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LHC constraints on scalar leptoquark models explaining lepton flavor violation in RD(∗)Author: Swapnil Raz Date: 2020-05-21 Report no: IIIT/TH/2020/36 Advisor:Subhadip Mitra AbstractIn this thesis, we investigate the competency of LHC data to constrain the RD(∗) favored parameter space in a charged scalar leptoquark (S1 ) model. We consider some scenarios with one large free coupling to accomodate the RD(∗) annomalies. As a result, some of them dominantly yield nonresonant ττ and τν events at the LHC through the t-channel S1 exchange. So far, no experiment has searched for leptoquarks using these signatures and the relevant resonant leptoquark searches are yet to put any strong exclusion limit on the parameter space. We recast the latest ττ and τν resonance search data to obtain new exclusion limits. The nonresonant processes strongly interfere (destructively in our case) with the Standard Model background and play the determining role in setting the exclusion limits. To obtain precise limits, we include non-negligible effects coming from the subdominant (resonant) pair and inclusive single leptoquark productions systematically in our analysis. To deal with large destructive interference, we make use of the transverse mass distributions from the experiments in our statistical analysis. In addition, we also recast the relevant direct search results to obtain the most stringent collider bounds on these scenarios to date. These are independent bounds and are competitive to other known bounds. Finally, we indicate how one can adopt these bounds to a wide class of models with S1 that are proposed to accommodate the RD(∗) anomalies. In the first chapter, we study the subject of high energy physics with a brief introduction to the Standard Model and some cases which it cannot explain. In the second chapter, we look at the experimentation involved at the LHC, majorly at the ATLAS and CMS experiments there. In the next chapter, we introduce leptoquarks and describe its productions. In the fourth chapter, we look at the anomalies which exist in B physics. The next few chapters deals with analysis of our study. In chapter eight, we present the results of the study. We finish with the summary and conclusions of our study in chapter nine. Full thesis: pdf Centre for Computational Natural Sciences and Bioinformatics |
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