The collective behavior of the partons and its influence on the jet suppression in heavy ion collisions

Abstract

We discuss the physical picture that a parton interaction with a coherent group of partons can lead to more jet quenching effect in the hot and dense matter created by heavy ion collisions at RHIC and LHC energies. We came to this picture after analyzing the behaviour of the nuclear modification factor as a function of $p_T$ for the charged particles produced in the most central Pb-Pb collisions at 2.76 A TeV. In the interval, $7-50 GeV/c$ the values of the factor as a function of $p_T$ increases almost linearly with a slope is very close to expected one for the inverse Compton effect. Around $p_T\simeq 60$ GeV/c, a regime change occurs, which is characteristic for the phenomenon. We propose that this similarity can be explained by the inverse Compton effect for partons, which occurs via a collective parton group formation ( through the appearance of a new string as a result of the fusion of strings) and its interactions with single partons in the interval of $5 < p_T < 10 GeV/c$. In the case of a coherent collision with a parton that has a lower energy than the group, the parton can gain energy through the inverse Compton effect, resulting in its acceleration and shifting to the region of $p_T >10$ GeV/c. After losing a significant part of its energy new string will decay into partons with lower energies - slowed partons in the interval of $p_T < 5 GeV/c$. This enhancement in the jet quenching can be observed in the interval of $2 <p_T <20 GeV/c$.