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Charm ...the issues

Charm ...the issues. Lifetime Rare decays Mixing Semileptonic sector Hadronic decays (Dalitz plot) Leptonic decays Multi-body channels (4,5,6 bodies!) Charm Baryons D* spectroscopy. A brief review of the measurements. for each topic: summary of the present experimental situation

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Charm ...the issues

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  1. Charm ...the issues • Lifetime • Rare decays • Mixing • Semileptonic sector • Hadronic decays (Dalitz plot) • Leptonic decays • Multi-body channels (4,5,6 bodies!) • Charm Baryons • D* spectroscopy Charm results overview

  2. A brief review of the measurements for each topic: • summary of the present experimental situation • a comment about the next futurereach to be done • a more precise picture of the experimental status within 5 and 10 years • BaBar, Belle, Cleo-c, CDF, BEPC, LHC-b, BTeV Charm results overview

  3. Charm lifetimes Motivation: investigation of non-spectator processes • FOCUS (*) produced new lifetimes results with precision better • than the previous world average (○), PDG 2002. • Already at the level of comparison with theory. • Systematics will dominate Charm results overview

  4. Rare decays Motivation: lepton number violation study investigation of long range effects and SM extention FOCUS improved results by a factor of 1.7 –14: approaching theoretical predictions for some of the modes but still far for the majority CDF Br(D0m+m-)<2.4 x10-6 @ 90% C.L. is the best limit for this mode (65 pb-1 data) CDF and D0 can trigger on dimuons promising Charm results overview

  5. Mixing Motivation: suppressed in the charm sector in the SM. If “measured”, would suggest SM extention Future is @ Babar & Belle Charm results overview

  6. Summary of reach • Where we are and where we go Charm results overview

  7. The semileptonic sector Motivation: semileptonic decays are the easiest way to determine CKM elements Branching ratio FOCUS number is 1.59 standard deviation below CLEO and 2.1 standard deviation above E691 All values consistent with their average value with a CL of 19% Charm results overview

  8. D+ s d u u Nominal spectroscopic pole masses d ...and form factors The vector and axial form factors are generally parametrized by a pole dominance form Charm results overview

  9. form factors FOCUS analysis is the first to include the effects on the acceptance due to changes in the angular distribution brought about the s-wave interference Form Factor lattice calculations available! Charm results overview

  10. Br(Ds fmn/Ds fp) Charm results overview

  11. form factors • Most precise measurement to date • very consistent with D+K0*m+n • very consistent with th. expectation Cleo-c expects experimental error in most of the measurements in the sl sector in the range 1 to a few % Charm results overview

  12. Hadronic decay investigation A few slides follow about Dalitz plot analysis Charm results overview

  13. “Future” of hadronic decays Motivation: Investigation of decay dynamics via Dalitz plot analysis • Full observation of the decay (for three-body channels) • Learn about strong effects (but also a complication • for the analysis!) • CP investigation (see example of D±K K±p±) • Interplay between charm (and beauty) decays and light meson spectroscopy (very clean samples!) The analysis is difficult, need an analysis strategy to keep under control the strong effects accompanying the weak decays of Heavy Flavours! Charm results overview

  14. An instructive example from FOCUS analogy withoperatively: complete Dalitz plot analysis (time-dependent) to deal with all interference with other (pp)p intermediate channels Milano group crucial for determination of the angle a of the SM unitarity triangle Charm results overview

  15. 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 f0(980) signal is clean! Charm results overview

  16. Low mass projection High mass projection decay channel phase (deg) fit fractions (%) First fits to charm Dalitz plots in the K-matrix approach! Projections of the f0(980) signal C.L fit 3 % Charm results overview

  17. 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 A reliable measurements of the annihilation processes in the hadronic sector is still missing.... need more data! Charm results overview

  18. FOCUS D+ p +p +p - analysis Yield D+ = 1527 51 S/N D+ = 3.64 Sideband Signal Charm results overview

  19. decay channel phase (deg) fit fractions (%) K-matrix fit results C.L fit 7.7 % High mass projection Low mass projection Good channel to investigate the nature of the s meson (aka the s puzzle). No new ingredient (resonance) required not present in the scattering! Charm results overview

  20. C.L.~ 7.5% C.L.~ 10-6 Isobar analysis of D+ p +p +p would instead require a new scalar meson: s m = 442.6± 27.0 MeV/c G= 340.4 ± 65.5 MeV/c preliminary Withs Withouts Charm results overview

  21. Another interesting example from FOCUS D+, Ds KK Ds+ K+ K- p+ D+ K+ K- p+ Charm results overview

  22. Decay Fraction and phases K*(892) = 20.7  1.0 % (0 fixed) f(1020) = 27.8  0.7 % (243.1 5.2)° K*(1410) = 10.7  1.9 % (-47.4  4.9)° K*(1430) = 66.5  6.0 % (61.8  3.8)° f0(1370) = 7.0  1.1 % (60.0  5.3) ° a0(980) = 27.0  4.8 % (145.6  4.3)° f2(1270) = 0.8  0.2 % (11.6  7.0) ° f(1680) = 1.6  0.4 % (-74.3  7.5) ° Yield D+ = 7106 92 S/N D+ = 8.62 Preliminary Possible investigation of a0(980) & the f0 series K+ K- projection K-p + projection Charm results overview

  23. Atot= g1M1eid1 + g2M2eid2 CP conjugate Atot= g1M1eid1 + g2M2eid2 * * 2Im(g2 g1*) sin(d1-d2)M1M2 |Atot|2- |Atot|2 aCP= = |Atot|2+ |Atot|2 |g1|2M12+|g2|2M22+2Re(g2 g1*)cos(d1-d2)M1M2 CP violation For a two amplitude decay di= strong phase CP asymmetry: strong phase-shift 2 different amplitudes Charm results overview

  24. f =-f d = d q =d-f CP violation via D+ K-K+p+ Dalitz analysis Dalitz plot = FULL OBSERVATION of the decay COEFFICIENTS and PHASES for each amplitude q =d+f Measured phase: CP conserving CP violating CP conjugate aCP=0.006±0.011±0.005 Measure of direct CP violation: asymmetrys in decay rates ofDKK p E831  Charm results overview

  25.               a0(980) K1(1410) K*(1430) f0(1370) phi(1680) phi(1020) f2(1270)               f2(1270) phi(1020) K1(1410) a0(980) phi(1680) f0(1370) K*(1430) Coefficients: D±,D+,D- Preliminary! Phases:D±,D+,D- No evidence of CPV Charm results overview

  26. Other Dalitz plot analyses • The Ks0+- channel could contribute to mixing studies • D0 is tagged from D* so CF decay makes K0 . DCS or mixing make K0 . • These interfere and it may be possible to determine + from Dalitz plot. • In any case, it contains much physics - a real challenge to fit well. BaBar Scale to the full sample! BaBar & Belle have the statistics to make it! The problem is the formalism! In Cleo-c there is a dedicated working group consisting of experimentalists and theoreticians 15,753 events 23 fb-1 Charm results overview

  27. Leptonic decays Motivations: decay constants present future Charm results overview

  28. for the future... • Multi-body charm decays • Charmed baryon spectroscopy • D* spectroscopy • Statistics is still limited: some results from BaBar, Belle, FOCUS • More data necessary: CDF, Cleo-c, B-factory, LHC-B, BTeV Charm results overview

  29. Some slides of general interest • Why charm at a B factory • How is Tevatron working • Cleo-c run plan • Comparison among experiments • BEPC future Charm results overview

  30. Charm at B Factory? • Cross section is large Present BaBar sample of 91 fb-1 contains • Compare with earlier charm experiments: • E791 - 35,400 1 • FOCUS - 120,000 2 • CDF - 56,320 (new number available soon) Charm results overview

  31. Temperature of Tevatron Charm results overview

  32. Cleo-c Charm results overview

  33. comparison Charm results overview

  34. BEPC future • Program and schedule Charm results overview

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