ASP Online Seminars: QCD Equation of State with a Critical Point

by Micheal Kahangirwe (Kent State University, USA)

Tuesday 20 Jan 2026, 13:00 → 14:30 UTC

Abstract:

Understanding the phase structure of Quantum Chromodynamics (QCD) at finite baryon density is essential for describing strongly interacting matter in environments ranging from heavy-ion collisions to neutron-star interiors. QCD predicts a transition from hadronic matter to a deconfined quark-gluon plasma, which is created experimentally at RHIC and the LHC. While lattice QCD calculations show that this transition is a smooth crossover at zero baryon density, the nature of the transition at finite density particularly the existence and location of a critical point remains uncertain due to the sign problem in lattice simulations. In this talk, I present a lattice-informed extrapolation framework that extends standard Taylor-expansion methods to construct reliable equations of state at finite baryon density. Building on this foundation, I incorporate a QCD critical point using the universality class of the three-dimensional Ising model, employing a tunable mapping that maintains thermodynamic consistency and causality. I will present results for key thermodynamic quantities, including the pressure, baryon density, entropy density, energy density, baryon number fluctuations, and the speed of sound, across regions of the QCD phase diagram relevant to ongoing and future heavy-ion experiments.

 

Bio of the speaker:

Dr. Michael Kahangirwe is a postdoctoral scholar at Kent State University, where he works on developing a unified equation of state that connects heavy-ion collision physics with neutron star matter. His research aims to provide a consistent theoretical framework to guide both heavy-ion experiments and neutron star observations and is carried out within the MUSES cyberinfrastructure, which is dedicated to developing universal equations of state. He earned his PhD in Physics in 2025 from the University of Houston, following a Master’s degree from the ICTP-East African Institute for Fundamental Research (EAIFR) in Rwanda, a partner institute of the Abdus Salam International Centre for Theoretical Physics (ICTP). He received his Bachelor of Science degree from Makerere University. His research interests include heavy-ion physics, neutron star physics, and critical phenomena.

ASP-20Jan2026.mp4

ASP_Micheal_Kahangirwe.pdf