标题： 功率修正和KLN抵消 显示英文标题

标题： Power Corrections and KLN Cancellations

摘要： 我们考虑具有红外截断$\lambda$的理论中的微扰展开。红外敏感项定义为在无穷小$\lambda^2$中非解析的项，这些截断的幂次决定了这些红外贡献的强度。有人指出，根据Kinoshita - Lee - Nauenberg定理，必须对初始和最终简并状态（如$\lambda \to 0$）求和，这消去了阶数为$\lambda^0$和$\lambda^1$的项。然而，一般情况下二次及更高阶项不会抵消。这是在与重粒子的包容衰变率相关的KLN抵消简单例子中，在单环层次进行研究的。 显示英文摘要

摘要： We consider perturbative expansions in theories with an infrared cutoff $\lambda$. The infrared sensitive pieces are defined as terms nonanalytic in the infinitesimal $\lambda^2$ and powers of this cutoff characterize the strength of these infrared contributions. It is argued that the sum over the initial and final degenerate ( as $\lambda \to 0$) states which is required by the Kinoshita - Lee - Nauenberg theorem eliminates terms of order $\lambda^0$ and $\lambda^1$. However, the quadratic and higher order terms in general do not cancel. This is investigated in simple examples of KLN cancellations, of relevance to the inclusive decay rate of a heavy particle, at the one loop level.