Event shape engineering of charged hadron spectra in isobar collisions at \sqrt{s_{NN}}= 200 GeV at STAR

Partonic scatterings with high momentum transfer occur before the formation of the quark-gluon plasma (QGP) in heavy-ion (A+A) collisions and result in collimated collections of hadrons called jets. The modification of the high-virtuality parton shower in the QGP compared to that in proton-proton (p+p) collisions offers insight into the nature of the medium's interactions with colored probes. Although the nominal A+A collision species at RHIC is gold (Au) with 197 nucleons, the high-statistics 2018 STAR isobar data from Zr+Zr and Ru+Ru collisions, each with 96 nucleons, consist of events with reduced uncorrelated background, in which the QGP is still expected to be formed. To study the dependence of hard partons traveling through the QGP on the path length within this medium, we use a technique known as event shape engineering. Within a given eccentricity and centrality class, charged hadrons traveling in the event plane direction (having shorter path length) are compared to those traveling perpendicular to it (having longer path length). Fixing the centrality allows for energy density to be controlled for, so that a comparison of the ratio of charged hadron spectra between two eccentricity classes accesses the dependence of energy loss on the collision geometry.