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What is the charmed analog of L (1405)?

What is the charmed analog of L (1405)?. Kiyoshi Tanida (Seoul National University) Aug. 23, 2011 APFB2011, Seoul. Λ （ 1405 ）. How is it in charmed sector?. Large mass difference of πΣ and DN → mixing should be small Both of Σπ resonance and ND bound state can be seen as separate peaks?.

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What is the charmed analog of L (1405)?

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  1. What is the charmed analog of L(1405)? Kiyoshi Tanida (Seoul National University) Aug. 23, 2011 APFB2011, Seoul

  2. Λ（1405）

  3. How is it in charmed sector? • Large mass difference of πΣ and DN→ mixing should be small • Both of Σπ resonance and ND bound state can be seen as separate peaks?

  4. Σcπresonance? • Just on Σcπ threshold • Still, the main decay mode is Σcπ

  5. Is there DN bound state? • JP are unknown, but they may be the bound state.Binding energies: 45MeV& 10MeV, respectively • In the strangeness sector, attraction for I=0 channel is stronger than I=1.

  6. Λc（2765） Λc（2880） PRL86（2001）4479 data from CLEO B decay →Λc*→Λcππ（Σcπ、Σc*π included） Width～50MeV Λc（2765）

  7. CLEO data Λc（2880） Λc（2765） Λc（2880） Σcπ BR=31±7% Rough estimation in similar way: Λc（2765）  Σcπ ～26% Λc（2765）  Σc*π ～33% via Σcπ via Σc*π

  8. BELLE data PRL98 (2007) 262001 This paper’s main subject is Λc(2880), but Λ(2765) was clearly seen, too. Black: via Σcπ Red：sideband background　　 （scaled） Width：73±5 MeV (Not used in PDG)

  9. Σcπ partial decay rate? • Λc(2595): • Full width=3.6+2.0-1.3 MeV • BR(Σcπ) > 70%. Partial width ~ 2.5 MeV • Λc(2765): • Rough estimation: Γ(Σcπ)～ 30MeV • Dividing by phase space・・・ • Λc(2595): Q-value too smallΣc++π-: 1.7±0.6MeV、 Σc+π0: 7.4±0.7 MeVQ may be < 0 （Threshold effect on spectrum）→Unmeasured Σc+π0 mode would be the main channel • Squared matrix element may be twice larger forΛc(2595)

  10. Λc(2595) shape • CLEO data fit with threshold effect considered. (PRD67 074033)  M(Λc*)- M(Λc) = 305.6±0.3 MeV  ~3 MeV below Scp

  11. Known things • Λ(1405)analog states • Σπ resonance certainly exists. • DN bound state: candidate exists. • Comparing partial decay rates, it seems Λc(2595) has a stronger coupling to Σcπ • Λc(2765) has too many unknowns, and the quality of data Λc(2595) is not enough.

  12. What we want to know • Is Λc(2765) really the ND bound state and can be considered as a Λ(1405) analog state? • Key measurements • Spin-parity:  Many controversial predictions • Decay width, branching ratios • Λc(2595) needs more data, too. • Need to consider threshold effect. Σc+π0 mode would be a key. • Need help from theory side • Threshold effect for Λc(2595) • Discussion from partial widths • Determination of parity (which was the case for Λc(2880))

  13. BELLEdata PRL98 (2007) 262001 This paper’s main subject is Λc(2880), but Λ(2765) was clearly seen, too. Black: via Σcπ Red：sideband background　　 （scaled） Width：73±5 MeV (Not used in PDG)

  14. Possibility at BELLE • Decay widths seem feasible • Is Λc(2595)→Σc+π0 possible? • Determination of spin • angular distribution ofΛc→Σcπ • Done for Λc(2880) • Parity • Most difficult • Λc(2880) parity was determined from BR ofΣcπand Σc*π using model (heavy quarksymmetry)

  15. Summary • Charmed analog of Λ(1405) • Σπresonance： Λc(2595) • DNbound state: Λc(2765)? • We want to know the nature of Λc(2765) • Spin-parity (1/2- ?) • Decay width measurements would help, too. • B-factory data contains huge statistics→ analysis seems feasible

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