Jet-Flow Tomography from Photon-Jet Acoplanarities*

Using a recently-derived theoretical framework to describe the coupling of jets to the velocity distribution in a nuclear medium, we consider the implications for photon-jet acoplanarities in heavy-ion collisions.  For a jet propagating in a large uniform slab of plasma, we find that the jet is deflected towards alignment parallel to the direction of the velocity, with the magnitude and direction of the jet deflection carrying significant information about the velocity field.  We show that the pattern of angular deflection carries sufficient information to reconstruct both the direction and the magnitude of the velocity.  In addition, we find that the time dependence of the deflection along the jet trajectory is also sensitive to the magnitude of the velocity.  When applied to the elliptical geometries produced in non-central heavy-ion collisions, this leads to a strong coupling of the photon-jet acoplanarity to the elliptic flow of the plasma itself, and we propose measurements at sPHENIX which may be able to confirm these predictions.