Colloquium: Sanjay Reddy (U. of Washington)

Abstract: While Quantum Chromodynamics (QCD) is widely recognized as the theory governing strong interactions, linking its parameters to observable nuclear phenomena—like binding energies—remains a challenge. Chiral Effective Field Theory offers a framework for studying how quark and pion masses influence nucleon-nucleon interactions, but many questions remain unresolved. In this presentation, I will outline our current understanding and highlight recent findings that shed new light on these relationships. Crucially, I will argue that the dependence of nuclear forces on quark mass is central to exploring the potential for QCD axion condensation in neutron stars. If nuclear forces become more attractive as pion mass decreases, large regions of a neutron star's core could develop a Bose-Einstein condensate of QCD axions. I'll explore the implications for observable neutron star properties and how these insights can help discover or rule out the QCD axions.