Recent results of charmonium decaying into baryons at BESIII

Xu XinpingXu Xinping1,2 1,2 ( (徐新平徐新平 )) on behalf of the BESIII Collaborationon behalf of the BESIII Collaboration

1.Depart. Physics 1.Depart. Physics & & Astronomy, Seoul National UniversitySeoul National University

2.2.Soochow University, Suzhou 215006, P.R. ChinaSoochow University, Suzhou 215006, 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, χcJ , ηc, ψ(2S),

2. Baryons final states, pp̅ , nn̅, ΛΛ� , Σ0Σ ̅0,

Σ+Σ ̅-, p̅ K+Λ, etc

Summary23/4/21 2013 YongPyong Winter Conference 2

RFRF SR

IP22

mra

d

2. 5m8ns

1. 5cm

0.1cmBeam energy: 1.0-2.3 GeVDesign Luminosity: 1×1033 cm-2s-1

Optimum energy: 1.89 GeVEnergy spread: 5.16 ×10-4

No. of bunches: 93Bunch length: 1.5 cmTotal current: 0.91 ACircumference： 237m

BEPC II Storage ringBEPC II Storage ring: Double ring: Double ring

The BESIII DetectorThe BESIII Detector

Be beam pipe

SC magnet, 1TMagnet yoke

MDC, 120 m

CsI(Tl) calorimeter, 2.5 %@ 1 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 WashingtonCarnegie 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 MainzRussia: JINR Dubna; BINP Novosibirsk Italy: Univ. of Torino ， Frascati Lab

Netherland ： KVI/Univ. of GroningenSweden: Uppsala Univ.

Turkey: Turkey Accelerator Center

China(30)IHEP, CCAST, GUCAS, Shandong Univ.,

Univ. of Sci. and Tech. of ChinaZhejiang 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 ChinaHunan 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 members52 institutions from 11 countries

BESIIIBESIII CollaborationCollaboration

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Data samples at BESIII experimentData 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-1 @ 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 χcJ, ηc etc.

Provide a good platform for precise measurement of charmonium decaying into baryonic final states

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Recent results on Charmonium decaying into baryon final states

BESIII Measurements:

Two body decay:

J/ψ→Λ Σ ̅0 +c.c.

χcJ → ΛΛ� , Σ0Σ ̅0, Σ+Σ ̅-

χcJ → ΛΛ̅ π+π-

J/ψ→pp ̅ , nn ̅

ηc → Σ+Σ̅ -, Ξ-Ξ ̅ +

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Three body decay:

J/ψ, ψ (2S)→Λ Λ̅ π0 /η

ψ(2S)→p ̅ K+Σ0 and χcJ→p ̅ K+Λ

ψ(2S)→pp ̅ π0

First Observation of J/ψ→Λ Σ ̅0 +c.c.

Motivation:

isospin symmetry breaking decay

Helpful to understand isospin breaking mechanisms

in J/ψ→B8 B̅ 8

BESIII Collaboration: PRD 86, 032008(2012)

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J/ψ, ψ (2S)→Λ Λ ̅ π0 /η Motivation:

Λ Λ ̅ π0 : isospin violating decay, first observation

Λ Λ ̅ η : isospin conserving decay

BESIII Collaboration,

arXiv:1211. arXiv:1211.4682

To be published in PRD

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χcJ → ΛΛ� , Σ0Σ̅ 0, Σ+Σ̅ -

Motivation:

Test color octet mechanism(COM)

for the P-wave charmonia decay.

High precision measurement is

Important!BESIII Collab. PRD87, 032007(2013)

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χcJ → ΛΛ ̅ π+π-

Data sample: 106M (2S) ΛΛ ̅ π+π- observed for the first

time χcJ → Σ̅ (1385)±Σ̅ (1385)-+

Observed for the first time

BESIII Collaboration,

PRD86, 052004 (2012)

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J/ψ→pp̅ , nn ̅

Based on 225M J/ events The most accurate measurements in the world Angular parameter α:

BESIII Collaboration PRD 86, 032014 (2012)

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First observation of ηc → Σ+Σ ̅ -, Ξ-Ξ ̅ +

Data sample: 225M J/ events Compared with intermediate meson loop(IML) calculation BESIII Collaboration, PRD 87, 012003 (2013)

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ψ(2S)→p̅ K+Σ0 and χcJ→p̅ K+Λ Data sample: 106M (2S) ψ(2S)→p ̅ K+Σ0 (first time observation) There is an enhancement in

the mass of p ̅ Λ in the decay

χcJ→p ̅ K+Λ

BESIII Collaboration,

PRD87, 012007(2013)

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ψ(2S)→pp̅ π0

Use Partial Wave Analysis Two new N* are observed BESIII Collaboration, PRL110, 022001(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. χcJ → ΛΛ� , Σ0Σ ̅0, Σ+Σ ̅-

χcJ → ΛΛ̅ π+π- J/ψ→pp ̅ , nn ̅

ηc → Σ+Σ̅ -, Ξ-Ξ ̅ + J/ψ, ψ (2S)→Λ Λ̅ π0 /η

ψ(2S)→p ̅ K+Σ0, χcJ→p ̅ K+Λ, ψ(2S)→pp ̅ π0

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Thank you