Decaying Dark Atom Constituents and Cosmic Positron Excess
M. Laletin (National Research Nuclear University “Moscow Engineering Physics Institute”, Moscow 115409, Russia); K. Belotsky (National Research Nuclear University “Moscow Engineering Physics Institute”, Moscow 115409, Russia, Centre for Cosmoparticle Physics “Cosmion”, Moscow 115409, Russia); M. Khlopov (National Research Nuclear University “Moscow Engineering Physics Institute”, Moscow 115409, Russia, APC laboratory 10, rue Alice Domon et Léonie Duquet, 75205 Paris Cedex 13, France, Centre for Cosmoparticle Physics “Cosmion”, Moscow 115409, Russia); C. Kouvaris (CP, -Origins, University of Southern Denmark, Campusvej 55, 5230 Odense, Denmark)
We present a scenario where dark matter is in the form of dark atoms that can accommodate the experimentally observed excess of positrons in PAMELA and AMS-02 while being compatible with the constraints imposed on the gamma-ray ux from Fermi/LAT. This scenario assumes that the dominant component of dark matter is in the form of a bound state between a helium nucleus and a particle and a small component is in the form of a WIMP-like dark atom compatible with direct searches in underground detectors. One of the constituents of this WIMP-like state is a metastable particle with a mass of 1 TeV or slightly below that by decaying to , and produces the observed positron excess. These decays can naturally take place via GUT interactions. If it exists, such a metastable particle can be found in the next run of LHC. The model predicts also the ratio of leptons over baryons in the universe to be close to .