Warped Seesaw is Physically Inverted

Understand

Warped extra dimensions can address both the Planck-weak and flavor hierarchies of the Standard Model (SM).

• In this paper we discuss the SM neutrino mass generation in a scenario in which a SM singlet bulk fermion - coupled to the Higgs and the lepton doublet near the IR brane - is given a Majorana mass of order the Planck scale on the UV brane.
• Despite the resemblance to a type I seesaw mechanism, a careful investigation based on the mass basis for the singlet 4D modes reveals a very different picture.
• Namely, the SM neutrino masses are generated dominantly by the exchange of the TeV-scale mass eigenstates of the singlet, that are pseudo-Dirac and have a sizable Higgs- induced mixing with the SM doublet neutrino: remarkably, in warped 5D models the anticipated type I seesaw morphs into a natural realization of the so-called "inverse" seesaw.