Cosmic Ray Positrons from Annihilations into a New, Heavy Lepton

Abstract

Recent results from the PAMELA experiment indicate an excess in the positron spectrum above 10 GeV, but anti-proton data are consistent with the expected astrophysical backgrounds. We propose a scenario that reproduces these features. Dark matter annihilates through channels involving a new heavy vectorlike lepton which then decays by mixing with Standard Model leptons. If charged, this heavy lepton might be produced at the LHC, and could lead to multi-lepton final states or to long-lived charged tracks. Large neutrino detectors such as ANTARES or IceCube might be sensitive to a monochromatic neutrino line. This scenario may be simply embedded in various models, including an extension to the NMSSM.

26 pages, 7 figures; refs added, SU(2) doublet model considered, discussion of monochromatic neutrino and electron signals