$Z_b(10650)$ and $Z_b(10610)$ states in a chiral quark model
  We perform a systematic study of $B\bar{B}^*$, $B^*\bar{B}^*$, $D\bar{D}^*$ and $D^*\bar{D}^*$ systems by using effective interaction in our chiral quark model. Our results show that the interactions of $B\bar{B}^*$, $B^*\bar{B}^*$, $D\bar{D}^*$ and $D^*\bar{D}^*$ states are attractive, which consequently result in $B\bar{B}^*$, $B^*\bar{B}^*$, $D\bar{D}^*$ and $D^*\bar{D}^*$ bound states. The recent observed exotic-like hadrons of $Z_b(10610)$ and $Z_b(10650)$ are, therefore in our approach, interpreted as loosely bound states of $B\bar{B}^*$ and $B^*\bar{B}^*$, while X(3872) and Y(3940) are $D\bar{D}^*$ and $D^*\bar{D}^*$ molecule states, respectively. 
M. T. Li, W. L. Wang, Y. B. Dong, Z. Y. Zhang
hep-ph nucl-th