Type-3/2 Seesaw Mechanism

TL;DR

The paper introduces a novel Type-3/2 seesaw mechanism using vector-spinors that naturally generate tiny neutrino masses without fine-tuning, and potentially explain dark matter, aligning with current experimental data.

Contribution

It proposes a new one-step seesaw mechanism involving vector-spinors that avoids fine-tuning and links neutrino masses, Higgs stability, and dark matter.

Findings

The mechanism naturally produces tiny neutrino masses.

It maintains Higgs mass stability at one loop.

Potential dark matter candidate as a pure spin-3/2 vector-spinor.

Abstract

Type-I seesaw provides a natural explanation for the tiny neutrino masses. The right-handed neutrino masses it requires are, however, too large to keep the Higgs boson mass at its measured value. Here we show that vector-spinors, singlet leptons like the right-handed neutrinos, generate the tiny neutrino masses naturally by the exchange of its spin-1/2 and spin-3/2 components. This one-step seesaw mechanism, which we call Type-3/2 seesaw, keeps the Higgs boson mass unchanged at one loop, and gives cause therefore to no fine-tuning problem. If the on-shell vector-spinor is a pure spin-3/2 particle then it becomes a potential candidate for hidden dark matter diluting due only to the expansion of the Universe. The Type-3/2 seesaw provides a natural framework for the neutrino, Higgs boson and dark matter sectors, with overall agreement with current experiments and observations.