- By:
- Bock, Friederike ; Schmidt, Nicolas V; Read Jr, Kenneth F; Jonas, Florian; Novitzky, Norbert ; Schambach, Joachim J; Fasel, Markus ; Poghosyan, Martin ; Loizides, Constantinos A; Glimos, Ewa ; Cormier, Thomas M
- Journal Name:
- Physical Review C
- Page Number:
- 44905-44905
- Volume:
- 113
- Issue Number:
- 4
- Publication Date:
- June 10, 2026
- View DOI Listing:
- https://doi.org/10.1103/5bdl-cry6
Abstract
This paper presents the first measurement of the angle between different jet axes (denoted as Δ𝑅axis) in Pb-Pb collisions. The measurement is carried out in the 0–10 % most-central events at √𝑠𝑁𝑁=5.02 TeV. Jets are assembled by clustering charged particles at midrapidity using the anti-𝑘T algorithm with resolution parameters 𝑅=0.2 and 0.4 and transverse momenta in the intervals 40<𝑝chjet T<140GeV/𝑐 and 80<𝑝chjet T<140GeV/𝑐, respectively. Measurements at these low transverse momenta enhance the sensitivity to quark-gluon plasma (QGP) effects. A comparison to models implementing various mechanisms of jet energy loss in the QGP suggests that the observed narrowing of the Pb-Pb distribution relative to 𝑝𝑝 can be explained if quark-initiated jets are more likely to emerge from the medium than gluon-initiated jets. These new measurements disfavor intrajet 𝑝T broadening as implemented in a simple model calculation with the Baier-Dokshitzer-Mueller-Peigne-Schiff formalism for energy loss in the QGP. The comparison of Pb-Pb and 𝑝𝑝 collisions shows sensitivity to the angular scale at which the QGP can resolve two independent splittings, favoring mechanisms that incorporate incoherent energy loss.
