11th Asian Triangle Heavy-Ion Conference

Semi-inclusive jet mass measurements in Zr+Zr and Ru+Ru collisions at $\sqrt{s_{\text{NN}}} = 200$ GeV with STAR

8 Nov 2026, 09:00

13m

Versailles Room, 2nd Floor, Building 1

Oral Presentation Jets and medium response Parallel 4

Speaker

Jeongmyung Kang (Sejong university)

Description

In relativistic heavy-ion collisions, jet substructure observables provide unique access to the interactions between energetic partons and the hot, dense QCD medium known as the Quark–Gluon Plasma (QGP). Among them, the jet invariant mass ($M_{\mathrm{jet}}$) is particularly sensitive to parton virtuality evolution and the pattern of final-state radiation. However, measurements of jets with low jet transverse momentum ($p_{\mathrm{T,jet}}$) are significantly limited due to the large combinatorial background originating from the underlying events of heavy-ion collisions. To address this challenge, we employ the semi-inclusive approach by analyzing jets recoiling from a high-$p_{\mathrm{T}}$ trigger hadron ($7 In this talk, we present semi-inclusive $M_{\mathrm{jet}}^2$ distributions in Zr+Zr and Ru+Ru collisions at $\sqrt{s_{\mathrm{NN}}}=200$ GeV measured with the STAR detector, and introduce a novel 2-dimensional semi-inclusive methodology as a function of $(p_{\text{T,jet}}, M_{\text{jet}}^2)$. Jets are reconstructed using the anti-$k_{\mathrm{T}}$ algorithm with jet resolution parameters ($R=0.2$ and $0.4$), and are selected in the recoil region ($|\pi-\Delta\phi|<\pi/4$) with respect to the trigger hadron. The comparison of the fully corrected $M_{\mathrm{jet}}^2$ distributions between the 0--10\% and 60--80\% centrality classes is performed to investigate modifications to the peak position and shape of the $M_{\mathrm{jet}}^2$ distributions. Such modifications serve as sensitive probes of medium-induced modifications to parton virtuality evolution.