Recent results of charmonium decaying into baryons at BESIII Xu Xinping 1,2 ( 徐新平 ) Xu Xinping 1,2 ( 徐新平 ) on behalf of the BESIII Collaboration on behalf of the BESIII Collaboration 1.Depart. Physics & Seoul National University 1.Depart. Physics & Astronomy, Seoul National University 2.Soochow University, Suzhou , P.R. China 2.Soochow University, Suzhou , P.R. China

Out line: The BEPCII and BESIII detector The BESIII Collaboration Data samples at BESIII Physics Results 1. Large number of charmonium: J/ψ, χ cJ, η c, ψ(2S), 2. Baryons final states, pp ̅, nn ̅, ΛΛ ̅, Σ 0 Σ ̅ 0, Σ + Σ ̅ -, p ̅ K + Λ, etc Summary YongPyong Winter Conference 2

RF SR IP Beam energy: GeV Design Luminosity: 1×10 33 cm -2 s -1 Optimum energy: 1.89 GeV Energy spread: 5.16 ×10 -4 No. of bunches: 93 Bunch length: 1.5 cm Total current: 0.91 A Circumference ： 237m BEPC II Storage ring: Double ring

The BESIII Detector Be beam pipe SC magnet, 1T Magnet yoke MDC, 120  m CsI(Tl) calorimeter, GeV TOF, 90ps RPC A total weight of 730t, ~40000 readout channels, data rate 6000Hz ~50Mb/s, ~1000 man*year, 30 M$

Japan (1) Tokyo Univ. US (6) Univ. of Hawaii Univ. of Washington Carnegie Mellon Univ. Univ. of Minnesota Univ. of Rochester Univ. of Indiana Europe (12) Germany: Univ. of Bochum, Univ. of Giessen, GSI Univ. of Johannes Gutenberg Helmholtz Ins. In Mainz Russia: JINR Dubna; BINP Novosibirsk Italy: Univ. of Torino ， Frascati Lab Netherland ： KVI/Univ. of Groningen Sweden: Uppsala Univ. Turkey: Turkey Accelerator Center China(30) IHEP, CCAST, GUCAS, Shandong Univ., Univ. of Sci. and Tech. of China Zhejiang Univ., Huangshan Coll. Huazhong Normal Univ., Wuhan Univ. Zhengzhou Univ., Henan Normal Univ. Peking Univ., Tsinghua Univ., Zhongshan Univ.,Nankai Univ. Shanxi Univ., Sichuan Univ., Univ. of South China Hunan Univ., Liaoning Univ. Nanjing Univ., Nanjing Normal Univ. Guangxi Normal Univ., Guangxi Univ. Suzhou Univ., Hangzhou Normal Univ. Lanzhou Univ., Henan Sci. and Tech. Univ. Hong Kong Univ., Hong Kong Chinese Univ. Korea (1) Seoul Nat. Univ. Pakistan (2) Univ. of Punjab COMSAT CIIT ~300 members 52 institutions from 11 countries BESIII Collaboration

YongPyong Winter Conference 6 Data samples at BESIII experiment   2009   106M  (2S) (4 times of CLEOc)   225M J/  (4 times of BESII)   2010   ~0.9 fb -1  (3770)   2011   ~2.0 fb -1  (3770) (3.5 times of CLEOc)   ~0.5 fb 4.01 GeV   2012   ~0.4 billion  (2S)   ~1 billion J/    515 pb -1 Y(4260) 40 times of the Cleoc; ~500 pb -1 Y(4360) The world Largest J/ ,  (2S),  (3770) Y(4260)data samples.

Charmonium decays to Baryons BESIII have the largest charmonium data samples (J/ ,  (2S)), including the transition charmonium states χ cJ, η c etc. Provide a good platform for precise measurement of charmonium decaying into baryonic final states YongPyong Winter Conference 7

Recent results on Charmonium decaying into baryon final states BESIII Measurements: Two body decay: J/ψ→Λ Σ ̅ 0 +c.c. χ cJ → ΛΛ ̅, Σ 0 Σ ̅ 0, Σ + Σ ̅ - χ cJ → ΛΛ ̅ π + π - J/ψ→pp ̅, nn ̅ η c → Σ + Σ ̅ -, Ξ - Ξ ̅ YongPyong Winter Conference 8 Three body decay: J/ψ, ψ (2S)→Λ Λ ̅ π 0 /η ψ(2S)→p ̅ K + Σ 0 and χ cJ →p ̅ K + Λ ψ(2S)→pp ̅ π 0

First Observation of J/ψ→Λ Σ ̅ 0 +c.c. Motivation: isospin symmetry breaking decay Helpful to understand isospin breaking mechanisms in J/ψ→B 8 B ̅ 8 BESIII Collaboration: PRD 86, (2012) YongPyong Winter Conference 9

J/ψ, ψ (2S)→Λ Λ ̅ π 0 /η Motivation: Λ Λ ̅ π 0 : isospin violating decay, first observation Λ Λ ̅ η : isospin conserving decay BESIII Collaboration, arXiv:1211. arXiv: arXiv: To be published in PRD YongPyong Winter Conference 10

YongPyong Winter Conference 11 χ cJ → ΛΛ ̅, Σ 0 Σ ̅ 0, Σ + Σ ̅ - Motivation: Test color octet mechanism(COM) for the P-wave charmonia decay. High precision measurement is Important! BESIII Collab. PRD87, (2013)

YongPyong Winter Conference 12 χ cJ → ΛΛ ̅ π + π - Data sample: 106M  (2S) ΛΛ ̅ π + π - observed for the first time χ cJ → Σ ̅ (1385) ± Σ ̅ (1385) -+ Observed for the first time BESIII Collaboration, PRD86, (2012)

YongPyong Winter Conference 13 J/ψ→pp ̅, nn ̅ Based on 225M J/  events The most accurate measurements in the world Angular parameter α: BESIII Collaboration PRD 86, (2012)

YongPyong Winter Conference 14 First observation of η c → Σ + Σ ̅ -, Ξ - Ξ ̅ + Data sample: 225M J/  events Compared with intermediate meson loop(IML) calculation BESIII Collaboration, PRD 87, (2013)

YongPyong Winter Conference 15 ψ(2S)→p ̅ K + Σ 0 and χ cJ →p ̅ K + Λ Data sample: 106M  (2S) ψ(2S)→p ̅ K + Σ 0 (first time observation) There is an enhancement in the mass of p ̅ Λ in the decay χ cJ →p ̅ K + Λ BESIII Collaboration, PRD87, (2013)

YongPyong Winter Conference 16 ψ(2S)→pp ̅ π 0 Use Partial Wave Analysis Two new N* are observed BESIII Collaboration, PRL110, (2013)

Summary Based on the largest charmonium data samples, the BESIII experiment obtained the most accurate results for charmonium decaying into baryonic final states. Some decays are measured for the first time, the others are measured with improved precision. J/ψ→Λ Σ ̅ 0 +c.c. χ cJ → ΛΛ ̅, Σ 0 Σ ̅ 0, Σ + Σ ̅ - χ cJ → ΛΛ ̅ π + π - J/ψ→pp ̅, nn ̅ η c → Σ + Σ ̅ -, Ξ - Ξ ̅ + J/ψ, ψ (2S)→Λ Λ ̅ π 0 /η ψ(2S)→p ̅ K + Σ 0, χ cJ →p ̅ K + Λ, ψ(2S)→pp ̅ π YongPyong Winter Conference 17

YongPyong Winter Conference 18 Thank you