Colloquium – Ron Belmont

Ron Belmont, University of North Carolina- Greensboro

Creating droplets of the early universe in the laboratory with nuclear collisions

Abstract:The universe today is very sparse and very cold. However, as we turn back the clock, things get hotter and denser. Eventually, things are so hot and so dense that ordinary nuclear matter melts into its constituent quarks and gluons, a state of matter called the quark-gluon plasma (QGP), which existed in the first few microseconds after the Big Bang. Today we can recreate the QGP in the laboratory with high-energy nuclear collisions. The QGP evolves hydrodynamically under its own pressure, which translates its initial shape into the final state angular distribution of produced particles. This experimental fact has been very useful in undertaking a campaign of geometry engineering to check for QGP formation in small asymmetric collision systems (like p/d/3He+Au), which was spectacularly confirmed by the PHENIX Collaboration in a landmark Nature Physics article in 2019. More recent results corroborate the clear geometrical dependence, and also indicate different contributions from intrinsic geometry vs sub-nucleonic fluctuations in different kinematic regions.  Finally, of great interest in the field recently has been small symmetric collisions systems like O+O. Such collisions provide a lot of important additional constraints, for example additional access to nucleonic vs subnucleonic fluctuations. In this talk I will give a pedagogical introduction to high energy nuclear collisions and the role of geometry, discuss the latest and greatest results in small systems, and give a brief outlook for the future.

Bio:

Ron Belmont is an internationally recognized expert in the physics of ultrarelativistic nucleus-nucleus collisions.  By colliding heavy nuclei at relativistic speeds, we create a new phase of matter called the quark-gluon plasma, which is believed to have existed in the very early universe, roughly a few microseconds after the big bang.  Ron is a member of the PHENIX Collaboration, where he is a physics working group convener and a member of the executive council and institutional board.  Ron is also a member of the sPHENIX Collaboration, where he is an institutional board member and one of the experts on the hadronic calorimeter subsystem. Ron received his Bachelor of Science degree from Seton Hall University and received his Master’s degree and PhD from Vanderbilt University.

September 16, 2026 @ 1:00pm (CST) in Commons Center 237

Host: Julia Velkovska