring new methods. Some satellites measurements have been performed, which provides a better understanding of old results. This field is sensitive to new physics effects, expecially in the penguin diagrams Measurements of the angles of the Unitarity Triangle contribute to the precise determination of the allowed region in the  plane. More results are expected to come in the future. 20 Francesco Polci UT Angles Measurements at BaBar Conclusions