Nambu-Goldstone dark matter in a scale invariant bright hidden sector

We consider a scale invariant extension of the standard model (SM) with a combined breaking of conformal and electroweak symmetry in a strongly interacting hidden SU(n(c)) gauge sector with n(f) vector-like hidden fermions. The (pseudo) Nambu-Goldstone bosons that arise due to dynamical chiral symmetry breaking are dark matter (DM) candidates. We focus on n(f) = n(c) = 3, where SU(3) is the largest symmetry group of hidden flavor which can be explicitly broken into either U(1) x U(1) or SU(2) x U(1). We study DM properties and discuss consistent parameter space for each case. Because of different mechanisms of DM annihilation the consistent parameter space in the case of SU(2) x (1) is significantly different from that of SU(3) if the hidden fermions have a SM U(1)(Y) charge of O(1).