Diquarks in QCD with a linear confinement potential

Abstract

We explore the diquark-quark picture of the octet and the decuplet of low-lying baryons in QCD with a linear confinement potential. The mass spectra of scalar, pseudoscalar, vector and axial-vector diquarks, transforming like\((\underline {\widetilde3} _f ,\underline {\widetilde3} _c )\) and\((\underline 6 _f ,\underline {\widetilde3} _c )\), are analysed. For scalar, pseudoscalar and vector diquarks we find bound states with massesMS≃MP=1.95 GeV, andMV=2.40 GeV, whereas for axial-vector diquarks no bound states exist. We conclude that low-lying baryons cannot be described by the diquark-quark picture. Our results confirm the three-body structure of low-lying baryons, and lead to an unambiguously fixed spinor structure of three-quark currents of low-lying baryons as proposed by Ioffe, Pascual and Tarrach.