Continuum bound states KL, D1(2420), Ds1(2536), and their partners KS, D1(2400),E. van Beveren1 and G. Rupp2
1 Centro de Física Teórica, Departamento de Física, Universidade de Coimbra, 3000 Coimbra, Portugal
2 Centro de Física das Interacções Fundamentais, Instituto Superior Técnico, Edifício Ciência, 1049-001 Lisboa Codex, Portugal
(Received: 7 June 2003 / Revised version: 20 October 2003/ / Published online: 18 December 2003)
The very recently observed 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 Ds1(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 Ds1(2536) are found to be mixtures of 33% and 67% , whereas their partners D1(2400) and have more or less the opposite -state content, but additionally with some or admixture, respectively. The employed mechanism also reproduces the ratio of the KL- KS mass difference and the KS width, by describing KL as a bound state embedded in the continuum. The model's results for states containing one b quark are also discussed. .40.Yx, 14.40.Aq, 14.40.Lb, 13.25.Es, 13.25.Ft, 13.75.Lb
1 - 2.
© Società Italiana di Fisica, Springer-Verlag 2004