Baryon-to-Meson Ratios in Jets from Au+Au and p+p Collisions at 200 GeV

Experimental results from RHIC and the LHC reveal a significant enhancement in baryon-to-meson yield ratios at intermediate $p_{\rm{T}}$ in high-energy nuclear collisions relative to $p$+$p$ collisions. Strong hydrodynamic expansion and parton recombination within the QGP are believed to be responsible for this enhancement. Jets have served as powerful probes of QGP properties, with numerous measurements revealing significant modifications to jet yields and internal structure. LHC measurements reveal that, despite observable medium effects on jet fragmentation, the baryon-to-meson ratios within jets remain consistent with $p$+$p$ values and are distinct from those of the surrounding QGP. We probe this behavior at RHIC by applying time-of-flight and TPC $dE/dx$-based particle identification in conjunction with jet-track correlation analysis to extract in-jet particle ratios for $p_{\rm{T}} < 5.0$ GeV/$c$. This work reports the first observation of in-cone baryon-to-meson yield ratios for fully reconstructed jets in both $p$+$p$ and Au+Au collisions at $\sqrt{s_{\mathrm{NN}}} = 200$ GeV, based on STAR data at RHIC. The in-jet ratios show little variation between Au+Au and $p$+$p$ collisions in the examined kinematic regime, contrasting with the pronounced differences seen in inclusive particle ratios.