STAR has previously reported significant transverse momentum imbalance of a specific set of di-jets selected with ``hard cores'', i.e. with a constituent cut of 2 GeV/c. After reclustering these same di-jets with a lower constituent cut of 200 MeV/c, the di-jet balance is restored to the level of pp collisions within the original cone size of R=0.4.
The interpretation of these observations as resulting from tangential bias with restricted in-medium path lengths promised \emph{Jet Geometry Engineering} of jet production vertices through systematic variations of parameters such as centrality, the constituent pT cutoff, and the initial imbalance between the hard cores. We examine the sensitivity of the di-jet imbalance observable to variations in the di-jet definition, and explore the possibility of using Jet Geometry Engineering to study the path length dependence of jet energy loss in the QGP.
