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Abstract

The recently proposed “mini-seesaw mechanism” combines naturally suppressed Dirac and Majorana masses to achieve light Standard Model neutrinos via a lowscale seesaw. A key feature of this approach is the presence of multiple light (order GeV) sterile-neutrinos that mix with the Standard Model. In this work we study the bounds on these light sterile-neutrinos from processes like μ → e + γ, invisible Z-decays, and neutrinoless double beta-decay. We show that viable parameter space exists and that, interestingly, key observables can lie just below current experimental sensitivities. In particular, a motivated region of parameter space predicts a μ → e + γ branching fraction within the range to be probed by MEG.