Photoproduction of strange hidden-charm and hidden-bottom states

Recently BESIII collaboration discovered a charged strange hidden-charm state Z cs (3985) in the D s - D ∗ 0 + D s ∗ - D 0 spectrum. A higher Z cs ′ state coupling to D ¯ s ∗ - D ∗ 0 is expected by SU(3)-flavor symmetry, and their bottom partners are anticipated by heavy quark flavor symmetry. Here we study the photoproduction of these exotic states and investigate carefully the background from Pomeron exchange. Our results indicate that the maximal photoproduction cross section of strange partner is around 1–2 orders of magnitude smaller than that of the corresponding non-strange states. The possibility of searching for them in future electron-ion colliders (EIC) is briefly discussed.