Neutralino Cold Dark Matter in a One Parameter Extension of the Minimal Supergravity Model

Within the minimal supergravity model (mSUGRA) framework, the expectation for the relic density of neutralinos exceeds the WMAP determination unless neutralinos a) have a significant higgsino component, b) have a mass close to half that of a heavy Higgs boson, or c)can efficiently co-annihilate with a charged or colored particle. Within a 1-parameter extension of the mSUGRA model which includes non-universal Higgs masses, we show that agreement with the WMAP data can be obtained over a wide range of mSUGRA parameters for scenarios a) and b), so that the phenomenological implications may be much more diverse than in mSUGRA. We show that direct and/or indirect detection of neutralino dark matter should be possible at various current and planned facilities.