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New States Containing Charm at B A B AR

New States Containing Charm at B A B AR. PHENO 06 Symposium A.J. Edwards - Stanford University May 15. Outline. Λ c (2880) + and Λ c (2940) + → D 0 p New measurements of the Λ c (2880) + First observation of the Λ c (2940) + Ξ cc + and Ξ cc ++ Are double-charm baryons among us?

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New States Containing Charm at B A B AR

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  1. New States Containing Charm at BABAR PHENO 06 Symposium A.J. Edwards - Stanford University May 15

  2. Outline • Λc(2880)+ and Λc(2940)+ → D0p • New measurements of the Λc(2880)+ • First observation of the Λc(2940)+ • Ξcc+ and Ξcc++ • Are double-charm baryons among us? • D*sJ(2317)+ and DsJ(2458)+ • An update on their properties; absolute BFs for DsJ(2458)+ • X(3872) and Y(4260) • Update & confirmation of X(3872) C-parity • Searches for new Y(4260) decay modes 2

  3. Λc(2940)+ 3

  4. Charm Baryon Spectroscopy Λc(2940)+ • Two new observations in cc continuum of particles with decays to D0p • Discovery of Λc(2940)+ • The first observation of Λc(2880)+→ D0p Λc(2880)+ D0p Threshold π 4

  5. Λc(2940)+ hep-ex/0603052 (sub. to PRL) 287 fb–1, A New State Λc(2880)+ N=2280±310 (>7 σ) Λc(2940)+ M = (2939.8±1.3±1.0) MeV/c2 Γ = (17.5±5.2±5.9) MeV Λc(2940)+ A New Decay Mode, Mass and width Λc(2880)+ M = (2881.9±0.1±0.5) MeV/c2 Γ = (5.8±1.5±1.1) MeV Wrong sign D0p PDG04: M=2880.9±2.3 MeV/c2 Γ< 8 MeV D0 mass sidebands 5

  6. Λc(2940)+ Sascha Migura et al. hep-ph/0602153 hep-ex/0603052 • Three Λc states predicted at mass ~2940 MeV/c2: JP= (1/2)+, (1/2)–, and (3/2)– • The Λc(2880)+ is near a predicted (3/2)– state. Λc(2940)+ not observed in Λc+π+π–. Suppression not understood. Expected signal size Neither signal in D+p distribution → both states are Λc’s 6

  7. Doubly Charmed Baryons 7

  8. Charm Strangeness I3 Doubly Charmed Baryons SU(4) 20'-plet • Theoretically Ξcc & Ωcc should exist. • The SELEX experiment (hyperon beam) reports Ξcc evidence (with 1,630 Λc) • The FOCUS experiment (photon beam) sees no Ξcc evidence (with 19,500 Λc) Can they be found in e+e–→ qq production? Ξc0→Ξ–π+ 232 fb–1 • Large numbers of single charm baryons in 232 fb–1 data set • e.g. ~600,000 Λc+ and ~12,000 Ξc0 • Double charm baryon e+e– cross section predictions: 1 - 250 fb • Theoretical BFs to Λc+K-π+, Λc+K-π+π+, Ξc0π+, Ξc0π+π+ ~ a few percent Λc+→pK–π+ 232 fb–1 8

  9. Λc+K–π+ p*>2.3 GeV/c Λc Sidebands Doubly Charmed Baryons SELEX Ξcc+ Λc+→pK–π+ 232 fb–1 95% C.L. SELEX Ξcc++ Λc+K–π+π– p*>2.3 GeV/c < 95% C.L. With some assumptions about branching fractions: < 1.5 pb @ 95% C.L. (p* > 2.3 GeV/c) < 1.3 pb @ 95% C.L. (p* > 2.3 GeV/c) This does not rule out any theoretical production cross sections. 9

  10. Doubly Charmed Baryons SELEX Ξcc+ Ξc0π+ p*> 2 GeV/c 95% C.L. < 1.3 fb < 3.4 fb 95% C.L. SELEX Ξcc++ Ξc0π+π+ p*> 2 GeV/c Ξc0→Ξ–π+ 232 fb–1 With some assumptions about branching fractions: The production cross section limits for doubly charmed baryons are near or below σ(e+e– → Ξc0X) 10

  11. DsJ*(2317) and DsJ(2460) 11

  12. Both masses unexpectedly low: below DK and D*K threshold, respectively Only isospin-violating or electromagnetic decays kinematically allowed  narrow widths Decay pattern and decay angular distributions consistent with interpretation as JP=0+ and JP=1+, respectively Charm-Strange Mesons • DsJ*(2317) and DsJ(2460) first observed by BABAR and CLEO in cc continuum events, and by Belle in B decays D*K D0K CLEO: 13.5 fb-1 PRD 68, 032002 (2003) Belle: 124M BB PRL 91, 262002 (2003) BABAR: 91 fb-1 PRL 90, 242001 (2003) 12

  13. Charm-Strange Mesons • Assuming DsJ*(2317) and DsJ(2460) have JP = 0+ and 1+ respectively, the decay channels below are allowed or forbidden as indicated. • All of the above decay modes have been searched for. • All “Seen” modes are also “Allowed” 13

  14. D*sJ(2317)+ 232 fb-1 sub. to PRD • Original D*sJ(2317) discovery mode update • No indication of neutral or doubly-charged signal, ruling out some exotic interpretations N=3180±80 2 MeV/c2 Bins Ds+π– Circles: Ds sidebands Ds*(2112) reflection Ds+π+ Dark shade: DsJ(2460) reflection 2317 MeV/c2 14

  15. DsJ(2460)+Ds+π0 Dark shade: DsJ*(2317)+ reflection Light shade: Ds*(2112)+ reflection DsJ(2460) → Ds+π+π- Open points: Ds sidebands DsJ*(2317) N=123±15 N=6±3 DsJ(2460)+Ds+ DsJ(2460)+ • DsJ(2460) decay channels • Original: Ds* π0,Ds*→Ds+  • Additional: Ds+ • Additional: Ds+π+π- N=560±40 232 fb-1 sub. to PRD Backgrounds N=920±60 15

  16. DsJ(2460)+ • From the Ds+π+π– decay channel • More precise BR measurements • Limits set for additional decay channels. 16

  17. p e- D* Breco e+ Bsignal D*0 D*+ D0 D+ X DsJ(2460)+ Absolute Branching Fractions • Sample with one B fully reconstructed (Breco) • Study decays of other B  (D*+, D+, D*0, D0) X • Observe DsJ(2460)- signals in the recoil mass (mX) hep-ex/0605036 BF( ) = (0.88 ± 0.20 ± 0.14) % 17

  18. DsJ(2460)+ Absolute Branching Fractions • Combine with previously measured product branching fractions 230M BB and Using B(Ds→φπ)=4.62 % • Sum of known branching fractions: 0.76±0.17 18

  19. X(3872) and Y(4260) 19

  20. X(3872) → J/ψπ+π– Updated result from BABAR • Initial discovery of B– → X(3872)K– → J/ψπ+π– K– by Belle • Confirmed by CDF, DØ andBABAR PRD 73, 011101 (2006), 232M BB N=49±8 N=61±15 (6.1 σ) hep-ex/0505038 Updated 256 fb-1 Solid Hist.: mES sidebands 20

  21. X(3872) → J/ψγ 287M BB N=19±6 (3.4 σ) • BABAR confirms X(3872) → γJ/ψ • This implies that X(3872) is a C=+1 state • All evidence points towards X(3872) being an isoscalar 1++ state 21

  22. (2S) Y(4260) → J/ψπ+π– → JPC = 1–– • Searching for X(3872) in ISR events but found Y(4260) 233 fb-1, PRL 95, 142001 (2005) Peak cross section: σ(e+e-Y)=(51±12) pb 22

  23. Y(4260) → J/ψππ CLEO results confirm Y(4260) • Consistent with BABAR cross section • No J/ψπ0 decay signal seen hep-ex/0602034 N=37 N=8 23

  24. M(K+K-) Y(4260) Y(4260) Searches in ISR Processes e+e– → γISR pp, (232 fb–1) PRD 73, 012005 (2006) e+e–→γISRΦπ+π– (232 fb-1) To.b.subm.to PRD e+e–→γISRDD (289 fb-1) To.b.subm.to PRL ψ(3770) γISR detected γISR detection not required γISR detected 24

  25. Summary 25

  26. Summary • Charm spectroscopy at BABAR is very active and pushing the boundaries of experimental knowledge. • Λc(2940)+ first observation; absence in D+p is consistent with Λc interpretation. • Λc(2880)+: first observation in D0p decay mode; improved (M,Γ); absence in D+p is consistent with Λc interpretation. • Ξcc+ and Ξcc++ are searched for but not found; limits not theoretically restrictive. • Updates on DsJ*(2317)+ and DsJ(2460)+; absolute branching fraction measurements for DsJ(2460)+ • X(3872) update and confirmation of positive C parity from J/ψγ mode • Y(4260): limits on DD, φπ+π–, and pp decay modes 26

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