04/19/23 Ping Wang (IHEP, Beijing) 1

Ping Wang

(for the collaboration of BESIII)

Institute of High Energy Physics, Beijing, China

PHIPSI11, Novosibirsk, Sept, 2011

Charmonium Decays at BESIII

04/19/23 Ping Wang (IHEP, Beijing) 2

Outline

Brief introduction of BEPCII & BESIIICharmonium decays: 'P , cJV, cJVVSummary

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BEPCII & BESIIIBEPCII & BESIII

Charm energy region

Updated detectors

Large luminosity

BESIII is special!

Abundant potential physics with BESIII.

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Charmonium spectrum below open charm threshold

106M 106M (2S) at BESIII(2S) at BESIII

0

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' P( P(00,,,,'), arise surprises), arise surprises

CLEO-c: J/ψ, ψ', ψ'' PRJ/ = (21.1± 0.9)%

No Evidence for ' 0 or Br(′′)=(1.19 ± 0.09)%

R' < 1.8% at 90% CL

R' << RJ/

PRD 79, 111101 (2009)

V P are important tests for various mechanisms:Vector meson Dominance Model (VDM); Couplings & form factor; Mixing of -′(-c); FSR by light quarks; 12% rule and “ puzzle”.

theorytheory experimentexperiment

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’’ P P at BESIIIat BESIIIψ'→ γη'ψ'→ γη

(First observation)ψ'→γ0

(First observation)

PRL 105, 261801 (2010)

Possible interpretation: Q. Zhao, Phys. Lett. B697, 52 (2011)

R′= 1.10±0.38±0.07% << RJ/

+-0

000

’+-

’+-

Mode B(’) [x10-6] B(J/) [x10-4] Q (%)0 1.580.42 0.350.03 4.5 1.3 1.380.49 11.040.34 0.13 0.04

’ 1269 52.81.5 2.4 0.2

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cJcJ V( V(,,,,) , prediction by pQCD ) , prediction by pQCD

much lower than experimentmuch lower than experiment• Information of C-even state• Two gluon coupling• Possible glue-ball or hybrid states• Hadronization

Br. are in unit of 10-6.

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cJcJ V( V(,,,,)) results at BESIII results at BESIII)(M )(M )(M

KK0

 Phys. Rev. D 83, 112005 (2011) 

An non-pQCD explanation “hadronic loop correction”, D.Y Chen et al. arXiv:1005.0066v2[hep-ph] EPJC70, 177-182 (2010)

BESIII

<10.5

228±13±16

<20.8<12.9

69.7±7.2±5.6

<6.1<16.2

25.8±5.2±2.0

<8.1

First First

observationobservation

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Polarization ofPolarization of c1c1 V( V(,,,,) ) L: Longitudinal polarization, T: Transverse polarization, θ: Helicity angle

015.0014.0034.0158.0

Tf044.0

026.0090.0087.0247.0

Tf

10.0

09.013.012.029.0

Tf

1c 1c 1c

22 sin2

1cos)1(

cos TT ffd

d

Longitudinal polarization dominates

D.V. Amelin et al. (VES Collaboration), Z. Phys. C 66, 71 (1995)C.N. Yang, Phys. Rev. 77, 242 (1950)

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ccVV(V=VV(V=, , , suppressed decays, suppressed decays cJ and cJ are Singly OZI suppressed

c1 and c1 is suppressed by helicity selection rule.

cJ is doubly OZI suppressed, not measured yetBESII on c0,2 / PLB 642,197(2006), PLB 630,7 (2005)

Reconstruct and via K+K- or +-0

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First observation Evidence

Accepted by PRLAccepted by PRLccVV VV at BESIIIat BESIII

Large distance effect: X. H. Liu, et al, PRD 81, 014017 (2010) D.Y. Chen, et al, PRD 81, 074006 (2010)

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summarysummary With very high luminosity, BEPCII/BESIII is the b

est instrument to study the physics at -charm region.

BESIII has obtained good measurements on decays of ′ P, cJ V and cJ VV.

With the accumulated 106M ′ sample, these results are precision measurements or first observation.

More exciting/interesting results are coming.