http://arxiv.org/abs/1609.04821
The long standing anomaly in the positron flux as measured by the PAMELA and AMS-02 experiments could potentially be explained by dark matter annihilations. This scenario typically requires a large “boost factor” to be consistent with a thermal relic dark matter candidate produced via freeze-out. However, such an explanation has been considered to be disfavored by constraints from CMB observations on energy deposition during the recombination epoch. In this work, we construct a scenario for late-decaying two-component dark matter (LD2DM) with almost degenerate dark matter species. We show that such a scenario can explain the observed AMS-02 positron flux through an annihilation of the lighter dark matter species, while avoiding CMB constraints. The observed relic density can be correctly reproduced as well, with simple s-wave annihilation cross-sections. We demonstrate that the scenario is robust, subject to constraints from structure formation and CMB constraints on late-time energy depositions during the cosmic “dark ages”. We briefly explore possible cosmological and particle physics signatures in a toy model that realizes this scenario.
J. Buch, P. Ralegankar and V. Rentala
Mon, 19 Sep 16
31/52
Comments: 31 pages, 4 figures
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