Neutralino with the Right Cold Dark Matter Abundance in (Almost) Any Supersymmetric Model

Abstract

We consider non-standard cosmological models in which the late decay of a scalar field $\phi$ reheats the Universe to a low reheating temperature, between 5 MeV and the standard freeze-out temperature of neutralinos of mass $m_{\chi}$. We point out that in these models all neutralinos with standard density $\Omega_{\rm std} \gtrsim 10^{-5} (100 {\rm GeV}/m_\chi)$ can have the density of cold dark matter, provided the right combination of the following two parameters can be achieved in the high energy theory: the reheating temperature, and the ratio of the number of neutralinos produced per $\phi$ decay over the $\phi$ field mass. We present the ranges of these parameters where a combination of thermal and non-thermal neutralino production leads to the desired density, as functions of $\Omega_{\rm std}$ and $m_{\chi}$.