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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 - PowerPoint PPT Presentation
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Ruslan Chistov (ITEP, Moscow) Charm Baryon Spectroscopy at Belle Charm 2006
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Charm Baryon SpectroscopyCharm Baryon Spectroscopy atat BelleBelle
(1) Introduction to charmed baryons at Belle (2) Observation of c(2800) in e+e- continuum (3) Improved measurement of c
0 and c+ masses
(4) Study of excited states c(2645) (preliminary)
(5) Observation of new charmed baryons decaying into c
+ K- + and c+ K0
S - (preliminary) (6) Search for the SELEX double charm baryon decaying into c
+ K- +
(preliminary) (7) Summary
Ruslan ChistovRuslan Chistov(ITEP, Moscow)(ITEP, Moscow)
Charm 2006 Bejing 5-7 June, 2006
Ruslan Chistov (ITEP, Moscow) Charm Baryon Spectroscopy at Belle Charm 2006
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Introduction to Charm Baryons at Introduction to Charm Baryons at BelleBelle
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+ K0
S - final states *and study of excited states c(2645)
Ruslan Chistov (ITEP, Moscow) Charm Baryon Spectroscopy at Belle Charm 2006
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Signal
c+ sideband
Feeddown from c(2880)+
Observation of Observation of cc(2800): (2800): (PRL 94, 12202 (2005))(PRL 94, 12202 (2005))
cc++-- cc
++00 cc++++
ISOTRIPLET!
Ruslan Chistov (ITEP, Moscow) Charm Baryon Spectroscopy at Belle Charm 2006
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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.
Observation of Observation of cc(2800): (2800): DiscussionDiscussion
Ruslan Chistov (ITEP, Moscow) Charm Baryon Spectroscopy at Belle Charm 2006
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Introduction to Charm Baryons at Introduction to Charm Baryons at BelleBelle
Improved measurement of Improved measurement of cc
00 and and cc++ masses masses
PLB 605, 237 (2005)
The c’s are reconstructed in 7 decay modes
K-+
pK-K-+
KS0 pKS
0KS0
K-++
-+
-++
Ruslan Chistov (ITEP, Moscow) Charm Baryon Spectroscopy at Belle Charm 2006
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Introduction to Charm Baryons at Introduction to Charm Baryons at BelleBelle
Improved measurement of Improved measurement of cc
00 and and cc++ masses masses
PLB 605, 237 (2005),Erratum PLB 617, 198 (2005)
+0.2-1.4
+0.2-1.4
Due to the mass scale
Ruslan Chistov (ITEP, Moscow) Charm Baryon Spectroscopy at Belle Charm 2006
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StudyStudy of excited states of excited states cc(2645)(2645)
Mass(c+ -) Mass(C
0 +)
CC(2645)(2645)00 CC(2645)(2645)++
Reflection from C(2790)0 c
’+ -,
c’+ c+
(verified with MC)
Reflection fromC(2790)+ c
’0 +
(verified with MC)c’0 c
0
C+ - ++ C
0 - +
LL450 fb450 fb-1-1
Firs
t co
nfirm
atio
n
Firs
t co
nfirm
atio
n
Ruslan Chistov (ITEP, Moscow) Charm Baryon Spectroscopy at Belle Charm 2006
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StudyStudy of excited states of excited states cc(2645):(2645):mass measurementsmass measurements
Belle (2006):
PDG(2005):
Pre
lim
inary
Ruslan Chistov (ITEP, Moscow) Charm Baryon Spectroscopy at Belle Charm 2006
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New Charmed Baryons from BelleNew Charmed Baryons from Belle
Near threshold in Mass(c+ K- +) two new charmed
baryons cxcx(2980)(2980)++ and and cxcx(3077)(3077)++ were observed
cx(2980)+
cx(3077)+
wrong-sign c+ K+ -
cx(3077)+: 9.7N=326.0 ± 39.6 events
M=3076.7 ± 0.9 ± 0.5 MeV=6.2 ± 1.2 ± 0.8 MeV
cx(2980)+: 6.3N=405.3 ± 50.7 events
M=2978.5 ± 2.1 ± 2.0 MeV=43.5 ± 7.5 ± 7.0 MeV
Preliminary
LL450 fb450 fb-1-1
Ruslan Chistov (ITEP, Moscow) Charm Baryon Spectroscopy at Belle Charm 2006
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New Charmed Baryons from BelleNew Charmed Baryons from BelleTo get more information about the properties of found states
we searched for their isopartners in Mass(c+ K0
S -) and observe cxcx(3077)(3077)00
cx(2980)0
cx(3077)0
wrong-sign c+ K+ -
High mass state - cx(3077)0
N=67.1 ± 19.9M=3082.8 ± 1.8 MeV=5.2 ± 3.1 MeVSignificance=5.1
Low mass state - cx(2980)0
N= 42.3 ± 23.8M=2977.1 ± 8.8 MeV=43.6 MeV FIXEDSignificance=2.0
Preliminary
LL450 fb450 fb-1-1
Ruslan Chistov (ITEP, Moscow) Charm Baryon Spectroscopy at Belle Charm 2006
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Recent Results from Belle Recent Results from Belle
Belle searched for the SELEX double charm baryon cc (3520)+ c
+ K- +
null result
Prelim
inary
N=8.3 ± 37.3 < 69.1 @ 90% CL
LL450 fb450 fb-1-1
Ruslan Chistov (ITEP, Moscow) Charm Baryon Spectroscopy at Belle Charm 2006
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Recent Results from Belle:Recent Results from Belle:upper limit on the production upper limit on the production
of the SELEX double charm baryon of the SELEX double charm baryon
Preliminary
(cc(3520)+)Br(cc(3520)+c+K-+ | p*(c
+)>2.5 GeV) <1.510-4
(c+ | p*(c+)>2.5 GeV) @ 90% CL
We reconstruct 835360 ± 13748 c+ pK-+decays
BaBar observes NO SIGNAL ALSO in a similar decay mode (hep-ex/0605075)
Ruslan Chistov (ITEP, Moscow) Charm Baryon Spectroscopy at Belle Charm 2006
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SummarySummary
(1) NEW Isotriplet of Charmed Baryons is observed by Belle: c(2800)(2) Belle measured with high accuracy the masses of cc
00 and cc++
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 Belle observed three new charm baryons
cx(3077)+ c+ K- +
cx(2980)+ c+ K- +
cx(3077)0 c+ KS
0 -
Studies of their properties are ongoing