Cross sections for dark matter particles and implications for allowed masses, interactions, and detection

Abstract

We present scattering and annihilation cross sections for a number of candidates for dark matter: heavy neutrinos, photinos, scalar-neutrinos, and higgsinos. In the mass region below about 10 GeV, annihilation cross sections can be enhanced at resonance masses, so some masses are allowed below the generally quoted continuum values of a few GeV. Use of conventional neutral current couplings of a heavy neutrino L0 to the Z0 implies mL0 > 3.3 GeV (rather than the usually quoted 2 GeV). Cross sections are generally expected to be small (of order 10-38 cm2, often smaller than might be naively expected) which affects possible implications involving concentration mechanisms, energy transfer, and detectability via energy transfer or annihilation products. Current limits on supersymmetric partners are incorporated.