Axions, instantons, and the lattice
Axions, instantons, and the lattice
If the QCD axion is a significant component of dark matter, and if the Universe was once hotter than a few hundred MeV, the axion relic abundance depends on the function $\ensuremath{\chi}(T)$, the temperature-dependent topological susceptibility. Uncertainties in this quantity induce uncertainties in the axion mass as a function of …