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Cutting the scotogenic loop: adding flavor to dark matter

  • Ranjeet Kumar,
  • Newton Nath,
  • Rahul Srivastava

摘要

We introduce a framework for hybrid neutrino mass generation, wherein scotogenic dark sector particles, including dark matter, are charged non-trivially under the A4 flavor symmetry. The spontaneous breaking of the A4 group to residual Z 2 \( {\mathcal{Z}}_2 \) subgroup results in the “cutting” of the radiative loop. As a consequence the neutrinos acquire mass through the hybrid “scoto-seesaw” mass mechanism, combining aspects of both the tree-level seesaw and one-loop scotogenic mechanisms, with the residual Z 2 \( {\mathcal{Z}}_2 \) subgroup ensuring the stability of the dark matter. The flavor symmetry also leads to several predictions including the normal ordering of neutrino masses and “generalized μτ reflection symmetry” in leptonic mixing. Additionally, it gives testable predictions for neutrinoless double beta decay and a lower limit on the lightest neutrino mass. Finally, A4 Z 2 \( {\mathcal{Z}}_2 \) breaking also leaves its imprint on the dark sector and ties it with the neutrino masses and mixing. The model allows only scalar dark matter, whose mass has a theoretical upper limit of ≲ 600 GeV, with viable parameter space satisfying all dark matter constraints, available only up to about 80 GeV. Conversely, fermionic dark matter is excluded due to constraints from the neutrino sector. Various aspects of this highly predictive framework can be tested in both current and upcoming neutrino and dark matter experiments.