於CMS質心能量十三兆電子伏特下透過雙光子終態尋找頂夸克與希格斯玻色子耦合之變味中性流

Search for top-Higgs flavor changing neutral coupling with H → γγ at √s = 13 TeV in CMS

陳孟呈(Meng-Cheng Chen)

指導教授 ： 陳凱風

國立臺灣大學/理學院/物理學研究所/碩士(2021年)

https://doi.org/10.6342/NTU202101097

摘要

本研究旨在找尋頂夸克和希格斯玻色子之間透過變味中性流的交互作用。所分析的質子對撞資料由緊湊緲子線圈偵測器蒐集於大型強子對撞機 Run 2 期間的 2017 年，質心能量為 13 兆電子伏特，對應之積分光度為 41.5 逆飛靶恩。本研究分析了兩種信號產生機制:於頂夸克成對生成事件中發生之從頂夸克衰變至上夸克(或魅夸克)及希格斯玻色子之異常現象，以及頂夸克及希格斯玻色子透過異常交互作用的成對生成。希格斯玻色子的衰變是藉由雙光子頻道觀測。先前於 8 兆電子伏特的分析並未在資料中發現事件的顯著過剩。本研究延續這項探索，並為頂夸克的變味中性流衰變設下新的衰變比率上限:在 95% 之信心水準下，頂夸克衰變為上夸克之觀測(預期)比率不超過 0.60%(0.28%)，頂夸克衰變為魅夸克之觀測(預期)比率不超過 0.74%(0.35%)。

關鍵字

變味中性流 ； 頂夸克 ； 希格斯玻色子 ； 緊湊緲子線圈 ； 大型強子對撞機

並列摘要

This study searches for the coupling between top quarks and Higgs bosons via flavor changing neutral interaction (FCNH). The analyzed data of proton-proton collision was collected by the Compact Muon Solenoid (CMS) detector in 2017, during Run 2 of the Large Hadron Collider (LHC), at center of mass energy of 13 GeV, corresponding to integrated luminosity of 41.5 / fb. Two different mechanisms of signal production are investigated: anomalous decay of a top quark into a light-flavor quark (up or charm) and a Higgs boson, where the top comes from top-antitop pair production, and the direct production of a top-Higgs pair by the anomalous coupling. The diphoton channel is observed for Higgs decays. The previous 8 TeV result shows no significant excess in data. This analysis continues the study and sets new observed (expected) upper limits on the branching fractions of top FCNH decays: BR(t → uH) < 0.60%(0.28%) and BR(t → cH) < 0.74% (0.35%) at 95% confidence level.

並列關鍵字

FCNH ； top quark ； Higgs boson ； CMS ； LHC

參考文獻

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