A generalization to all system sizes of DGLV energy loss in the quark-gluon plasma

Abstract

In the last few years, experiments with small colliding systems (such as p/d + A) have yielded some evidence for the presence of small droplets of quark-gluon plasma (QGP). The collective behavior, strangeness enhancement and quarkonium suppression that have been seen beg the question: What of the energy loss? However, in order to answer such a question, one must apply existing perturbative Quantum Chromodynamical (pQCD) energy loss calculations to systems that are much smaller than the systems in which pQCD energy loss calculations were originally so successful, a process that is not currently allowed for in any pQCD energy loss calculation. We relax the large system assumption in the well-known DGLV formalism (an assumption that is also utilized in the ASW, BDMPS-Z, AM and HT calculations), but find, alarmingly, that the correction terms dominate at large energies, resulting in ∼ 100% negative correction, calling into question the validity of the large formation time assumption used in all pQCD-based energy loss calculations. Our results demand a complete overhaul of energy-loss calculations for all system sizes.