双时间—温度格临函数的二元碰撞展开

应用李政道和杨振宁提出的二元碰撞展开法,对于有强短程排斥互作用的多粒子系发展了一种按图形计算双时间-温度格临函数的规则,其各级近似由二体散射相移的各次幂所表征。文中得出了玻色和费米统计情形的计算规则,并且研究了有凝聚相存在的玻色系统。本文主要讨论了单粒子格临函数的图形技术,但容易将它们推广应用于计算各种时间-温度格临函数。

THE BINARY COLLISION EXPANSION OF DOUBLE-TIME-TEMPERATURE-DEPENDENT GREEN'S FUNCTIONS

The method of binary collision expansion has been employed to obtain series developments in powers of the scattering length between two particles for double-time-temperature-dependent Green's functions of statistical mechanics. We have studied the cases of Bose and Fermi statistics as well as the case of a Bose system in the presence of a condensed phase, and have established rules for computation of the successive terms of expansion with the aid of diagrams. The present method is applicable to many particle systems with strong and short-ranged mainly repulsive two-body interactions.