Indirect detection signatures for the origin of asymmetric dark matter

Abstract

Abstract:We study the decay signatures of Asymmetric Dark Matter (ADM) via higher dimension operators which are responsible for generating the primordial dark matter (DM) asymmetry. Since the signatures are sensitive both to the nature of the higher dimension operator generating the DM asymmetry and to the sign of the baryon or lepton number that the DM carries, indirect detection may provide a window into the nature of the mechanism which generates the DM asymmetry. We consider in particular dimension-6 fermionic operators of the form(or operators related through a Hermitian conjugate) with the scale M around or just below the GUT scale. We derive constraints on ADM particles both in the natural mass range (around a few GeV), as well as in the range between 100 GeV to 10 TeV. For light ADM, we focus on constraints from both the low energy gamma ray data and proton/antiproton fluxes. For heavy ADM, we consider γ-rays and proton/anti-proton fluxes, and we fit e + /e − data from AMS-02 and H.E.S.S. (neglecting the Fermi charged particle fluxes which disagree with AMS-02 below 100 GeV). We show that, although the best fit regions from electron/positron measurement are still in tension with other channels on account of the H.E.S.S. measurement at high energies, compared to an ordinary symmetric dark matter scenario, the decay of DM with a primordial asymmetry reduces the tension. Better measurement of the flux at high energy will be necessary to draw a definite conclusion about the viability of decaying DM as source for the signals.

Unconventional dark matter models: a brief review

“…It is thus natural to expect that the approximate baryon/lepton symmetry may also be responsible to stabilize DM particles. Since those symmetries are approximate, DM is meta-stable and its decay may be observed through the measurements of cosmic ray [19]. More interestingly, the decay products of ADM may be asymmetric if there are charged particles in the decay final states.…”

Annihilation signals from asymmetric dark matter

“…Whilst decay signals of ADM can readily arise, see e.g. [11], in general, we do not expect late-time annihilation signals from ADM, since the symmetric component is assumed to have annihilated early on. However, if the symmetric component is later 'regenerated', this may give rise to annihilation signals.…”

Continuous flavor symmetries and the stability of asymmetric dark matter

“…The light blue line shows the result of an analysis [64] assuming χ →νν decay based on Super-Kamiokande [63] bounds. The purple line is an exclusion curve from [33] based on galactic and extragalactic gamma ray flux measurements by Fermi [65][66][67]. The authors in [33] consider χ → uds and χ → cbs decays as two extreme choices for the flavor structure of the final states.…”

“…The purple line is an exclusion curve from [33] based on galactic and extragalactic gamma ray flux measurements by Fermi [65][66][67]. The authors in [33] consider χ → uds and χ → cbs decays as two extreme choices for the flavor structure of the final states. The derived bounds on χ lifetime differ by less then a factor of 2 such that the two bounds overlap on the scale of Fig.…”