UBC Theses and Dissertations
Effective field theory interpretation of tt̅ lepton+jets differential cross-section Mukherjee, Shourya
Since 2012, the Large Hadron Collider (LHC) has not found any deviation from the Standard Model (SM) to be statistically significant, although it has been collecting a huge amount of data. This motivates us to use the framework of Effective Field Theories (EFTs) to perform model-independent searches to characterize all the deviations from SM predictions systematically, order by order, in an EFT expansion. Top physics is one such area of interest as it is highly prone to Beyond the Standard Model (BSM) effects, and the LHC is reaching a precision era with tops. In this thesis, we first generate ATLAS-wide common Monte Carlo (MC) EFT samples for our analysis but also to be used by the collaboration for global EFT combinations across Electroweak, Higgs and Top physics. In our analysis here, we reinterpret the top-pair production differential cross-section measurements to constrain the coefficients of dimension-6 operators. Specifically, we use the differential cross sections data for top-quark pair production in pp collisions, measured at √s = 13 TeV with the ATLAS detector at the LHC using an integrated luminosity of 139fb⁻¹, to constrain fourteen four-quark operators and three bosonic operators affecting the top-gluon and gluon-gluon interactions at the particle level. All limits are in accordance with SM predictions and are found to be more stringent than the known theory bounds.
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