Measurement of the Lund Jet Plane using charged particles with the ATLAS detector from 13 TeV proton--proton collisions

The prevalence of hadronic jets at the Large Hadron Collider (LHC) requires that a deep understanding of jet formation and structure must be achieved in order to reach the highest levels of experimental and theoretical precision. There have been many measurements of jet substructure at the LHC and previous colliders, but the targeted observables mix physical effects from various origins. Based on a new proposal to factorize physical effects, this note presents a double-differential cross section measurement of the Lund jet plane using 139 fb$^{-1}$ of $\sqrt{s}=$13 TeV $pp$ data collected with the ATLAS detector. The measurement uses charged particles to achieve a fine angular resolution and is corrected for acceptance and detector effects. Several parton shower Monte Carlo models are compared with the data. Multiple parton shower Monte Carlo simulations are compared with data to study the modeling of various physical effects across the plane.