Structure of the X ( 3915 ) meson and its production in heavy ion collisions

We study the structure of the X ( 3915 ) meson in a quark model and explore how its production in heavy ion collisions depends on its internal structure. We first analyze the X ( 3915 ) as a c c ¯ s s ¯ state and solve the Hamiltonian with color-spin interactions within the quark model. We find that the ground state of the c c ¯ s s ¯ with total spin 0 obtained from the quark model analysis favors a separated D s D ¯ s state. To probe its structure further, we study its production in relativistic heavy ion collisions for various proposed configurations. We calculate the transverse momentum distributions and yields for the X ( 3915 ) assuming its structure to be either a charmonium, a tetraquark, or a hadronic molecular state. We argue that, by measuring the transverse momentum distributions and yields of the X ( 3915 ) produced in heavy ion collisions, one can identify the structure of the X ( 3915 ) .