高能强子–强子碰撞中喷注性质的蒙特卡洛研究

在喷注“圆锥判定法”的基础上,对高能强子–强子碰撞中产生的喷注(微喷注)的性质进行了蒙特卡洛研究.采用以喷注动量为z轴的“喷注坐标系”,给出了表征喷注性质的各物理量在新坐标系中的分布情况.结果表明,圆锥判定法能够作为一种有效手段来对高能强子–强子碰撞和相对论重离子碰撞中发生的硬和半硬过程开展实验研究.由有喷注事件和无喷注事件的多重数分布可以看到,E_t=2GeV是用圆锥法确定喷注的合理的横能截断值.

Monte Carlo Study of the Properties of Jets in High Energy Hadron-Hadron Collisions

On the basis of "cone" jet algorithm, a Monte Carlo study of the properties of (mini) jets in high energy hadron hadron collsions is carried out. Using the "jetty frame", in which the momentum of jet is chosen as Z axis, the distributions of physical quantities inside jets multiplicity, pseudorapidity, azimuthal angle and transverse momentum are obtained. The pseudorapidity distribution is asymetric, concentrating in the forward direction, which means that all the particles in the jet are moving forward in the direction of the total momentum of jet. This is further proved by a particle momenta plot in the axial coordinate which shows that the jets look like sharp arrows with small forward pointing feathers at the ends. The transverse momentum distribution for the event sample with respect to the direction of incident hadrons diviates from an exponential distribution considerably, in consistent with the productuon of (mini )jets, while that inside jets with respect to the jet axis is basically an exponential. This means that the production of (mini ) jets is hard process, while the developement of jets is basically soft. These results show that "cone algorithm" is an effective method for the study of hard and semi hard processes in high energy hadron hadron and relativistic heavy ion collisions. It is found through the comparison of the distributions in jetty events and no jet events that E t 2GeV is a more reasonable cut for the "cone algorithm" in finding jets.