CERN Accelerating science

This thesis focuses on exploring the properties of the quark-gluon plasma (QGP) through studying jet quenching effects. The work begins to investigate whether there is a jet quenching effect in small systems. Subsequently, we effectively control the complex background in heavy-ion collisions using the hadron-jet correlation method to explore jet quenching over a wide kinematic range and for large-radius jets. Finally, the shape and composition of jets, as well as the hadronization mechanisms of baryons and mesons, are studied through correlations between jets and heavy-flavor hadrons. First, measurements of charged-particle jet yield production in proton-proton collisions at $\sqrt{s}=13$ TeV with ALICE are presented, along with the charge-particle multiplicity dependence of jet yields. The results show better agreement with next-to-leading-order perturbative quantum chromodynamics (NLO pQCD) calculations in the higher transverse momentum range. Additionally, the jet yield was observed to increase with rising charge-particle multiplicity. However, comparisons of jet yields between different multiplicity events and minimum-bias (MB) events reveal that this increase shows a weak dependence on jet transverse momentum and resolution parameters. Next, semi-inclusive recoil jet yields in proton-proton collisions at $\sqrt{s} = 5.02$ TeV are measured using hadron-jet correlations. Recoil jets' transverse momentum and azimuthal angle distributions are compared with various model predictions, showing consistency within uncertainties. By comparing these results with those from central Pb--Pb collisions, we observed, for the first time, an enhancement of jet yields and medium-induced acoplanarity broadening effects simultaneously at low transverse momentum with large radii, as well as suppression effects in higher transverse momentum range. Comparisons of different model calculations with experimental results suggest that medium-induced acoplanarity broadening mechanisms may be related to jet scattering from QGP quasi-particles, medium-induced wake effects, and jet fragmentation. Finally, heavy-flavor quark jets produced in hard scatterings were investigated as probes of the QGP. The feasibility of identifying and tagging charm quark jets was explored, helping to understand heavy-quark energy loss mechanisms and medium properties.