Probes for constituents of composite dark matter

The nonbaryonic dark matter of the Universe can consist of new stable charged particles, bound in heavy “atoms” by the ordinary Coulomb interaction. If stable particles O −− with charge −2 are in excess over their antiparticles (with charge +2) and there are no stable particles with charges +1 and −1, the primordial helium, formed in Big Bang Nucleosynthesis, captures all O −− in neutral “atoms” of O-helium (OHe), playing the role of specific nuclear interacting dark matter. O-helium dark atoms can provide a solution for the puzzles of dark matter searches. A successful development of composite dark matter scenarios appeals to an experimental search for charged constituents of dark atoms. Estimates of production cross section of such particles at LHC are presented, and experimental signatures of new stable quarks are outlined.