Speaker
Description
Accurate calculations of ionisation cross-sections are essential for constraining dark matter–electron interactions, neutrino scattering, and precision Standard Model and beyond-Standard Model (BSM) physics. We present a generalised framework for computing ionisation cross-sections for scattering and absorption processes, fully incorporating relativistic effects and avoiding the use of the dipole approximation, which is not valid for scattering and breaks down for certain absorption processes. This approach is applicable to a broad class of models, including dark matter and relativistic particles such as neutrinos, and accommodates general interaction structures, including vector, axial-vector, scalar, pseudoscalar couplings, and their interference. We calculate relativistic atomic ionisation form factors for xenon and argon across an energy range spanning eV to MeV. These form factors provide essential input for the interpretation of dark matter direct-detection experiments, neutrino scattering measurements, and searches for exotic interactions, enabling model-independent constraints to be placed on a wide class of relativistic and non-relativistic new physics scenarios.