  The minimal seesaw extension of the Standard SU(3) x SU(2) x U(1) Model
requires two electroweak singlet fermions in order to accommodate the neutrino
oscillation parameters at tree level. Here we consider a next to minimal
extension where light neutrino masses are generated radiatively by two
electroweak fermions: one singlet and one triplet under SU(2). These should be
odd under a parity symmetry and their mixing gives rise to a stable weakly
interactive massive particle (WIMP) dark matter candidate. For mass in the
GeV-TeV range, it reproduces the correct relic density, and provides an
observable signal in nuclear recoil direct detection experiments. The fermion
triplet component of the dark matter has gauge interactions, making it also
detectable at present and near future collider experiments.
