The search for rare decays at ATLAS and CMS
The search for rare decays at ATLAS and CMS
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DOI：
10.22323/1.397.0038
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发表时间：
2021-10
期刊：
影响因子：
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通讯作者：
R. Salvatico
中科院分区：
文献类型：
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作者：
R. Salvatico
标准模型描述了大量粒子及其衰变，包括 W 和 Z 玻色子的衰变。尽管这种衰变的很大一部分早已为人所知，并且已经非常精确地测量了相应的分支分数，但仍然有一些罕见的过程从未被观察到，甚至从未被实验探测过。他们的观察可以帮助验证通常用于计算其分支分数的理论框架，而且还提供了测量矢量玻色子基本特性的可行替代方案，并可能提供标准模型之外的新物理学的提示。大型强子对撞机的两个通用实验涵盖了丰富的稀有衰变搜索计划。本报告重点关注电弱领域的研究，包括由 CMS 协作组进行的 W± → π±γ 和 W± → π±π±π∓ 的搜索、Z → 4` 支化分数的测量，以及由 ATLAS 协作组进行的轻子风味破坏衰变 Z→ e/μτ 的搜索。此类搜索和测量部分或全部利用了 2015-2018 年数据采集期间两个实验收集的综合光度，在某些情况下代表了各自领域的最新技术。
The standard model describes a vast number of particles and their decays, including those of theW and Z bosons. Even though a large fraction of such decays have been known for a long time and the respective branching fractions have been measured with great accuracy, there remain several rare processes that have never been observed or even experimentally probed. Their observation could help validate the theoretical frameworks commonly used to calculate their branching fractions, but also provide viable alternatives to measure fundamental properties of the vector bosons, and possibly offer hints of new physics beyond the standard model. The two general-purpose experiments at the LHC cover a rich program of rare decay searches. This report focuses on those in the electroweak sector, including the search for W± → π±γ and W± → π±π±π∓, performed by the CMS Collaboration, the measurement of the Z → 4` branching fraction, and the search for lepton flavor-violating decays Z→ e/μτ, performed by the ATLAS Collaboration. Such searches and measurements exploit either partially or fully the integrated luminosity collected by the two experiments in the 2015–2018 data-taking period, and in some cases represent the state of the art in the respective fields.