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@PHDTHESIS{Sinha:619072,
      author       = {Sinha, Supriya},
      othercontributors = {Moenig, Klaus and Lohse, Thomas and Hansmann-Menzemer,
                          Stephanie},
      title        = {{E}xtraction of top-{Y}ukawa coupling from $t\bar{t}$
                      cross-section in single-leptonic final state with $\sqrt{s}$
                      = 13{T}e{V} data from the {ATLAS} detector},
      school       = {Humboldt University},
      type         = {Dissertation},
      reportid     = {PUBDB-2024-07359},
      pages        = {185},
      year         = {2024},
      note         = {Dissertation, Humboldt University, 2024},
      abstract     = {In the Standard Model (SM) of particle physics, the
                      interaction of fermions with the Higgs field is referred to
                      as the Yukawa interaction, the strength of which is
                      proportional to the mass of the fermions. The top quark,
                      being the heaviest fermion, exhibits the largest value of
                      the Yukawa coupling strength. Conventionally, the pp→t¯tH
                      process has been extensively used to extract the top-Yukawa
                      coupling. However, this thesis aims to measure the ratio of
                      the top-Yukawa coupling strength over its SM value, i.e.,
                      Yt=gt/gSMt using differential distributions of the t¯t
                      cross-section. This method has an advantage that the
                      obtained Yt is independent of the Higgs coupling to other
                      particles. The analysis is conducted on the single-leptonic
                      decay channel using 2015−2018 data with a centre-of-mass
                      energy of √s=13TeV from the ATLAS detector at the Large
                      Hadron Collider (LHC), corresponding to an integrated
                      luminosity of 140fb−1. The presence of a virtual Higgs
                      boson between the two top quarks modifies the t¯t
                      differential cross-section. The electroweak correction,
                      which is a function of Yt, starts to enter the cross-section
                      at one-loop order. The largest Yt sensitivity is observed in
                      the regions close to the t¯t production threshold energy,
                      i.e., at low t¯t invariant mass (mt¯t) regions. An angular
                      dependence is also observed on the scattering angle of the
                      top quark in the t¯t rest frame, at large mt¯t values.
                      Events are reconstructed with at least four jets in the
                      final state, two of them with a requirement that they
                      originate from a B-hadron decay. An algorithm is devised to
                      specifically reconstruct the mt¯t for each event. A
                      detailed statistical analysis is then conducted, taking into
                      account all relevant backgrounds, whose contribution to the
                      total Monte Carlo prediction is very small. A profile
                      likelihood fit is performed on data using binned mt¯t
                      distributions for different Yt values. Due to a linear
                      dependence of the electroweak corrections on Y2t, the fit is
                      performed with Y2t as the parameter of interest. The
                      analysis is dominated by systematic uncertainties, with the
                      jet energy modelling and resolution uncertainties
                      contributing the most to the resultant error on Y2t. This is
                      followed by theoretical modelling uncertainties on the t¯t
                      sample. The fit results in an expected Y2t of 1.0+1.8−1.7,
                      with the observed Y2t of 2.3+1.8−1.7. An upper limit on Yt
                      at $95\\%$ confidence level is extracted using the obtained
                      Y2t. An observed upper limit of 2.32 on Yt is thus achieved,
                      with the expected upper limit of 2.06. The resulting Yt from
                      this method is less precise, but complementary to the Yt
                      obtained from other measurement methods due to its
                      sensitivity to a heavy Higgs sector.},
      cin          = {ATLAS},
      cid          = {I:(DE-H253)ATLAS-20120731},
      pnm          = {611 - Fundamental Particles and Forces (POF4-611)},
      pid          = {G:(DE-HGF)POF4-611},
      experiment   = {EXP:(DE-H253)LHC-Exp-ATLAS-20150101},
      typ          = {PUB:(DE-HGF)11},
      urn          = {urn:nbn:de:kobv:11-110-18452/33188-0},
      doi          = {10.3204/PUBDB-2024-07359},
      url          = {https://bib-pubdb1.desy.de/record/619072},
}