Evidence for right-handed neutrinos at a neutrino factory

TL;DR

A neutrino factory could detect light right-handed neutrinos through a measurable event deficit, revealing new physics beyond the Standard Model, especially if additional scalar fields are involved.

Contribution

The paper proposes a simple model with right-handed neutrinos and scalar fields that could produce observable deficits at neutrino factories, indicating new physics.

Findings

Potential 10% event deficit detectable at neutrino factories.

Adding scalar fields reduces the deficit, requiring specific Yukawa couplings.

The scenario is consistent with current electroweak and lepton flavor violation constraints.

Abstract

We emphasize that a muon based neutrino factory could show the existence of light right-handed neutrinos, if a deficit in the number of detected events is observed at a near detector. This could be as large as ~10% if the size of the new interactions saturates the present limits from electroweak precision data, what is not excluded by the oscillation experiments performed up to now. A simple model realizing such a scenario can be obtained adding right-handed neutrinos to the minimal Standard Model, together with an extra scalar doublet and a triplet of hypercharge 1. In this case, however, the possible deficit is reduced by a factor of ~3, and the Yukawa couplings must be adequately chosen. This is also generically required if lepton flavour violation must be below present bounds.