Production of meson molecules in ultraperipheral heavy ion collisons
In this work we present a calculation of exotic charmonium production in ultraperipheral collisions, in which the exotic state is explicitly treated as a meson molecule. Our formalism is general, but we focus on the lightest possible exotic charmonium state: a 𝐷 + 𝐷 − molecular bound state. It was proposed some time ago, and it has been an object of experimental searches. Here we study the production of the open charm pair in the process 𝛾𝛾 → 𝐷 + 𝐷 − . Then we use a prescription to project the free pair |𝐷 + 𝐷 − ⟩ onto a bound state at the amplitude level and compute the cross section of the process 𝛾𝛾 → 𝐵 (where 𝐵 is the bound state). Finally, we convolute this last cross section with the equivalent photon distributions coming from the projectile and target in an ultraperipheral collision and find the 𝐴𝐴 → 𝐴𝐴𝐵 cross section, which, for 𝑃𝑏 −𝑃𝑏 collisions at $\sqrt{s_{NN}}$ =5.02 TeV, is of the order of 3 μb.