5 th APFB Conference August 22-26, 2011, Seoul, Korea Hyperons analogous to  Yongseok Oh (Kyungpook National University, Korea)

APFB 2011, Seoul, Korea 2 Overview 1.Introduction 2.Bound state approach to the Skyrme model 3.Outlook

APFB 2011, Seoul, Korea 3 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

APFB 2011, Seoul, Korea 4  spectrum Cf. spin of W- (=3/2) was confirmed only recently by BaBar, PRL 97 (2006) P is not directly measured

APFB 2011, Seoul, Korea 5 Experiments on multi-strangeness PDG 2008 No meaningful information on  spectrum Open a new window for studying baryon structure

APFB 2011, Seoul, Korea 6 Questions The 3 rd lowest state CLAS: PRC 76 (2007) Babar: J P of  (1690) is 1/2  PRD78 (2008)

APFB 2011, Seoul, Korea 7 Summary QM (Pervin, Roberts) PRC (expt.) 1320 (expt.) 1530 (expt.) : the 3 rd lowest state Expt:  (1620)*,  (1690)***

APFB 2011, Seoul, Korea 8 Highly model-dependent !

APFB 2011, Seoul, Korea 9 2. Bound state approach to the Skyrme model bound kaon SU(3) is badly broken Treat light flavors and strangeness on the different footing L = L SU(2) + L K/K* Soliton provides background potential which traps K/K* (or heavy) meson Bound state approach (Callan, Klebanov)

APFB 2011, Seoul, Korea 10 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

APFB 2011, Seoul, Korea 11 Some details Other approaches Kaons: one in p-wave and one in s-wave J=J sol + J m (J m = J 1 + J 2 ) J sol : soliton spin (=1/2), J 1 (J 2 ): spin of the p(s)-wave kaon (=1/2) J m = 0 and 1: both of them can lead to J P = 1/2 -  states Therefore, two J P = 1/2 -  states and one J P = 3/2 -  state In this model, it is natural to have two J P = 1/2 -  states and their masses are close to each other. Clearly, different from quark models Unitarized 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

APFB 2011, Seoul, Korea 12 Hyperon spectrum 289 MeV 290 MeV 285 MeV positive parity negative parity parity undetermined

APFB 2011, Seoul, Korea 13 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: J P of  (1690) is 1/2 - PRD 78 (2008) NRQM predicts 1/2 +

APFB 2011, Seoul, Korea 14 Outlook

APFB 2011, Seoul, Korea 15 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 for heavy-quark baryons –More analyses are needed Heavy quark baryons