Abstract
We consider the phenomenology of the gauged Abelian symmetry . Right-handed neutrinos necessary to cancel triangle anomalies are used in a type-I seesaw scheme to create active neutrino masses. Breaking the symmetry spontaneously below the seesaw scale generates low-energy neutrino mass matrices with the approximate symmetries (leading to normal hierarchy) or (inverted hierarchy). For the latter we need to introduce a symmetry which decouples one of the right-handed neutrinos. If exact, this leads to a Majorana dark matter candidate that interacts with the standard model via the and a scalar originating from spontaneous breaking of the new symmetry. The measured relic abundance of the dark matter particle can be obtained around the scalar and resonances, while direct detection experiments are mainly sensitive to scalar exchange, which is induced by mass mixing of with the standard Higgs.
- Received 19 March 2012
DOI:https://doi.org/10.1103/PhysRevD.85.113017
© 2012 American Physical Society