Study of the cc¯ss¯ system in the chiral quark model

Abstract

Recently, a charmonium X(3960) in B decays in the Ds+Ds− invariant-mass spectrum is discovered by the LHCb collaboration with the quantum number JPC=0++. Motivated by the discovery, in this work, we systematically investigated the cc¯ss¯ tetraquark states with the quantum numbers JPC=0++,1++,1+−,2++ in the framework of the chiral quark model. In our calculations, we considered the meson-meson structure of the tetraquark states and the diquark-antidiquark structure, as well as the channel coupling of all channels of these two configurations are considered in this work. For example, all color structures including color singlet, hidden color channel, and the mixing of them are also taken into account. The numerical results indicate that no bound states were found in our model. There exist several resonant states by using the stabilization method, the so-called real scaling method. Among these states, the 0++ resonant state with mass 3927 MeV matches very well with the energy of the newly discovered exotic state X(3960) reported by the LHCb collaboration. As a result, our calculations suggest that X(3960) can be interpreted as a cc¯ss¯ tetraquark state with quantum number JPC=0++. Apart from that, we also find several resonance states with mass 4179 and 4376 MeV with 0++. For 1++, there is likely one resonance state in the energy range of ∼4310–4336 MeV, along with two resonance states at the energy of 4395 and 4687 MeV, respectively. Besides, two resonance states at 4300 and 4355 MeV for 1+−, as well as one state at 4788 MeV for 2++, are found, which are likely to be new exotic states. More experimental data is needed to confirm the existence of these resonance states. Published by the American Physical Society 2025