First, in Chapter 4, we consider the direct instanton effect in the QCD sum rules for the $0^{++}$ glueball mass. 首先是第四章,在考虑了直接的瞬子效应后,我们在QCD求和规则的框架内研究了$0^{++}$胶球的质量问题。
An instanton (or pseudoparticle) is a notion appearing in theoretical and mathematical physics. An instanton is a classical solution to equations of motion with a finite, non-zero action, either in quantum mechanics or in quantum field theory. More precisely, it is a solution to the equations of motion of the classical field theory on a Euclidean spacetime.