Jet substructure measurements and precision measurements of multijet production with the ATLAS experiment

Jets, the collimated streams of hadrons resulting from the fragmentation of highly energetic quarks and gluons, are some of the most commonly observed radiation patterns in hadron collider experiments. The distribution of Quantum Chromodynamics radiation within jets is determined by complex processes, the production of showers of quarks and gluons and their subsequent recombination into hadrons. In this talk, two recent measurements of the jet substructure from the ATLAS experiment at the Large Hadron Collider are presented. The first concerns the measurements of the differential cross-section of Lund subjet multiplicities. The second measurement introduces new event-shape jet observables defined in terms of reference geometries with cylindrical and circular symmetries using the energy mover’s distance.