Dark matter: The leptonic connection

Recent observations of high-energy positrons and electrons by the PAMELA and ATIC experiments may be an indication of the annihilation of (lark matter into leptons and not quarks. This leptonic connection was foreseen already some years ago in two different models of radiative neutrino mass. We discuss here the generic interactions (nu eta(0) - l eta(+))chi and l(c) zeta(-) chi(c) which allow this to happen, where chi and/or chi(c) are fermionic dark-matter candidates. We point out in particular the importance of chi chi -> l(+) l(-) gamma to both positron and gamma-ray signals within this framework. (C) 2009 Published by Elsevier B.V.