Explaining the AMS positron excess via Right-handed Neutrinos

Abstract

We have witnessed in the past decade the observation of a puzzling cosmic-ray excess at energies larger than $10$ GeV. The AMS-02 data published this year has new ingredients such as the bump around $300$ GeV followed by a drop at $800$ GeV, as well as smaller error bars. Adopting the background used by the AMS-02 collaboration in their analysis, one can conclude that previous explanations to the new AMS-02 such as one component annihilating and decaying dark matter as well as pulsars seem to fail at reproducing the data. Here, we show that in the right-handed neutrino portal might reside the answer. We discuss a decaying two-component dark matter scenario where the two-body decay products are right-handed neutrinos that have their decay pattern governed by the type I seesaw mechanism. This setup provides a very good fit to data, for example, for a conservative approach including just statistical uncertainties leads to ${\chi }^2/d.o.f\sim 2.3$ for $m_{D{M}_1}=2150$ GeV with ${\tau }_1=3.78\times 10^{26}$ s and $m_{D{M}_2}=300$ with ${\tau }_2=5.0\times 10^{27}$ s for $M_N=10$ GeV, and, in an optimistic case, including systematic uncertainties, we find ${\chi }^2/d.o.f\sim 1.12$, for $M_N=10$ GeV, with $m_{D{M}_1}=2200$ GeV with ${\tau }_1=3.8\times 10^{26}$ s and $m_{D{M}_2}=323$ GeV with ${\tau }_2=1.68\times 10^{27}$ s.

Comments: 9 pages, 10 figures; Accepted for publication in PRD