Behind the success of the quark model Original Research Article

The ground-state three-quark (3Q) potential V3Qg.s. and the excited-state 3Q potential V3Qe.s. are studied using SU(3) lattice QCD at the quenched level. For more than 300 patterns of the 3Q systems, the ground-state potential V3Qg.s. is investigated in detail in lattice QCD with 123 × 24 at β = 5.7 and with 163 × 32 at β = 5.8, 6.0. As a result, the ground-state potential V3Qg.s. is found to be well described with Y-ansatz within the 1%-level deviation. From the comparison with the Q-View the MathML source potential, we find the universality of the string tension as View the MathML source and the one-gluon-exchange result as View the MathML source. The excited-state potential V3Qe.s. is also studied in lattice QCD with 163 × 32 at β = 5.8 for 24 patterns of the 3Q systems. The energy gap between V3Qg.s. and V3Qe.s., which physically means the gluonic excitation energy, is found to be about 1GeV in the typical hadronic scale, which is relatively large compared with the excitation energy of the quark origin. This large gluonic excitation energy justifies the great success of the simple quark model.