标题： 量子色动力学低能有效理论中的非微扰效应 显示英文标题

标题： Nonperturbative effects in low energy effective theories of QCD

摘要： 在本次演讲中，我关注手征对称性通过自旋-1场在低能QCD有效拉格朗日量中的实现。我假设手征对称性是非线性实现的，并且自旋-1场在手征旋转下均匀变换，这与之前的工作形成鲜明对比，在之前的工作中，$\rho$和$a_1$介子被当作某种手征群的近似规范玻色子。我强调四介子耦合的作用，在我们的方案中，这些耦合对于理论有意义是必不可少的。通过要求理论的动能密度从下方有界，我们找到了三介子和四介子耦合之间的不等式。最后展示了我们的分析与单位性要求的结合如何自然地导致$\pi\rho a_1$强相互作用非异常部分的低能现象学拉格朗日量。 显示英文摘要

摘要： In this talk I concentrate on the role of chiral symmetry realisation by spin-1 fields in the low energy QCD effective lagrangian. I assume that chiral symmetry is nonlinearly realised and that spin-1 fields transform homogeneously under chiral rotations, which is in sharp contrast to previous works where the $\rho$ and the $a_1$ mesons were treated as approximate gauge bosons of some chiral group. I emphasise the role played by four-meson couplings which in our scheme are essential for the theory to make sense. By requiring the kinetic energy density of the theory to be bounded from below we find inequalities relating three- and four-point meson couplings. It is finally shown how the combination of our analysis and of unitarity requirements naturally leads to a low-energy phenomenological lagrangian for the nonanomalous sector of $\pi\rho a_1$ strong interactions.