Heavy Flavours through Quark Matter 2012
The ALICE collaboration has shown at the Quark Matter 2012 conference results on heavy-flavour particle production measured in lead–lead collisions at the LHC. In head-on (central) collisions, a large suppression of the heavy-flavour particle yield is observed with respect to expectations at large transverse momentum. In non-central collisions, heavy-flavour particles have non-isotropic azimuthal emission with respect to the reaction plane. Both observations are understood as resulting from the interaction of heavy quarks with the partonic medium formed in the collisions.
Heavy quarks play a special role in heavy-ion physics because they constitute a tagged (identified) probe (from production to observation), which enables a unique access to their interactions in the Quark-Gluon Plasma, the highly excited system (medium) formed in high-energy nucleus–nucleus collisions. This allows us to gain microscopic insights into the transport properties of the medium. Heavy-flavour particles may be thought of as “Brownian motion'' markers, the kinematical distributions of which (especially in momentum and azimuthal angle) reflect their re-interaction history.