Dynamical Study Of Meson-meson Molecular State With Heavy Flavors

Recently, a lot of new hadrons have been observed experimentally, especially in the sector of heavy-flavor mesons, such as Ds(2317),Ds(2457),X(3872),X(3915),Y (3940),Z(3939),Y(4260,Z±(4430) and so forth, some of which have been confirmed by different collaborations and collected by Particle Data Group (PDG). There exist apparent deviations in spectrum observables which give warnings to a simple quark-antiquark treatment and more complicated mechanisms may play a role. A example is the newly identified state X(3872) and possible assignments for it as quark-antiquark(cc), tetraquark, D0-D*0 molecule or a mixture of cc and D0-D*0. So far, many efforts have been dedicated to the investigation of the hadron-hadron molecule, the multi-quark state and the exotic state based on various QCD-inspired model to identify these new hadrons theoretically, but there is still a long road to go before these new states are truly understood.In this thesis, we focus on the dynamical study of the heavy-flavor meson-meson molecular states in potential model.Generally, the interaction between heavy-flavor meson and meson is thought to be performed throughπandσexchange. Nevertheless, the short-distance interaction induced by quark exchange (OGEP) isn't taken into account to form a molecule. We incline to calculate D0-D*0 system, including three parts of interaction:the short-distance interaction induced by quark exchange(OGEP),the intermediate-distance one-sigma-exchange potential (OSEP) and long-distance one-pion-exchange potential (OPEP). In present work, we mainly study whether X(3872) could be a D0-D*0 molecular state. By solving the SchrOdinger equation, we calculate the bound energy with different potentials, and find that there exists a weakly bound S-wave state and the binding energy is less sensitive to the potential parameter. With the reasonable parameters, we obtain the binding energy -0.11 MeV for the D0-D*0system. Therefore, the X(3872) is a probable loose molecular state. In addition, we also investigate whether the B-B* system may form a bound state. Since the larger reduced mass and the lower kinetic energy, we calculate and find an S-wave bound state for the B-B system with much larger binding energy, which indicates that it's easier to form a molecular state. Thereby, we expect that the bound state would be found in LHCb.