Searching for Exclusive W decays in ttbar events using the ATLAS detector at the Large Hadron Collider

标准模型预测了W玻色子的独有强子衰变，但从未观测到。根据衰变模式的不同，预期的分枝比例可能高达百万分之一。这个项目的目的是利用大型强子对撞机第二次实验中可获得的1亿个顶夸克对产生事件的大样本来寻找这种衰变，以及第三次实验中新的类似大小的数据集。每个顶夸克衰变到一个底部夸克和W玻色子。然后，通过要求一个W玻色子衰变到带电的轻子和中微子，然后研究另一个W玻色子的衰变，可以寻找独有的W衰变事件。要研究的衰变模式的准确选择将在博士期间确定，但初始候选衰变是：i)W+-&GT；Rho_0+pi+/Rho+，ii)W+-&gt；D_S+伽马，iii)W-+&gt；D0pi+/Rho+，iv)W+-&gt；D_S+J/Psi。除了对ttbar数据集的分析外，作为该博士项目的一部分，计划研究和开发用于直接生产W的排他性衰变的专用触发器。如果部署成功，与顶夸克对生产数据集相比，这些可能潜在地将W玻色子的可搜索样本提高两个数量级。

Exclusive hadronic decays of the W-boson are predicted by the Standard Model but have never been observed. Depending on the decay mode, the expected branching fractions could be as high as 1 per million. This project aims to exploit the large sample of > 100 million top-quark-pair production events available from Run 2 of the LHC to search for such decays, as well as new similarly sized datasets from Run 3. Each top quark decays to a bottom quark and W-boson. Exclusive W decay events can then be searched for by requiring that one W Boson decays to a charged lepton and neutrino and then studying the decay of the other W boson. The precise selection of which decay modes to study will be determined during the Ph.D, but initial candidate decays are: i) W+-> rho_0 + pi+/rho+, ii) W+-> D_s + gamma , iii) W-+> D0 pi+/rho+, iv) W+ -> D_s + J/Psi . In addition to analysis of ttbar datasets, it is planned to study and develop dedicated triggers for exclusive decays in direct W production as part of this Ph.D. project. If successfully deployed these could potentially enhance the searchable sample of W bosons by two orders of magnitude compared to the top-quark pair production dataset.