Beauty physics with heavy ions and prospects

Abstract

Heavy flavours are generally considered one of the fundamental probes of the Quark-Gluon Plasma (QGP), the state of matter in which partons are deconfined, that can be created in relativistic heavy-ion collisions. Due to their large mass, heavy quarks are predominantly produced in hard scattering processes during the early stages of the collision lie Open heavy flavour measurements may probe the energy density of the system by means of the energy loss through elastic scatterings and gluon radiation. The radiative energy loss is predicted by QCD to be larger for gluons than for quarks, and light quark energy loss should be larger than that for heavy quarks due to the dead cone effect. The measurement of the yield of beauty hadrons can therefore shed light on the energy loss mechanism and on the mass hierarchy. Quarkonia are another crucial probe of the QGP. They can melt in the medium due to color screening at a temperature which increases with the binding energy of the system, thus acting as a probe of the QGP temperature. Bottomonia are of particular interest in this respect, since they can provide a clear suppression pattern. Beauty and bottomonia measurements in heavy-ion collisions at the LHC are reviewed. Results based on semi-leptonic decays of charm and beauty hadrons, non-prompt J/y from B decays and b-tagged jets in Pb-Pb collisions are discussed, as well as the measurements of i suppression at mid and forward rapidity provided by the CMS and ALICE experiments. Cold nuclear matter effects are investigated through the measurements in p-Pb collisions.