FONLL calculations for heavy quark production in nuclear collisions

The ALICE detector at the LHC has been designed to study the collisions of heavy nuclei at energies much higher then the previous dedicated experiments at the Relativistic Heavy-Ion Collider (RHIC) of the Brookhaven National Laboratory. Colliding heavy nuclei allows to reproduce the hot and dense plasma of quarks and gluons (QGP) existing right after the Big Bang and hence study the very first instants of universe’s existence. In heavy ions collisions, heavy flavours, such as beauty and charm quark, are fundamental probes for the quark gluon plasma properties. That is because they experience the entire evolution of the system since they are produced at the very beginning. They are indeed a very powerful tool to test field theories such as Quantum Chromodynamics (QCD). Theoretical models predict that a fast parton(quark or gluon) looses energy while traversing a medium composed of colour charges. This phenomenon is called "jet quenching", it can be used to describe the QGP. It was first observed at RHIC by measuring the yields of hadrons. These particles are produced via the hadronization of the scattered energetic partons. In this project some theoretical predictions on the behaviour of heavy flavoured(charm and beauty) partons and hadrons produced in heavy ions collisions(p-Pb and Pb-Pb) are studied using QCD calculations. The initial production of heavy flavoured quarks is implemented using the fixed-to-next-to-the-leading order (fonll) approximation model. The calculation should also take into account the nuclear effects present in the heavy nuclei before the collision due to the high number of nucleons. The nuclear parton distribution functions(nPDF) are introduced for this purpose. The predictions are then use to scale the experimental data and get information about the effects due only to the QGP. The project has been done in the contest of the Summer Student School of CERN.