Disappearance of the Mach Cone in heavy ion collisions
  We present an analysis of di-hadron correlations using recently developed methods for background subtraction which allow for higher precision measurements with fewer assumptions about the background. These studies indicate that low momentum jets interacting with the medium do not equilibrate with the medium, but rather that interactions with the medium lead to more subtle increases in their widths and fragmentation functions, consistent with observations from studies of higher momentum fully reconstructed jets. The away-side shape is not consistent with a Mach cone. 
Christine Nattrass, Natasha Sharma, Joel Mazer, Meghan Stuart, Aram   Bejnood
nucl-ex