Speaker: Krishna Rajagopal, Massachusetts Institute of Technology (MIT)

Title: The Condensed Matter Astrophysics of QCD

Abstract: Experiments done at the Relativistic Heavy Ion Collider are teaching us that at the highest experimentally accessible temperatures, the quark-gluon plasma that filled the microseconds old universe was much more like an ideal liquid than an ideal gas. At much lower temperatures but at the highest conceivable densities dense enough that neutrons and protons have been crushed quark matter turns out to also have surprising properties whose understanding requires borrowing both ideas and techniques from condensed matter physics and applying them to quarks described by QCD. The phenomena that may occur include color superconductivity with attendant Meissner effects, a dielectric insulator, and a form of crystallization. I will begin this colloquium with an introduction to the phase diagram of QCD more broadly, and then focus on dense quark matter, describing what we know from QCD and what the remaining puzzles are. The only place in the universe where color superconducting quark matter may occur is in compact stars, so I will close with a look at some astrophysical observations that may help us to resolve the remaining puzzles.