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Towards a …?

Towards a …?. Brian Meadows University of Cincinnati. Outline. Issues of uniformity Discussions with CLEO and BELLE What methods have been used? A new kind of fit?. Towards Uniformity (with CLEO and BELLE anyway). Discussions were held earlier this year between Alex

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Towards a …?

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  1. Towards a …? Brian Meadows University of Cincinnati Brian Meadows, U. Cincinnati.

  2. Outline • Issues of uniformity • Discussions with CLEO and BELLE • What methods have been used? • A new kind of fit? Brian Meadows, U. Cincinnati

  3. Towards Uniformity(with CLEO and BELLE anyway) • Discussions were held earlier this year between • Alex 1975: Open charm discovered (c, FNAL BC 1975 ; D0, D+, SLAC 1976) 1976: De Rujula, Georgi, Glashow – light and heavy degrees of freedom decouple. 1989: Heavy Quark Symmetry Brian Meadows, U. Cincinnati

  4. SQ L Sq Heavy-Light Systems areLike the Hydrogen Atom • When mQ ! 1, sQ is fixed. • So jq = L­sq is separately conserved • Total spin J = jq­sQ • Ground state (L=0) is doublet with jq=1/2 • Orbital excitations (L>0) – two doublets (jq=l+1/2 and jq=l-1/2). • For decays to ground state (L=1)! (L=0) +  : • for jq=3/2 state, final hadrons are in orbital D wave !jq= 3/2 states are narrow. • for decay of DJ(jq=1/2) state, final hadrons are in orbital S wave !jq=1/2 states are expected to be broad. Brian Meadows, U. Cincinnati

  5. Heavy-Light Systems (2) 2jqLJ  JP • Narrow statesare easy to find. • Two wide states are harder. • Since charm quark is not infinitely heavy, some jq=1/2, 3/2 mixing can occur for the JP=1+ states. jq = 3/2 2+ small 3P2 large 1+ 1P1 L = 1 1+ 3P1 small jq = 1/2 1P0 0+ large tensor spin-orbit jq = 1/2 1- small 1S1 L = 0 small 0- 1S0 Brian Meadows, U. Cincinnati

  6. Charmed Meson Spectroscopy • This picture worked well prior to this year with all narrow L=0 and L=1 states found by 1995. • The wide, nonstrangejl=1/2 states were found in B decays by CLEO (1999) and BELLE (2002). Subsequently confirmed by BABAR in 2003. • Most potential model calculations had correctly predicted masses above threshold for  emission for these states, with broad widths. BUT they also • Generally agreed that strange jl=1/2 states 1Ds0,1Ds1 would be above threshold for K emission. Brian Meadows, U. Cincinnati

  7. Charmed Meson Spectroscopy c. 1995 Brian Meadows, U. Cincinnati

  8. Charmed Meson Spectroscopy pre 2003 D*0K+threshold D0K+threshold BABAR may have found these – but below threshold. Brian Meadows, U. Cincinnati

  9. The BaBar Detector at SLAC (PEP2) • Asymmetric e+e- collisions at (4S). •  = 0.56 (3.1 GeV e+, 9.0 GeV e-) • Principal purpose – study CPV in B decays 1.5 T superconducting field. Instrumented Flux Return (IFR) Resistive Plate Chambers (RPC’s): Barrel: 19 layers in 65 cm steel Endcap: 18 “ “ 60 cm “ Brian Meadows, U. Cincinnati

  10. Electromagnetic Calorimeter • CsI (doped with Tl) crystals • Arranged in 48()£120() • » 2.5% gaps in . • Forward endcap with 8 more  rings (820 crystals). BABAR  0  Brian Meadows, U. Cincinnati

  11. 144 quartz bars Particle ID - DIRC • Measures Cherenkov angle in 144 quartz bars arranged as a “barrel”. • Photons transported by internal reflection • Along the bars themselves. • Detected at end by ~ 10,000 PMT’s Detector of Internally Reflected Cherenkov light PMT’s Brian Meadows, U. Cincinnati

  12. Drift Chamber 40 layer small cell design 7104 cells He-Isobutane for low multiple scattering dE/dx Resolution »7.5% Mean position Resolution 125 m Brian Meadows, U. Cincinnati

  13. Silicon Vertex Tracker (SVT) • 5 Layers double sided AC-coupled Silicon • Rad-hard readout IC (2 MRad – replace ~2005) • Low mass design • Stand alone tracking for slow particles • Point resolution z» 20 m • Radius 32-140 mm Brian Meadows, U. Cincinnati

  14. Run 3 Run 4 Run 2 Run 1 Off Peak PEP-II performances Peak Luminosity ~ 6 £ 1033 cm-2/ s-1 24 fb-1 in run 1 70 fb-1 in run2 36 fb-1 so far in run3 10 fb-1 so far in run4 This analysis uses runs 1 and 2 » 110 M cc pairs 9% off peak Currently (Nov 2003) run 4 is in progress with ~155 fb-1 Brian Meadows, U. Cincinnati

  15. On Off Charm at the BABARB Factory? • Cross section is large Can use “off peak” data • Also • Relatively small combinatorial backgrounds in e+e- interactions. • Good particle ID. • Detection of all possible final states including neutrals. • Good tracking and vertexing • Very high statistics. Brian Meadows, U. Cincinnati

  16. Charm at the BABARB Factory? • Present sample of 91 fb-1 sample contains • Compare with other charm experiments: • E791 - 35,400 1 • FOCUS - 120,000 2 • CDF - 56,320 • Approximately 1.12 £ 106 untagged D0!K-+ events 1. E791 Collaboration, Phys.Rev.Lett. 83 (1999) 32. 2. Focus Collaboration, Phys.Lett. B485 (2000) 62. Brian Meadows, U. Cincinnati

  17. Data Selection • All pairs of ’s, each  having energy > 100 MeV, are fitted to a 0 with mass constraint. • Each 0 is fitted twice: • To the production vertex to investigate the Ds+0 mass. • To the K+K-+ vertex so that we can also use the Ds! K+K-+0 mode. D’s from B decays were removed: - each event was required to have pD* > 2.5 GeV/c BABAR results from B decays are forthcoming however. Brian Meadows, U. Cincinnati

  18. K+K-+ Mass Spectrum Approx. 131,000 Ds+ events above large background. 4 3 2 1 0 X 103 X 103 60 40 20 0 D0! K+K- Events / 3 MeV/c2 1.75 1.85 1.95 m(K-K+) GeV/c2 1.8 1.9 2.0 m(K-K++) GeV/c2 Small bump at 2010 MeV/c2 from Brian Meadows, U. Cincinnati

  19. The Ds+ Dalitz Plot • Data sample: D*s(2112)+!Ds+: • NOTE • K* and  bands do not cross (no double counting). • cos2 distributions evident in vector bands. Selection essentially keeps events in the 4 peaks. Brian Meadows, U. Cincinnati

  20. Total K+K-+ Mass Spectrum • Sum of + and K¤0K+ contributions is » 80,000 Ds+ above background. • We define signal region: 1954 < m(K+K-+) < 1980 MeV/c2 and two sideband regions: 1912 < m(K+K-+) < 1934 MeV/c2 1998 < m(K+K-+) < 2020 MeV/c2 Brian Meadows, U. Cincinnati

  21. The Ds(2317)see PRL 90, 242001 (2003) • When Antimo Palano studied the Ds0 system he found a huge, unexpected peak. There is no signal from Ds+ sidebands. The Ds*!Ds+0 signal is clear too. How did CLEO miss it?! CLEO discarded All these events. Brian Meadows, U. Cincinnati

  22. The Ds(2317) • The signal is clearly associated with both Ds+ and 0. There is no signal from 0 sidebands either. [NOTE – smearing the 0 signal smears the Ds*! Ds+0 signal too.] Brian Meadows, U. Cincinnati

  23. A Real Particle? • Is the signal due to reflection of a known resonance? Approximately 80 £ 106e+e-!cc reactions simulated. All that was known about charm spectroscopy was included. Conclude signal is not a reflection. Brian Meadows, U. Cincinnati

  24. CMS Momentum (p*) Dependence • Signal seen in all p* ranges. • Background less significant at higher p* values • Yield maximum at ~3.9 GeV/c • Excitation curve appears to be compatible with charm fragmentation process. Brian Meadows, U. Cincinnati

  25. 250 200 150 100 50 0  200 150 100 50 0 K* Events / 5 MeV/c2 2.1 2.3 2.5 2.1 2.3 2.5 m(Ds+0)GeV/c2 Multiple Ds+ Modes • Separate + and K¤0K+ subsamples: • Ds*+(2112) and signal at 2.317 GeV/c2 present in both channels with roughly equal strength. p* > 3.5 GeV/c Brian Meadows, U. Cincinnati

  26. 400 300 200 100 0 Events / 5 MeV/c2 2.1 2.2 2.3 2.4 2.5 m(Ds+0) GeV/c2 Fit to the Signal Require p* > 3.5 GeV/c Fit to polynomial and a single Gaussian. N = 1267 § 53 Events m = 2316.8 § 0.4 GeV/c2 = 8.6 § 0.4 MeV/c2 (errors statistical only).  is compatible with detector resolution. m requires small correction due to Ds(2458) overlap. Brian Meadows, U. Cincinnati

  27. Cross Check - a Different Topology Select Ds+! K-K++0 N = 273 § 33 events m = 2317.6 § 1.3 MeV/c2  = 8.8 § 1.1 MeV/c2 (consistent with detector resolution). Results agree with those from other Ds+ modes Brian Meadows, U. Cincinnati

  28. Conclusions on the state so far • Real and it decays to Ds+0: Implies natural parity. • Narrow - consistent with BaBar resolution : < 10MeV/c2. • If a normal Ds+ then this decay violates I spin conservation. • This could explain the narrowness. • Being below D0K+ threshold may force such a decay. • Could be the missing 0+ BUT if so, its mass is lower by » 170 MeV/c2 than expected by potential models. We label it “DsJ*(2317)+” • What else … Brian Meadows, U. Cincinnati

  29. DsJ+(2317) Decay Angular Distribution • Helicity angle distribution could provide spin information. • The corrected distribution in cos  is consistent with being flat (43% probability). • This could mean that J=0 or just that state is unaligned. Acceptance Uncorrected Corrected 0  DsJ(2317) 10 x Efficiency Ds cos cos cos Brian Meadows, U. Cincinnati

  30. Search for Other DsJ+(2317) Decay Modes • We have studied the mass spectra for • Ds+0 0 • Ds+ • Ds+  • Ds*+(2112) • Ds+0  • In all cases, we require that: • The ’s are not part of any 0 candidate. • The combination has p* > 3.5 GeV/c. None of these found Brian Meadows, U. Cincinnati

  31. Ds+, Ds+, Ds*(2112) • No evidence for DsJ(2317) in any of these decays. • Absence of Ds+ weakly suggests J = 0 • However other two modes would be expected for a JP = 0+. Brian Meadows, U. Cincinnati

  32. Ds+0, Ds*(2112)0- Other Possibilities • No evidence for D*sJ(2317)+ either of these modes • BUT … • Is there a second state at ~ 2460 MeV/c2 ? Events / 7 MeV/c2 Ds*(2112)0 m(Ds+0) Brian Meadows, U. Cincinnati

  33. 2.4 2.3 2.2 2.1 2.0 m(Ds+)GeV/c2 2.1 2.2 2.3 2.4 2.5 m (Ds+0) GeV/c2 A Second State ? • The decays DsJ(2317)+!Ds+0 and Ds*(2112)+!Ds+ overlap kinematically just where m(Ds+0)~2460 MeV/c2. • Gives us two problems: • Produces a kinematic peak at 2460 MeV/c2 – signal? • Resolution smearing makes it difficult to distinguish decays of a 2460 MeV/c2 state to Ds*(2112)+0 or D*sJ(2317)+ ? m(Ds+0)= 2.46 GeV/c2 Brian Meadows, U. Cincinnati

  34. A Second State ? • Another concern we resolved: Is the D*sJ(2317) signal just a reflection of the higher mass state?! • NO – such reflection is • Too wide • Wrong mass • Too small by factor ~ 5. Brian Meadows, U. Cincinnati

  35. A Second State ? … from our PRL 90 (2003) 242001. • “Although we rule out the decay of a state of mass 2.46 GeV/c2 as the sole source of the Ds+0 mass peak corresponding to the D*sJ(2317)+, such a state may be produced in addition to the D*sJ(2317)+. However, the complexity of the overlapping kinematics of the Ds*(2112)+!Ds+ and D*sJ(2317)+!Ds+0 decays requires more detailed study, currently underway, in order to arrive at a definitive conclusion.” Meanwhile … Brian Meadows, U. Cincinnati

  36. CLEO Sees D*sJ(2317) Too m(Ds0) – m(Ds) 350.0 § 1.2 (stat) § 1.0 (syst) (MeV/c2) Not in Ds+- • From 13.5 fb-1 CLEO II • Signal seen in Ds0 • Not seen in Ds+-, • Ds, Ds1(2112) Signal has events (» same yield / fb-1 as BABAR). PRD 68, 032002 (2003) Brian Meadows, U. Cincinnati

  37. So Does Belle (in continuum) • 78 fb-1 sample • Ds!, p* > 3.5 GeV/c • M = 2317 § 0.5 MeV/c2 • = 8.1 § 0.5 MeV/c2 • N = 770 § 43 events • They also observe it in • B!D DsJ decays. Y. Mikami, et al, hep-ex/0307052v2 (2003) Brian Meadows, U. Cincinnati

  38. The DsJ (2458)+ • CLEO results are published with title: “Observation of a Narrow Resonance of Mass 2.46-GeV/c2 Decaying to Ds*(2112)+0 and Confirmation of the D*sJ(2317)+ State.” in PRD 68, 032002 (2003) • BELLE has also observed the DsJ (2458)+ • In continuum – hep-ex/0307052 • In B!DDsJ decay – hep-ex/0308019 • What BABAR says about the second state now … Brian Meadows, U. Cincinnati

  39. 2.4 2.3 2.2 2.1 2.0 m(Ds+)GeV/c2 2.1 2.2 2.3 2.4 2.5 m (Ds+0) GeV/c2 Recap - theProblem • The decays DsJ(2317)+!Ds+0 and Ds*(2112)+!Ds+ overlap just where m(Ds+0)~2460 MeV/c2. • This gives us two problems: • Produces a kinematic peak at 2460 MeV/c2 • Resolution smearing makes it difficult to distinguish decays of a 2460 MeV/c2 state to Ds*(2112)+0 or DsJ(2317)+ m(Ds+0)= 2.46 GeV/c2 Brian Meadows, U. Cincinnati

  40. BABAR - There is a Signal! Data MC A strong peak appears in BABAR data that is absent in generic MC [e+e-!cc that includes D*sJ(2317)+ production]. Attribute the excess to a new signal at 2458 MeV/c2. DsJ(2458)+ m() ´ m(KK0) - m(KK0) m(0) ´ m(KK0) - m(KK) NOTE – Change of variables Next: a) extract signal strength and properties; b) distinguish Ds*(2112)+0 from DsJ(2317)+ Brian Meadows, U. Cincinnati

  41. 100 80 60 40 20 0 0.3 0.2 0.1 80 60 40 20 0 Events / 7 MeV/c2 m() GeV/c2 0.25 0.50 m(0) GeV/c2 0.25 0.50 m(0) GeV/c2 0.25 0.50 m(0) GeV/c2 Extraction of Signal from Background Seems most obvious method - make a (peaking) sideband subtraction and fit to Gaussian: ! m = 344.6 § 1.2 MeV/c2. BUT: • Assumes background is linear. • Not true as resolution of m(0) changes with m(). • Width of signal depends on width of sideband selected. • Ignores D*sJ(2317)+ decay possibility. Brian Meadows, U. Cincinnati

  42. Monte Carlo for DsJ(2458)+!Ds*(2112)0 Monte Carlo for DsJ(2458)+!DsJ(2317) Decay Mode • Distinction between Ds*(2112)0 and DsJ (2317)+ decays is possible from different line shapes each produces. • Data clearly prefer the shape for DsJ (2458)+! Ds*(2112)0 Brian Meadows, U. Cincinnati

  43. Channel Likelihood1 Method • Determine fractions xi of processes producing events and best mass (m) and Gaussian width () for DsJ (2458). • Each Ds+0 combination is assigned a likelihood: L = x1P1 + x2P2 + … + (1 - x1 - x2 - …) where Pi are normalized Probability Density Functions. Processes included were: P1: DsJ(2458) !Ds*0 P2: DsJ(2458) !DsJ(2317) P3: Ds+0!Ds* + random  P4: Ds+0!DsJ(2317) + random 0 P5: Ds+0! combinatorial background Assumption: that DsJ(2458) decay is all quasi two body with no interference (reasonable since the states are all narrow). 1 P.E. Condon and P.L. Powell, PRD 9, 2558 (1974) Brian Meadows, U. Cincinnati

  44. Fit Results • Important results from the fit are: • The DsJ(2458)+ width is consistent with detector resolution indicating that the state is narrow. • We infer that: Brian Meadows, U. Cincinnati

  45. Fit Results (2) • The fit assigns a probability xiPi to each event to belong to a process, so weighted plots take account of all reflections. Unweighted Ds+0 Weighted Data Weighted DsJ(2458)+!Ds*+0 Fit Weighted DsJ(2458)+!DsJ(2317)+ Brian Meadows, U. Cincinnati

  46. Correction to DsJ (2317)+ Mass • Distortion of the DsJ(2317)+ signal due to background from DsJ(2458)+!Ds*(2112)+0decays can be estimated from a Monte Carlo study. • Re fitting to include this, DsJ(2317)+ parameters are: m = 2317.3 § 0.4 MeV/c2 ;  = 7.3 § 0.2 MeV/c2. Brian Meadows, U. Cincinnati

  47. Spin-Parity of DsJ(2458)+ • The decay observed here violates I-spin. The width is small. • So natural parity (0+, 1-, 2+, …) appear to be ruled out as this state could decay to D0K+, conserving I-spin. • It is below D*K threshold, a decay accessible to unnatural parity, so its width is compatible with JP=0-, 1+, 2-, … • The helicity distribution is also consistent with this hypothesis. Brian Meadows, U. Cincinnati

  48. Spin-Parity of DsJ (2458)+ • Helicity angle of : • JP = 0- agrees worst. 1- and 2+ cannot be ruled out. • Unnatural parity distributions depend on alignment of DsJ(2458)+.  Ds*(2112) h 0 Ds No conclusive information on spin here Brian Meadows, U. Cincinnati

  49. Belle 86.9 fb-1 CLEO “Ds(2463)” 13.5 fb-1 D*(2112) D*(2112) sidebands N = 41§ 12 events (>5) m = 349.8 § 1.3 MeV/c2 N = 126§ 25 events m = 345.4 § 1.3 MeV/c2 CLEO and Belle See Ds(2458) in Continuum PRD 68, 032002 (2003) hep-ex/0307052 Brian Meadows, U. Cincinnati

  50. More Observations by Belle • See both states in B decay • See DsJ(2458)+!Ds+ Continuum B!D DsJ DsJ(2317)+ !Ds+0 DsJ(2458)+ !Ds*(2112)+0 DsJ(2458)+ !Ds+ Rules out J = 0 Brian Meadows, U. Cincinnati

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