Measurement of jet-axis differences in pp and PbPb collisions with ALICE

Jets are a powerful tool to study quantum chromodynamics (QCD) and can be used to study the physical properties of quark-gluon plasma (QGP) created in heavy-ion collisions. In this talk, we review recent jet-substructure measurements carried out in ALICE - a systematic study of the opening angle between different jet axes denoted $\Delta R_{\rm axis}$. Studies of $\Delta R_{\rm axis}$ are an attractive experimental strategy since these observables are infrared and collinear safe, sensitive to transverse momentum dependent (TMD) physics and analytically calculable in perturbative QCD (pQCD). In consequence, these measurements in pp collisions can be used to test the universality of the TMD evolution kernel constrained from processes such as semi-inclusive deep-inelastic scattering and Drell-Yan. Moreover, comparisons between distributions obtained in PbPb and pp collisions provide a novel perspective on the relationship between competing effects induced by the QGP such as parton energy loss and intra-jet transverse momentum broadening. The new experimental results are compared to predictions from a selection of event generators and pQCD calculations.