Recent results on Upsilon meson production in PbPb collisions with CMS.

One of the fundamental aspects of the formation and interaction of heavy-quark bound states in the quark-gluon plasma is amount of their suppression, expected to be stronger with quarkonia with smaller binding energies. Past results show a significant suppression of Upsilon(1S) mesons in heavy ion collisions, with Upsilon(2S) mesons being even more suppressed. However, for the Upsilon(3S) meson, only upper limits had been reported. In this talk, we report on the observation of the Upsilon(3S) meson and the recent studies of the production of Upsilon mesons in lead-lead collisions reported by CMS. For the first time, the nuclear modification factor has been extended to the Upsilon(3S) state, which is the most strongly suppressed meson measured to date. The results are compared with model calculations describing the dynamics of quarkonia in a hot environment. Relevant Upsilon results from pPb collisions in CMS will be discussed as well.