Jet Fragmentation in Vacuum and Medium with gamma-hadron Correlations in PHENIX

TL;DR

This paper investigates jet fragmentation in proton-proton and gold-gold collisions using gamma-hadron correlations, revealing insights into quark jet behavior and medium effects in high-energy nuclear collisions.

Contribution

It introduces a method to study jet fragmentation via gamma-hadron correlations and compares results with pQCD calculations, enhancing understanding of medium modifications.

Findings

Charged hadron yields are modified in Au+Au collisions.

Data aligns with quark jet fragmentation expectations.

The analysis supports the use of isolated direct photons for jet studies.

Abstract

Jet fragmentation in p+p and Au+Au collisions is studied via back-to-back correlations of direct photons and charged hadrons. The direct photon correlations are obtained by statical subtraction of the background from decay photons. Results on the nuclear modification to the associated charged hadron yields are reviewed. Further studies of jet fragmentation in p+p using isolated direct photons are also presented. A kT-smeared LO pQCD calculation is used to interpret the data. The sensitivity of the data to the underlying fragmentation function is tested and the results are found to be compatible with expectations of a sample dominated by quark jet fragmentation.