Dark Atoms of Dark Matter from New Stable Quarks and Leptons

The nonbaryonic dark matter of the Universe can consist of new stable charged leptons and quarks, if they are hidden in elusive "dark atoms" of composite dark matter. Such possibility can be compatible with the severe constraints on anomalous isotopes, if there exist stable particles with charge -2 and there are no stable particles with charges +1 and -1. These conditions cannot be realized in supersymmetric models, but can be satisfied in several recently developed alternative scenarios. The excessive -2 charged particles are bound with primordial helium in O-helium "atoms", maintaining specific nuclear-interacting form of the Warmer than Cold Dark Matter. The puzzles of direct dark matter searches appear in this case as a reflection of nontrivial nuclear physics of O-helium.