Neutralino relic density from direct non-equilibrium production and intermediate scales

Abstract

We review the calculation of the LSP relic density in alternative cosmological scenarios where contributions from direct decay production are important. We study supersymmetric models with intermediate unification scale. We find concrete scenarios where the reheating temperature is of order one GeV ($M_I\sim 10^{12}$) and below. If the case that this reheating temperature is associated to the decay of oscillating moduli fields appearing in string theories, we show that the LSP relic density considerably increases with respect to the standard radiation-dominated case by the effect of the direct non-thermal production by the modulus field. The LSP can become a good dark matter candidate ($0.01-0.1 \gsim \Omega h^2 \lsim 0.3-1$) for $M_I\sim 10^{12}-10^{14}$ Gev and $m_\phi\sim 1-10$ TeV.