Study Of Decays Of Exotic Hadron States

In the past decade,a growing numbers of new hadron states have been observed experimentally.The properties of some new hadron states could not be understood in the conventional quark model,which indicates that they could be the candidate of the exotic state.The particular properties of the new hadron states stimulate great interest of the-orists.The spectroscopy,production mechanism,and decay behaviors have been in-vestigated intensively.The decay properties of the new hadron state could provide us more information on their inner structures.In this thesis,the study of decay behaviors of the exotic states were carried out.In terms of the effective lagrangian approach,the decay properties of some exotic states are calculated in the molecule frame,in-cluding the decays from the molecular state to the conventional hadron and transitions between two molecular states.Besides,the decay behaviours of some exotic states are also investigated with the final state interaction.The main contents of this thesis include:?1?Considering the D^*_s0?2317?and D_s1?2460?as DK and D^*K molecular states,respectively,the pionic and radiative transitions from D_s1?2460?to D^*_s0?2317?are e-valuated.Our results are consist with the experimental observations,which indicate that D^*_s0?2317?and D_s1?2460?could be DK and D^*K molecular states.?2?The strong and radiative decays of the fully open flavor states X?5568?are studied in a molecular scenario.We find that the X?5568?could be a deeply bounded B?K molecular state.?3?The D_s⁺D_s^-molecule assignment for the X?3915?is studied.Our results point out that the X?3915?dominantly decays to D?D if considering X?3915?as a D_s⁺D_s^-molecular state.The branching ratio of the experimentally observed channel J/??are too small to be observed.In another word,the X?3915?can not be a D_s⁺D_s^-molecular state.?4?As for Y?4390?,the observation in?⁺?^-h_cchannel and absence in?⁺?^-J/?channel could be naturally understood in the?D^*?D₁+h.c.?interpretation.Also,our results of?J/?and?h_cmodes are in agreement with the experimental observation.?5?The final state interaction mechanism are applied to study the decays from Z_b?10610?and Z_b?10650?to??,and further predict the branching ratios of?_b?and?_b?modes.?6?In the D?scenario,the decays of the five newly observed?_cbaryons,which were observed by LHCb in 2017,are investigated.Our results indicate that?_c?3119?and?_c?3050?could be D?molecular state,while the other three states?_c?3000?,?_c?3066?and?_c?3090?can not be D?molecular state.?7?The strange partner of pentaquark state P_c?4380?and P_c?4450?—the S-wave?^*K molecular states are discussed,where some possible decay modes are estimated.The studies of the present thesis indicate some new hadron states could be good candidates of molecular states.In the molecule frame,we also predict some new decay modes of these states.The predictions in the present thesis could provide some theoretical information for further experimental searches,and on the other hand,the new experimental measurement could be a crucial test of the molecular interpretations.