Hyperons analogous to L(1405)
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Transcript of Hyperons analogous to L(1405)
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5th APFB ConferenceAugust 22-26, 2011, Seoul, Korea
Hyperons analogous to Hyperons analogous to
Yongseok Oh(Kyungpook National University,
Korea)
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Overview
1. Introduction2. Bound state approach to the Skyrme model3. Outlook
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• Hyperon spectrum– Completeness of the observed hyperon resonances– Theoretical models for hyperon structure– Structure of (1405)
• uds• Five quark• K-bar N bound state
- baryon analogous to (1405)?
1. Introduction
PDG
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spectrum
Cf. spin of W- (=3/2) was confirmed only recently by BaBar, PRL 97 (2006)
P is not directly measured
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Experiments on multi-strangeness
PDG 2008
No meaningful information on spectrum
Open a new window for studying baryon structure
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Questions
The 3rd lowest state
CLAS: PRC 76 (2007)Babar: JP of (1690) is 1/2 PRD78
(2008)
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Summary
QM (Pervin, Roberts)132518912014
PRC 75
15201934202017251811
17591826
1820 (expt.)
1320 (expt.)
1530 (expt.)
: the 3rd lowest stateExpt: (1620)*, (1690)***
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Highly model-dependent !
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2. Bound state approach to the Skyrme model
bound kaon
SU(3) is badly broken
Treat light flavors and strangenesson the different footing
L = LSU(2) + LK/K*
Soliton provides background potentialwhich traps K/K* (or heavy) meson
Bound state approach(Callan, Klebanov)
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Bound state model
270 MeV energy difference
• Includes parameters• They should be computed with a given Lagrangian
(dynamics).• Or fix them to known masses and then predict.
Mass formula
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Some details
Other approaches
Kaons: one in p-wave and one in s-waveJ=Jsol + Jm (Jm = J1 + J2)
Jsol: soliton spin (=1/2), J1(J2): spin of the p(s)-wave kaon (=1/2)
Jm = 0 and 1: both of them can lead to JP = 1/2- states Therefore, two JP = 1/2- states and one JP = 3/2- stateIn this model, it is natural to have two JP = 1/2- states and their masses are close to each other.
Clearly, different from quark modelsUnitarized extension of chiral perturbation theory Ramos, Oset, Benhold PRL 89 (2002) 1/2- state at 1606 MeV Garxia-Recio, Lutz, Nieves, PLB 582 (2004) (1620) and (1690) are 1/2- states
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Hyperon spectrum
289 MeV
290 MeV
285 MeV positive parity
negative parity
parity undetermined
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Hyperon spectrum
YO, PRD 75 (2007)
spin-parity
Recently confirmed by COSY
PRL 96 (2006)
High precision experiments are required!
’s would be discovered in future.
Babar: JP of (1690) is 1/2-PRD 78 (2008)
NRQM predicts 1/2+
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Outlook
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• Similar mass splitting between parity partners– c(1/2+): 2286 MeV, c(1/2-): 2595 MeV– The mass difference between the two = 309 MeV– Potential is almost flavor-blind but gives richer spectrum
forheavy-quark baryons
– More analyses are needed
Heavy quark baryons