Heavy-ion collisions exhibit distinctive phenomenological characteristics relative to pp collisions due to the formation of a considerably larger quark–gluon plasma (QGP). In the seminal work of Satz & Matsui, color screening effects of in-medium heavy-quark pairs were proposed, introducing the concept of quarkonium “melting”. Owing to its unusually large spatial extent and weak binding energy, the X(3872) provides a particularly compelling probe of the QGP, as its internal structure is compatible with a mixed configuration in turn very sensitive to the degree of separation of charm systems in the QGP. We employ simple theoretical arguments to quantify this separation, combining many experimental results by the LHC collaborations on the hidden-charm sector, including the X(3872).
This approach can be naturally extended to the bottomonia sector, and, leveraged together with the charmonia results, used to understand the distinction between in-medium and vacuum quarkonia production, incorporating results from the Belle II, CLEO and BESIII experiments.
Through this unified phenomenological study, we show how quarkonia measurements can provide insights into the spacial dependencies of hadronisation.