2003 Fiscal Year Final Research Report Summary
Study of baryon structure and baryon-baryon interaction in a chiral quark model
| Project/Area Number |
12640290
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
素粒子・核・宇宙線
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| Research Institution | Sophia University |
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Principal Investigator |
SHIMIZU Kiyotaka Sophia University, Department of Physics, Professor, 理工学部, 教授 (00143363)
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| Co-Investigator(Kenkyū-buntansha) |
TAKEUCHI Sachiko Japan College of Social Work, Department of Social Work, Associate Professor, 社会福祉学部, 助教授 (90251503)
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| Project Period (FY) |
2000 – 2003
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| Keywords | Chiral Quark Model / Quark Cluster Model / Roper Resonance / Di-quark Model / Inverse Scattering Method / Tensor Force / Quark Pauli-Blocking / Repulsive Core |
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| Research Abstract |
First we have investigated the structure of SU(3) octet and decuplet baryons including the s-wave and p-wave excited states employing the chiral quark model. We have found that the relativistic treatment of the kinetic energy term and the inclusion of the goldstone boson exchange potentials are essential in order to explain the spectrum of the Roper, p-wave excited states and ground state baryons simultaneously. Here we have also shown that the relativistic treatment of the potential terms is necessary when the relativistic form of the kinetic energy is employed. In order to solve a three body system, we have used the di-quark like model which can take into account the di-quark correlation due to the strong attractive pion exchange potential. Because of the strong attractive pion exchange potential, the mass of the Roper resonance can be nicely reproduced as the radial excited state of the nucleon.
Next, we have investigated the effects of quark degrees of freedom on the baryon-baryon scattering by employing the quark cluster model (QCM). We are mainly interested in the origin of the repulsive core in the quark cluster model, where the non-locality plays the most important role. We have employed the inverse scattering method in order to obtain the equivalent local potential which gives the same on-shell values as those of the original QCM non-local potential. We have found that the smallness of the norm kernel produces the repulsion at low energy region and give an attraction when the energy increases. In terms of the local potential, there appears a strong attractive pocket at short distances with the repulsive core outside. Because of this structure, there appears a resonance at a certain energy where the phase shift changes from negative to positive values.
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