Baryon Spectrum In The Chiral SU(3) Quark Model

Conventional quark model think that a baryon is constituted by three quarks and a meson by a quark and an anti-quark. However, more precise experiment show that the baryon not only contains three-quark component,but so there have pentaquark component.These have prompted us to re-examine the nature and structure of baryons.This paper starting from the chiral SU(3) quark model,by group theory to construct the pentaquark function,and combination of three-quark model and pentaquark model.Finally obtain baryon spectrum. For the pentaquark,there are many quark groups structure.This paper study structure qqq-qq and qq-qq-q.Generally we believe that:the three-quark baryon model for further stimulating the formation of a pair of positive and negative quark pentaquark system. So there are four quarks and one anti-quark in the pentaquark. Here we consider the taste, color and spin space coupling between the quarks.According to angular momentum coupling, We know that the isospin is 1/2,the spin is 1/2 of the nucleon N, its flavor symmetry of the structure can only be [42]F,[33]F,[321]F. its symmetry of the structure can only be [32]S.The colorless structure of the system can only be [222]C.[222]C color space structure can only be broken down into the structure of [211]C[11]C (anti-quark structure of color space is [11]C).Because of the Pauli exclusion principle, four quarks are restricted in the full symmetric state,so they are in all antisymmetric, [1111]OFSC. In this article, orbit space does not only consider the case of excitation, [1111]OFSC=[4]O[1111]FSC, [1111]FSC=[31]FS[211]C, four-quark part of the flavor and spin space must be coupled into the structure of [31]. According to the CG sequences can obtain FS decomposition,then obtain the pentaquark baryon wave function.After construct the pentaquark wave function,will have the same quantum number of the three-quark and pentaquark wave function components baryon spectrum.The results showed that in the chiral SU (3) quark model, the introduction of five-quark component and three-quark mixing with the pentaquark better than the representation of three-quark model baryon spectrum.