Assessment of the Dimension-5 Seesaw Portal and Impact of Exotic Higgs Decays on Non-Pointing Photon Searches

Understand

The Dimension-5 Seesaw Portal is a Type-I Seesaw model extended by $d=5$ operators involving the sterile neutrino states, leading to new interactions between all neutrinos and the Standard Model neutral bosons.

• In this work we focus primarily on the implications of these new operators at the GeV-scale.
• In particular, we recalculate the heavy neutrino full decay width, up to three-body decays.
• We also review bounds on the dipole operator, and revisit LEP constraints on its coefficient.