Bound state problem of S-wave heavy quark meson-antimeson systems

We investigated systematically whether the S-wave (Qq) meson and the (Qq) 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=(1/2)(Ql)-(Qs) molecules (l=u,d) but favors the existence of isoscalar BB, B*B*(J=2), and BB*(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*D* molecule.