论文标题
在$ \ sqrt {s} = $ 13 tev中搜索质子proton碰撞中的稀有腐烂到质子和光子的光子
Search for the rare decay of the W boson into a pion and a photon in proton-proton collisions at $\sqrt{s} = $ 13 TeV
论文作者
论文摘要
在$ \ sqrt {s} = $ 13 tev的质子 - 普罗顿碰撞中，对稀有衰减W $^\ pm \toπ^\pmγ$进行了搜索。与CMS检测器一起收集了与2016年至2018年期间收集了与137 fb $^{ - 1} $的ON w集成光度相对应的数据。该分析利用了基于顶级夸克对中W玻色子产生的新型搜索策略。由于高触发阈值，对W $^\ pm \toπ^\pmγ$衰减的包容性搜索不是最佳的。取而代之的是，利用了触发选择，其中使用Q Quarks之一的W Boson用于在麻风衰减中标记事件。从另一个顶部夸克出现的W玻色子用于搜索W $^\ pm \toπ^\pmγ$签名。这样的衰减的特征是孤立的轨道指向大能量矿床，以及大型横向动量的孤立光子。 B Quark喷气式的存在可从浅味夸克和胶子的强发化中降低背景。未观察到w $^\ pm \toπ^\pmγ$衰减。该分支部分设置了上限的限制，对应于95％置信度的1.50 $ \ times $ 10 $^{ - 5} $，而预期的上限限制限制为0.85 $^{+0.52} _ { - 0.29} _ { - 0.29} $ $ $ $ $ \ times $ 10 $^$ 10 $^{ - 5} $。
A search is performed for the rare decay W$^\pm\toπ^\pmγ$ in proton-proton collisions at $\sqrt{s} =$ 13 TeV. Data corresponding to an on W integrated luminosity of 137 fb$^{-1}$ were collected during 2016 to 2018 with the CMS detector. This analysis exploits a novel search strategy based on W boson production in top quark pair events. An inclusive search for the W$^\pm\toπ^\pmγ$ decay is not optimal at the LHC because of the high trigger thresholds. Instead, a trigger selection is exploited in which the W boson originating from one of the top quarks is used to tag the event in a leptonic decay. The W boson emerging from the other top quark is used to search for the W$^\pm\toπ^\pmγ$ signature. Such decays are characterized by an isolated track pointing to a large energy deposit, and by an isolated photon of large transverse momentum. The presence of b quark jets reduces the background from the hadronization of light-flavor quarks and gluons. The W$^\pm\toπ^\pmγ$ decay is not observed. An upper exclusion limit is set to this branching fraction, corresponding to 1.50 $\times$ 10$^{-5}$ at 95% confidence level, whereas the expected upper limit exclusion limit is 0.85 $^{+0.52}_{-0.29}$ $\times$ 10$^{-5}$.
