X iv : h ep - p h / 04 07 09 1 v 2 1 6 A ug 2 00 4 A note on possible interpretations for the D + SJ ( 2632 ) observed by SELEX

We suggest some possible interpretations for the D SJ (2632) observed by SELEX. The D SJ (2632) could be the first radial excitation of the 1 ground state Ds (2112), and its unusual decay patten might be hopefully explained by the node structure of the wave functions. In addition, the D SJ (2632) could also be a cs̄g hybrid state or a (cs)3∗ − (s̄s̄)3 (diquark-antidiquark) bound state. Very recently the SELEX Collaboration has reported the first observation of a charmstrange meson D SJ (2632) in the charm hadro-production experiment E781 at Fermilab[1]. The D SJ(2632) is observed in the D + s η decay channel with a significance of 7.2σ and in the D K decay channel with a significance of 5.3σ. The mass and width of this state are found to be M = 2632.6 ± 1.6MeV and Γ < 17MeV (at 90% confidence level). This narrow state has a rather unusual decay patten that it is dominated by the D s η decay mode with a very small ratio R = Γ(DK)/Γ(D s η) = 0.16± 0.06. For the cs̄ mesons, aside from the ground state doublet [Ds(1969), Ds ∗(2112)] of [0, 1] states, as well as the Ds1(2536), DsJ(2573), which probably correspond to the J P = 1, 2 states being the P-wave excitations with the light quark angular momentum j = 3/2, in 2003 the BaBar collaboration reported the first observation of a massive, narrow charm-strange meson Ds0(2317) below the DK threshold [2]. CLEO [3] and BELLE [4] subsequently confirmed the existence of DsJ(2317), and further found another narrow higher-lying state DsJ(2460). The finding of [DsJ(2317), DsJ(2460)] has stimulated many theoretical explanations for these two states[5]. Most likely, they may correspond to the J = 0, 1 states being the P-wave excitations with the light quark angular momentum j = 1/2. In particular, in the chiral models for the heavy-light mesons, parity doublers are predicted to have the same mass splittings, and the ground state doublet [Ds(1969), Ds ∗(2112)] of [0, 1] states would have a parity-partner [0, 1] pair, which are very likely to be the observed [DsJ(2317), DsJ(2460)][6, 7]. In 2004, the new stateD SJ (2632) observed by SELEX with unusual decay modes will certainly be interesting in finding its own place in the heavy-light systems. In the following we will present some discussions on the possible interpretations for the D SJ (2632) state. (1). The D SJ(2632) could be the first radial excitation of the 1 − ground state Ds ∗(2112).