A measure for isotropy-equilibrium degree of a multi-particle system

作者:Liu Zhi Qing*; Li Run Ze; Xu Ming Mei; Liu Lian Shou
来源:Chinese Physics Letters, 2008, 25(2): 447-450.
DOI:10.1088/0256-307X/25/2/026

摘要

Aiming at using sphericity as a tool to study the isotropy-equilibrium property of a multi-particle system, in particular the hadronic final state IFS produced in instanton-induced DIS events, we discuss in detail the dependence of sphericity on multiplicity and the multiplicity distribution, as well as on the isotropy degree of the system. A rotational symmetric model with a fluctuating isotropy-degree is constructed, which can fit the mean and width of sphericity of the Monte Carlo IFS-results simultaneously. The IFS from the Monte Carlo simulation is found to be not ideally isotropic but has a probability of 4.7% to be isotropic within error of 5%. The results provide us a description of how far the IFS departs from equilibrium. The method developed is applicable to any Monte Carlo generated multi-particle system, for which the isotropy-equilibrium property is significant.