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| Home > Publications database > Towards global interpretation of LHC data: SM and EFT couplings from jet and top quark measurements at CMS |
| Book/Dissertation / PhD Thesis | PUBDB-2022-04804 |
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2022
Verlag Deutsches Elektronen-Synchrotron DESY
Hamburg
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Please use a persistent id in citations: doi:10.3204/PUBDB-2022-04804
Report No.: DESY-THESIS-2022-017
Abstract: This thesis presents the first global interpretation of the measurements of doubledifferentialcross sections of inclusive jet and top quark-antiquark pair (tt) productionin proton-proton collisions at the Large Hadron Collider (LHC) at the center ofmass energy of √s = 13TeV, together with inclusive measurements in Deep Inelasticelectron-proton Scattering (DIS) at HERA. The LHC data have been recordedby the Compact Muon Solenoid (CMS) experiment in 2016, and correspond to theintegrated luminosity of 33.5 fb−1 for inclusive jet measurement or 35.9 fb−1 for the ttmeasurement.This novel analysis is performed at next-to-leading order (NLO) of perturbative quantumchromodynamics (QCD), where the inclusive neutral and charged current DISmeasurements at HERA, the CMS jet measurements and the normalized triple-differentialcross sections of tt production are used together to constrain the parametersof QCD and impose constraints on new physics. In particular, the StandardModel Lagrangian is extended to incorporate effective contributions from quark contactinteractions (CI). In this analysis, the constraints on the parton distributions,the strong coupling constant αS(mZ) and the top quark pole mass mpolet are obtainedand, simultaneously, limits on the scale Λ of the CI are imposed. This results inαS(mZ) = 0.1188±0.0031, mpolet = 170.4±0.7GeV and the 95% confidence level limitsof Λ > 24TeV for purely left-handed, Λ > 32TeV for vector-like and Λ > 31TeVfor axial vector-like exchanges. For the first time, the LHC data are used for extractingthe Wilson coefficient of the CI, unbiased from the assumptions on the StandardModel parameters.The jet and top quark production at the LHC are further investigated individually,to determine the QCD parameters at highest precision. A Standard Model analysisis performed at next-to-next-to-leading order (NNLO) of perturbative QCD usingthe CMS jet cross section measurements together with the HERA DIS data. Theparton distribution functions in the proton are extracted simultaneously with thestrong coupling constant αS(mZ) = 0.1166 ± 0.0017. This the most precise singlemeasurement of the strong coupling constant at the LHC, to date.Further, the CMS measurements of the tt cross sections are used to extract the topquark mass in the MSR renormalisation scheme. In this scheme, the mass dependencevin the difference of the pole and modified minimal subtraction (MS) masses is replacedby a scale parameter R. The first study of the behaviour of the R scale is presented.The exctracted top quark MSR mass obtained using CMS measurements results inmMSRnt (R = 80GeV) = 169.3+0.6−0.7 GeV, which is up to now the most precise value ofthe top quark MSRn mass extracted from experimental data.The presented investigations of the fundamental couplings of the Standard Model, andof new physics, are at the edge of precision in experimental physics and high-energyphenomenology, paving the road towards a global interpretation of LHC data.
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