Twin Higgs Asymmetric Dark Matter

We study asymmetric dark matter (ADM) in the context of the minimal (fraternal) twin Higgs solution to the little hierarchy problem, with a twin sector with gauged SU(3)^'×SU(2)^', a twin Higgs doublet, and only third-generation twin fermions. Naturalness requires the QCD^' scale ΛQCD^'0.5--20 GeV, and that t^' is heavy. We focus on the light b^' quark regime, m_b^'ΛQCD^', where QCD^' is characterized by a single scale ΛQCD^' with no light pions. A twin baryon number asymmetry leads to a successful dark matter (DM) candidate: the spin-$3/2$ twin baryon, Δ^'~b^'b^'b^', with a dynamically determined mass (~5ΛQCD^') in the preferred range for the DM-to-baryon ratio ΩDM/Ωbaryon5. Gauging the U(1)^' group leads to twin atoms (Δ^'-τ^' bound states) that are successful ADM candidates in significant regions of parameter space, sometimes with observable changes to DM halo properties. Direct detection signatures satisfy current bounds, at times modified by dark form factors.