A Simulation Study Of Jet-Medium Interaction

In modern physics, it has been proved that hadrons are made up of quarks and gluons. Quantum Chromodynamics is generally considered to be the correct theory for the interaction of quarks and gluons. Lattice Quantum Chromodynamics predicted that a Quark-Gluon-Plasma(QGP) can be formed, when the temperature of matter is high enough, or when the baryon number density is large enough. Thus high energy heavy ion collisions is an appropriate approach to realize the formation of QGP because very high energy deposited by the colliding nuclear matter in a very limited space which causes a very high energy density and a high temperature in this space. In fact several evidences indicate that QGP has been produced in Au+Au collision at (?)= 200GeV, in the Relativistic Heavy Ion Collider(RHIC) at Brookhaven National Laboratory(BNL) in USA, i.e., collective flow such as directed flow and elliptic flow etc, strangeness increase and J/ψsuppression and so on. Among them, the most convincing evidences are jet quenching and dihadron correlation.Many people study the mechanism of the double-hump at away-side in dihadron correlation. One possible choice is proposed by Ma et al that this phenomenon is induced by parton cascade procedure during the propagation of energetic partons in QGP and the afterwards hadrons rescattering. In this study, parton cascade is necessary to the arising of double-hump.To test their conclusion, we construct a Monte carlo generator to simulate the parton cascade procedure based on Boltzmann equation. Only elastic scattering be-tween the energetic partons and thermal partons is considered in our calculation. We find that when the energetic partons are produced at the same point and propagate in the QGP along the same direction, then the away-side double-hump appears due to the parton cascade procedure. However, if all possible starting point and all pos-sible directions are considered for energetic partons to propagate in QGP created in Au+Au collisions at 200AGeV, the away-side double bump disappears.It is very convenient to study energy loss based our Monte Carlo generator. Usually small angle approximation has been employed in the theoretical calculation of elastic energy loss. Our study tells that this approximation will make a certain enhancement of the energy loss of hard parton per unit distance.