Photoproduction of Upsilon meson in PbPb collisions with CMS

Exclusive photoproduction of vector mesons represents a powerful tool to explore the gluonic structure of nuclei, given that this reaction proceeds through $\gamma$A interaction, in which a two-gluon exchange is involved. In particular, the photoproduction of $\Upsilon$ mesons provides a large energy scale, defined by the quark mass, so it can be studied with perturbative QCD. In this talk we present our progress on the observation of $\Upsilon$ meson in ultra-peripheral PbPb collisions in CMS.