Comparison of fragmentation functions for light-quark- and gluon-dominated jets from $pp$ and Pb+Pb collisions in ATLAS

Understand

Charged-particle fragmentation functions for jets azimuthally balanced by a high-transverse-momentum, prompt, isolated photon are measured in $25$ pb$^{-1}$ of $pp$ and $0.49$ nb$^{-1}$ of Pb+Pb collision data at $5.02$ TeV per nucleon pair recorded with the ATLAS detector at the Large Hadron Collider.

• The measurements are compared to predictions of Monte Carlo generators and to measurements of inclusively selected jets.
• In $pp$ collisions, a different jet fragmentation function in photon-tagged events from that in inclusive jet events arises from the difference in fragmentation between light quarks and gluons.
• The ratios of the fragmentation functions in Pb+Pb events to that in $pp$ events are used to explore the parton color-charge dependence of jet quenching in the hot medium.