Sterile neutrinos and Rₖ

Original · EN

We study the violation of lepton flavour universality in light meson decays due to the presence of non-zero mixings between the active neutrinos with new sterile states. The modified W ℓ ν vertices, arising from a non-unitarity leptonic mixing matrix intervening in charged currents, might lead to a tree-level enhancement of Rₚ = Γ(P → e ν) / Γ(P → μν), with P=K, π. These enhancements are illustrated in the case of the inverse seesaw, showing that one can saturate the current experimental bounds on Δrₖ (and Δrπ), while in agreement with the different experimental and observational constraints.