Speaker
Description
Axion-like particles are a well-motivated candidate for ultralight dark matter. Because dark
matter must be non-relativistic, the effects of its scattering with Standard Model particles are
negligible and generally go unnoticed. However, due to the large occupation number of ultralight
dark matter, the sum of all scatterings leads to a classical field-like interaction with Standard Model
particles. In the case of an axion-like particle, this scattering imparts a parity violating effect. If this
collective scattering with axion-like particles is inserted into the one-loop quantum electrodynamics
diagram, the parity violation imparted by this scattering will convert the anomalous magnetic
moment contribution into an electric dipole moment. This contribution is quite large and leads
to a prediction inconsistent with precision measurements of the proton and electron electric dipole
moments, unless their couplings to the axion-like particles are very weak. As a result, the constraints
on the couplings of axion-like particle dark matter to the electron and proton are improved by as
much as eleven and six orders of magnitude, respectively."
