DARK-MATTER IN THE UNIVERSE

Sinse the last 20 years the problem of dark matter (DM) in the Univers e has become a central one. The Einstein equation in the Friedmann - R obertson - Walker metric and for homogeneous and isotropic Universe ca n be written in the formOmega(t) - 1 = k/(H)2(a)2((t)), where Omega(t) = rho(t)/rho(c),rho(t) is the total density of matter at the moment t , rho(c) approximate to 1.05 . 10(4) eV/cm(3) is the critical density, H is the Hubble parameter, a(t) is a scale factor and k = -1,0,1 is t he sign of survature. Hence we will have the closed (k = 1), flat (k = 0) or open (k - -1) Universe depending on relations rho > rho(c), rho = rho(c) or rho < rho(c). So for the fate of our Universe in the futu re the present value Omega(0) of Omega is of extreme interest. There a re strong arguments to believe that the value Omega(0) is very near to 1. It is essential that invisible (dark) matter constitutes a large a mount of total matter and can exist in the form different from all kno wn forms matter. Possible candidates for DM are massive neutrinos as w ell as axions and supersymmetric partners of the known particles. It i s considered in details the contribution of each sort of these particl es into DM density. The conclusion in that 1) light neutrinos are allo wed if their masses satisfy the estimate GRAPHICS < 92 eV, 2) heavy neutrinos neled out if their masses are less then 46.5 GeV and 45.5 Ge V for Dirac and Majorana particles, respectively, though there is stil l room for heavier neutrinos. The most probable candidate for DM is th e neutralino lambda (the lightest supersymmetric partner of elecroweak gauge bosons, photon and of the Higgs scalars). The present experimen ts limit its mass to be greater than or equal to 20 GeV. Search of neu tralinos is a rather hard problem since they are neutral and interact weakly. This well require substantial improvement in the Sensitivity o f present experiments (by a factor greater than or equal to 10). The a ccurate determination of DM density and its composition is a great end eavour for cosmologists and particle physicists as it can shed light b oth on very early history of the Universe and on new properties of mat ter.