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Experimental results in charmonium decays from BES Rong-Gang Ping (presented by F. Harris) for BES collaboration Charm 2007 Aug. 6, 2007
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(2s) data samples ’ decays Leptonic decays Radiative decays Hadronic decays cJ decays VV PPP 3M 14M 4M outline 26M Also 6.42 pb -1 of data at Ecm=3.65 GeV for background study.
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Expected? Sequential lepton hypothesis:
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BESII: remeasure with larger sample Measured in e e Characterized by 2 charged tracks; 1 and 1 e missing energy and momentum no extra hits in BSC = 17.8%
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BESII Result: B( ) = (3.10 0.21 0.38) x 10 -3 B ee (10 -3 )B (10 -3 )B /0.3885 (10 -3 ) 7.35 0.387.3 0.88.0 1.1 Lepton universality is tested in charmonium decays. PRD 74: 112003 (2006)
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’ radiative decays PRL 99, 011802 (2007)
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Observation of ’ radiative decays Mode BR ( 10 -5 ) [m<2.9 GeV/c 2 ] pp-bar 2.9 ± 0.4 ± 0.4 ’ ’ 12.6 ± 2.9 ± 1.5 2( + - ) 39.6 ± 2.8 ± 5.0 K S K + - +c.c. 25.6 ± 3.6 ± 3.6 +-K+K- +-K+K- 19.1 ± 2.7 ± 4.3 + - ppbar 2.8 ± 1.2 ± 0.7 2(K + K - ) < 4.0 3( + - ) < 17 2( + - )K + K - < 22 Expect ~1% BR, but only 0.05% previously observed. Potential channels for hadron spectroscopy study, including search for non-qqbar states, if enough statistics. ~ 0.1% more observed in this analysis. PRL99, 011802 (2007)
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PRD74, 072001 (2006).
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K*K ρπ MARK-II
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x 10 -4 Angular distribution: 2
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Baryonic decays Rich structure (N*s), statistics (~850 evts in each mode). Still low for a partial wave analysis. PRD74, 012004 (2006)
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Test I-spin symmetry (prediction: 1:2:2)
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PRL 99,011802 (2007)
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cJ → 2(K + K ) Improved precision over PDG (BESI) results on cJ KKKK and . First measurement of cJ KK. c2 c0 c1 Pair production of vectors PLB642, 197 (2006)
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PRD 74, 072001 (2006) c2 c1 c0 → PPP is suppressed by spin-parity selection; cJ decays into PPP PRD74, 072001 (2006) cJ → KK and c1 → K S K + - +c.c. K*
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N sig =418 ± 60 Nsig=58 ± 14 (4.5 )N sig =222 ±28 (8.8 ) sideband a sideband c1 → + -
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BES: cJ → KK and PRD 74, 072001 (2006 ) CLEO-c, PRD75, 032002
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’ (J/ ) + 0 / Is it really B( 0 )>B( )? arXiv: 0707.1127 [hep-ex] Submitted to PRD First measurement! background from J/ ΣΛπ signal
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’ leptonic decays, hadronic decays, radiative decays are studied to search for new phenomena and to test QCD predictions. c decays are studied using ’ data sample. CLEOc will take the leading role in ’ and c decays; we are now preparing for the BESIII data taking and the physics analysis. Summary Thanks a lot !
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