Communication with SIMP dark mesons via Z′-portal

We consider a consistent extension of the SIMP models with dark mesons by including a dark U(1)(D) gauge symmetry. Dark matter density is determined by a thermal freeze-out of the 3 -> 2 self-annihilation process, thanks to the Wess-Zumino-Witten term. In the presence of a gauge kinetic mixing between the dark photon and the SM hypercharge gauge boson, dark mesons can undergo a sufficient scattering off the Standard Model particles and keep in kinetic equilibrium until freeze-out in this SIMP scenario. Taking the SU(N-f) x SU(N-f)/SU(N-f) flavor symmetry under the SU(N-c) confining group, we show how much complementary the SIMP constraints on the parameters of the dark photon are for current experimental searches for dark photon. (C) 2015 The Authors. Published by Elsevier B.V.