Andrew Tamis

Hard-scattered partons ejected from high-energy proton-proton collisions undergo parton shower and hadronization, resulting in collimated collections of particles that are clustered into jets. An observable that highlights the transition between the perturbative and non-perturbative regimes of jet evolution in terms of the angle between two particles is the two-point energy correlator (EEC). In this thesis, the first measurement of the EEC at RHIC is presented, using data taken by the STAR experiment from p+p collisions with a center of mass energy of 200GeV. These measurements demonstrate that the transition between perturbative and non-perturbative effects occurs within an angular region that is consistent with expectations of a universal hadronization regime that scales with jet momentum for a given initiator flavor. Additionally, a deviation from Monte-Carlo predictions at small angles observed when selecting on particle charge could result from mechanics of hadronization not fully captured by current models. This observable can also be measured in heavy-ion collisions, where the quark-gluon plasma has been seen to quench jets and modify their substructure. Therefore, an extension of energy correlators into a heavy-ion environment can potentially isolate these modifications to identifiable angular scales, including the onset of effects such as color coherence and the medium wake. These measurements necessitate subtraction of both background-background and background-signal correlations via a novel background subtraction technique, which will be defined and demonstrated.