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.
Categories: hep-ph hep-ex nucl-ex nucl-th