Scotogenic Dark Symmetry as a residual subgroup of Standard Model Symmetries

We show that the scotogenic dark symmetry can be obtained as a residual subgroup of the global $U(1{)}_{B-L}$ symmetry already present in Standard Model. We propose a general framework where the $U(1{)}_{B-L}$ symmetry is spontaneously broken to an even ${\mathcal{Z}}_{2n}$ subgroup, setting the general conditions for neutrinos to be Majorana and the dark matter stability in terms of the residual ${\mathcal{Z}}_{2n}$. Under this general framework, as examples, we build a class of simple models where, in the scotogenic spirit, the dark matter candidate is the lightest particle running inside the neutrino mass loop. The global $U(1{)}_{B-L}$ symmetry in our framework being anomaly free can also be gauged in a straightforward manner leading to a richer phenomenology.