Measurements of tt¯ differential cross sections in proton-proton collisions at √s = 13 TeV using events containing two leptons

• Autor(a) principal: Sirunyan, A. M.
• Data de Publicação: 2019
• Outros Autores: Silveira, Gustavo Gil da, CMS Collaboration
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UFRGS
• Texto Completo: http://hdl.handle.net/10183/194767
• topic: Aceleradores de partículas; Colisões proton-proton; Quarks; Hadron-Hadron scattering (experiments); Top physics

Measurements of di erential top quark pair tt cross sections using events produced in proton-proton collisions at a centre-of-mass energy of 13TeV containing two oppositely charged leptons are presented. The data were recorded by the CMS experiment at the CERN LHC in 2016 and correspond to an integrated luminosity of 35.9 fb1. The di erential cross sections are presented as functions of kinematic observables of the top quarks and their decay products, the tt system, and the total number of jets in the event. The di erential cross sections are de ned both with particle-level objects in a ducial phase space close to that of the detector acceptance and with parton-level top quarks in the full phase space. All results are compared with standard model predictions from Monte Carlo simulations with next-to-leading-order (NLO) accuracy in quantum chromodynamics (QCD) at matrix-element level interfaced to parton-shower simulations. Where possible, parton-level results are compared to calculations with beyond-NLO precision in QCD. Signi cant disagreement is observed between data and all predictions for several observables. The measurements are used to constrain the top quark chromomagnetic dipole moment in an e ective eld theory framework at NLO in QCD and to extract tt and leptonic charge asymmetries.