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D m d , CP, CPT Results

This collaborative effort presents detailed measurements of Dmd and CPT violations, focusing on different modes of decay. The analysis includes Belle and BaBar results, systematics, uncertainty assessments, and the need for technical advancements. The study delves into indirect CP violation, mixing phenomena, and master equations for CPT. Explore the accurate event reconstructions, systematic evaluations, and implications for precise measurements.

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D m d , CP, CPT Results

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  1. From theCollaboration of Dmd, CP, CPT Results CKM2008: WG4Rome, Italy

  2. Introduction • Dmd measurements • Indirect CP violation measurements. • CPT violation measurements – dilepton mode • CPT violation measurements – hadronic mode (including Belle’s status and prospect on this issue) • Summary Contents

  3. The analysis procedure of the Dmd and CPT is quite compatible to the standard mixing-induced CP one. Analysis Procedure Brec e- e+ Recon. (4S) Btag Flavor tag Dz • Fully / partially reconstruct B decays • Measure proper-time difference: Dt • Determine Btag flavor and its ambiguity: q and w • Evaluate Dmd / CPT asymmetry from the Dt and q

  4. Predefinition of decay amplitudes • Predefinition of intermediate parameters • The most generic equation of the Dt distribution Master Equation for the Dt In BaBar’s paperh = a z: CPT-violatingparameter.

  5. Derivation from the master equation Dmd Measurement Opposite flavor Same flavor

  6. Belle (latest) • 152M BB pairs: D(*)-h+, D*ln • # of total neutral B used in the fit = 122349. • K.Abe et al., Phys. Rev. D71, 072003 (2005). • BaBar (latest) • 50k partially reconstructed D*ln events • B.Aubert et al., Phys. Rev. D73, 012004 (2006). Dmd Measurements _

  7. Event reconstruction • Vertex reconstruction,Flavor tagging, thenMaximum likelihood fit Dmd Measurement by Belle N=84,823 log lin For D*ln events N=37,562 cos qB,D*l: D*ln Mbc: D(*)+h- OF/SF asymmetrydistribution

  8. Systematic uncertainty Dmd Measurement by Belle Syst. and stat. errors getcomparable. This item may be improved ifthe track selection criteriatuned more… Due to uncertainty of componentfractions categorized inD**ln decay.

  9. Event reconstruction Vertex reconstruction,Flavor tagging, thenExtended maximumlikelihood fit Dmd Measurement by BaBar Opposite flavor Same flavor 50k signal events in total. Binomial factor to account for the expected SF/(OF+SF) fraction to the observed one.

  10. Systematic uncertainty Dmd Measurement by BaBar Syst. and stat. errors getcomparable as well. Quoted as “possible fit bias” In the Belle’s analysis. Similar amount. Both Belle and BaBar results indicate we need technicalbreak through to proceed further precise Dmd measurement.

  11. Dmd Average PDG2008 average Dmd = 0.5070.005 ps-1  

  12. Indirect CP Violation _ Mixing (1) B0 B0 Mixing (1) = Mixing (2) ? … yes: CP conservation … no: CP violation _ Mixing (2) B0 B0 Measurement or equivalently where p and q are defined in

  13. Belle • 78 fb-1: 92k same-charge dilepton events. • E.Nakano et al., Phys. Rev. D73, 112002 (2006). • BaBar • 200.8 fb-1: Dilepton and/or dipion events from D*ln decay. • B.Aubert et al., hep-ex/0607091 (2006). • DØ • 3M dilepton events. • E.Cheu et al., Nucl. Phys. Proc. Suppl. 170, 153 (2007). Indirect CP Violation – Cont’d

  14. CPT violating parameter z in mixing • Different notations of the z CPTViolation in Mixing CPT violation In BB mixing _ The z is a complex number.Non-zero z indicates the CPT violation in mixing. BaBar (z, q/p) Belle (q, f) 

  15. Applications of the master equation • CP eigenstate • Flavor specific final state (e.g.: B0 D-p+, B0  D+p- case) Master Equationof CPT Study Let ‘1’ for fully reconstructedside B, and ‘2’ for tag side B. TSI is ignored. _ _ DCSD and TSI are ignored. If DCSD is accounted for.

  16. Brec fCP (hCP = -1), Basc  flavor specific • Brec flavor specific, Basc  flavor specific Examples of Dt Distribution (log(y)) default Re(z) = +0.2 Im(z) = +0.2 DG/G = +0.2 DG/G = +0.2Im(z) = +0.2 default Re(z) = +0.2 Im(z) = +0.2

  17. Belle (latest) • 32 fb-1: 281k dilepton events. • N. Hastings et al., Phys. Rev. D67, 052004 (2003). • BaBar (latest) • 232M BB pairs: 11M dilepton event candidates. • B. Aubert et al., Phys. Rev. Lett. 96, 251802 (2006). CPT Measurements – Dilepton _

  18. Lepton charge determines B flavor. Lepton is primarily decayed from B B decay positions can be determined from the lepton track and an IP profile. Detector response can be precisely determined fromJ/yll events (with no secondary particle effect). Dilepton Event Analysis l1 n B1 D Interaction point profile Y D B2 Dz n l2

  19. Belle • 535M BB pairs: D(*)-h+, D*ln, J/yK0 • Not completed yet; Belle people are working on this issue now. • BaBar • 88M BB pairs:D(*)-h+, J/yK*(K+p-), J/yK0, J/yKL, y(2S)KS, cc1KS • B. Aubert et al., Phys. Rev. Lett. 92, 181801 (2004). CPT Measurements – Hadronic _ _

  20. Data set • 535M BB pairs • Decay modes (# of events including background) • D-p+(39,366), D*-p+(46,292), D*-r+(45,913) • D*ln(383,818) • J/yKS(7,713), J/yKL(10,966) • Monte Carlo data sets • Parameterized simulation (“toy MC”) – for linearity study. • GEANT full simulation – for detector response study, etc. • 3 times of the data set, 81 input parameter variations for each 3-sets. Status of Belle CPT –Hadronic _ Same sample as K.-F.Chenet al., PRL 98 031802.

  21. Extraction of CPT violating parameters • CPT fitter w/ event-by-event maximum likelihood method. • Parameters to be floated in the final fit:Re(z), Im(z), |q/p|, arg(q/p), DGd/Gd, Dmd,10 wrong-flavor-tag probabilities, and ~15 detector response parameters. • Linearity test with “Toy MC” • “Toy MC” indicates Im(z) and arg(q/p) cannot be determined simultaneously unless both CP-even and CP-odd are used. • Mathematically, this is due to the coefficient for a sin-term. • This effect causes biasedoutput from the likelihood fit. Status of Belle CPT –Hadronic Correlations btw. Im(z) and arg(q/p) J/yKS J/yKS+J/yKL

  22. Status of Belle CPT –Hadronic 270 “toy MC” sets with DGd/Gd=0and variant arg(q/p) and z. Pull  (output-input)/fit_error Mean shiftobserved Mean shiftcanceled arg(q/p) arg(q/p) Mean shiftobserved Mean shiftcanceled J/yKS J/yKS+ J/yKL Beside them, the linearity of DGd/Gd and Re(z) are found OK. Im(z) Im(z)

  23. Linearity test with GEANT full simulation • Going on; very preliminarily, no serious non-linearity is observed up to now. • Expected statistical error • e(Re(z)) < 0.027 • e(Im(z)) < 0.006 • Prospects • The Belle tries to obtain central values within this month. Status of Belle CPT –Hadronic ~ ~

  24. Both Dmd measurements by Belle and BaBar show the statistical uncertainties are comparable to the systematic ones. We need technical break through to access more precise measurement. • Indirect CP violation measurements by Belle, BaBar, and DØ indicate the |q/p| is consistent to unity. • CPT-violating parameter measurements with dilepton events by Belle and BaBar are reviewed. The one with hadronic event is only available by BaBar. Belle is making effort to update the numbers with 535M BB pairs. Summary _

  25. Backup

  26. Belle (latest) BaBar (latest) Mixing-Induced CP Violation K.-F.Chen et al., Phys. Rev. Lett.98, 031802 (2007). 535M BB pairs. _ B.Aubert et al., Phys. Rev. Lett.99,171803 (2007). 383M BB pairs. _ (hCP is CPeigenvalue.)

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