WIMP dark matter expected in the parity solution to the strong CP problem.

We construct an extended Standard Model (SM), motivated by the strong CP problemand dark matter. In our model, parity symmetry is conserved at high energy by introducing a mirrorsector with the extra gauge symmetry, $SU(2)_R \times U(1)_R$. The charges of $SU(2)_R \times U(1)_R$ are assigned to the mirrorfields in the same way as in the SM, but the chirality of the mirrorfermions is opposite to respect the parity symmetry. The strong CP problemis resolved, since the mirrorquarks are also charged under the $SU(3)_c$ in the SM. In the minimal setup, the mirror gauge symmetryleads stable colored particles, so that we introduce two scalars in order to avoid the stable colored particle. Interestingly, one of the scalars becomes stable because of the gauge symmetry, so that it can be a good dark mattercandidate. In this paper, we especially study the phenomenology relevant to the dark matter. We also discuss the neutrino sector and show that the right-handed neutrinos from the mirrorsector can increase the effective number of neutrinos or dark radiationby $0.14$.