Dark Matter and neutrino masses from global symmetry breaking (original) (raw)

We present a scenario were neutrino masses and Dark Matter are related due to a global U (1) B−L symmetry. Specifically we consider neutrino mass generation via the Zee-Babu two-loop mechanism, augmented by a scalar singlet whose VEV breaks the global U (1) B−L symmetry. In order to obtain a Dark Matter candidate we introduce two Standard Model singlet fermions. They form a pseudo-Dirac particle and are stable because of a remnant Z 2 symmetry. Hence, in this model the stability of Dark Matter follows from the global U (1) B−L symmetry. We discuss the Dark Matter phenomenology of the model, and compare it to similar models based on gauged U (1) B−L. We argue that in contrast to the gauged versions, the model based on the global symmetry does not suffer from sever constraints from Z searches.