Canonical seesaw implication for two-component dark matter

Abstract

We show that the canonical seesaw mechanism implemented by the U ( 1 ) B − L gauge symmetry provides two-component dark matter naturally. The seesaw scale that breaks B − L defines a residual gauge symmetry to be Z 6 = Z 2 ⊗ Z 3 , where Z 2 leads to the usual matter parity, while Z 3 is newly recognized, transforming quark fields nontrivially. The dark matter components—that transform nontrivially under the matter parity and Z 3 , respectively—can gain arbitrary masses, despite the fact that the Z 3 dark matter may be heavier than the light quarks u , d . This dark matter setup can address the XENON1T anomaly recently observed and other observables, given that the dark matter masses are nearly degenerate, heavier than the electron and the B − L gauge boson Z ′ , as well as the fast-moving Z 3 dark matter has a large B − L charge, while the Z ′ is viably below the beam dump experiment sensitive regime.