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Charm Baryon Spectroscopy at Belle

Charm Baryon Spectroscopy at Belle. Charm 2006 Bejing 5-7 June, 2006. Ruslan Chistov (ITEP, Moscow). Introduction to charmed baryons at Belle Observation of  c (2800) in e + e - continuum (3) Improved measurement of  c 0 and  c + masses

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Charm Baryon Spectroscopy at Belle

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  1. Charm Baryon SpectroscopyatBelle Charm 2006 Bejing 5-7 June, 2006 Ruslan Chistov (ITEP, Moscow) • Introduction to charmed baryons at Belle • Observation of c(2800) in e+e- continuum • (3) Improved measurement of c0 and c+ masses • (4) Study of excited states c(2645) (preliminary) • (5) Observation of new charmed baryons decaying into • c+ K- +andc+ K0S -(preliminary) • (6) Search for the SELEX double charm baryon decaying into c+ K- + • (preliminary) • (7) Summary Ruslan Chistov (ITEP, Moscow) Charm Baryon Spectroscopy at Belle Charm 2006

  2. Introduction to Charm Baryons at Belle Charmed baryon spectroscopy is an excellent laboratory to study the dynamics of light diquark in the environment of heavy C-quark.  Many theoretical predictions and approaches could be tested. History: ARGUS(1993) observed first excited charmed baryon c(2625)+, then CLEO(1993) confirmed it and observed c(2593)+, E687 and ARGUS subsequently confirmed the latter. Next observations came from CLEO: c(2520)+, c(2765)+, c(2880)+. Belle(2005): Observation of first orbital excitation of c : c(2800). This year recent results from Belle include also *observation of new charm baryons in c+ K- +andc+ K0S - final states *and study of excited states c(2645) Ruslan Chistov (ITEP, Moscow) Charm Baryon Spectroscopy at Belle Charm 2006

  3. Observation of c(2800): (PRL 94, 12202 (2005)) c+- c+0 c++ Feeddown from c(2880)+ Signal c+sideband ISOTRIPLET! Ruslan Chistov (ITEP, Moscow) Charm Baryon Spectroscopy at Belle Charm 2006

  4. Observation of c(2800): Discussion Theoretical models predict a rich spectrum of excited charmed baryons in the vicinity of the c(2800) [L.A.Copley, N.Isgur and G.Karl, Phys. Rev D 20, 768 (1979)]. One of the candidates is a c2 doublet with JP=3/2- and 5/2- (subscript 2 denotes the total angular momentum of light diquark.) c2 is expected to decay principally intoc+ in D-wave. The predicted mass is close to the measured but the predicted width is only 15 MeV. But the c2 (3/2-) can mix with the nearby c1 (3/2-) which would produce a wider physical state. Ruslan Chistov (ITEP, Moscow) Charm Baryon Spectroscopy at Belle Charm 2006

  5. Introduction to Charm Baryons at Belle Improved measurement of c0 and c+ masses PLB 605, 237 (2005) The c’s are reconstructed in 7 decay modes K-++ K-+ -+ pK-K-+ -++ pKS0KS0 KS0 Ruslan Chistov (ITEP, Moscow) Charm Baryon Spectroscopy at Belle Charm 2006

  6. Introduction to Charm Baryons at Belle Improved measurement of c0 and c+ masses PLB 605, 237 (2005), Erratum PLB 617, 198 (2005) Due to the mass scale +0.2-1.4 +0.2-1.4 Ruslan Chistov (ITEP, Moscow) Charm Baryon Spectroscopy at Belle Charm 2006

  7. Study of excited states c(2645) L450 fb-1 C(2645)+ C(2645)0 Reflection from C(2790)0c’+-, c’+  c+  (verified with MC) Reflection from C(2790)+c’0+ (verified with MC) c’0  c0  First confirmation Mass(C0+) Mass(c+-) C+-++ C0-+ Ruslan Chistov (ITEP, Moscow) Charm Baryon Spectroscopy at Belle Charm 2006

  8. Study of excited states c(2645):mass measurements Belle (2006): Preliminary PDG(2005): Ruslan Chistov (ITEP, Moscow) Charm Baryon Spectroscopy at Belle Charm 2006

  9. New Charmed Baryons from Belle Near threshold in Mass(c+ K- +) two new charmed baryons cx(2980)+ and cx(3077)+ were observed L450 fb-1 cx(3077)+: 9.7 N=326.0 ± 39.6 events M=3076.7 ± 0.9 ± 0.5 MeV =6.2 ± 1.2 ± 0.8 MeV cx(2980)+: 6.3 N=405.3 ± 50.7 events M=2978.5 ± 2.1 ± 2.0 MeV =43.5 ± 7.5 ± 7.0 MeV cx(3077)+ cx(2980)+ wrong-sign c+ K+ - Preliminary Ruslan Chistov (ITEP, Moscow) Charm Baryon Spectroscopy at Belle Charm 2006

  10. New Charmed Baryons from Belle To get more information about the properties of found states we searched for their isopartners in Mass(c+ K0S -) and observe cx(3077)0 L450 fb-1 High mass state - cx(3077)0 N=67.1 ± 19.9 M=3082.8 ± 1.8 MeV =5.2 ± 3.1 MeV Significance=5.1 cx(3077)0 cx(2980)0 Low mass state - cx(2980)0 N= 42.3 ± 23.8 M=2977.1 ± 8.8 MeV =43.6 MeV FIXED Significance=2.0 wrong-sign c+ K+ - Preliminary Ruslan Chistov (ITEP, Moscow) Charm Baryon Spectroscopy at Belle Charm 2006

  11. Recent Results from Belle Belle searched for the SELEX double charm baryon cc (3520)+ c+ K- + L450 fb-1 null result N=8.3 ± 37.3 < 69.1 @ 90% CL Preliminary Ruslan Chistov (ITEP, Moscow) Charm Baryon Spectroscopy at Belle Charm 2006

  12. Recent Results from Belle:upper limit on the production of the SELEX double charm baryon We reconstruct 835360 ± 13748 c+ pK-+decays (cc(3520)+)Br(cc(3520)+c+K-+ | p*(c+)>2.5 GeV) <1.510-4 (c+ | p*(c+)>2.5 GeV) @ 90% CL Preliminary BaBar observes NO SIGNAL ALSO in a similar decay mode (hep-ex/0605075) Ruslan Chistov (ITEP, Moscow) Charm Baryon Spectroscopy at Belle Charm 2006

  13. Summary • NEW Isotriplet of Charmed Baryons is observed by Belle: • c(2800) • (2) Belle measured with high accuracy the masses of • c0 and c+ • c(2645)0 and c(2645)+ • (3)Belle searched for the SELEX double charm baryon cc(3520)+, • found no signal and set an UL on its production cross-section • Belle observed three new charm baryons • cx(3077)+ c+ K- + • cx(2980)+ c+ K- + • cx(3077)0 c+ KS0 - • Studies of their properties are ongoing Ruslan Chistov (ITEP, Moscow) Charm Baryon Spectroscopy at Belle Charm 2006

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