Speaker
Description
Within the overwhelming majority of models, light quark and gluon jet quenching in heavy ion collisions is described as resulting predominantly from pQCD-type gluon radiation, but details of the underlying mechanisms differ greatly. One key difference lies in the treatment of the Altarelli-Parisi, AP, splitting functions. While in some models, such as Q-PYTHIA, the splitting functions are directly modified in the medium, this core component remains unchanged in others (e.g. YaJEM). The shared momentum fraction $z_g$ was shown to be a Sudakov-safe measurement of the splitting function [1].
This quantity measures the $p_T$ ratio between the two dominant branches
as determined by the SoftDrop grooming process.
An inclusive measurement of $z_g$ in p+p collisions at top RHIC energy will be presented.
The focus of our Au+Au results will be on a comparative study to p+p
using the specific di-jet selection introduced in our previous momentum imbalance measurement,
i.e. jets geometrically matched to "hard core" jets found using only constituents above 2 GeV/$c$ and with a high tower above 5.5 GeV. Such di-jet pairs were found to be significantly imbalanced with respect to p+p, yet regained balance when all soft constituents were included. Individual examination of the splitting behavior of leading and recoil jet adds a new dimension to this observation, and new input to energy loss models.
[1] A. J. Larkoski, S. Marzani and J. Thaler, Phys. Rev. D 91, 111501 (2015)
| Preferred Track | Jets and High pT Hadrons |
|---|---|
| Collaboration | STAR |
