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Abstract

A dark sector containing a confining non-abelian gauge group with multiple flavors of light dark quarks is expected to have dark pions being the lightest dark hadrons. The lightest dark pion can be a dark matter candidate if it is protected by some symmetry to be stable. Heavier dark mesons neutral under the symmetry can decay to Standard Model states through some portal interactions. The dark pion relic density is determined by the forbidden channel of light dark pions up-scattering to heavier dark mesons, or the heavy dark meson decay rate. The decay lengths of the heavy dark mesons are typically macroscopic, resulting in distinctive collider signals. The vector current interaction between the dark pions and SM states is absent so both direct and indirect detections of dark matter are not effective. The dark shower searches from the heavier dark mesons decays at the colliders and the FCNC decays of Standard Model mesons may provide the best probes of this model.