2019 Impact factor 4.389
Particles and Fields
Eur. Phys. J. C 32, 493-499 (2004)
DOI: 10.1140/epjc/s2003-01465-0

Continuum bound states KL, D1(2420), Ds1(2536), and their partners KS, D1(2400), $D^{\ast}_{sJ}(2463)$

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 $D^{\ast}_{sJ}(2463)$ meson is described as a $J^{P}\!=\!1^{+}$ $c\bar{s}$ bound state in a unitarised meson model, owing its existence to the strong OZI-allowed $^{3}\!P_{0}$ coupling to the nearby S-wave $D^{\ast}\!K$ 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 $D^{\ast}\!K$ 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 $c\bar{n}$ partners, as a result of the strong OZI-allowed $^{3}\!P_{0}$ coupling to the nearby S-wave $D^{\ast}\!\pi$ threshold. The continuum bound states D1(2420) and Ds1(2536) are found to be mixtures of 33% $^{3\!}P_{1}$ and 67% $^{1\!}P_{1}$, whereas their partners D1(2400) and $D^{\ast}_{sJ}(2463)$ have more or less the opposite $^{2S+1}\!P_1$-state content, but additionally with some $D^{\ast}\!\pi$ or $D^{\ast}\!K$ 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 $\pi\pi$ continuum. The model's results for $J^{P}\!=\!1^{+}$ 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

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© Società Italiana di Fisica, Springer-Verlag 2004