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LP07, August 13-18, 2007, Daegu, Korea. Heavy flavor baryons. Roman Mizuk (ITEP, Moscow). Belle Collaboration. charm and beauty baryons pentaquark searches. Reminder on Heavy Quark Baryons. Baryons made from u,d,s,c quarks . similar multiplets if c quark is exchanged by b quark. - PowerPoint PPT Presentation
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Heavy flavor baryonsRoman Mizuk (ITEP, Moscow)
LP07, August 13-18, 2007, Daegu, Korea
charm and beauty baryonspentaquark searches
Belle Collaboration
Reminder on Heavy Quark Baryons
Total space-flavor-spin wave functionmust be symmetric
similar multiplets if c quark is exchanged by b quark
S-wave
8 S-wave isospin multiplets, 35 P-wave, 85 D-wave,..
Baryons made from u,d,s,c quarks
One heavy quark –
symmetric 6Fantisymmetric 3F
3F 6F
slight=0 slight=1
JP=1/2+ JP=1/2+ or 3/2+
Heavy Quark Symmetry jlight decouples excitation spectra are independent of heavy quark flavor
Simplification: Heavy quark - light diquark picture. Laboratory to test QCD.
example
exact for mQ →
Charmed baryons Beauty baryons
Experimental Status
2 years ago
Experimental Status
Charmed baryons Beauty baryons
Many new states observed recently at
B-factories TEVATRONImportant ingredients
PID, high momentum detached vertex
Λcc[ud]
Observation of Λc(2940)+ by BaBar
Σc(2455)π→Λc+π+π-
Λc(2880)
Λc(2940)Λc(2765)
BaBar: no isospin partners in D+p 2880, 2940 are isoscalars
PRL98,262001
D0p
Λc(2880)
Λc(2940)NEW
PRL98,012001
D0 sidebands
wrong-sign combinationsNew decay mechanism: heavy quark → meson.
Belle confirmed
Λc(2940)+ mass is 5MeV below D*p threshold molecule?
He, Li, Liu, Zeng, hep-ph/0606015
CLEOΛcπ+π-
Measurements of M and Γ are consistent
Exotics?
( mass, decay pattern)Chen, Chua, PRD75, 094017 (2007)Garcilazo, Vijande, Valcarce, JPG34, 961 (2007)Chen, Chen, Liu, Deng, Zhu, PRD75, 094017 (2007)
More experimental studies to discriminate.
Conventional baryon? JP=5/2-, 1/2+, 3/2+,..
Γ(Σc*π):Γ(Σcπ):Γ(D0p), …
Λc(2880)+ spin-parity from Belle
helicity angle
J=5/2 is favored over 3/2 (4.5σ) or 1/2 (5.4σ)
@ leading Regge trajectory with Λc+ 1/2+ and Λc(2625)+ 3/2-
m(Λcπ)
Σc(2520) evidence
Σc(2455)
PRL98,262001
Angular analysis of Λc(2880)→Σc(2455)π
Heavy Quark Symmetry:5/2- R=1.45/2+ R~0.3
Capstick, Isgur PRD34,2809 (1986)Quark Model:
5/2- 2900 31307/2- 31255/2+ 2910 31407/2+ 3175
Resonant structure of Λc(2880)→Λc+π+π-
0.03 0.06 0.23](2455)
(2520) Rc
c
[][
Chen, Chua, PRD75, 094017 (2007)
Selem, Wilczek, hep-ph/0602128predicted in string theory
5/2+ is favored over 5/2-
Λc(2880)+ is likely 5/2+
Σccdd, c{ud}, cuu
Observation of Σc(2800) isotriplet by Belle
Mass, width Σc(2800) can be 3/2- (?)
Mass of Σc(2800) is at D0p threshold.
Pirjol,PRD56,5487 (1997)
PRL94,122002Λc+π- Λc
+π0 Λc+π+
Σc(2800)+
NEW
Σc(2800)++
NEW
Σc(2800)0
NEW
Feed-down from Λc(2880)+→Σcπ→Λc+π+π-
feed-downfeed-down
Measurements of M, Γ and σ are consistent
Capstick, Isgur, PRD34,2809 (1986)More experimental studies to confirm JP.
Ξccsd, csu
Observation of Ξc(2980) and Ξc(3080) by Belle
resonant structure
Mass D-wave excitations ?Ξc(2980) 1/2+, 3/2+,.. Ξc(3080) 5/2+,..
BaBar confirmed also Ξc(3080)0
Λc+K-π+
Ξc(3080)+
NEW
Λc+K-π+
Ξc(2980)+
NEW
Ξc(3080)+
Ξc(2980)+
Λc+Ksπ-
Ξc(3080)0 NEW
PRL97,162001 hep-ex/0607042
BaBar confirmed
Measurements of M and Γ are consistent
New decay mechanism:s-quark → meson.
More experimental studies to assign JP.
Rosner JPG34,S127 (2007)Chen, Chua, PRD75, 094017 (2007)Garcilazo, Vijande, Valcarce, JPG34, 961 (2007)Chen, Chen, Liu, Deng, Zhu, PRD75, 094017 (2007)Ebert, Faustov, Galkin, arXiv:0705.2957
Evidence for Ξc(3055) and Ξc(3123) from BaBar
Ξc(3080)+
Ξc(3080)+
Ξc(2980)+
Σc(2455)++K-→Λc+K-π+
Σc(2520)++K-→Λc+K-π+
Ξc(3055)+
NEW
Ξc(3123)+
evidence
hep-ex/... (preliminary)
More experimental studies to assign JP.
Presented at EPS-HEP 2007
Study of B+→Λc+Λc
-K+ by BaBar
B+→Λc+Λc
-K+ decay has been observed by Belle
BaBar: confirmation, resonant structure.
Λc+K-
BaBar “More data are needed before firm conclusions can be drawn.”
Excited Ξc? not seen in continuum
Λc+ Λc
- K-
mbc (GeV/c2)
B- meson
NEW
confirmed
NEW
PRL97,202003 (2006)
phase-space
sidebands
Ωccss
Observation of Ωc* by BaBar
significance 5.2σ Ωc0
Ωc* NEW
Last unobserved ground state charmed baryon.
m(Ωc*) – m(Ωc) = (70.8 ± 1.0 ± 1.1) MeV/c2
PRL97,232001
Comparison with predictions
data
Rosner, PRD52, 6461 (1995)Spin-flavor wave-functions
Ebert et al, PRD72,034026 (2005)QM with heavy-quark-light-diquark
Burakovsky et al, PRD56, 7124 (1997)Regge framework
Lichtenberg et al, PRD53, 6678 (1996)Mass sum rules
Martin et al, PLB355, 345 (1995)potential model
m(Ωc*) – m(Ωc)
Result
Mathur et al, PRD66,014502 (2002)Lattice NRQCD (quenched)
Roncaglia et al, PRD52,1722 (1995)Feynman-Hellman theorem
Jenkins, PRD54, 4515 (1996)1/MQ and 1/Nc expansion
Savage, PLB359, 189 (1995)Chiral Perturbation Theory
Good agreement
Σbbdd, b{ud}, buu
Blind signal region
arXiv:0706.3868
Λb0π+
Λb0π-
Λb0→Λc
+π-
Observation of Σb and Σb* by CDFarXiv:0706.3868
blind
blind
BG fixed
arXiv:0706.3868
Λb0π+
Λb0π-
Λb0→Λc
+π-
Observation of Σb and Σb* by CDFarXiv:0706.3868
blind
blind
BG fixed
arXiv:0706.3868
Fix all widths:
Λb0π+
Λb0π-
Σb*-NEW
Σb-NEW
Σb*+NEW
Σb+NEW
Results (MeV/c2):
Korner et al, PPNP33,787
Λb0π+
Λb0π-
Λb0→Λc
+π-
Observation of Σb and Σb* by CDF
Fix shape and normalization of bg.
Significance >5.2σ (4 peaks vs. BG only)Each peak >3 σ (except Σb
+)
arXiv:0706.3868
blind
blind
BG fixed
arXiv:0706.3868
Fix all widths:
Λb0π+
Λb0π-
Σb*-NEW
Σb-NEW
Σb*+NEW
Σb+NEW
Results (MeV/c2):
Korner et al, PPNP33,787
Λb0π+
Λb0π-
Λb0→Λc
+π-
Observation of Σb and Σb* by CDF
Fix shape and normalization of bg.
Significance >5.2σ (4 peaks vs. BG only)Each peak >3 σ (except Σb
+)
Comparison with predictions
Mathur et al, PRD66,014502 (2002)Lattice NRQCD (quenched)
Karliner, Lipkin, PLB575,249 (2003)QM
Roncaglia et al, PRD52,1722 (1995)Feynman-Hellman theoremCapstick, Isgur, PRD34,2809 (1986)
relativised QM
m(Σb)–m(Λb) m(Σb*)–m(Σb)
data
Jenkins, PRD54, 4515 (1996)1/MQ and 1/Nc expansion
Ebert et al, PRD72,034026 (2005)QM with heavy-quark-light-diquark
Good agreement
m(Σb–) – m(Σb
+) = 5-7 MeVexpect
arXiv:0706.3868
Ξbbsd, bsu
Observation of Ξb- by D0 and CDF
arXiv:0706.1690 J/ψ Ξ- J/ψ Ξ-
Ξb-
NEW
arXiv:0707.0589
Ξb-
NEW
Lattice QCD QM HQET
Comparison with predictionsMass measurements are consistent
Ξb-→ J/ψ Ξ-
Good agreement
PRL99,052001 PRL99,052002
(syst) (stat) 0.09 0.28)/()() /()( 0.09
0.08 -
JBRbfJBRbf
bb
bb
Proper decay time distribution consistent with expected Ξb lifetime
Ground state SU(3) multiplets of charmed baryons are complete.
Flood of highly excited charmed baryons.
Charmed baryons Beauty baryons
Summary on Heavy Quark Baryons
Λc(2880)
Σb*
Σb
Ξb
Σc(2800)
Ξc(3080)
Ξc(2980)
Ωc*
Ξc(3055)
Λc(2940)
CLEOBelleBaBar
D0CDF
New era in beauty baryon
spectroscopy.
Reminder on Pentaquarks
Repeat measurements with high statistics
+ LEPS– CLAS – Belle + SVD-2
Group Reaction σ’sLEPS C K+K- X 4.6DIANA K+Xe K0p Xe’ 4.4CLAS-d d K+K-p(n) 5.2SAPHIR p K+K0(n) 4.8ITEP- A K0p X 6.7CLAS-p p + K-K+(n) 7.8HERMES e+d K0p X ~5ZEUS e+p e’K0p X ~5SVD-2 pA K0pX 5.5TOF pp K0p+ 4-6
Θ(1540)+ predicted in Chiral Soliton ModelObserved in γn→Θ+K- → (K+n)K- and K+n→Θ+→pKS
M ~ 1540 MeV/c2
Γ < 1 MeVLow Γ and M are difficult to explain
Θ(1540)+ |uudds>
Initial evidence:
Also many null results, not easily comparable.
Introduction to Pentaquarks
Repeat measurements with high statistics
+ LEPS– CLAS – Belle + SVD-2
Group Reaction σ’sLEPS C K+K- X 4.6DIANA K+Xe K0p Xe’ 4.4CLAS-d d K+K-p(n) 5.2SAPHIR p K+K0(n) 4.8ITEP- A K0p X 6.7CLAS-p p + K-K+(n) 7.8HERMES e+d K0p X ~5ZEUS e+p e’K0p X ~5SVD-2 pA K0pX 5.5TOF pp K0p+ 4-6
PDG2006NEW?
Θ(1540)+ predicted in Chiral Soliton ModelObserved in γn→Θ+K- → (K+n)K- and K+n→Θ+→pKS
M ~ 1540 MeV/c2
Γ < 1 MeVLow Γ and M are difficult to explain
Θ(1540)+ |uudds>
Initial evidence:
Also many null results, not easily comparable.
Statistics x1.6 Θ(1540)+ signal confirmed, significance increased from 4.4 to 5.3σ
MC verified on tagged kaon data at Belle
New DIANA result
NEW estimation of Θ(1540)+ width
K+ Xe → p KS Xe’
AssumptionΓ, MeV
DIANA BelleNuclear suppression
is the same for Θ+ and nonresonant K0p
0.9 ± 0.3 <0.64
No nuclear suppression for Θ+ 0.36 ± 0.11 <0.28 ?
my estimate
Contradiction with Belle persists (2.2σ, 2.4%)Inelastic Θ(1540)+ production will decrease Belle upper limit
M(pKS)
M(pKS)
DIANA finds no Θ+ signal for pK+>525MeV
445<pK+<525MeV
pK+>525MeV 2.9σ fluctuation, decreases significance of DIANA signal
17 events expected-3 found
Evidence for Θ(1540)+ from DIANA is weak.
PAN70,35 (2007)
NOMAD Preliminary
New NOMAD result
N → Θ+X
For large part of xF range NOMAD and ITEP- results are in conflict.
Θ+
based on subsaple
Θ+
Upper Limit on Θ+ production rate per interaction vs. xF
NOMAD result can be compared with ITEP- result
Θ+ production rate ~10-3
Θ(1540)+ signal is not confirmed
EPJC49,499 (2007)
New COSY-TOF results
In previous analysis background was underestimated significance lower than claimed.
PLB649,252 (2007)
Statistics x10, improved detection capability Θ(1540)+ signal not confirmed
pp → pK0Σ+
Evidence for Θ(1540)+ from COSY-TOF is negated.
NEW
Previous Comparison
Background shape from new data.
Θ+
New H1 resultep → pKSX No Θ+ signal
H1 result can be compared with ZEUS result
ZEUS
H1
H1 and ZEUS results are in conflict.
Extrapolated to ZEUS y-region.
(preliminary) Q2>20GeV2, 0.04<y<0.95
ZEUS
M(pKS)
PLB639,202 (2006)
Statistics x8 Θ(1540)+ signal confirmed, significance increased from 5.5 to ~8σ
SVD-2 result: the most significant Θ+ signalpA → KSpX
KS decays inside / outsideVertex Detector
M(pKS)
SVD-2 result strongly contradicts HERA-B, CDF.
Θ(1540)+ is produced with small xF
Group σ[Θ(1540)+] / σ[Λ(1520)]
s, GeV
SVD-2 8-12% 12
HERA-B <2% at 95% C.L. 40
CDF <3% at 90% C.L. 2000
For central production difference in energy should not be important.
M(pKS)
M = 1523 MeV= 12 MeVNevnt = 165
M = 1522 MeV= 12 MeVNevnt = 205
hep-ex/0509033
Other new results on pentaquarks
KEK-PS E522PLB635,72(2006)
“Search for Θ+ via π-p→K-X reaction near threshold”
OBELIX (LEAR,CERN)NPA779,116(2006)
“Search for the Θ+ pentaquark in antiproton 4He annihilation at rest”.
CLASPRL97,032001(2006)
“Search for the Θ+ pentaquark in the γd→ΛnK+ reaction measured at CLAS”
CLASPRD74,032001(2006)
“Search for the Θ+ pentaquark in the reactions γp→K0K+n and γp→K0K0p ”
FOCUSPLB639,604(2006)
“Search for a pentaquark decaying to pKS”
DELPHIarXiv:0708.0415
Search for Pentaquarks in the Hadronic Decays of the Z Boson with the DELPHI Detector”
2.5σ signal at M=1530MeV
No new positive results for doubly strange pentaquark Φ(1860) or charmed pentaquark Θc(3100)0.“No stars” in PDG2006 not discussed here.
No significant Θ+ signals.
Summary on Θ(1540)+
For experiment with positive result experiment with similar conditions but null result.
Group Reaction σ’s
LEPS C K+K- X 4.6
LEPS d pK- XDIANA K+Xe K0p Xe’ 4.4
CLAS-d d K+K-p(n) 5.2
SAPHIR p K+K0(n) 4.8
ITEP- A K0p X 6.7
CLAS-p p + K-K+(n) 7.8
HERMES e+d K0p X ~5
ZEUS e+p e’K0p X ~5
SVD-2 pA K0pX 5.5
TOF pp K0p+ 4-6
Evidence for Θ(1540)+ pentaquark is weak
Not a single convincing evidence for Θ(1540)+
unpublished~5σ New data are taken (2007).
Statistics x3.~5σ
In conflict with NOMAD.
Not accessible in new data (energy too low).
Contradicts BaBar eBe→pKSX (statistics x100 larger).
In conflict with H1.
~8σ Contradicts HERA-B, CDF.
5.4σ Contradiction with Belle persists.
unpublished
Conclusions
Experimental evidence for pentaquarks is weakMore null results since PDG2006: COSY-TOF, H1, NOMAD, ...Very low Θ+ width: DIANA Γ = (0.36 ± 0.11) MeV
New results are expected from LEPS, HERA-II.
Impressive progress in heavy flavor baryons# charmed baryons 12 → 18# beauty baryons 1 → 4Λc(2880)+, Ωc*, Σb, Σb*, Ξb provide important constraints for theory. To use other new states: Λc(2940), Σc(2800), Ξc(2980), Ξc(3055), Ξc(3080), we need symbiosis between theory and experiment.
Experiments are consistent and experimental results are robust.
over last 2 years
New challenges for theory?
Back-up
Doubly charmed baryons
Λc+K-π+ Ξc
+π+π-
Ξcc+
Ξcc+
SELEX
New decay channel.
cc+ c
+ K- +
Selex’s cc(3520)+ is found neither in c+ K- + nor in c
0 +
cc+ c
+ K- +
cc+ cc
0 +
also not seen in photo production (FOCUS)
hep-ex/0702001
Not confirmed by BaBar and Belle.