Jet and Di-jet Underlying Event in p+Au Collisions at $\sqrt{s_{NN}}$ = 200 GeV at STAR

Proton-ion collisions have been included in runs at the LHC and RHIC in addition to proton-proton and heavy-ion collisions as a means of studying cold nuclear matter (CNM) effects. These asymmetric systems have yielded some unexpected trends, notably in measurements of jet nuclear modification factors at different centralities. Detectors at forward/backward rapidity have been used to measure quantities as a proxy for centrality or event activity (EA) in p+Au collisions in order to avoid auto-correlations resulting from EA and physical observables both being measured at mid-rapidity. In this talk, we show correlations of backward-rapidity (Au-going) event activity with mid-rapidity underlying event (UE) in p+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV measured with the STAR detector. We present UE measurements and show the trends of UE in relation to EA for high-transverse momentum ($p_{\mathrm{T}}$) jet events vs. di-jet events. Additionally, we will study collision kinematics via observables including jet pseudorapidity ($\eta$) and jet $p_{\mathrm{T}}$ as a means of investigating the initial hard scatterings of partons in these events.