Speaker
Description
Ultrarelativistic heavy-ion collisions generate a powerful electromagnetic field that produces photonuclear reactions. Recently, coherent $J/\psi$ photoproduction has been observed in nucleus–nucleus (A–A) collisions with nuclear overlap, based on the measurement of an excess of $J/\psi$ production with respect to hadron-production expectations at very low $p_{\rm T}$. In this context, a polarization measurement can confirm the electromagnetic origin of the very low $p_{\rm T}$ $J/\psi$ yield excess, since the produced quarkonium is expected to inherit the transverse polarization of the incoming photon. ALICE can measure inclusive and exclusive quarkonium production down to $p_{\rm T}$ = 0. In this contribution, preliminary measurements of the $y$-differential cross section and the polarization analysis of coherently photoproduced $J/\psi$ in peripheral Pb–Pb collisions will be presented together with recent results on coherent $J/\psi$ photoproduction as a function of centrality. Comparison with models will be shown when available.
| Category | Experiment |
|---|---|
| Collaboration | ALICE |
