Princeton University, Department of Physics Jadwin Hall, Washington Rd. Princeton, NJ , U.S.A. XXXIII International Conference on High Energy Physics Moscow, Russia Session 8: CP violation, Rare decays, CKM Friday, July 28, 2006, 10:06 Alexandre V. Telnov Princeton University for the BaBar Collaboration Measurements of the CP angle  with the BaBar experiment

Alexandre V. Telnov (Princeton University) Measurements of the CP angle  with the BaBar experiment 2 Current BaBar dataset: 347 million BB pairs (±1.1%) _ Theoretical and experimental introduction to the CKM angle  New BaBar results; their interpretation and implications for  : B →  +  −,  ±  0,  0  0 B →  0  0,  ±  0,  +  − B 0 → (  ) 0 Summary and outlook Outline

Alexandre V. Telnov (Princeton University) Measurements of the CP angle  with the BaBar experiment 3 Penguin Measuring  A CP (t) in decay to a CP eigenstate at the tree level : Measure Penguins: A CP (t )  sin(2  eff );  eff =    Δ  direct A CP ≠ 0 Tree

Alexandre V. Telnov (Princeton University) Measurements of the CP angle  with the BaBar experiment 4 Isospin analysis in B → , ρρ In B → ρρ, there are 3 such relations (one for each polarization) M. Gronau, D. London, Phys. Rev. Lett. 65, 3381 (1990) Neglecting EW penguins, ±0 is a pure tree mode, and so the two triangles share a common side: 4-fold ambiguity in 2 Δ  : either triangle can flip up or down 6 unknowns, 6 observables in  (there is no vertex to measure S  0  0 ) 5 observables in  (or 7, when both C  0  0 and S  0  0 are measured)

Alexandre V. Telnov (Princeton University) Measurements of the CP angle  with the BaBar experiment 5 The B 0 →  +  − analysis Simultaneous ML fit to B 0 →  +  −, K +  −,  + K −, K + K − Using DIRC Cherenkov angle to separate pions and kaons Additional  / K  / KK separation from ΔE Also measure A K +  − : see talk by Emanuele Di Marco at 12:12 today DIRC: 144 quartz bars 0.84 x 4 π coverage; 97% 3 GeV/ c 12 σ  /K separation at 1.5 GeV/ c, 2 σ at 4.5 GeV/ c Calibration sample: B − →  − D 0, D 0 →  + K −

Alexandre V. Telnov (Princeton University) Measurements of the CP angle  with the BaBar experiment 6 New BaBar results: B 0 →  +  − New BaBar results: B 0 →  +  − (1) signalbackground m ES ΔtΔt ΔtΔt M. Pivk and F. R. Le Diberder, “ sPlot: a statistical tool to unfold data distributions,” Nucl. Instrum. Meth. A 555, 356 (2005) [arXiv:physics/ ]. B 0 tags _ asymmetry BaBar-CONF-06/039 N  +  − = 675 ± 42 s Plot: Builds a histogram of x excluding it from the Maximum- Likelihood fit, assigning a weight to each event, keeping all signal events, getting rid of all background events, and keeping track of the statistical errors in each x bin

Alexandre V. Telnov (Princeton University) Measurements of the CP angle  with the BaBar experiment 7 New BaBar results: B 0 →  +  − New BaBar results: B 0 →  +  − (2) 3.6 σ BaBar has observed a 3.6 σ evidence for CP violation in B 0 →  +  − S  = −0.53 ± 0.14 ± 0.02 C  = −0.16 ± 0.11 ± 0.03 (S,C) = (0.0, 0.0) is excluded at a confidence level of (3.6 σ) BaBar-CONF-06/039

Alexandre V. Telnov (Princeton University) Measurements of the CP angle  with the BaBar experiment 8 The B →  ±  0,  0  0 analysis Simultaneous fit to B 0 →  +  0, K +  0 (using DIRC Cherenkov angle to separate pions and kaons) B 0 →  0  0 : branching fraction and time-integrated direct CP asymmetry new: in addition to  0 → , we use merged  0 and  → e + e − conversions  10% efficiency increase per  0 (4% from merged  0, 6% from  conversions) merged  0 : the two photons are too close to one another in the EMC to be reconstructed individually; can be recovered using, where S is the second EMC moment of the merged  0 →  The control sample:  →   → e + e − conversions: result from interactions with detector elements DCH inner wall SVT outer layers

Alexandre V. Telnov (Princeton University) Measurements of the CP angle  with the BaBar experiment 9 New BaBar results: B →  ±  0,  0  0 m ES ±0±0 0000 N  0  0 = 140 ± 25N  ±  0 = 572 ± 53 C  0  0 = −0.33 ± 0.36 ± 0.08 Br  0  0 = (1.48 ± 0.26 ± 0.12)  10 −6 Br  ±  0 = (5.12 ± 0.47 ± 0.29)  10 −6 B ± →  ±  0 background BaBar-CONF-06/039 s Plot

Alexandre V. Telnov (Princeton University) Measurements of the CP angle  with the BaBar experiment 10 Here is one of the possible solutions to the Gronau- London isospin triangle in B →  according to the central values of the latest BaBar results: An interpretation of the new B →  results ΔΔΔΔ This is a frequentist interpretation: we use only the B →  isospin-triangle relations in arriving at these constraints on Δ  =  −  eff and on  itself | Δ  | < 41º at 90% C.L. BaBar-CONF-06/039  = 0 excluded at 1−C.L. = 4.4  10 − 5  near 0 can be disfavored by additional experimental information

Alexandre V. Telnov (Princeton University) Measurements of the CP angle  with the BaBar experiment 11 B →  angular analysis pure CP = +1 transverse is not a CP eigenstate “helicity frame” B →  is a vector-vector state; angular analysis is required to determine CP content: Fortunately, the fraction f L of the helicity-zero state in B →  decays is very close to 1: Heavy Flavor Averaging Group, April 2006 update: f L (B 0 →  +  − ) WA = −0.028 f L (B ± →  ±  0 ) WA = 0.96 ± 0.06

Alexandre V. Telnov (Princeton University) Measurements of the CP angle  with the BaBar experiment 12 ΔΕΔΕ m ES 0f00f0 0000 New BaBar results: Incremental improvements in the event selection and the analysis technique Results are statistically consistent with the previous BaBar analyses N  0  0 = ± 22 −31 Br  0  0 = ( ± 0.27)  10 −6 −0.36 f L (B 0 →  0  0 )= ± 0.05 −  evidence for B 0 →  0  0 The systematic error is dominated by interference with B 0 → a ± (1260)   and by PDF parameter uncertainties 1 BaBar-CONF-06/027 hep-ex/ , accepted by PRL Br (B 0 → a ± (1260)   )  Br ( a ± (1260) →    ±  ± ) = (16.6 ± 1.9 ± 1.5)  10 −6 1 1 Br (B 0 →  0 f 0 )  Br ( f 0 →  +  − ) < 0.68  10 −6 (at 90% C.L.) Br (B 0 → f 0 f 0 )  Br 2 ( f 0 →  +  − ) < 0.33  10 −6 (at 90% C.L.) Also measure:

Alexandre V. Telnov (Princeton University) Measurements of the CP angle  with the BaBar experiment 13 New BaBar results: B ± →  ±  0 ΔΕΔΕ Br  ±  0 = (16.8 ± 2.2 ± 2.3)  10 −6 The systematic error is dominated by modeling of backgrounds, signal misreconstruction, and by statistical PDF uncertainties m ES continuum + BB backgrounds N  ±  0 = 390 ± 49 B A B AR preliminary B A B AR preliminary Based on 232 million BB pairs; BaBar-PUB-06/052 _ Phys. Rev. Lett. 91, (2003) Phys. Rev. Lett. 91, (2003) PDG 2004: (26 ± 6)  10 −6 Belle: (31.7 ± )  10 −6 Previous BaBar : ( ± 5.8 )  10 −6 − 6.7 − 5.4 } −/√2 “before”: old  ±  0 WA isospin prediction f L (B ± →  ±  0 ) = ± −0.027 The new BaBar measurement in B ± →  ±  0 allows the  isospin triangle to close

Alexandre V. Telnov (Princeton University) Measurements of the CP angle  with the BaBar experiment 14 Br (B 0 → a ±   )  Br ( a ± →  +  −  ± ) < 30  10 −6 (90% C.L.) 1 1 B 0 tags _ asymmetry Δt (ps) New BaBar results: B 0 →  +  − N  +  − = 615 ± 57 f L (B 0 →  +  − ) = ± −0.013 S long = −0.19 ± −0.07 Br  +  − = (23.5 ± 2.2 ± 4.1)  10 −6 C long = −0.07 ± 0.15 ± 0.06 dominated by self-crossfeed distributions for the highest-purity tagged events m ES sum of backgrounds ΔΕΔΕ m±0m±0  helicity BaBar-CONF-06/016 B A B AR preliminary reduced systematics thanks to hep-ex/ , accepted by PRD

Alexandre V. Telnov (Princeton University) Measurements of the CP angle  with the BaBar experiment 15 As datasets increase, determination of both C and S will become possible in B 0 →  0  0, leading to an improvement in the precision of the the  isospin analysis BaBar-CONF-06/27, BaBar-CONF-06/016 An interpretation of the new B →  results This is a frequentist interpretation: we use only the B →  branching fractions, polarization fractions and isospin-triangle relations in arriving at these constraints on Δ  =  −  eff and  ΔΔΔΔ | Δ  | < 21º at 90% C.L. | Δ  | < 18º at 68% C.L. B A B AR preliminary  [74, 117]º at 68.3% C.L. B A B AR preliminary Due to the new B 0 →  0  0 BF result, the constraint on  from B →  has become less stringent

Alexandre V. Telnov (Princeton University) Measurements of the CP angle  with the BaBar experiment 16 B 0 → (  ) 0 : Dalitz-plot analysis BaBar-CONF-06/037 and references therein  is not a CP eigenstate An isospin-pentagon analysis method exists but is not fruitful  Time-dependent Dalitz-plot analysis assuming isospin symmetry, measuring 26 coefficients of the bilinear form factors 0000 −− +−+− The  (1450) and  (1700) resonances are also included in this analysis Interference in the corners of the Dalitz plot provides information on strong phases between resonances A. Snyder and H. Quinn, Phys. Rev. D, 48, 2139 (1993)  00 ++     00 ++ Monte Carlo

Alexandre V. Telnov (Princeton University) Measurements of the CP angle  with the BaBar experiment 17 New BaBar results: B 0 → (  ) 0 New BaBar results: B 0 → (  ) 0 (1) m ES Δt/  (Δt) BaBar-CONF-06/037 ΔΕΔΕ NN output m'm'  ' ' data projection of the fit result signal misreconstruction expected B background continuum background minimum of the three di-pion invariant masses

Alexandre V. Telnov (Princeton University) Measurements of the CP angle  with the BaBar experiment 18 New BaBar results: B 0 → (  ) 0 New BaBar results: B 0 → (  ) 0 (2) S  = 0.01 ± 0.12 ± C  = ± ± ΔS  = 0.06 ± 0.13 ± ΔC  = ± ± parameters from the quasi-two-body description of B →  : a more physically intuitive way to represent direct-CP quantities: A  = −0.142 ± ± A  = 0.03 ± 0.07 ± −+− A  = − ± 0.07 −0.16 −+ BaBar-CONF-06/037 For results on Direct CP Violation, attend talk by Emanuele Di Marco at 12:12 today

Alexandre V. Telnov (Princeton University) Measurements of the CP angle  with the BaBar experiment 19 An interpretation of the new B 0 → (  ) 0 results + −+ −+ −+ − [5, 63]º at 68.3% C.L.  [75, 152]º at 68.3% C.L. no constraint at 2 σ level BaBar-CONF-06/037  + − = arg(A +* A − ) : the relative phase between the amplitudes of B 0 →  −  + and B 0 →  +  − The constraint on  from B 0 → (  ) 0 is relatively weak – but free from ambiguities!

Alexandre V. Telnov (Princeton University) Measurements of the CP angle  with the BaBar experiment 20 Recap of new results Br (B 0 → a ± (1260)   )  Br ( a ± (1260) →    ±  ± ) = (16.6 ± 1.9 ± 1.5)  10 −6 1 1 Br (B 0 → a ±   )  Br ( a ± →  +  −  ± ) < 30  10 −6 (90% C.L.) 1 1 Br  0  0 = ( ± 0.27)  10 −6 First evidence, at 3.0  −0.36 f L (B 0 →  0  0 )= ± 0.05 −0.13 Br  ±  0 = (16.8 ± 2.2 ± 2.3)  10 −6 f L (B ± →  ±  0 ) = ± −0.027 S  = −0.53 ± 0.14 ± 0.02 C  = −0.16 ± 0.11 ± 0.03 CP violation at 3.6  Br  ±  0 = (5.12 ± 0.47 ± 0.29)  10 −6 Br  0  0 = (1.48 ± 0.26 ± 0.12)  10 −6 C  0  0 = −0.33 ± 0.36 ± 0.08 f L (B 0 →  +  − ) = ± −0.013 Br  +  − = (23.5 ± 2.2 ± 4.1)  10 −6 B 0 → (  ) 0 : see page 18 S long = −0.19 ± −0.07  C long = −0.07 ± 0.15 ± 0.06 

Alexandre V. Telnov (Princeton University) Measurements of the CP angle  with the BaBar experiment 21 CKM fit no  in fit °   [164, 176]º at 68.3% C.L. Global fits for the value of  CKMfitter Group (J. Charles et al.), Eur. Phys. J. C 41, (2005), [hep-ph/ ], updated results and plots available at M. Ciuchini, G. D'Agostini, E. Franco, V. Lubicz, G. Martinelli, F. Parodi, P. Roudeau, A. Stocchi, JHEP 0107 (2001) 013 [hep-ph/ ], updated results and plots available at Please see talks by S. T'Jampens (CKMfitter) and V. Vagnoni (UTfit) for details 97.5 °   [86, 114]º at 68.3% C.L. Two interpretations currently exist that convert the B → , ,  measurements to constraints on  : CKMfitter talk: 17:30 tomorrowUTfit talk: 17:48 tomorrow

Alexandre V. Telnov (Princeton University) Measurements of the CP angle  with the BaBar experiment 22 Summary and outlook The ability of existing B-meson factories to measure the angle  with a precision of a few degrees crucially depends on the developments in measuring the branching fractions and CP parameters in B 0 →  0  0 and B 0 →  0  0 The BaBar experiment has observed evidence of Time-dependent CP violation in B 0 →  +  − The decay process B 0 →  0  0 and improved the precision of other measurements related to the extraction of . The extraction of  depends significantly on the statistical and theoretical treatment; The larger of the CKMfitter and UTfit 68.3% C.L. intervals is   [86, 114]º (CKMfitter)