1 / 112

Hadron Physics at the B Factories

Hadron Physics at the B Factories. Brian Meadows University of Cincinnati. Outline. B Factories and Hadron Studies Charm meson spectroscopy Baryons Charmonium and Double Charmonium Dalitz Plots Pentaquarks Summary and Discussion. Non- B Hadrons at the B Factories?.

nitza
Download Presentation

Hadron Physics at the B Factories

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Hadron Physics at the B Factories Brian Meadows University of Cincinnati Brian Meadows, U. Cincinnati.

  2. Outline • B Factories and Hadron Studies • Charm meson spectroscopy • Baryons • Charmonium and Double Charmonium • Dalitz Plots • Pentaquarks • Summary and Discussion Brian Meadows, U. Cincinnati

  3. Non-B Hadrons at the B Factories? • Cross sections are 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. On Off ECM (GeV) Brian Meadows, U. Cincinnati

  4. M 2+ M 2+ M 2- M 2- CKM Angle g from Direct CP Violationand Hadrons =rb ei ( B § )x § K0+- § § § K0+- § • Angle  relates the two decays B- D 0K-andB-  D 0K- • SupposeD0(D 0) K-(K 0) +- • If CP conserved in D0 decay, Dalitz plot for D0 is identical except that+  - • The final states are indistinguishable • So, the two Dalitz plots interfere Brian Meadows, U. Cincinnati

  5. PRL 95: 121802 (2005) 205 fb-1 D0 K0+- Dalitz Plot Analysis • Use large available sample of D0 from e+e- cc continuum to determine the Dalitz plot density for D 0 • Two models used: • “Breit-Wigner Isobar model” Requires 13 resonances including “(500)” and “(1000)” • K-matrix model (fit shown) better way to describe the  S-wave – no ’s needed Brian Meadows, U. Cincinnati

  6. PRD 71: 032005 (2005) 89 fb-1 CKM Angle  and Hadrons • B factories measure sin 2β - golden channel is B0 J/Ks • Leads to a four-fold ambiguity in the determination of the angle β. • Babar used B 0 J/K-+ to find sign of cos 2 • An amplitude analysis was made of the K-+ system to determine the relative phase between S- and P-wave contributions to the decay • A clear choice agrees with the LASS data Brian Meadows, U. Cincinnati

  7. B Factory Luminosities Peak luminosity 1.001034 cm–2s–1 Integrated luminosity 299 fb–1 Peak luminosity 1.581034 cm–2s–1 Integrated luminosity 488 fb–1 e+ e- (3.1 x 9.0 GeV/c) e+ e- (3.5 x 8.0 GeV/c) 1 fb-1 ~1.1M BB events Brian Meadows, U. Cincinnati

  8. BaBar and Belle • Main purpose: Study CP violation in asymmetric e+e- (4S)  BB • A major difference between the two detectors is the PID system: • Babar: Dirc ring imaging C • Belle: TOF and Threshold C with aerogel v v Brian Meadows, U. Cincinnati

  9. Fixed Target Experiments Too? BaBar Belle e-NK 0p Vertices No  (1540) pentaquark signal seen: M (K0p) (GeV/c2) M (K0p) (GeV/c2) Brian Meadows, U. Cincinnati

  10. 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

  11. Particle ID - DIRC It Works Beautifully! Provides excellent K/ separation over the whole kinematic range Brian Meadows, U. Cincinnati

  12. DsJ Mesons Brian Meadows, U. Cincinnati

  13. Heavy-Light Systems 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 between the two 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

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

  15. 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

  16. DsJ(*) in B decays Advantages of exclusive reconstruction: • Kinematic constraints • Backgrounds reduced • Measure of branching fractions • Measure spin of resonances Brian Meadows, U. Cincinnati

  17. PRL 93, 181801 113 fb-1 MASS DISTRIBUTIONS • Sum of the 4 B modes: Clear signals in 3 DsJ* modes Yield = 88  17 m(DsJ*) = 2317.2  1.3 Yield = 112  14 m(DsJ) = 2458.9  1.5 Yield = 139  17 m(DsJ) = 2461.1  1.6 m(DsJ(*)+) (GeV/c2) MES (GeV/c2) m(DsJ(*)) sidebands Fit result 1 candidate per event Brian Meadows, U. Cincinnati

  18. Values of the branching fractions for the 12 modes: = 0.274 ± 0.045 ± 0.020 In agreement with prediction from PRD 68, 054024 PRL 93, 181801 113 fb-1 Results Brian Meadows, U. Cincinnati

  19. PRL 93, 181801 113 fb-1 Helicity Analysis • Two body decay BDDsJ forces DsJ to be polarized (if it is not a scalar) • Use low background mode: B  DsJ(2460)+ D, DsJ(2460)+  Ds+ • 5 m(Ds) fits for different cos h regions • Good agreement with J = 1 J = 1 J = 2 DsJ(2460)+ DsJ  h B Ds D Brian Meadows, U. Cincinnati

  20. B DsJK and B DsJ • First search for these decays • B 0 Ds(J)K - is especially interesting none of the final state quarks (cuss) are in the initial B (bd) meson. • Decay ofB 0 DsK –has been measured(3.8 § 1.0) x 10-5(average of Babar and Belle) • B 0 Ds(J)- is expected to be small. Brian Meadows, U. Cincinnati

  21. Only signal seen B0 DsJ(2317)+K - B0 DsJ(2317)-+ B0 DsJ(2460)+K - B0 DsJ(2460)-+ -1.3 Compare with B{B0 Ds+K-} = (3.8 ± 1.0) x 10-5 (average of Babar and Belle) Brian Meadows, U. Cincinnati

  22. New Results onDsJ(*) in e+e− ccfrom Babar hep-ex/0408067 Brian Meadows, U. Cincinnati

  23. 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 Dsp0g – A KinematicProblem • The decays Ds*(2112)+!Ds+ and DsJ(2317)+!Ds+0 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)+0orDsJ(2317)+?? m(Ds+0)= 2.46 GeV/c2 Brian Meadows, U. Cincinnati

  24. 125 fb-1 hep-ex/0408067 Ds+0 Final States • p(0) > 400 MeV/c, E > 135 MeV • Requirement: M(Ds+) ~ m(Ds*(2112)+) • Clear peak from DsJ(2460)+ • Peaking background from: DsJ(2460)+: 292  29 events M[DsJ(2460)+] = 2459.1  1.3  1.2 MeV/c2 • DsJ(2460)+ decays entirely through the channel Ds*(2112)+ 0 DsJ*(2317)+ Ds+0 Ds*(2112)+ Ds+  Ds+ 0 invariant mass (GeV/c2) Brian Meadows, U. Cincinnati

  25. 125 fb-1 hep-ex/0408067 Ds+0 Final States • Selections: p*(Ds+0) > 3.2 GeV/c, p(0) > 400 MeV/c • Clear peak from DsJ*(2317)+ • Background: • Combinatorial • Contribution from DsJ(2460)+ (mutual cross feed) • Contribution from Ds*(2112)+ • DsJ*(2317)+: 1275  45 events • m(DsJ*(2317)+) = 2318.9  0.3  0.9 MeV/c2 No DsJ(2460)+ Ds+0 Ds+0 invariant mass (GeV/c2) Brian Meadows, U. Cincinnati

  26. 125 fb-1 hep-ex/0408067 Ds+ Final States • Selections: p*(Ds+) > 3.2 GeV/c, E > 500 MeV • Clear peak from DsJ(2460)+ • First peak is a combination of 2 contributions: • DsJ*(2317)+  Ds+0 • DsJ(2460)+  Ds+0  • DsJ(2460)+: 509  46 events • m(DsJ(2460)+) = 2457.2  1.6  1.3 MeV/c2 DsJ(2460)+ Background subtracted No DsJ*(2317)+ Ds+ Ds+  invariant mass (GeV/c2) Brian Meadows, U. Cincinnati

  27. 125 fb-1 hep-ex/0408067 Ds++ - Final States Ds1(2536)+ • p() > 250 MeV/c • Clear peak from DsJ(2460)+ (and from Ds1(2536)+) • DsJ(2460)+: 67  11 • m(DsJ(2460)+) = 2460.1  0.3  1.2 MeV/c2 DsJ(2460)+ Ds+ + - invariant mass (GeV/c2) No DsJ*(2317)+ Ds++ - Brian Meadows, U. Cincinnati

  28. Ds+± Final States PRD 68, 054006 • Test the 4 quark hypothesis for DsJ*(2317)+ • We might expect a neutral and doubly-charged partners with a similar mass • Use of Ds+± to test this possibility • p() > 300 MeV/c • No resonance observed • No DsJ*(2317)0 and DsJ*(2317)++ seen Ds+- Ds++ Ds+ ± invariant mass (GeV/c2) Brian Meadows, U. Cincinnati

  29. Selex reported the observation of a new narrow charm-strange meson : the D+sJ (2632)→ D+sh, D0K+ SELEX: Phys. Rev. Lett. 93:242001 (2004) Search for DsJ(2632) N(Ds+) = 544  29 N(h) = 5087  863 uncorrelated h SELEX Ds+h D0K+ SELEX Brian Meadows, U. Cincinnati

  30. hep-ex/0408087 126 fb-1 Search for DsJ(2632) BaBarsees no evidence for production of DsJ(2632) inD+sh , D0K+norD*+K0sin 126 fb-1 of data N(Ds+) = 196000 N(h) = 3900 correlated h Ds2(2573)+ Ds1(2536)+ D+h D0K+ D*K0 p* > 4.0 GeV/c D0K- Fit after 2D bckg subtr. Brian Meadows, U. Cincinnati

  31. Charmed Meson Spectroscopy Now John Bartelt, Sept, 2003 Brian Meadows, U. Cincinnati

  32. Charm Baryons Brian Meadows, U. Cincinnati

  33. hep-ex/0507011 230 fb-1 Decay Branching Ratios of c • Hyperon events are reconstructed in the decay chains - --  K -  p -  p - • c0 signals are seen in - + and -K-++ decay modes Brian Meadows, U. Cincinnati

  34. hep-ex/0507011 230 fb-1 Production of c Kinematic region allowed for B decay First evidence for c in B decay Brian Meadows, U. Cincinnati

  35. hep-ex/0507011 230 fb-1 Decay Branching Ratios of c • c0 signals are seen in - K+ and -+ decay modes (c0 - K+ ) / (c0 -+)= 0.294 ± 0.018 (stat) ± 0.016 (sys) Previous Best: 0.50 ± 0.21 (stat) ± .05 (sys) (9 evs CLEO) -+ -K+ Brian Meadows, U. Cincinnati

  36. Production of c0 On-resonance 0c in B decay Off-resonance PRL 95:142003 (2005) 116 fb-1 B(Bc0X) × B(c0−+) = (2.11 ± 0.19 ± 0.25) × 10−4 (e+e-c0X) × B(c0−+) = (388 ± 39 ± 41) fb at 10.58 GeV/c2 Brian Meadows, U. Cincinnati

  37. Precision Measurement of c Mass • Motivation: • Best previous measurement from CLEO using 1134 events: (2284.7 § 0.6 § 0.7) MeV/c2P. Avery et al., Phys. Rev. D43, 3599 • Most charm baryon masses measured relative to this • Babar detector offers: • Huge number of charmed hadron decays • Excellent particle ID capability for clean samples • Great vertex and momentum resolution • Good knowledge of magnetic field and material distribution Brian Meadows, U. Cincinnati

  38. Precision Measurement of c Mass • Method: • Choose decay modes with small Q-value/large BR: c K+Ks0and0K+Ks0 • Estimate major systematic uncertainties in: • Material audit – determine  and K0 mass vs. decay path length • Magnetic field – determine  and K0 mass vs. momentum in lab. • Much larger control samples: • c+ pK-+ 1.5 x 106 evs. • c+  pK0 2.4 x 105 evs. Q = 177.8 MeV/c2 Q = 100.9 MeV/c2 Brian Meadows, U. Cincinnati

  39. Combined measurement : m(Lc) = 2286.46  0.14 MeV/c2 hep-ex/0507009 232 fb-1 Results Large Q • Most precise measurement of charm mass to date • Approximately 4 x more precise than Current PDG value: 2284.9 § 0.6 MeV/c2 and about 2.5  higher Brian Meadows, U. Cincinnati

  40. hep-ex/0507011 125 fb-1 Some Branching Fractions of c+ • Most decay branching ratios in the PDG are relative to pK-+ and have typically 40% uncertainties • Few Cabbibo suppressed rates observed are p (CLEO), 0K+ and K+ (Belle) • Babar has new measurements on several Cabbibo suppressed modes with uncertainties at the ~10% level •  modes are normalized to + and 0 modes to 0+ modes c+ + c+0+ c+ 0+ Brian Meadows, U. Cincinnati

  41. Results : Ratios of Branching Fractions with Respect to C+ + Cabibbo-suppressed Cabibbo-allowed In PDG ratios of Branching Fractions are with respect to  C+ pK-+ Brian Meadows, U. Cincinnati

  42. Brian Meadows, U. Cincinnati

  43. Scanning the e+e- Energy Brian Meadows, U. Cincinnati

  44. New Parameters for the . • JPC=1-- resonances can be probed using formation processes e+e- g*  X Can measure MX, GX, line shape and e+e- coupling • Results from PEP2 beam energy scan: PRD in press (hep-ex/040525) Brian Meadows, U. Cincinnati

  45. ISR Studies • Wider energy range covered by capitalizing on ISR: Reconstruct the ISRphoton Energy E*angle wrt e- *in e+e- CMS • Good systematics on shape • Poorer resolution on energy scale • R must still be JPC=1-- • Cross-section measured as fn of s0=mR2: R Brian Meadows, U. Cincinnati

  46. ISR Results • For example, study e+e- p-p+p0 • The reactions are dominated by formation of wand f resonances • These provide the best parameters for w0(1350) and w00(1660) to date. PRD 70, 072004 Brian Meadows, U. Cincinnati

  47. ISR Production of pp Pairs • The reaction e+e- gISRg*  ppISRis used to provide information on the electric and magnetic moments of the produced pp system. • For * >> me / \/s • The pp cross-section is where Magnetic Electric form-factor Brian Meadows, U. Cincinnati

  48. Preliminary 240 fb-1 Proton Form-Factor Very strong variation near threshold confirmed •  (e+ e- pp) is measured from threshold to 4.5 GeV/c2 • Extending range of previous measurements • Covers several decades • Excellent point-to-point precision • Effective form-factor extracted • For comparison with previous measurements, |GE| ¼ |GM| is assumed. • Clear dips are seen at ~2.25 and at ~3 GeV/c2 • Also seen in cross-section  (e+ e- pp). pQCD predicts fall off /s(s’)/s’2 Brian Meadows, U. Cincinnati

  49. E/M Ratio RG = |GE|/|GM| p • Most previous measurements assumed RG = 1.0 • Babar results clearly show: • RG > 1.0 at low mass • RG» 1.0 above 2.5 GeV/c2 p pp in e+e- CMS GE GE cos p Brian Meadows, U. Cincinnati

  50. Other ISR Studies Hadron or di-lepton states • BaBar has a program of studies of many final states looking for • Resonance formation in (s0) • Resonance production within final state • Odd threshold behaviour Brian Meadows, U. Cincinnati

More Related