Julian Heeck, Werner Rodejohann
We consider the phenomenology of the gauged abelian symmetry B + 3 (L_e - L_mu - L_tau). Right-handed neutrinos necessary to cancel triangle anomalies are used in a type-I seesaw scheme to create active neutrino masses. Breaking the B + 3 (L_e - L_mu - L_tau) symmetry spontaneously below the seesaw scale generates low energy neutrino mass matrices with the approximate symmetries L_e (leading to normal hierarchy) or L_e - L_mu - L_tau (inverted hierarchy). For the latter we need to introduce a Z_2 symmetry which decouples one of the right-handed neutrinos. Accidently, the Z_2 makes it a dark matter candidate that interacts with the Standard Model via the Z' and a scalar s originating from spontaneous breaking of the new symmetry. The measured relic abundance of the Majorana dark matter particle can be obtained around the scalar and Z' resonances, while direct detection experiments are mainly sensitive to scalar exchange, which is induced by mass mixing of s with the standard Higgs.
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http://arxiv.org/abs/1203.3117
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