Continuum bound states K L, D 1(2420), D s1(2536), and their partners K S, D 1(2400), D * sJ(2463)

The very recently observed D^*_sJ(2463) meson is described as a bound state in a unitarised meson model, owing its existence to the strong OZI-allowed coupling to the nearby S-wave threshold. By the same non-perturbative mechanism, the narrow axial-vector D_s1(2536) resonance shows up as a quasi-bound-state partner embedded in the continuum. With the same model and parameters, it is also shown that the preliminary broad 1 ⁺ D₁(2400) resonance and the established narrow 1 ⁺ D₁(2420) may be similar partners, as a result of the strong OZI-allowed coupling to the nearby S-wave threshold. The continuum bound states D₁(2420) and D_s1(2536) are found to be mixtures of 33% and 67% , whereas their partners D₁(2400) and D^*_sJ(2463) have more or less the opposite -state content, but additionally with some or admixture, respectively. The employed mechanism also reproduces the ratio of the K_L-K_S mass difference and the K_S width, by describing K_L as a bound state embedded in the continuum. The models results for states containing one b quark are also discussed.Received: 7 June 2003, Revised: 20 October 2003, Published online: 18 December 2003PACS: 12.40.Yx, 14.40.Aq, 14.40.Lb, 13.25.Es, 13.25.Ft, 13.75.Lb