The B? Molecular State And Its Radiative Decay

Since the discovery of X(3872)by the Belle cooperation group in 2003,many of the charmed particles have been found and confirmed.These particles can not be explained by a simple quark model,that is,they can not explain the positive and negative quarks,called the exotic hadrons,usually called XYZ particles.The discovery of XYZ particles is of great significance for people to better understand the quark model and to develop the theoretical method of QCD,so it has been a hot research focus in the last decade.In the current theoretical study,people tend to think that the exotic hadrons found in these experiments are multi-quark states,but there are still some arguments about their inner structures,namely if they are tetraquarks or the molecular states.In this paper,if the molecular states are formed by pion and some heavy flavor baryon,its mass is much lighter than that of the corresponding tetraquarks,the reason is that pion is lighter than u or d quark,It can be used as an important experimental criterion for the existence of molecular states.We have studied the possible molecular states under the framework of the B-S equation.We use the effective interaction derived from the chiral perturbation theory in the B-S framework.By solving the B-S equation,we calculate the potential spectrum of the possible molecular states.In the reasonable range of parameters,we find that the isospin |1/2,1/2>can not form bound states.While the isospin |3/2,1/2->can form bound states.In addition,we propose to find the particle by the radiative decay of the molecular states,and we theoretically calculate its radiative decay width.If this state is found in the future experiment,it should be a definite molecular states,which will provide more information for us to understand the multi-quark states and its inner structure.