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NEW CHARM RESULTS FROM FOCUS

NEW CHARM RESULTS FROM FOCUS. Stefano Bianco Laboratori Nazionali di Frascati dell’INFN La Thuile - March 3 rd , 2004. OVERVIEW. Measurement of masses and widths of excited charm mesons, and evidence for broad states J.M.Link et al. (FOCUS Coll.) hep-ex/0312060 accepted by Phys.Lett.B

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NEW CHARM RESULTS FROM FOCUS

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  1. NEW CHARM RESULTS FROM FOCUS Stefano Bianco Laboratori Nazionali di Frascati dell’INFN La Thuile - March 3rd, 2004

  2. OVERVIEW • Measurement of masses and widths of excited charm mesons, and evidence for broad states J.M.Link et al. (FOCUS Coll.) hep-ex/0312060 accepted by Phys.Lett.B • Measurement of Ds+fm+n formfactors J.M.Link et al. (FOCUS Coll.) hep-ex/0401001 accepted by Phys.Lett.B • K-matrix analysis of charm mesons Dalitz plots J.M.Link et al. (FOCUS Coll.) hep-ex/0312040 accepted by Phys.Lett.B Sorry, no time to report on these 2003-2004 results: • Measurements of six body hadronic decays of the D0 charmed meson. By FOCUS Collaboration [hep-ex/0401019] • Charm - anti-charm baryon production asymmetries in photon nucleon interactions. By FOCUS Collaboration Phys.Lett.B581:39-48,2004 • Study of hadronic five body decays of charmed mesons involving K0(S). By FOCUS Collaboration [hep-ex/0310051] • Study of the decay mode D0 ---> K- K- K+ pi+. By FOCUS Collaboration Phys.Lett.B575:190-197,2003. [hep-ex/0308054] • Search for rare and forbidden three body dimuon decays of the charmed mesons D+ and D(s)+. By FOCUS Collaboration Phys.Lett.B572:21-31,2003. [hep-ex/0306049] • Measurements of Xi(c)+ branching ratios. By FOCUS Collaboration Phys.Lett.B571:139-147,2003. [hep-ex/0305038] • Studies of correlations between D and anti-D mesons in high-energy photoproduction. By FOCUS Collaboration Phys.Lett.B566:51-60,2003. [hep-ex/0305018] • Measurement of the Omega0(c) lifetime. By FOCUS Collaboration Phys.Lett.B561:41-48,2003. [hep-ex/0302033] La Thuile 2004

  3. Spectrometer at FERMILAB Wide Band Photon Beam Over 1 million reconstructed! Successor to E687. Designed to study charm particles produced by ~200 GeV photons using a fixed target spectrometer with updated Vertexing,Cerenkov,EM Calorimeters, and Muon id capabilities. Member groups from USA, Italy, Brazil, Mexico, Korea. DATA COLLECTED IN 1996-1997 La Thuile 2004

  4. Charmed mesons spectroscopy chart (ante Spring 2003) SQ Sq L In the heavy-quark limit, the heavy-quark spin SQ and the total angular momentum of the light-quark jq=L+S are conserved Each level is composed of a degenerate doublet of states with the same jq and total angular momentum J=jq± ½. jq=½ states are predicted to be broad (100-200MeV width). THIS PICTURE QUESTIONED BY BABAR AND CLEO DISCOVER OF Dsj. For a recent review see SB Fabbri Benson Bigi Hep-ex/0309021 La Thuile 2004

  5. Measurement of masses and widths of excitedcharm mesons, and evidence for broad statesJ.M.Link et al. (FOCUS Coll.) hep-ex/0312060 accepted by Phys.Lett.B • Processes studied: • gN  D0p++ X, D0K-p+,K-p+p+p- • gN  D+p-+ X, D+K-p+p+ • Feeddowns: • D1+(jq=3/2)D*0p+, D*0D0(p0,g) • D2*+D*0p+, D*0D0(p0,g) • D1+(jq=1/2)D*0p+, D*0D0(p0,g) La Thuile 2004

  6. D and D* sample • Processes studied: • gN  D0p++ X, • D0Kp • D0 Kppp • gN  D+p-+ X, • D+Kpp • Remove Dp combinations from D* La Thuile 2004

  7. D0p+and D+p- mass distributions Feed down from D2*, D1 partial reconstruction Feed down from D2*, D1 partial reconstruction Entries / 10 MeV/c2 Entries / 10 MeV/c2 Combinatoric background Wrong sign Wrong sign M(D+p--)-M(D+)+1.8693 (GeV/c2) M(D0p+)-M(D0)+1.8646 (GeV/c2) Shorthand:DM0 Shorthand: DM+ La Thuile 2004

  8. Fitting D0p+and D+p- mass distributions • D-wave fixed • to PDG D2* mass and • width 2. D-wave free fit parameter Bad fits, excess of events between D2* and the feeddowns La Thuile 2004

  9. Fitting D0p+and D+p- mass distributions • Add S-wave • Fit cl=22% now • Recompute the • feeddown lineshape • using the D2* parameters • measured in Step 3. • Fit cl=28% now La Thuile 2004

  10. Significance of S-wave excess The broad excess observed could be the broad state D0*, or the feeddown from a broad D1 state goto feedown list . La Thuile 2004

  11. RESULTS Errors on D2* masses and widths smaller than or equal to PDG03 Agreement with the recent BELLE result (hep-ex/0307021). La Thuile 2004

  12. SYSTEMATICS STUDIES I La Thuile 2004

  13. SYSTEMATICS STUDIES II • Background shapes: • (E687) • (L3) La Thuile 2004

  14. THIS RESULT AND THEORY PREDICTIONSPredicted mass differences with respect to the D meson compared to this result La Thuile 2004

  15. New measurements of the Ds+fm+nform factor ratios J.M.Link et al. (FOCUS Coll.) hep-ex/0401001 accepted by Phys.Lett.B • A long-standing problem: the form factor ratios rv and r2 describing D+K0*m+n should be close to Ds+fm+n since only difference is a spectator quark d replaced with a s • Lattice gauge calculations: max diff= 10% • Experiment: • rv OK • r2 inconsistent (3.3s). ??? La Thuile 2004

  16. Form factor formalism for Ds+fm+n Ds+ s s La Thuile 2004

  17. Searching for s-wave interference in fmn FOCUS published observation for a very strong s-wave interfering with p-wave in the Kpsystem forDK*mn NO evidence for s-wave interference in Dsfmn events cos qV dataccbar mc events cos qV events cos qV data K*mn K*mn fmn La Thuile 2004

  18. The mKK distribution for Ds+K-K+m+n candidates Data (solid) and cc background MonteCarlo (dashed). Main background from D+K-K+p+ where a pion is misidentified as a muon La Thuile 2004

  19. Comparing data and model Histogram:data- dots:model-dashed histogram: cc Montecarlo La Thuile 2004

  20. RESULTS rv=1.549 ± 0.250 ± 0.145 r2=0.713 ± 0.202 ± 0.266 • Most precise measurement to date • very consistent with D+K0*m+n • very consistent with expectation that the form • factors for the two processes should be very similar Solid green: world av. Ds+fm+n Dashed blue: world av. D+K0*m+n La Thuile 2004

  21. Form Factors D+K0*m+n and Ds+fm+n THIS RESULT La Thuile 2004

  22. DP analysis of Ds+ and D+ decay to p+p-p+ using the K-matrix formalism J.M.Link et al. (FOCUS Coll.) hep-ex/0312040 accepted by Phys.Lett.Bsee also : S.Malvezzi Workshop on B physics, Rome Italy January 15, 2004. • Dalitz plots have been proved to be a powerful tool in three-body decays, investigating • Resonant substructure • Interference patterns • Final state interactions • Relationships to light-meson spectroscopy • Traditionally, isobar formalism used • Decay amplitude is a sum of Breit-Wigner propagators • Breit-Wigner amplitudes for a resonance which is broad and overlaps with other resonances can be connected to the pole positions only through models of analytic continuation La Thuile 2004

  23. describes coupling of resonances to D known from scattering data K-matrix picture • The amplitude is written as a sum • The amplitude F takes care of S-wave component by integrating over the scattering amplitudes of the five virtual states pp, KK, hh, hh’, 4p La Thuile 2004

  24. pp-  KKn : * GAMS ppp0p0n,hhn, hh’n, |t|0.2 (GeV/c2) CERN-Munich * GAMS ppp0p0n, 0.30|t|1.0 (GeV/c2) * BNL pp  p0p0p0, p0p0h , p0hh pp  p0p0p0, p0p0h * p+p-  p+p- At rest, from liquid * Crystal Barrel pp  p+p-p0, K+K-p0, KsKsp0, K+Ksp- * Crystal Barrel At rest, from gaseous * Crystal Barrel At rest, from liquid np  p0p0p-, p-p-p+, KsK-p0, KsKsp- * Crystal Barrel At rest, from liquid E852 * p-pp0p0n, 0|t|1.5 (GeV/c2) To describe the scattering a global fit to all available data was performed “K-matrix analysis of the 00++-wave in the mass region below 1900 MeV’’ V.V Anisovich and A.V.Sarantsev Eur.Phys.J.A16 (2003) 229 La Thuile 2004

  25. FOCUS D s + p +p +p -analysis • Observe: • f0(980) • f2(1270) • f0(1500) Sideband Signal Yield Ds+ = 1475 50 S/N Ds+ = 3.41 La Thuile 2004

  26. Low mass projection High mass projection decay channel phase (deg) fit fractions (%) First fits to charm Dalitz plots in the K-matrix approach C.L fit 3 % La Thuile 2004

  27. p+ p- r p- p+ p+ p+ • No significant direct three-body-decay component • No significant r(770) p contribution Marginal role of annihilation in charm hadronic decays But need more data! La Thuile 2004

  28. D+ p +p +p - analysis Yield D+ = 1527 51 S/N D+ = 3.64 Sideband Signal La Thuile 2004

  29. K-matrix fit results C.L fit 7.7 % High mass projection Low mass projection decay channel phase (deg) fit fractions (%) No new resonance required not present in the scattering. La Thuile 2004

  30. SUMMARY AND CONCLUSIONS • New precise measurements of mass and widths of D2*+ and D2*0, with errors better than or equal to PDG03 • Evidence for broad states in D+p- and D0p+ final states • Puzzle of Ds+ fm+n form factors discrepancy solved with new precise measurement • First DP analysis of Ds+,D+ p +p +p -charm decays using K-matrix formalism • Use information from light-quark scattering experiments (five virtual channels considered pp, KK, hh, hh’, 4p). CONCLUSIONS: • Non-resonant components are described by known two-body S-wave dynamics • Negligible role of annihilation diagram in Ds  p +p +p – • Possible applications in Brp (not discussed here) • DP analysis of Ds+,D+ p +p +p -charm decays using traditional isobar model is also in progress to compare to K-matrix model. La Thuile 2004

  31. 2 3 3 r r | 1 2 1 How can we formulate the problem? The problem is to write the propagator for theresonance r For a well-defined wave with specific isospin and spin (IJ) characterized by narrow and well-isolated resonances, we know how. La Thuile 2004

  32. La Thuile 2004

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