New Z' gauge bosons arise in many extensions of the Standard Model and predict resonances in the dilepton invariant mass spectrum. Searches for such resonances therefore provide important constraints on many models of new physics, but the resulting bounds are often calculated without interference effects. In this work we show that the effect of interference is significant and cannot be neglected whenever the Z' width is large (for example because of an invisible contribution). To illustrate this point, we implement and validate the most recent 139 fb$^{-1}$ dilepton search from ATLAS and obtain exclusion limits on general Z' models as well as on simplified dark matter models with spin-1 mediators. We find that interference can substantially strengthen the bound on the Z' couplings and push exclusion limits for dark matter simplified models to higher values of the Z' mass. Together with this study we release the open-source code ZPEED, which provides fast likelihoods and exclusion bounds for general Z' models.

中文翻译：

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Z′玻色子和暗物质介体的双轻子共振搜索中的干涉效应

新的 Z'规范玻色子出现在标准模型的许多扩展中，并预测双轻子不变质谱中的共振。因此，对这种共振的搜索为许多新物理学模型提供了重要的约束，但结果边界通常是在没有干扰效应的情况下计算的。在这项工作中，我们表明干扰的影响是显着的，并且在 Z' 宽度很大时不能被忽略（例如，由于不可见的贡献）。为了说明这一点，我们实施并验证了来自 ATLAS 的最新 139 fb$^{-1}$ 双光子搜索，并获得了对一般 Z' 模型以及具有自旋 1 介体的简化暗物质模型的排除限制。我们发现干扰可以大大加强 Z' 上的界限 耦合并将暗物质简化模型的排除限制推到更高的 Z' 质量值。连同这项研究，我们发布了开源代码 ZPEED，它为一般 Z' 模型提供了快速的可能性和排除范围。