解析验证b→sγ单圈图中的Ward恒等式

ANALYTIC VERIFICATION OF WARD IDENTITY OF b→sγAT THE ONE-LOOP LEVEL

Ward恒等式是量子场论中的重要关系。本文以b→sγ为例,在费曼规范下,利用维数正规化方案,以圈图函数展开的方式验证了一圈图领头阶满足Ward恒等式。这个验证方法可以作为场论课程的实例,其中使用的一些技巧也可以应用到其他物理过程中。结果表明,不但发散项之和在一圈水平上自动相消,Ward恒等式在一圈水平上也是成立的,此性质是检验计算结果是否正确的一个重要依据。该验证不仅仅适用于标准模型,也可在具有相同性质的各种新物理模型中应用。同时,在其他类似的过程中,也可运用同样的验证技巧。

Ward identity is an important relation in quantum field theory.Under the Feynman gauge(ξ=1),this paper takes the leading order of b→sγat the one-loop level as an example and uses the dimension regularization scheme to verify the ward identity by expanding the oneloop diagram functions.This verification method can be applied as an example of field theory course,and some of the techniques adopted can also be used to other physical processes.The results show that not only the sum of divergent terms is automatically eliminated at one-loop,but also the Ward identity is true at the level of one-loop.This property is an important basis for checking whether the calculation results are correct.This verification is not only applicable to standard models,but also to various new physical models with the same properties.Meanwhile,the same verification techniques can be used into other similar processes.