Speaker
Description
$\mu \to e$ conversion in nuclei gives one of the leading limits on BSM lepton-flavor violating (LFV) processes. Upcoming measurements call for a more consistent theoretical description of $\mu \to e$ conversion. This can be done model independently using an effective field theory framework in terms of effective BSM operators, which however crucially depends on hadronic and nuclear matrix elements.
In particular, the uncertainties inherent in these non-perturbative inputs, limit the discriminating power that can be achieved. In order to quantify the associated uncertainties, we revisit nuclear charge densities and propagate uncertainties from elastic electron scattering experiments. These charge densities, parametrized in terms of Fourier-Bessel series, can be correlated with results from modern ab-initio methods and will thus allow for the evaluation of general $\mu \to e$ conversion rates with quantified uncertainties.
The resulting description of $\mu \to e$ conversion enables improved studies of the appearing effective operators, which can also be related to LFV pseudoscalar decays.
partly based on: Phys.Rev.Lett. 130 (2023) 13, 131902
