Title: Condensed matter physics at the nuclear scale: probing the Quark-Gluon Plasma with jets

 

Abstract: A common theme in many-body physics is that of “emergence:” systems comprising many elementary quanta exhibit collective phenomena that cannot be predicted from the elementary interactions themselves. The Quark-Gluon Plasma (QGP), a hot fireball of quarks and gluons which is generated in collisions of heavy nuclei at the world’s most energetic accelerators, exhibits such complex emergent phenomena at the nuclear scale. How can we probe the QGP and study its structure, to understand how it works? A scattering experiment using a controlled external beam would be ideal, but is unachievable. Instead we utilize “jets,” which are the hadronic remnants of rare, hard-scattered quarks and gluons generated in the same collision as the QGP, as an internally-generated probe beam. I will describe recent measurements by the STAR experiment at RHIC and the ALICE experiment at the LHC which seek to observe Rutherford-like scattering of such jets off of quasi-particles in the QGP, and what these measurements tell us about QGP dynamics and structure. I will briefly touch on the larger program for comprehensive understanding of the QGP by the JETSCAPE Collaboration, and some of the key open questions in the field that will be addressed in the coming years.