Neutral pion production in $\sqrt{s_{NN}}$=200 GeV Cu+Au collisions at PHENIX

Cu+Au collisions at RHIC generate asymmetric initial geometries and densities in both azimuth and rapidity. High p_T π⁰s produced in $\sqrt{s_{NN}}$ = 200 GeV Cu+Au collisions provide new environments to study parton energy loss in the Quark Gluon Plasma, including very central events where the Cu nucleus is enveloped by the Au nucleus. By measuring π⁰ yields in ϕ relative to the event plane, we can probe different core-corona regions in these very central events and study the path length dependence of energy loss in various lopsided initial geometries. PHENIX has observed the suppression of π⁰s as a function of the azimuthal angle with respect to the event plane in $\sqrt{s_{NN}}$ = 200 GeV Au+Au collisions and found it consistent with a larger than quadratic path length dependence suggesting a non-perturbative energy loss model applies. The unique collision geometries available in Cu+Au provide new settings to explore and possibly confirm this path length dependence. The status of the Cu+Au π⁰ analysis is presented. (paper)