Baryon-to-Meson Ratios in Jets from Au+Au and $p$+$p$ Collisions at $\sqrt{s_{\mathrm{NN}}} = 200$ GeV

Abstract

Jet probes have been used extensively to gain insights into QGP properties, with substantial modifications to jet yields and internal structures seen across multiple measurements, compared against $p$+$p$ results. Despite apparent medium-induced changes to jet fragmentation patterns and strong modifications of particle production at intermediate momenta ($2.0 < p_{\rm{T}} < 5.0$ GeV/$c$) in heavy ion collisions, RHIC hadron-hadron correlation results indicate that jet-related baryon-to-meson ratios remain similar to those of $p$+$p$ measurements and are significantly different from those of the QGP bulk. To look for possible medium effects on jet fragments at RHIC, we employ jet-track correlation and particle identification to perform the first measurement of in-jet proton-to-pion yield ratios for charged-hadrons with $2.0 < p_{\rm{T}} < 5.0$ GeV/$c$. We present the first in-cone (within a radial distance of $R$ from the determined jet axis direction) baryon-to-meson yield ratios associated with reconstructed charged-particle jets from Au+Au and $p$+$p$ collisions at $\sqrt{s_{\mathrm{NN}}} = 200$ GeV using the STAR detector at RHIC. The measured in-jet ratios are found to be consistent within uncertainties between the two systems for the selected kinematic regime, despite significant differences between inclusive ratios for the same systems.