The 1-loop computation of the processes ${\tilde{\chi }}_i^0{\tilde{\chi }}_j^0\to \gamma Z$ has been performed at an arbitrary c.m. energy for any pair of MSSM neutralinos. As an application suitable for dark matter (DM) searches, the neutralino-neutralino annihilation is studied at the limiting case of vanishing relative velocity, describing the present DM distribution in the galactic halo; and at a relative velocity of about 0.5, determining the neutralino relic density contributions. The most useful situation is obviously for $i=j=1$, but the case of nonidentical neutralinos may also be useful in some corners of the parameter space. Our results are contained in the FORTRAN code PLATONdmgZ, applying to any set of real MSSM parameters. Numerical results are also presented for a sample of 6 MSSM models, describing the various possible neutralino properties. A comparison with other existing works is also made.

• Received 9 February 2006

DOI:https://doi.org/10.1103/PhysRevD.73.073003