2025/04/07 by ATLAS Collaboration · 2 citations
#FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #Nuclear Experiment (nucl-ex)
paper · doi:10.48550/arxiv.2504.04805
Measurements of jet substructure in Pb+Pb collisions provide key insights into the mechanism of jet quenching in the hot and dense QCD medium created in these collisions. This Letter presents a measurement of the suppression of large-radius jets with a radius parameter of R = 1.0 and its dependence on the jet substructure. The measurement uses 1.72 nb-1 of Pb+Pb data and 255 pb-1 of pp data, both at √sNN = 5.02 TeV, recorded with the ATLAS detector at the Large Hadron Collider. Large-radius jets are reconstructed by reclustering R = 0.2 calorimetric jets and are measured for transverse momentum above 200 GeV. Jet substructure is evaluated using charged-particle tracks, and the overall level of jet suppression is quantified using the jet nuclear modification factor (RAA). The jet RAA is measured as a function of jet pT, the charged kt splitting scale (√d12), and the angular separation (dR12) of two leading sub-jets. The jet RAA gradually decreases with increasing √d12, implying significantly stronger suppression of large-radius jets with larger kt splitting scale. The jet RAA gradually decreases for dR12 in the range 0.01-0.2 and then remains consistent with a constant for dR12 \gtrsim 0.2. The observed significant dependence of jet suppression on the jet substructure will provide new insights into its role in the quenching process.