Overall momentum balance and redistribution of the lost energy in asymmetric dijet events in 2.76A TeV Pb-Pb collisions with a multiphase transport model

Abstract

The overall transverse momentum balance and the redistribution of the lost energy from hard jets for asymmetric dijet events in PbPb collisions at 2.76A TeV at the LHC is studied within a multiphase transport (AMPT) model. A detailed analysis is performed for the projected transverse momentum / p || T contributed from the final charged hadrons carrying different transverse momenta and emitted from different angular directions. We find that the transverse momentum projection / p || T in the leading jet direction is mainly contributed by hard hadrons (p T > 8.0 GeV/c) in both peripheral and central PbPb collisions, while the opposite direction in central collisions is dominated by soft hadrons (p T = 0.5-2.0 GeV/c). The study of in-cone and out-of-cone contributions to / p || T shows that these soft hadrons are mostly emitted at large angles away from the dijet axis. Our AMPT calculation is in qualitative agreement with the CMS measurements and the primary mechanism for the energy transported to large angles in the AMPT model is the elastic scattering at the partonic stage. Future studies including also inelastic processes should be helpful in understanding the overestimation of the magnitudes of in-cone and out-of-cone imbalances from our AMPT calculations, and shed light on different roles played by radiative and collisional processes in the redistribution of the lost energy from hard jets.

Medium response in JEWEL and its impact on jet shape observables in heavy ion collisions

“…While these approaches rely on a clear separation between jet and medium degrees of freedom, transport codes treat all partons, whether they are hard or soft, on equal footing. In these calculations, soft partons that interacted with a jet, undergo further re-scattering and thereby thermalise [26][27][28]. Recently, hybrid approaches have been developed, that describe the propagation of jets in transport theory, but treat the thermal medium and its response to energy and momentum depositions by jets in hydrodynamics [15,17,29].…”

Jet quenching and medium response in high-energy heavy-ion collisions: a review

“…In literature, an alternative approach is applying a full Boltzmann simulation for both jet partons and medium partons, although it is still under debate whether the strongly coupled QGP can be modeled with quasi-particles within the perturbative framework. One example is the Ampt model [127,[139][140][141][142][143][144]. In Ampt, the initial spatial and momentum information of high-p T jets, mini-jets and soft string excitations are taken from Hijing simulations [145,146], which are further converted into individual quarks via the string melting model [127].…”

“…Nevertheless, they provide an alternative method that naturally simulates jet and medium evolution concurrently. For instance, by using the Ampt model, reference [189] investigates how to isolate the effects of jet-induced Mach cone and expanding hot spots on the di-hadron vs γ-hadron correlation; reference [144] studies how the lost energy from di-jets is redistributed in the lower p T hadrons. Similar to figure 7, the viscous effects on the Mach cone structures have been studied within the Bamps model [175,190], where effects of different energy loss rates have also been discussed.…”