Measurement of the cross-section ratio of four-jet production over three-jet production in the ATLAS experiment*

Measurements of multi-jet cross-section ratios are presented. The data were collected with the ATLAS detector in proton-proton collisions at a center of mass energy of 13.6 TeV during 2015-2018 (Run 2) at the Large Hadron Collider. 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 results are presented as a function of the jet transverse momentum. Predictions from different Monte Carlo event generators are compared to the data. The values of the strong coupling constant are extracted from the jets cross-sections ratios.