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The dynamic mechanism of short range interaction between $u/d$ quarks is still an open and challenging problem. In order to reveal this quark dynamics, we perform a systematic analysis of $NN$, $D_{03}$, and $D_{30}$ systems in the (extended) chiral SU(3) constituent quark models. By comparing results calculated with different models and different parameter sets, the effects of one gluon exchange and vector meson exchange terms are carefully examined. The results indicate that the vector meson exchange interactions dominate the short range interactions between $u/d$ quarks, while the small residual one gluon exchange coupling strength is also allowed., Comment: 8 pages, 2 figures, comments and suggestions are welcome

$d^\ast(2380)$ was observed by WASA-at-COSY collaborations in the nuclear reaction recently. Its particularly narrow width may indicate the new QCD-allowed hadronic structure. To further confirm the existence of this peculiar particle in a totally different kind of reaction, we study the opportunity for searching $\bar{d}^\ast$ in the $\Upsilon(nS)$ (with n=1, 2, 3) decay. As a phenomenological study, our framework is based on SU(3) chiral quark model. By virtue of the unitarity of $S$-matrix and crossing symmetry, we study the imaginary part of the forward scattering amplitudes between $\Upsilon(nS)$ and $d^\ast$. The scattering process is mainly governed by the quark-meson interaction. We examine both the pseudoscalar and vector meson contribution in the intermediate state. Hopefully, our results show that it's quite possible to find $\bar{d}^\ast$ in this decay mode in the future., Comment: 7 pages, 3 figures, 1 table

The structure of $d^*(2380)$ is re-studied with the single cluster structure in the chiral SU(3) quark model which has successfully been employed to explain the $N-N$ scattering data and the binding energy of deuteron. The binding behavior of such a six quark system is solved by using a variational method. The trial wave function is chosen to be a combination of a basic spherical symmetric component of $[(0s)^6]_{orb}$ in the orbital space with $0\hbar\omega$ excitation and an inner structural deformation component of $[(0s)^5(1s)]_{orb}$ and $[(0s)^4(0p)^2]_{orb}$ in the orbital space with $2\hbar\omega$ excitation, both of which are in the spatial [6] symmetry. It is shown that the mass of the system is about $2356$ MeV, which is qualitative consistent with the result both from the two-cluster configuration calculation and from the data measured by the WASA Collaborations. This result tells us that as long as the medium-range interaction due to the chiral symmetry consideration is properly introduced, the mass of system will be reduced in a rather large extent. It also implies that the observed $d^*$ is a six-quark bound state with respect to the $\Delta\Delta$ threshold, which again supports the conclusion that $d^*$ is a hexaquark dominant state., Comment: 6 pages, 3 figures.

The structure of $d^*(2380)$ is re-studied with the single cluster structure in the chiral SU(3) quark model which has successfully been employed to explain the scattering and binding behaviors of baryonic systems. The mass and width are explicitly calculated with two types of trial wave functions. The result shows that the $(0s)^6 [6]_{orb}$ configuration is easy to convert to the configuration with the same $[6]_{orb}$ symmetry but $2\hbar \omega$ excitation back and forth, however, it is seldom to turn into a two-cluster configuration with a (1s) relative motion in between. The resultant mass and width are about $2394$MeV and $25$MeV, respectively, and the stable size is about $0.75fm$, which are consistent with both the results in the two-cluster configuration calculation and the data measured by the COSY collaboration. It seems that the observed $d^*$ is a six-quark dominated exotic state with a spherical shape and breath mode in the coordinate space. Moreover, if $d^*$ does have $2\hbar \omega$ excitation, the $d^* \to np\pi\pi\pi$ decay mode might be a good place to distinguish the real structure of the observed phenomenon by COSY. The masses of various isospin-spin states of six-light-quark systems are also computed. It is shown that by considering the coupling with the configurations with $2\hbar \omega$ excitations, only the mirror state with $IS$=$30$ will be lower down to the place where whose mass is slightly higher than the value of the $\Delta\Delta$ threshold., Comment: This paper has been withdrawn by the author as the further investigation is needed

The analytical forms of the interaction potentials between one S-wave and one P-wave heavy mesons as well as the potentials between two P-wave heavy mesons are deduced based on a chiral quark model. Our results explicitly show the attractive property between two heavy mesons. Consequently, a series of possible molecular states are obtained. It is expected that our study might shed some light on the popular discussions of the newly observed XYZ states., Comment: arXiv admin note: substantial text overlap with arXiv:1206.0523

An effective potential in a meson-meson system is discussed based on the SU(3) chiral constituent quark model, and the analytic form of the potential is explicitly given. In addition, the effective potential is employed to study the bound state problem of \omega \phi which is related to the new resonance of f0(1810) observed in BESII very recently., Comment: this paper has been withdrawn

An effective potential in a meson-meson system is discussed based on the SU(3) chiral constituent quark model, and the analytic form of the potential is explicitly given. In addition, the effective potential is employed to study the bound state problem of $\omega\phi$, which is related to the new resonance of $f_0(1810)$ observed in BESII very recently., Comment: 7 pages, 4 figures

We investigated the bound state problem of the S wave charged $D_1 \bar{D}^*$ ($D_1' \bar{D}^*$) system in a chiral quark model by solving the resonating group method equation. Our preliminary study does not favor the molecular assumption of $Z^+(4430)$. On the contrary, if $Z^+(4430)$ is really a molecule, its partner with opposite $G$-parity should also exist and probably may be found in the $\pi^+\eta_c(2S)$, $J/\psi \pi^+\pi^0$, or $\psi'\pi^+\pi^0$ channel. For the bottom systems, we found the existence of both $I^G$=$1^+$ and $I^G$=$1^-$ $B_1 \bar{B}^*$ ($B_1' \bar{B}^*$) molecules is possible., Comment: 6 pages, 3 figures

We investigated systematically whether the S-wave ($\bar{Q}q$) meson and the ($Q\bar{q}$) meson may form S-wave bound states in a chiral SU(3) quark model by solving the resonating group method equation. Here $Q=c$ or $b$ and $q=u$, $d$ or $s$. Our preliminary calculation disfavors the existence of $I=\frac12$ ($\bar{Q}l$)-($Q\bar{s}$) molecules ($l=u,d$) while favors the existence of isoscalar $B\bar{B}$, $B^*\bar{B}^*$ (J=2) and $B\bar{B}^*$ (C=+) molecules. The existence of isovector (charm-anticharm) and (charm-bottom) molecules is also disfavored. Therefore the resonance-like structure $Z^+(4051)$ is unlikely to be an S-wave $D^*\bar{D}^*$ molecule., Comment: 8 pages, 7 tables, accepted by Phys. Rev. C

The bound state problem of $D^0\bar{D}^{\ast0}$ ($\bar{D}^0{D}^{\ast0}$) is relevant to the molecular interpretation of the X(3872). We investigated this problem in a chiral quark model by solving the resonating group method equation. We found the system is unbound through S-wave $\pi$ and $\sigma$ interactions. The inclusion of $\rho$ and $\omega$ meson exchanges is helpful to the formation of a molecule. Because the binding energy relies on the coupling constants, we cannot draw a definite conclusion whether a molecular state exists in $D^0\bar{D}^{\ast0}$ ($\bar{D}^0{D}^{\ast0}$) system. When moving on to the bottom counterpart, we obtained an S-wave $B\bar{B}^\ast$ state., Comment: 8 pages, 2 figures, 7 tables, published in Phys. Rev. C

The structure of $(\Omega\Omega)_{0^+}$ dibaryon with strangeness $s=-6$ is studied in the extended chiral SU(3) quark model, in which vector meson exchange dominates the short range interaction. The resonating group method (RGM) is adopted, in which the $\Omega\Omega$ and $CC$ (hidden color) channels are involved. The color screening effect and the effects of mixing of scalar mesons on $(\Omega\Omega)_{0^+}$ are also investigated., Comment: submitted to Physical Review C