Like in the past cosmic rays (CR) may help us extend our knowledge of Particle Physics. Such a case is the nature of Dark Matter (DM). That question lies in the intersection of particle physics and astrophysics. It involves both questions of particle physics modeling, as well as of production and propagation of cosmic rays.Cold dark matter (CDM) has been established by many evidence as the stan-dard paradigm for the missing matter of the universe. Beginning with early obser-vations of velocity dispersions of galaxies in clusters [358], and later measurements of galactic rotation curves [296, 295], CDM has been supported by numerous ad- ditional observations. These include strong lensing of background galaxies [339], x-ray emission from galaxy clusters [91], the combination of CMB and type Ia supernovae data [313], measurements of the distributions of galaxies [118, 334], as well as the highly remarkable recent study of the bullet cluster [117].Measurements of the CMB, the need for early structure growth, and the success of big-bang nu-cleosynthesis rule out baryonic matter as being the dark matter, necessitating anew particle beyond the standard model.