Title: QCD Axion Dark Matter in String Theory

Abstract: In this talk, I will attempt to answer the question “If we detect the QCD axion, what will we learn about string theory?” In recent years, we have observed a striking fact in the largest class of explicit compactifications of string theory: they all come with axions, and the properties of these axions correlate strongly with the number of four-dimensional “holes” in the compactification geometry. Specifically, I will show that the mass of the QCD axion in these theories increases as the number of holes increases. We can therefore use resonator and broadband searches for the QCD axion as a probe of the topology of string theory’s extra dimensions. I will explain what signals from some common axion dark matter experiments (BREAD, MADMAX, ADMX, and DMRadio) would suggest about our place in the string landscape.

https://lbnl.zoom.us/j/94928022788?pwd=emVQWG1mTnhSbHVqekVuenk0VEVQZz09