Abstract
Annihilation of light dark matter of mDM≈(10–40) GeV into the Standard Model fermions has been suggested as a possible origin of the gamma-ray excess at GeV energies in the Fermi-LAT data. In this paper, we examine possible model-independent signatures of such dark matter models in other experiments such as AMS-02, colliders, and cosmic microwave background (CMB) measurements. We point out that first generation of fermion final states is disfavored by the existing experimental data. Currently AMS-02 positron measurements provide stringent bounds on cross sections of dark matter annihilation into leptonic final states, and e+e− final state is in severe tension with this constraint, if not ruled out. The e+e− channel will be complementarily verified in an early stage of ILC and future CMB measurements. Light quark final states (qq¯) are relatively strongly constrained by the LHC and dark matter direct detection experiments even though these bounds are model-dependent. Dark matter signals from annihilations into qq¯ channels would be constrained by AMS-02 antiproton data which will be released in very near future. In optimistic case, diffuse radio emission from nearby galaxy (clusters) and the galactic center might provide another hint or limit on dark matter annihilation.
Highlights
The identity of dark matter (DM) is one of the most profound mysteries in particle physics and cosmology
Anomalous signals have been reported by many experiments including PAMELA, AMS-02, Fermi-LAT, SPI/INTEGRAL, and XMM-Newton: excesses in the cosmic-ray positron fraction [9, 10], 130 GeV [11, 12] and 511 keV [13] γ-rays from the galactic center (GC), and X-ray emission around Eγ 3.5 keV [14, 15] detected in galaxy clusters
We include the upper limit (95% CL) on the e+e− final state from the AMS-02 positron fraction data in Ref. [37] as a magenta dot-dashed line which can vary by a factor of 4 − 5 as indicated by yellow shaded band depending on the local DM density and energy loss rate
Summary
The identity of dark matter (DM) is one of the most profound mysteries in particle physics and cosmology. Recent analyses [16,17,18,19,20,21,22,23,24,25] based on the data from Fermi-LAT showed an excess at energies around 1 − 3 GeV in the gamma-ray spectrum coming from around the GC, which is consistent with the emission expected from DM annihilations. We choose annihilations of dark matter intoand bb final states as our reference, and present results in a (mDM, σv ) plane
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