Two-component dark matter and a massless neutrino in a new B-L model

Understand

We propose a new extension of the Standard Model by a $U(1)_{B-L}$ gauge symmetry in which the anomalies are canceled by two right-handed neutrinos plus four chiral fermions with fractional B-L charges.

• Two scalar fields that break the B-L symmetry and give masses to the new fermions are also required.
• After symmetry breaking, two neutrinos acquire Majorana masses via the seesaw mechanism leaving a massless neutrino in the spectrum.
• Additionally, the other new fermions arrange themselves into two Dirac particles, both of which are automatically stable and contribute to the observed dark matter density.