Top-Quarks under the LHC's Magnifying Glass: From Process Modelling to Parameter Extraction

• Applicant: Professorin Dr. Malgorzata Worek
• Subject Area: Nuclear and Elementary Particle Physics, Quantum Mechanics, Relativity, Fields
• Term: from 2016 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 321941428

• Final Report Year: 2020

Final Report Abstract

In this research project state-of-the-art NLO and NNLO theoretical predictions have been provided for tt, ttj, tt and ttZ(Z ! ``) processes for the LHC Run II centre of mass system energy of ps = 13 TeV. In each case di-lepton top quark decay channel has been employed and either NNLO QCD (for the tt process) or NLO QCD corrections (for the following processes ttj; tt; ttZ(Z ! ``)) have been incorporated both in the production and top quark decays. As it is common for such studies, we presented results for both integrated and differential cross sections for a few renormalisation and factorisation scale choices and for various parton distribution functions. Overall, our theoretical high precision results increased the SM prediction, significantly decreased the dominant scale uncertainty and improved the agreement with data. In many cases already with the fairly inclusive cut selection non-at dierential K-factors have been obtained for various observables that are relevant for new physics searches. Taking into account that good theoretical control over the SM background is a fundamental prerequisite for a correct interpretation of possible signals of new physics our precise theoretical predictions are simply indispensable. All our NLO and NNLO theoretical results are available either as Ntuple les or are are stored in special repository. They might be directly used for experimental analyse at the LHC as well as for obtaining accurate SM predictions in BSM studies. In many cases they have already shown huge impact on the analysis of the LHC data. We shall continue collaboration with experimental colleagues from ATLAS and CMS experiments to improve our understanding of top quark physics With the large amount of top quarks produced at pp collisions at the LHC with ps = 13 TeV and with future runs with ps = 14 TeV more and more exclusive nal states will be more precisely measured. Consequently, they will be compared with the high precision theoretical predictions. Any deviations from the SM might show us the path to possible extensions of the SM.

Publications

• Off-shell Top Quarks with One Jet at the LHC: A comprehensive analysis at NLO QCD. JHEP 1611 (2016) 098
  G. Bevilacqua, H. B. Hartanto, M. Kraus, M. Worek
  
• Off-shell ttj production and top quark mass studies at the LHC Acta Phys. Polon. B48 (2017) 2251. Proceedings of the XLI International Conference of Theoretical Physics: Matter To The Deepest, 3 − 8 September 2017, Podlesice, Poland
  G. Bevilacqua, H. B. Hartanto, M. Kraus, M. Schulze, M. Worek
  
• Hard Photons in Hadroproduction of Top Quarks with Realistic Final States. JHEP 1810 (2018) 158
  G. Bevilacqua, H. B. Hartanto, M. Kraus, T. Weber, M. Worek
  
• Top quark mass studies with ttj at the LHC. JHEP 1803 (2018) 169
  G. Bevilacqua, H. B. Hartanto, M. Kraus, M. Schulze, M. Worek
  
• Higher order corrections to spin correlations in top quark pair production at the LHC. Phys. Rev. Lett. 123 (2019) no.8, 082001
  A. Behring, M. Czakon, A. Mitov, A. S. Papanastasiou, R. Poncelet
  
• Precise predictions for ttγ/tt cross section ratios at the LHC. JHEP 1901 (2019) 188
  G. Bevilacqua, H. B. Hartanto, M. Kraus, T. Weber, M. Worek
  
• Towards constraining Dark Matter at the LHC: Higher order QCD predictions for tt¯ + Z (Z → νℓv¯ℓ). JHEP 1911 (2019) 001
  G. Bevilacqua, H. B. Hartanto, M. Kraus, T. Weber, M. Worek