Many groups of scientists studying jets at RHIC have focused on a phenomenon known as jet quenching, an apparent suppression of energetic jets emerging from the QGP. The idea is that jets are losing energy through their interactions with the QGP.

RHIC’s measurements of jet quenching to date have focused primarily on the most energetic, leading jet particles, because they are straightforward to measure. However, such leading particles provide only limited insight into the process. The new results from STAR reconstruct a wider correlated spray of particles making up the jets, revealing much more detail about how the QGP is “excited” and responds to the jet — and where the “lost” energy goes.

The new analysis, for the first time, included the reconstruction of jets produced back-to-back with photons.