Jets serve as an important tool to probe QCD both in the vacuum and in the hot and dense medium. The STAR experiment at RHIC plays a key role in studying QCD phenomena across different collision systems (p+p, p+A, A+A), offering access to a kinematic regime that complements that of the LHC. Building on recent jet and event activity studies at STAR, we present recent measurements on charged-particle jets at s₍₍~=~200 GeV. In p+Au collisions, we explore event activity (EA) measured in the Au-going direction and its correlation with particle production at mid-rapidity. While soft particle production increases with EA, high-pₓ jets are found to be inversely related to EA. Ratios of pₓ imbalance and azimuthal dijet separation between high- and low-EA events show no significant differences, suggesting no strong evidence of jet quenching in high-EA p+Au collisions. In Au+Au collisions, we report semi-inclusive measurements of jets recoiling from γ and π⁰ triggers, using mixed-event techniques to subtract background and study jet suppression, intra-jet broadening, and acoplanarity. Additionally, we present inclusive charged-particle jet spectra corrected for background fluctuations, extending the kinematic reach of previous measurements. These results provide crucial insight into the modification of jets in the medium and contribute to a deeper understanding of QCD in heavy-ion collisions.
M. Svoboda (Thu,) studied this question.