论文标题
环路可观察物和应用于$（g-2）_ $ $ $ $的宽度新共振的宽度效果
Width effects of broad new resonances in loop observables and application to $(g-2)_μ$
论文作者
论文摘要
在强烈相互作用的现象学中，大多数物理状态都具有很大的宽度，因此只能按照$ s $ -matrix的极点位置和残基以模型独立的方式定义。该信息已包含在Källén-Lehmann表示中，其光谱函数表征了共振的形状，并且可以受到主要衰减通道的约束。在这里，我们认为，每当超出标准模型颗粒具有相当大的衰减宽度时，类似的效果就变得很重要 - 例如，在对黑暗部门的分支分数较大或强烈耦合的情况下，并显示如何将其宽度纳入循环可观测值的计算中。作为一种应用，我们考虑了哑光的异常磁矩，包括新物理学的直接效果以及广泛的光$ z'$对$ e^+e^ - \ to \ to \ text {hadrons} $ cross部分的间接影响。在整个过程中，我们从一环假想部分为一般光谱函数及其重建提供了结果，后者捕获了领先的两环效应。
In the phenomenology of strong interactions most physical states acquire a substantial width, and thus can only be defined in a model-independent way by pole positions and residues of the $S$-matrix. This information is incorporated in the Källén-Lehmann representation, whose spectral function characterizes the shape of the resonance and can be constrained by the dominant decay channels. Here, we argue that similar effects become important whenever beyond-the-Standard-Model particles possess a sizable decay width - as possible for instance in cases with a large branching fraction to a dark sector or strongly coupled scenarios - and show how their widths can be incorporated in the calculation of loop observables. As an application, we consider the anomalous magnetic moment of the muon, including both the direct effect of new physics and the possible indirect impact of a broad light $Z'$ on $e^+e^-\to\text{hadrons}$ cross sections. Throughout, we provide results for a general spectral function and its reconstruction from the one-loop imaginary part, where the latter captures the leading two-loop effects.
