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Charm Dalitz Analyses at BaBar

Charm Dalitz Analyses at BaBar . Marco Pappagallo Durham IPPP & University of Warwick On behalf of BaBar Collaboration. Charm06, Beijing June 05-07, 2006. Outline. BaBar Detector D 0  K 0 K + K - decay and a 0 (980) meson Partial Wave Analysis Dalitz Plot Fit

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Charm Dalitz Analyses at BaBar

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  1. Charm Dalitz Analyses at BaBar Marco Pappagallo Durham IPPP & University of Warwick On behalf of BaBar Collaboration Charm06, Beijing June 05-07, 2006

  2. Outline • BaBar Detector • D0K0K+K- decay and a0(980) meson • Partial Wave Analysis • Dalitz Plot Fit • D0K0π+π- decay and CKM angle  • Dalitz Plot Fit (Isobar Model) • Dalitz Plot Fit (K-matrix Model) Phys.Rev.D72:052008,2005 Phys.Rev.Lett.95:121802,2005 hep-ex/0507101 Marco Pappagallo, Durham IPPP & University of Warwick

  3. D0K0K+K- decay and a0(980) meson Marco Pappagallo, Durham IPPP & University of Warwick

  4. Scalar mesons and D meson decays • On the experimental side: • Scalar mesons are difficult to resolve because of their large decay widths. • On the QCD theory side: • Scalar meson candidates are too numerous to fit in a single qq nonet. Some of them may be multiquark, KK or other meson-meson bound states. • Many models expect a glueball with mass in the range 1.5 - 1.8 GeV. • Large coupling to scalar mesons; • An initial state which is always defined: JP=0-; • Spectrum is not constrained by isospin and parity conservation. • D meson decays: • Charmed meson decays have unique features, making them a very powerful tool for light quark spectroscopy: Marco Pappagallo, Durham IPPP & University of Warwick

  5. a0/f0(980) mesons & D0K0K+K- decay There are experimental evidences that clearly indicate the existence of non-strange and strange content in f0(980) and in a0(980) mesons. Their quark content mixture is not understood yet. a0/f0(980) mesons lie close to the KK threshold which can strongly influence the resonance shape. A Flatte’ formula is usually used to parameterize these state but mass and coupling constant are still affected by large uncertainties The D0K0K+K- decay provides a tool to study these resonances in the final states KK Marco Pappagallo, Durham IPPP & University of Warwick

  6. D0K0K+K- decay selection 4σ Event selection uses: Sample = 12540 Events Purity = 97.3% @ 91.5 fb-1 • D* tagging procedure is two-fold useful: • Selection of high purity sample • D0 and K0 flavour set by the charge of the slow pion πs+ Presence of Doubly Cabibbo Suppressed contribution may lead to misidentification of K0 flavour. Marco Pappagallo, Durham IPPP & University of Warwick

  7. Partial Wave Analysis Large Forward-Backward Asymmetry variation with the K+K- mass due to interference between K+K- S-wave(a0(980)/f0(980)) and K+K-P-wave(Φ(1020)) Contribution due to a0(980)+ doesn’t overlap with the Φ(1020) region. A partial wave analysis in the low mass K+K- region allows the K+K- scalar and vector components to be separated resolving: S.U. Chung, Phys. Rev. D56, 7299(1997) Marco Pappagallo, Durham IPPP & University of Warwick

  8. Partial Wave Analysis Helicity angle θK Each event was weighted by the spherical harmonicY0ℓ(cos K) (ℓ=0,1,2) divided by its estimated efficiency. Marco Pappagallo, Durham IPPP & University of Warwick

  9. Simultaneous fit to P2, S2, φSP and m(K0K+) FREE Fixed to Crystal Barrel measurement A. Abele et al., Phys. Rev. D57, 3860(1998) • K+K- system: Φ(1020) and a0(980)0 • [No evidence of f0(980) (I=0) comparing K0K+ and K+K- (normalized) S-waves] • K0K+ system: a0(980)+ Marco Pappagallo, Durham IPPP & University of Warwick

  10. Result of a Partial Wave Analysis P2 S2 φSP gkk= 464 ±29(stat.) (MeV)1/2 Marco Pappagallo, Durham IPPP & University of Warwick

  11. Isobar model formalism D0 three-body decay D0ABC decaying through an r=[AB] resonance S. Kopp et al., Phys.Rev.D63:092001,2001 D0 three-body amplitude NR term(direct 3 body decay) a0, δ0, ar, δr : Free parameters of fit Relativistic Breit-Wigner a0(980)/f0(980) Angular distribution D and r Blatt-Weisskopfform factors Marco Pappagallo, Durham IPPP & University of Warwick

  12. Dalitz Plot Fit of D0K0K+K- Results of an unbinned maximum likelihood fit • Decay is dominated by D0K0a0(980)0, D0K0(1020) and D0K- a0(980)+ • DCS and f0(980) contributions consistent with zero • Presence of tail of a broad resonance (f0(1400)?) gkk= 473 ±29(stat.) ±40(syst.) (MeV)1/2 f0(980) parameters M. Ablikim et al., Phys.Lett.B607:243-253,2005 Marco Pappagallo, Durham IPPP & University of Warwick

  13. D0K0π+π- decay and CKM angle  Marco Pappagallo, Durham IPPP & University of Warwick

  14. D0K0+-decay & CKM angle γ bc transition bu transition i δB -i γ e e Vub Vcb γ can be measured from the interference between decays with bcus and bucs transitions Interference occurs when some final state is accessible by both D0 and D0Giri-Grossman-Soffer-Zupan: PRD68, 054018 (2003): Final state = Ks0π+π- Dalitz Plot Analysis 2 Schematic view of the interference |A-|2 = Simultaneous fit to the |A_(m-2, m+2)|2 and |A+(m-2, m+2)|2distributions to determine the CP parameters rB, δB and γfor each decay mode(B± D(*)0 K(*)±). Marco Pappagallo, Durham IPPP & University of Warwick

  15. D0K0π+π- decay selection Event selection uses: D0’s are required to result from a D* meson decay + Sample = 81496 Events Purity = 97% @ 91.5 fb-1 Analysis will be updated to the full data set Marco Pappagallo, Durham IPPP & University of Warwick

  16. Dalitz plot fit(Isobar Model) Isobar model resonances + Non resonant term DCS DCS DCS Fit requires two additional BW amplitudes but… …in this analysis the Dalitz amplitude is only a means to extract the CP parameters Total fit fraction = 1.24 χ2/dof3824/3022=1.27 γ systematic errors include a fit without ’s Marco Pappagallo, Durham IPPP & University of Warwick

  17. K-Matrix Model in ππS-wave K-Matrix formalism overcomes the main limitation of the BW model to parameterize large and overlapping S -wave ππ resonances. D0K0π+π-amplitude + + I.J.R. Aitchison, Nucl. Phys. A189, 417 (1972) + … Initial production vector Pj [I-iKρ]1j-1 Provided by scattering experiment 5 channels: 1=pp2=KK 3=multi-meson 4= hh5= hh´ V.V. Anisovitch, A.V Sarantev Eur. Phys. Jour. A16, 229 (2003) Marco Pappagallo, Durham IPPP & University of Warwick

  18. Dalitz plot fit (K-Matrix Model) K-Matrix model resonances + pp S-wave term DCS DCS DCS pp S-wave term Value of 2 compatible with nominal model since it is dominate by the P-wave components, which are identical between the two model Total fit fraction = 1.16 Marco Pappagallo, Durham IPPP & University of Warwick

  19. Influence of Dalitz model on γ γ=(67 ± 28stat ± 13syst ± 11Dalitz)0 • Remove combinations of higher K* and ρ resonances (with low fit fraction) • Change the functional form of the resonance shapes • Fit without the σ and σ’ • ππ S-wave described by K-matrix model Small effect: 30 Marco Pappagallo, Durham IPPP & University of Warwick

  20. Summary D0K0K+K- anda0(980) parameters • Partial Wave Analysis • Dalitz Plot Fit • Measurement of the coupling gKK of a0(980) to the KK system • Small contribution of DCS and f0(980)KK decays D0K0π+π- and CKM angle γ • Dalitz Plot Fit with an Isobar model • Dalitz Plot Fit with a K-matrix model • Small effect on γmeasurement due to IsobarK-matrix model Charm Dalitz plot analyses will continue to play an important rule: measurement of resonances parameters, investigation of controversial scalar mesons, D0-D0 mixing,… Marco Pappagallo, Durham IPPP & University of Warwick

  21. Back up slides

  22. PEP II and BaBar (e+e-cc) = 1.3 nb 450M cc pairs! Marco Pappagallo, Durham IPPP & University of Warwick

  23. B+K+K-K+ Dalitz Plot Marco Pappagallo, Durham IPPP & University of Warwick

  24. B+K+K-K+ Dalitz Plot Marco Pappagallo, Durham IPPP & University of Warwick

  25. Partial Wave Analysis S.U. Chung, Phys. Rev. D56, 7299(1997): Marco Pappagallo, Durham IPPP & University of Warwick

  26. Partial Wave Analysis Dalitz Plot Projection (1020) reflection Marco Pappagallo, Durham IPPP & University of Warwick

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