CHARM^2: Measuring charm-(anti)charm correlations in heavy-ion collisions

The goal of the project is to measure for the first time the correlation between two charm-quark (D) mesons in heavy-ion collisions.

From the correlation functions, the charm-anticharm balance function will be extracted and used to probe the hot medium created in these collisions.

The project takes advantage of the upgraded ALICE experiment at the CERN LHC facility, which from 2022 will take data in a completely new configuration with significantly increased rate capabilities and improved precision relevant for these studies.

The project will run over a four year period and be conducted by the PI and a PhD student.The motivation to study correlations between heavy-quarks comes from the following shift in the field. For a long time it was conjectured that the large flow observed in heavy-ion collisions implied early thermalization.

However, after the discovery of flow in small systems (where thermalization is questionable), it was realized that flow can build up out-of-equilibrium (chemical and thermal) in a purely gluonic system.

This would mean that light quarks first are produced when the system is already flowing and so they cannot probe early-time dynamics.

In this project, I want to study the pairs of charm quarks that are produced mainly in the initial collisions and use them to probe the whole final-state evolution, in particular the build up of flow.