Searches for dark matter

The particle which constitutes probably more than 90% of the mass of the universe is something unknown in the Standard Model of particle physics. There are few constraints on what it may be, and hence broad-ranging searches are needed. A combination of non-accelerator experiments, particularly those using Ge and Si ionization detectors, and recent accelerator experiments, especially at SLC and LEP, have eliminated as dark matter wide classes of formerly popular candidate particles. Examples are weak isodoublet neutrinos more massive than ∼30 eV/c2, sneutrinos, technibaryons, and microcharged shadow matter. Also almost ruled out are Cosmions with coherent nuclear interactions, particles proposed to be both the dark matter of the universe and also to explain the solar neutrino deficit by cooling the solar core. (author) 38 refs.; 4 figs