Systematic Studies of Jet Quenching in Hot Nuclear Matter

Abstract

The early universe was filled with a primordial form of matter called Quark Gluon Plasma that only exists at extremely high temperatures and densities, many times hotter than the core temperature of suns. By colliding heavy nuclei at top energies at machines like the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC) we can create and investigate tiny bubbles of Quark Gluon Plasma for very short periods of time before they cool and decay. We can use so-called QCD jets i.e. highly energetic quarks and gluons to penetrate and probe these artificially created Quark Gluon Plasma bubbles by comparing them with jets created in vacuum in control experiments. This is a wonderful tool to study properties of this exotic form of matter. We conduct a systematic study of the functional relationship between the so-called jet quenching strength ̂ and the plasma entropy density s. Our main goal is to explore the possibility of enhanced energy loss when the plasma temperature is close to the phase transition, temperature between the Quark Gluon Plasma and ordinary nuclear matter. We will simulate jets in Quark Gluon Plasma for a variety of colliding nuclei and collision energies. Existing experimental data will lead to constraints on the relationship between the plasma entropy density and the quenching strength. We were able to qualitatively confirm the results by Liao and Shuryak [8] who postulated an enhancement of ̂ around the phase transition. For Pb Pb collisions at the LHC we can show that such scenario leads to predictions of relatively small energy loss and small elliptic flow which can be compared to future experimental data.