Dark matter stability and Dirac neutrinos using only Standard Model symmetries

We provide a generic framework to obtain stable dark matter along with naturally small Dirac neutrino masses generated at the loop level. This is achieved through the spontaneous breaking of the global $U(1{)}_{B-L}$ symmetry already present in Standard Model. The $U(1{)}_{B-L}$ symmetry is broken down to a residual even ${\mathcal{Z}}_n$; $n\ge 4$ subgroup. The residual ${\mathcal{Z}}_n$ symmetry simultaneously guarantees dark matter stability and protects the Dirac nature of neutrinos. The $U(1{)}_{B-L}$ symmetry in our setup is anomaly free and can also be gauged in a straightforward way. Finally, we present an explicit example using our framework to show the idea in action.