Searching for GUT-scale QCD axions and monopoles with a high-voltage capacitor

The QCD axion has been postulated to exist because it solves the strong-CP problem. Furthermore, if it exists axions should be created in the early Universe and could account for all the observed dark matter. In particular, axion masses of order 10-10 eV to 10-7 eV correspond to axions in the vicinity of the grand unified theory scale (GUT-scale). In this mass range many experiments have been proposed to search for the axion through the standard QED coupling parameter gaγγ. Recently axion electrodynamics has been expanded to include two more coupling parameters, gaEM and gaMM, which could arise if heavy magnetic monopoles exist. In this work we show that both gaMM and gaEM may be searched for using a high-voltage capacitor. Since the experiment is not sensitive to gaγγ, it gives a new way to search for effects of heavy monopoles if the GUT-scale axion is shown to exist, or to simultaneously search for both the axion and the monopole at the same time.