AMEND: A Model Explaining Neutrino masses and Dark matter testable at the LHC and MEG

TL;DR

This paper proposes a unified extension of the Standard Model that simultaneously explains neutrino masses and dark matter, with testable predictions at colliders and in dark matter experiments.

Contribution

It introduces a new model linking neutrino masses and dark matter via a U(1) symmetry, with neutrino masses generated at loop level and accessible phenomenology.

Findings

Neutrino masses arise at loop level with small explicit symmetry breaking.

Dark matter stability is guaranteed by a residual Z_2 symmetry.

Model predicts observable signals at the LHC and in dark matter searches.

Abstract

Despite being very successful in explaining the wide range of precision experimental results obtained so far, the Standard Model (SM) of elementary particles fails to address two of the greatest observations of the recent decades: tiny but nonzero neutrino masses and the well-known problem of missing mass in the Universe. Typically the new models beyond the SM explain only one of these observations. Instead, in the present article, we take the view that they both point towards the same new extension of the Standard Model. The new particles introduced are responsible simultaneously for neutrino masses and for the dark matter of the Universe. The stability of dark matter and the smallness of neutrino masses are guaranteed by a U(1) global symmetry, broken to a remnant Z_2. The canonical seesaw mechanism is forbidden and neutrino masses emerge at the loop level being further suppressed by the small explicit breaking of the U(1) symmetry. The new particles and interactions are invoked at the electroweak scale and lead to rich phenomenology in colliders, in lepton flavour violating rare decays and in direct and indirect dark matter searches, making the model testable in the coming future.