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Recent Results from FOCUS

Recent Results from FOCUS. Sandra Malvezzi I.N.F.N. Milano. FOCUS Collaboration. SLAC 16 March 2004. A new charm physics era. The high statistics and excellent quality of data allow for unprecedented sensitivity & sophisticated studies

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Recent Results from FOCUS

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  1. Recent Results from FOCUS Sandra Malvezzi I.N.F.N. Milano FOCUS Collaboration SLAC 16 March 2004 Sandra Malvezzi - Recent results from FOCUS

  2. A new charm physics era The high statistics and excellentquality of data allow for unprecedented sensitivity & sophisticated studies • Investigation of decay dynamics both in the hadronic and semileptonic sector Phases andQuantum Mechanics interference FSI role & CP studies • Lifetime measurements @ better than 1% non-spectator processes • Mixing and rare & forbidden decays possible window on physics beyond SM What can we learn for the future (charm and beauty @ higher statistics )? Sandra Malvezzi - Recent results from FOCUS

  3. Over 1 million reconstructed!! FOCUS Spectrometer Successor to E687. Designed to study charm particles produced by ~200 GeV photons using a fixed target spectrometer with upgraded Vertexing, Cerenkov, E+M Calorimetry, and Muon id capabilities. Includes groups from USA, Italy, Brazil, Mexico, Korea 1 million charm particles reconstructed into DK , K2 , K3 Sandra Malvezzi - Recent results from FOCUS

  4. FOCUS role • Lifetime • Mixing • Rare & forbidden decays • Semileptonic • Hadronic decays (Dalitz plot) • Multi-body channels (4,5,6 bodies!) • Charm Baryons • D* spectroscopy ]not covered here Sandra Malvezzi - Recent results from FOCUS

  5. Charm lifetimes FOCUS (*) produced new lifetimes results with precision better than the previous world average (○), PDG 2002 Sandra Malvezzi - Recent results from FOCUS

  6. Rare & forbidden decays Phys.Lett. B572 (2003) 21 8 rare & SM forbidden decays improvement over previous results by a factor of 1.7 -14 Sandra Malvezzi - Recent results from FOCUS

  7. Preliminary FOCUS semimuonic mixing Mixing I play in the enemy’s territory! Sandra Malvezzi - Recent results from FOCUS

  8. the unexpected • i.e. the analysis complications • i.e the lessons for the future • Higher charm statistics • Beauty accurate studies ...the semileptonic sector Sandra Malvezzi - Recent results from FOCUS

  9. New results on Our Kp spectrum looks like 100% K*(892) This has been known for about 20 years ...but a funny thing happened when we tried to measure the form factor ratios by fitting the angular distributions Sandra Malvezzi - Recent results from FOCUS

  10. Decay is very accessible to theory Assuming the Kp spectrum contains nothing but K*, the decay rate is straight-foreward Sandra Malvezzi - Recent results from FOCUS

  11. forward-backward asymmetry in cos below the K* pole but almost none above the pole A 4-body decay requires 5 kinematics variables: 3 angles and 2 masses An unexpected asymmetry in the K* decay Sounds like QM interference Sandra Malvezzi - Recent results from FOCUS

  12. We simply add a constant amplitude in the place where the K* couples to an m=0 W+ with amplitude Try an interfering spin-0 amplitude Phys.Lett.B535,43,2002 (plus mass terms) will produce 3 interference terms Sandra Malvezzi - Recent results from FOCUS

  13. Studies of the acoplanarity-averaged interference Extract this interference term by weighting data by all c-averaged terms in the decay intensity for pure are constant or We begin with the mass dependence: A constant 45º phase works great.... ...but the solution is not unique . Sandra Malvezzi - Recent results from FOCUS

  14. .. other options would work as well. Asymmetry expected directly from LASS s-wave K p phase shift analysis. And Kappa with no fsi phase shift and with a 100 degree phase shift. cos qV term cos qv weighted M(Kp), GeV/c2 Sandra Malvezzi - Recent results from FOCUS

  15. Sandra Malvezzi - Recent results from FOCUS

  16. FOCUS D+K*0m+n semileptonic BRs Our 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% Sandra Malvezzi - Recent results from FOCUS

  17. 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 Sandra Malvezzi - Recent results from FOCUS

  18. rad Form Factor Ratios Phys.Lett.B 544(2002) 89 Our 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 calculation Damir Becirevic (ICHEP02)RV = 1.55  0.11which is remarkably close tothe FOCUS result. Sandra Malvezzi - Recent results from FOCUS

  19. Phys.Lett.B 541 (2002), 243 Baseline cuts a) 2682 evts b) 4695 evts Baseline, out-of-material. isolation cuts c) 793 evts d) 2192 evts Sandra Malvezzi - Recent results from FOCUS

  20. BRs FOCUS All values consistent with an average of 0.54  0.04 Sandra Malvezzi - Recent results from FOCUS

  21. New measurement of the Ds+fm+n ff hep-ex/0401001 • According to flavor SU(3) symmetry the form factor ratios rv and r2 describing D+K0*m+n should be close to Ds+fm+n since the only difference is a spectator quark d replaced with a s • Lattice gauge calculations: max diff= 10% • Experiment: • rv OK • r2 inconsistent (3.3s). Sandra Malvezzi - Recent results from FOCUS

  22. Comparing data and model Data: histogram: Model:dots ccbar background: dashed Sandra Malvezzi - Recent results from FOCUS

  23. events cos qV dataccbar mc events cos qV fmn S-wave interference in fmn? K*mn events cos qV NO evidence for s-wave interference in Ds fmn data Sandra Malvezzi - Recent results from FOCUS

  24. Most precise measurement to date • very consistent with D+K0*m+n • very consistent with theoretical expectation form factor results Sandra Malvezzi - Recent results from FOCUS

  25. ....the lesson “The advantages of high-statistics for the interpretation of Heavy-Flavour hadronic-decay dynamics will vanish without a strategy for controlling strong effects among particles involved in weak-decay processes ” If unexpectedcomplications arise in the semileptonic sector what happens in the three-body hadronic decay dynamics study? Sandra Malvezzi - Recent results from FOCUS

  26. had to face the problem of dealing with light scalar particles populating charm meson hadronic decays, such as Dppp, D Kpp Complication for Dalitz plot analysis Require understanding of light-quark hadronicphysics including the riddle of s(600)and k(900), (i.e, pp and Kp states produced close to threshold), whose existence and nature is still controversial Sandra Malvezzi - Recent results from FOCUS

  27. A bridge of language, knowledge and measurements between the two worlds of Light MesonsandHeavy Flavours is necessary • S-matrix and its representations • Two-body unitarity • Analyticity • Limits of the Breit-Wigner approximation etc.. Sandra Malvezzi - Recent results from FOCUS

  28. Analysis techniques CAN and MUST be improvednow in view of extensive application in high-statistics experiments (Cleo-c, Babar, Belle, BTeV, LHC-b etc...) for precision studies of CP and reliableNew Physics measurements Pioneering work performed by hep-ex/0312040to appear in PLB 585 (2004) 200 Sandra Malvezzi - Recent results from FOCUS

  29. 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 Sandra Malvezzi - Recent results from FOCUS

  30. 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. Sandra Malvezzi - Recent results from FOCUS

  31. Spin 0 Spin 1 Spin 2 • the propagator is of the simple Breit-Wigner type • the decay amplitude is • the decay matrix element traditional isobar model Sandra Malvezzi - Recent results from FOCUS

  32. In contrast when the specific IJ–wave is characterized by large and heavily overlapping resonances (just as the scalars!), the problem is not that simple. Indeed, it is very easy to realize that the propagation is no longer dominated by a single resonance but is the result of a complicated interplay among resonances. In this case, it can be demonstrated on very general grounds that the propagator may be written in the context of the K-matrix approach as where K is the matrix for the scattering of particles 1 and 2. i.e., to write down the propagator we need the scattering matrix Sandra Malvezzi - Recent results from FOCUS

  33. We may summarize by saying that: The decay amplitude may be written, in general, as a coherent sum of BW terms for waves with well-isolated resonances plus K-matrix terms for waves with overlapping resonances. Where the general form of for scalars is Sandra Malvezzi - Recent results from FOCUS

  34. E.P.Wigner, Phys. Rev. 70 (1946) 15 The K-matrix formalism S.U. Chung et al. Ann. Physik 4 (1995) 404 Based on “first principles” of S-matrix scattering theory r = phase space S scattering matrix Sandra Malvezzi - Recent results from FOCUS

  35. From scattering to production: the P-vector approach I.J.R. Aitchison Nucl. Phys. A189 (1972) 514 From T to F describes coupling of resonances to D known from scattering data Sandra Malvezzi - Recent results from FOCUS

  36. K-matrix picture Sandra Malvezzi - Recent results from FOCUS

  37. K-matrix advantages • An elegant and direct way of incorporating the two-body unitarity constraint • Proper handling of overlapping and wide resonances • Straightforward inclusion of already known physics and disadvantages requires translation into T-matrix to get the “physics” Sandra Malvezzi - Recent results from FOCUS

  38. 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) A description of the scattering ... A global fit to all the available data has been 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 goto F amplitude formula Sandra Malvezzi - Recent results from FOCUS

  39. is a 5x5 matrix (i,j=1,2,3,4,5) 1=pp, 5= 4= 2= 3=4p A&S is the coupling constant of the bare state a tothe meson channel and describe a smooth part of the K-matrix elements suppresses the false kinematical singularity at s = 0 near the pp threshold Sandra Malvezzi - Recent results from FOCUS

  40. A&S K-matrix poles, couplings etc. Sandra Malvezzi - Recent results from FOCUS

  41. A&S T-matrix poles and couplings A&S fit does not need a s as measured in the isobar fit Sandra Malvezzi - Recent results from FOCUS

  42. 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 Sandra Malvezzi - Recent results from FOCUS

  43. 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 % Sandra Malvezzi - Recent results from FOCUS

  44. 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! Sandra Malvezzi - Recent results from FOCUS

  45. decay channel amplitude coefficient phase (deg) fit fractions (%) f0(980) f2(1270) f0(980) f2(1270) S0(1475) Isobar approach results: an effective description C.L. Fit 7.2% preliminary Non-resonant absorbs parametrization problem.....no robust conclusion on annihilation possible goto Dalitz picture Sandra Malvezzi - Recent results from FOCUS

  46. if f0(1500) PDGm=15075 MeV/c G =1097 MeV/c “Effective resonance” m = 1473.0  8.8 MeV/c G= 109.5  16.3 MeV/c S0(1475) then preliminary fit fractions instability more complicate interplay between S-wave resonances and underlying non-resonant S-wave component Sandra Malvezzi - Recent results from FOCUS

  47. FOCUS D+ p +p +p - analysis Yield D+ = 1527 51 S/N D+ = 3.64 Sideband Signal Sandra Malvezzi - Recent results from FOCUS

  48. decay channel phase (deg) fit fractions (%) K-matrix fit results C.L fit 7.7 % High mass projection Low mass projection No new ingredient (resonance) required not present in the scattering! Sandra Malvezzi - Recent results from FOCUS

  49. 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 Sandra Malvezzi - Recent results from FOCUS

  50. s in Brp CKM03 A.D. Polosa: “ Hadronic pollution in Brp ”? J.A. Oller: “On the resonant and non-resonant contributions to Brp” Sandra Malvezzi - Recent results from FOCUS

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