The Genuine Resonance of Full-Charm Tetraquarks

In this work, the genuine resonance states of full-charm tetraquark systems with quantum numbers JPC=0++,1+−,2++ are searched in a nonrelativistic chiral quark model with the help of the Gaussian Expansion Method. In this calculation, two structures, meson-meson and diquark–antidiquark, as well as their mixing with all possible color-spin configurations, are considered. The results show that no bound states can be formed. However, resonances are possible because of the color structure. The genuine resonances are identified by the stabilization method (real scaling method). Several resonances for the full-charm system are proposed, and some of them are reasonable candidates for the full-charm states recently reported by LHCb.

Investigation of $$\varXi _c^0$$ in a chiral quark model

Recently, three new states of $$\varXi _c^0$$ Ξ c 0 were observed in the invariant mass spectrum of $$\varLambda ^+_cK^-$$ Λ c + K - by LHCb collaboration. In this work, we use a chiral quark model to investigate these three exited states with the help of Gaussian expansion method both in three-quark structure and in five-quark structure with all possible quantum numbers $$IJ^P=\frac{1}{2}(\frac{1}{2})^-$$ I J P = 1 2 ( 1 2 ) - , $$\frac{1}{2}(\frac{3}{2})^-$$ 1 2 ( 3 2 ) - , $$\frac{1}{2}(\frac{5}{2})^-$$ 1 2 ( 5 2 ) - , $$\frac{3}{2}(\frac{1}{2})^-$$ 3 2 ( 1 2 ) - , $$\frac{3}{2}(\frac{3}{2})^-$$ 3 2 ( 3 2 ) - and $$\frac{3}{2}(\frac{5}{2})^-$$ 3 2 ( 5 2 ) - . The calculations shows that the masses of 2S and 1D states of $$\varXi _c$$ Ξ c are comparable to experimental results; In addition, the resonance states of five-quark configuration are possible candidates of these new states with negative parity by using the real scaling method and their decay width is also given.

Coupling Hadron-Hadron Thresholds within a Chiral Quark Model Approach

Heavy hadron spectroscopy was well understood within the naive quark model until the end of the past century. However, in 2003, the X(3872) was discovered, with puzzling properties difficult to understand in the simple naive quark model picture. This state made clear that excited states of heavy mesons should be coupled to two-meson states in order to understand not only the masses but, in some cases, unexpected decay properties. In this work, we will give an overview of a way in which the naive quark model can be complemented with the coupling to two hadron thresholds. This program has been already applied to the heavy meson spectrum with the chiral quark model, and we show some examples where thresholds are of special relevance.