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Charmed Meson Spectroscopy

Charmed Meson Spectroscopy. Robert K. Kutschke Fermilab HQL04 June 4, 2004. For L=1:. Heavy-Light Mesons: Coupling Angular Mommenta. L. Spin of Q can be treated as a small perturbation. S q. q=u,d,s. Heavy Quark Symmetry (HQS):. S Q.

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Charmed Meson Spectroscopy

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  1. Charmed Meson Spectroscopy Robert K. Kutschke Fermilab HQL04 June 4, 2004

  2. For L=1: Heavy-Light Mesons: Coupling Angular Mommenta L Spin of Q can be treated as a small perturbation. Sq q=u,d,s Heavy Quark Symmetry (HQS): SQ jl = total angular momentum of the light degrees of freedom. Main features understood by treating jl as a good Q#! Heavy Quarks and Leptons. 2004

  3. P-Wave Charmed Mesons • For each of cd, cu, cs, expect two doublets: • Narrow doublet: • JP = ( 2+, 1+) • jlight = 3/2 • D(*)p decay: D wave. • G  O( 10 MeV ) • All well established. • Broad doublet: • JP = ( 1+, 0+) • jlight = ½ • D(*)p decay: S wave. • G  O( 100 MeV ) • First observations recently. Heavy Quarks and Leptons. 2004

  4. Cartoon of Dominant Decay Modes When permitted by conservation of Energy, J and P. Heavy Quarks and Leptons. 2004

  5. What’s Overly Simplified in the Ideal Picture? • Doublets may overlap ( which 1+ is more massive?) • Are all states above Dp and DK thresholds? • Is suppression of S wave widths complete? • Ds1 right at threshold for D*K: • Very narrow, G < 2.3 MeV/c2 @ 90% CL. • Data suggests mostly S-wave! Heavy Quarks and Leptons. 2004

  6. Where Were We at HQL02? • All data consistent with simple picture of HQS. • Narrow doublet well established: D0, D+, DS. • Broad states not observed ( except for an unpublished CLEO result ). • Delphi D’ still not confirmed by anyone. What’s New Since HQ&L 2002? • Observation of the expected broad DJ states. • Observation of two new narrow DSJ states which decay to DSp0 and DS*p0. • Are these the expected broad states ? Heavy Quarks and Leptons. 2004

  7. FOCUS’ Starting Point: D and D* Signals K-p+p+p- K-p+ K-p+p+ D*+D0p+ Heavy Quarks and Leptons. 2004

  8. FOCUS Phys. Lett. B586, 11-20 (2004) Feeddown: Neutrals are unobserved FOCUS BG Function: A,B,C,D Free parameters Horrible Fit! M(D0p+) Heavy Quarks and Leptons. 2004

  9. Same problem for M(D+p-): Horrible Fit FOCUS explored many BG models but all failed. FOCUS Idea: We expect a broad state so add one to the fit. Caveat: 2 broad states M(D+p-) Heavy Quarks and Leptons. 2004

  10. Add a single S-wave resonance to the fit. • Get excellent fit quality. • Fit is robust against many variations in background. • Yield of broad resonance: • 18754  2200 • 8.5 stnd. dev. • Relative yields of signals and feed-downs consistent with expectations. FOCUS Heavy Quarks and Leptons. 2004

  11. Add a single S-wave resonance to the fit. • Get excellent fit quality. • Fit is robust against many variations in background. • Yield of broad resonance: • 9810  2700 • 3.6 stnd. dev. • Relative yields of signals and feed-downs consistent with expectations. FOCUS Heavy Quarks and Leptons. 2004

  12. Changing of the Guard • To date all published measurements of D** come from inclusive measurements. • A more powerful way of doing charm spectroscopy is to look at the Dalitz plots in BD(*)pp Dalitz decays. • The penalty is small product branching ratios. • We have been waiting a long time for this. • Remember the power of D Dalitz plots for light quark spectroscopy. • CLEO CONF-99-6, unpublished, uses this technique but with partial reconstruction of the final state. • Last year Belle submitted the first use of this technique with full reconstruction. Heavy Quarks and Leptons. 2004

  13. Belle: hep-ex/0307021 To Appear in PRD. Good signal to background ratio. Delta E cut kills Feed-down. Heavy Quarks and Leptons. 2004

  14. Belle BD+pp Dalitz Plot Signal Region DE Sideband Heavy Quarks and Leptons. 2004

  15. Resonances Included: • Free M and G: • D2*(2460) • D0* • Virtual States: • B* • D*0D+p- • All have significant fit fractions. • Most new features established by interference effects. • No constant term in final fit. It does not improve the likelihood. Belle Heavy Quarks and Leptons. 2004

  16. Belle BD*+pp Dalitz Plot Signal Region DE Sideband Belle Belle Heavy Quarks and Leptons. 2004

  17. Resonances included: • D2*(2460) • Free M and G • D1(2420) • D1(broad) • Virtual States: • B* • D* • All have significant fit fractions. • Most new features established by interference effects. • No constant term in final fit. It does not improve the likelihood. Belle Heavy Quarks and Leptons. 2004

  18. Summary of D2* Data Heavy Quarks and Leptons. 2004

  19. Summary of Data for D1(2420)0 Heavy Quarks and Leptons. 2004

  20. FOCUS measurements are of an unknown superposition of D1*0 and D10. So it does not make sense to take an average of BELLE and FOCUS. Heavy Quarks and Leptons. 2004

  21. Summary of Charm Non-Strange Spectroscopy • Broad states have now been seen. • Above threshold for decay to D(*)p. • Masses and widths approximately as expected. • Angular distributions in the B Dalitz plots supports the conventional spin parity assignments: • D1(2427): 1+ • D0*(2308): 0+ • Mass ordering of the two 1+ states is not yet resolved. • More statistics will help, especially the broad states. Heavy Quarks and Leptons. 2004

  22. Could this be the DS*0? Mass is below most, but not all predictions, Nowak, Rho and Zahed, PRD 49, 4370 (1993). Bardeen and Hill, PRD 49, 409 (1994). A Surprise from BaBar: PRL 90, 242001 (2003) • Narrow peak in DSp0. • JP = natural • Width consistent with detector resolution, about 9 MeV. • Mass near 2317 MeV. • About 40 MeV below DK threshold. • Second state near 2456? BABAR 91 fb-1 + M(DSp0) Heavy Quarks and Leptons. 2004

  23. Where to Look if DK and D*K are Forbidden Isospin violating! Cho and Wise, PRD 49, 6228 (1994) mixing Heavy Quarks and Leptons. 2004

  24. Ds* signal region 55±10 events Ds* sideband region CLEO Sees Two States • Confirms BaBar state at 2317 MeV. • Establishes new state near 2460 MeV. Heavy Quarks and Leptons. 2004

  25. Belle Confirms Both States Ds sidebands * M(Ds+π0 )-M(Ds+) M(Ds*+π0 )-M(Ds*+) Sidebands: DS solid, p0 dashed. Heavy Quarks and Leptons. 2004

  26. A Conspiracy ! • Feed-down: • DS(2460)  DS*p0 (DS*g)p0 • Miss gamma and reconstruct as: DSp0 • Makes a narrow peak near 2317 MeV. • Feed-up: • DS(2320)  DSp0. • Add a random photon and require that DSg combination fall in DS* mass region. Plot mass of DSgp0 combinations. • Makes a narrow peak near 2460 MeV. • Most signal are about 75% pure and 25% feed up/down. • CLEO, BaBar, Belle: different methods to deconvolve. Heavy Quarks and Leptons. 2004

  27. Example: BaBar’s Method Points: M(DSg) in DS* region. Shaded: DS* sideband Subtract distributions on the right. Heavy Quarks and Leptons. 2004

  28. Belle: Two New Decay Modes of DS(2460) DS*(2112) DS(2320) DS(2460) DS1(2536) ! Histogram: DS sidebands. Forbids J=0 Heavy Quarks and Leptons. 2004

  29. Belle: Sees the Decays BDDsJ Ds(2317)poDs 2+ Ds(2460)poDs* 1+ Ds(2460)gDs DS in B Frame DSJ Frame Histograms: DE sidebands DS Heavy Quarks and Leptons. 2004

  30. Focus Sees DS(2317) in Photoproduction • Histograms: DS and p0 sidebands. • First observation outside of e+e- at 10 GeV. • M = 2323  2 MeV ( stat only; uses PDG DS mass). • About 2 sigma above average of other experiments. • Width consistent with detector resolution. • Energy calibration: DS*DSp0 and D0 K-p+p0. Heavy Quarks and Leptons. 2004

  31. Some Suggestions? • HQS plus chiral symmetry explain low masses below DK threshold. • Bardeen, Eichten & Hill hep-ph/0305049. • Nowak, Rho & Zahed hep-ph/0307102. • DK molecule • Barnes, Close & Lipkin hep-ph/0305025 • Mixture with 4-quark state above DK threshold • Browder et al. hep-ph/0307054 • Unitarized meson model • Van Beveran & Rupp hep-ph/0305049 • Masses using QCD Sum Rules • Dai, Huang & Zhu hep-ph/0306274 Heavy Quarks and Leptons. 2004

  32. Some Suggestions? • Can the lattice explain these as csbar states? • No: Bali hep-ph/0305049, • Yes: Dougall et al hep-ph/0307001 • On the importance of radiative decays: • Colangelo & De Fazio hep-ph/0305140 • Godfrey hep-ph/0305122 • Branching Fractions in B decay DDSJ are much smaller than for DDS. Factorization suggests that they should be similar. Is this a sign of non c-sbar nature? • Chen and Li hep-ph/0307075 • Datta and O’donnel hep-ph/0307106 • Cheng and Hou hep-ph/0305038 Heavy Quarks and Leptons. 2004

  33. Miscellany • No signals seen in DSp ( CLEO and CDF ). • Excludes some molecule interpretations. Heavy Quarks and Leptons. 2004

  34. Summary of New DS States M=2459.2  1.1 MeV M=2317.6  0.8 MeV G < 4.6 MeV (90% CL) G < 5.5 MeV (90% CL) JP=0+ Favored JP=1+ Favored Heavy Quarks and Leptons. 2004

  35. An Important Measurement to Do • Set the scale of the partial widths. This will help sort out competing models. • Hard to impossible with g and p0 final states. • An idea: • Measure the width of the DS1(2536). • Better measurements of DS1(2536) DSpp. • Measure: DS1(2536) DS(*)g. • This can calibrate the models which can then be applied to the 0+ and 1+ states. Heavy Quarks and Leptons. 2004

  36. What’s Interesting to do Next • Increase statistics on BD(*)pp Dalitz plot analyses. • Improve measurements of the broad states and find charged broad 1+ state. • Look for new states. • Discover DS2 D*K. • Dalitz plot analyses of B decays with DSJ in final state. • This will be hard and require lots of data but Belle has shown that it is not out of the question. • CDF, D0, LHC-b and BTeV. • Combinatoric BG kills inclusive measurements. • Should do well with analysis of B Dalitz plots. Heavy Quarks and Leptons. 2004

  37. Summary and Conclusions • The charmed-non-strange P-wave broad states are established with their expected properties. • Waiting for BaBar’s results. • Can CDF and D0 compete here?. • The charmed-strange “broad” states are really strange. They are narrow! • Below threshold for decay to D*K so they appear in unexpected decay modes, DS*p0, DSg and DSpp. • Their JP are constrained but not fully determined. • Lots still to do. Especially important to establish the widths of the narrow states. Heavy Quarks and Leptons. 2004

  38. Observation of the Ds2* at Focus D0K+ D+KS0 First observation of the D+KS0 mode! FOCUS Preliminary There are some real KS0 in the sideband sample. Heavy Quarks and Leptons. 2004

  39. Simultaneous Fits to D0K+ and D+KS0 Spectra Preliminary Terms in the fit: • DS2 Signal: D-wave Rel. BW • Smooth background shape • MC DS1 feeddown shape • MC DS2 feeddown shape. Significance is not stable with cut variations! • Simultaneous: M and G same. • Errors are statistical only PDG: M = 2573.5 ± 1.7 MeV/c2 G = 15 ± 5 MeV/c2 First observation of D+KS0 mode Heavy Quarks and Leptons. 2004

  40. Observation of the DS1 at FOCUS Terms in the fit: Preliminary • DS1 Signal: Non Rel BW, convoluted with a gaussian. • Smooth background shape. • DS2* Signal: D-wave Rel BW. • Errors are statistical only PDG: D = 525.35 ± 0.34 MeV/c2 G < 2.3 MeV/c2 @ 90 % CL. M(D*+Ks0)-M(D*+) Heavy Quarks and Leptons. 2004

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