Abstract
Jet substructure observables have significantly extended the search program for physics beyond the standard model at the Large Hadron Collider. The state-of-the-art tools have been motivated by theoretical calculations, but there has never been a direct comparison between data and calculations of jet substructure observables that are accurate beyond leading-logarithm approximation. Such observables are significant not only for probing the collinear regime of QCD that is largely unexplored at a hadron collider, but also for improving the understanding of jet substructure properties that are used in many studies at the Large Hadron Collider. This Letter documents a measurement of the first jet substructure quantity at a hadron collider to be calculated at next-to-next-to-leading-logarithm accuracy. The normalized, differential cross section is measured as a function of log_{10}ρ^{2}, where ρ is the ratio of the soft-drop mass to the ungroomed jet transverse momentum. This quantity is measured in dijet events from 32.9 fb^{-1} of sqrt[s]=13 TeV proton-proton collisions recorded by the ATLAS detector. The data are unfolded to correct for detector effects and compared to precise QCD calculations and leading-logarithm particle-level MonteCarlo simulations.
Highlights
The dynamics of strong interactions, described by quantum chromodynamics (QCD), are responsible for most of the physical processes occurring in proton-proton scattering at the Large Hadron Collider (LHC)
Prior to this work, there has never been a direct comparison between collision data and calculations beyond the leading-logarithm (LL) accuracy of parton shower (PS) Monte Carlo (MC) programs [9]
The comparisons presented here begin the field of precision jet substructure, wherein data and calculations in the collinear regime of QCD can be used to test the modeling of final state radiation and maybe even extract fundamental parameters of the SM such as the strong coupling constant or the top quark mass [10]
Summary
The comparisons presented here begin the field of precision jet substructure, wherein data and calculations in the collinear regime of QCD can be used to test the modeling of final state radiation and maybe even extract fundamental parameters of the SM such as the strong coupling constant or the top quark mass [10]. The soft-drop procedure acts on the clustering history of a sequential recombination jet algorithm [19]. MaTsshiussiLnegtt3e2r .p9refbse−n1tosfapmffisffie1⁄4asu1r3emTeeVnt of pp the soft-drop jet data collected in 2016 by the ATLAS detector, and the first comparison to predictions of jet substructure that are formally more accurate than the LL PS approximation.
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