Light relic neutralinos

Abstract

The relic abundance and the scalar cross section off the nucleon for light neutralinos (of mass below about 45 GeV) are evaluated in an effective MSSM model without GUT-inspired relations among the gaugino masses. It is shown that these neutralinos may provide a sizable contribution to the matter density in the Universe and produce measurable effects in WIMP direct detection experiments. These properties are elucidated in terms of simple analytical arguments.