Measurements of multi-jet cross-section ratios are presented.
The measured quantities are the ratio of the four-jet and three-jet
cross-sections and the ratio of the four-jet and two-jet cross-sections.
The data were collected with the ATLAS detector in proton-proton
collisions at a center of mass energy of 13 TeV during 2015-2018.
The results are presented as a function of the transverse...
The cross-sections of prompt and non-prompt production of $J/\psi+W^{\pm}$ are being measured by the ATLAS Collaboration using the $139~\textrm{fb}^{-1}$ Run II 13 TeV $pp$ collision data set. The prompt production of $J/\psi$ associated with a $W^{\pm}$, where both particles are produced in a single parton-parton interaction, provides constraints on models of non-relativistic QCD, especially...
Measurements of the production rate of Z bosons in association with heavy quarks provide sensitive tests of perturbative quantum chromodynamics (pQCD) predictions, which are made at next-to-leading-order (NLO) accuracy using either a 4-flavor number scheme (4FNS) or 5-flavor number scheme (5FNS). In the 4FNS, b-quarks are not present in the parton distribution functions (PDFs) and only appear...
