Nuclear modification of full jet energy and jet structure at the LHC energies

Abstract

With our coupled jet-fluid model, we study the evolution of the full jet shower in quark-gluon plasma (QGP) and calculate the observables related to the nuclear modification of jet energy and jet structure in Pb+Pb collisions at $2.76$~ATeV and $5.02$~ATeV. The full jet shower evolution in QGP medium is described by a set of coupled Boltzmann transport equations which includes the effects of collisional energy loss, transverse momentum broadening and medium-induced splitting process. The jet observed in heavy-ion collisions also includes the particles from the QGP medium excitated by the energy and momentum transported from jet shower to QGP medium. To take account of this effect, the dynamical evolution of QGP medium need to be simulated by solving relativistic hydrodynamic equation with source terms which is provided by the jet evolution equations. Our results can describe the experimental data of jet nuclear modification factor $R_{AA}$ with different cone size and catch the features of jet shape modification for inclusive jets and $\gamma-$jets. Our study demonstrates that the effect of medium response is essential for the cone size dependence of jet energy loss and jet $R_{AA}$, and becomes important for the modification of jet shape function at large radius. For the different modification pattern of the jet shape function in single inclusive jet events and $\gamma$-jet events observed by the CMS Collaboration, our results show that the difference comes from the dependence on jet energy instead of the flavor of the parton that initiates the jet. Our theory can be tested in the future by measuring the modification of jet shape function over a wider range of jet energy in heavy-ion collisions.