Measurements of Jet Anisotropy in Ru+Ru and Zr+Zr Collisions at $\sqrt{s_{NN}}=200$ GeV at STAR

Tristan Protzman (For the STAR Collaboration)

In ultra-relativistic heavy-ion collisions, hard scattered partons, which form jets, traverse and interact with the Quark-Gluon Plasma (QGP).  Through these interactions, jets lose energy via collisional and radiative processes, known as jet quenching.  The path-length dependence of jet quenching can be studied by measuring $v_2^{\hbox{jet}}$, the second-order Fourier coefficient quantifying the differential jet yield relative to the event plane.  A finite $v_2^{\hbox{jet}}$ is expected in mid-central heavy-ion collisions where a highly ellipsoidal QGP is produced, resulting in jets traversing in-plane interacting with less medium than those out-of-plane.  To remove combinatorial jets that are created by clustering particles from the underlying event, a geometric matching requirement between hard core jets, found using only high transverse momentum ($p_T$) tracks, and jets found including also low-$p_T$ constituents is utilized.  The sensitivity of this method to the details of jet fragmentation is studied, and results of $v_{2}^{\hbox{jet}}$ in Ru+Ru and Zr+Zr collisions at $\sqrt{s_{NN}}=200\hbox{ GeV}$ with the STAR experiment will be shown, spanning multiple jet resolutions.  Such measurements in medium-sized collision systems such as Ru+Ru and Zr+Zr can help distinguish between competing models and bridge the gap between smaller $p$+A and larger A+A systems.