Speaker
Description
We identify the Standard Model–charged portal multiplets that can connect the visible sector to a massive dark photon while preserving an exact dark charge conjugation that protects it from decay. Requiring the Standard Model gauge fields to remain invariant under this symmetry forces the portal to carry zero hypercharge and to transform in self-conjugate representations of (SU(3)_c\times SU(2)_L). We classify the allowed fermionic and scalar portals and consider, within an effective field theory framework, the minimal colored realization containing a vectorlike color-adjoint fermion. If this fermion thermalizes in the early Universe, its freeze-out leaves stable colored bound states subject to stringent cosmological and direct-detection constraints. We therefore introduce a charge-two dark Higgs whose renormalizable Majorana interactions split the Dirac fermion into two Majorana states. Heavier-state cascades and efficient QCD annihilations can then reduce the colored relic abundance by several orders of magnitude. Charge-two Higgsing nevertheless leaves a residual gauge parity that stabilizes the lightest colored state. Charge-one Higgsing removes this remnant and allows dark-charge-conjugation-preserving higher-dimensional operators to split the fermion and induce its decay. The dark photon can then constitute dark matter if it is the lightest accessible state odd under dark charge conjugation.