c c c c c c c c c c a Charmed baryon spectroscopy at Belle Y. Kato(KMI, Nagoya University) Phys. Rev. D 89, 052003 arXiv:1312.1026 c c Introduction Charmed strange baryons(Ξc) s s d a u c Physics of charmed baryons Ξc is a good probe to study u/d-s diquark system. This correlation can be studied only in the charm sector because in the strange sector, s quark is heavier than u/d quarks and weak u-d diquark correlation emerges. Charm quark is heavy (~1.5 GeV) compared with ..... Momentum of quarks inside the hadron (200 MeV) → Doubly charmed baryon is a good probe to study the potential between heavy quarks. Similar to the study of QQbar potential by charmonium spectroscopy. 2. Mass of u,d,s quarks (300-500 MeV) → Singly charmed baryon is a good probe to study the diquark correlation of light quarks. This is because spin-spin interaction is proportional to 1/m1m2. λmode s u ρ mode BaBar c c c c Belle Belle found Ξc(2980) and Ξc(3080) in the Λc+K-π+ final state. Later, BaBar studied the same final state. They required Λc+π+ mass to be Σc(*) and reported another two resonances, Ξc(3055) and Ξc(3123) Ξc(3080) Σc(2520) d u Σc(2455) c Ξc(2980) Ξc(2980) Ξc(3080) Ξc(3055)? Require Σc(2455) λ mode Ξc(3123)? Ξc(3080) q q ρmode Experimental situation M(Λc+K-π+) diquark Require Σc(2520) Re-analysis by Belle M(Λc+K-π+) ・All the ground states of single charmed baryon has discovered 　mainly by e+e- collideer experiments like CLEO, BaBar, Belle. ・Many excited states has been also discovered. ・Almost no quantum numbers has been measured. ・No doubly charmed baryons including ground states. Ξc(2980)+ Ξc(3080)+ Ξc(3080)+ Ξc(3055) is confirmed in Σc(2455) K- while Ξc(3123) in Σc(2520) is not confirmed. U.L of the cross section is 0.34 fb ⇔ (1.6±0.6±0.2)fb by BaBar. Ξc(3055)+ spin=3/2 spin=1/2 charm Further study with ΛD final state ΛD0 ΛD+ M(ΛD0) D0 sideband M(ΛD0bar) M(ΛD+) D+ sideband M(ΛD-) Ξc(3055)+ Ξc(3055)0 We observe Ξc(3055)/(3080) in the ΛD final state. This is the first observation of the Ξc(3055)0. As discussed later, The relative branching fraction is sensitive to the excitation modes (ρ,λ) c c Ξc(3080)0 Search for doubly charmed baryons u Experimental situation ？ The SELEX experiment in FNAL reported evidence of Ξcc+ in the Λc+K-π final state at 3520 MeV. However, this result was not supported by Belle, BaBar, Focus and LHCb. To discover the ground state is a big milestone. Discussion on the Ξc states Comparison of Λc+ and Ξc, Σc and Ξc’ New analysis by Belle Jp Λc+ (cud) Ξc (cus) ΔM(Mev/c2) Note 1/2+ Λc(2286)+ Ξc(2470) 181 ground state 1/2- Λc(2595)+ Ξc(2790) 194 Λ(1405) like 3/2- Λc(2625)+ Ξc(2815) 188 Λ(1520) like ?? Λc(2765)+? Ξc(2980)? 205 Isospin not determined 5/2+ Λc(2880)+ Ξc(3080)? 200 ・Use full statistics (980fb-1) of Belle data. =2 (4) times of previous Belle (BaBar) anslysis ・Study not only Λc+K-π+ final state but also Ξc0π+ decay mode (Belle studied Λc+K-π+ only but BaBar studied both) ・Add several sub decay of Λc+ (pK-π+, pKS0)and Ξc0 (Ξ-π+, ΛK-π+, pK-K-π+) → yield is increased by 20% for Λc+ and 3 times for Ξc0 spin0 di-quark Jp Σc Ξc’ ΔM(Mev/c2) Note 1/2+ Σc(2455) Ξc(2575) 120 ground state 3/2+ Σc(2520) Ξc(2645) 125 Σ(1385) like ?? Σc(2800) spin1 di-quark Ξc0π+ mode Λc+K-π+ mode Ξc0→Ξ-π+ Ξc0→pK-K-π+ ・Thee mass difference of Λc+ and Ξc is ~200 MeV, Σc and Ξc’ is ~120 MeV. Λc+ with 3055-200 = 2855 MeV, or Σc with 3055-120 = 2935 MeV ? Ξc(3055) is a pecial state by including strange quark?? Discussion from decay modes. Data Expectation of signal (assuming σ=500fb, Br=5%) Ξc0→ΛK-π+ Prediction from chiral quark model for relative branching fraction for Ξc(3055) arXiv:1205.2943 Lei-Hua Liu et al No significant signal! Close to the some of theoretical prediction. Possible to access in the BelleⅡ? Large branching fraction to ΛD is inconsistent Ξc(3055)/(3080) can decay into （heavy baryon+ light meson） and (light meson + heavy baryon) Σc Λ D K- UL of σ(e+e-→ΞccX)×Br(Ξcc+→Ξc0π+)×Br(Ξc+→Ξ-π+) σ(e+e-→ΞccX)×Br(Ξcc+→ΛcK-π+) c Naively thinking… λ mode→ (light baryon) + (heavy meson) ρ mode→ (heavy baryon) + (light meson) This study 4.1-25 fb Theory 3.5-10fb (assuming Br=5%) This study 0.076-0.35 fb Theory 0.175-0.5 fb (assuming Br=5%) λ mode s u Excitation of both λ and ρ mode? Further theoretical study is necessary. ρ mode