Abstract :
The mass spectrum of the ground state 1S0, 3S1 and orbitally excited 3P0, 1P1, 3P1, 3P2 mesons is considered in a nonrelativistic constituent quark model. A good description of the mass spectrum of these mesons is obtained with the same constituent quark masses mu=md=305±2 and ms=483±3 MeV/c2. It is suggested that the nonrelativistic quark model describes better the masses of “bare” qq̄ states, such as found in the K-matrix analysis, than the measured ones, at least for such broad states as the K∗0(1430). The a0(980) is a quarkonium in this scheme and belongs to the lightest scalar nonet together with the K∗0(1430), with the “bare” qq̄ mass 1191±8 MeV/c2, f0(980) and f0(1370). The extracted value of the K1(3P1)−K1(1P1) mixing angle (θK) is (31±4)°. A constant in the mass formulae for P-wave mesons might be interpreted as the effective gluon “mass”.
