Self-interacting dark baryons
  Using results from lattice QCD, it is possible to quantitatively design
models of dark baryons leading to velocity-dependent self-interaction cross
sections that match the values needed for solving small-scale structure
problems of standard cold dark matter. However it is not obvious that the main
dark matter component in such models will be nucleons rather than large nuclei,
or dark pions or atoms, whose scattering properties would be different. We
first identify the parameters of a dark SU(3) sector analogous to QCD -- the
confinement scale $\Lambda$ and pion mass $m_\pi$ -- needed to reproduce
desired self-interaction cross sections. Then we show that these values can
generically be compatible with the absence of a sufficiently stable deuteron
bound state, and hence leading to no heavier nuclei, thus establishing the
consistency of the scenario for self-interacting dark nucleons. The range of
dark photon masses needed to avoid dominant pion or atomic dark matter is
determined, as well as allowed values for the kinetic mixing parameter. The
dark proton might be detected directly in future searches, by dark photon
exchange.
