Exact cross sections for the neutralino Wimp pair-annihilation

We derive a full set of exact, analytic expressions for the annihilation of the lightest neutralino pairs into all two-body tree-level final states in the framework of minimal supersymmetry. We make no simplifying assumptions about the neutralino nor about sfermion masses and mixings other than the absence of explicit CP-violating terms. The expressions should be particularly useful in computing the neutralino WIMP relic abundance without the usual approximation of partial wave expansion. (author)