Novel Dark Matter Constraints from Antiprotons in Light of AMS-02

Abstract

We evaluate dark matter (DM) limits from cosmic-ray antiproton observations using the recent precise AMS-02 measurements. We properly take into account cosmic-ray propagation uncertainties, fitting DM and propagation parameters at the same time, and marginalizing over the latter. We find a significant (∼ 4.5 σ) indication of a DM signal for DM masses near 80 GeV, with a hadronic annihilation cross-section close to the thermal value, σv ≈ 3 × 10 −26 cm 3 s −1 . Intriguingly, this signal is compatible with the DM interpretation of the Galactic center gamma-ray excess. Confirmation of the signal will require a more accurate study of the systematic uncertainties, i.e., the antiproton production cross-section, and the modeling of the effect of solar modulation. Interpreting the AMS-02 data in terms of upper limits on hadronic DM annihilation, we obtain strong constraints excluding a thermal annihilation cross-section for DM masses below about 50 GeV and in the range between approximately 150 and 500 GeV, even for conservative propagation scenarios. Except for the range around ∼ 80 GeV, our limits are a factor ∼ 4 stronger than the limits from gamma-ray observations of dwarf galaxies. INTRODUCTIONCosmic-ray (CR) antiprotons are a powerful tool to investigate the particle nature of dark matter (DM), see, for example, [1][2][3][4][5][6][7][8][9][10][11][12][13]. DM constraints from CRs are, however, affected by uncertainties in the description of CR propagation in the Galaxy. Thus, CR DM limits have so far been derived for benchmark propagation models, like the MIN/MED/MAX scenarios [2] obtained from observations of the Boron over Carbon (B/C) ratio. Such benchmark models introduce an order-of-magnitude uncertainty in the DM interpretation of CR fluxes.The antiproton CR spectrum has recently been measured by the AMS-02 experiment with high precision [14]. It is thus timely to evaluate the antiproton DM constraints in the light of the new data. We will improve on previous analyses in two crucial aspects: First, the new AMS-02 data allow us to significantly reduce the uncertainties in the CR propagation. Although B/C data from AMS-02 have been recently published [15], there is, however, evidence that the propagation of heavy nuclei like B and C is different from the propagation of light nuclei like p andp [16] (but, see also [17][18][19]). Thus, using B/C data to constrain CR propagation is likely to introduce a bias when analysing antiprotons. We will instead follow the analysis of Ref. [20] (hereafter KC16) and use the measuredp flux to directly constrain the propagation scenario, thus avoiding any bias. In addition, as a second important new feature, we will constrain CR propagation including a potentialp flux from DM annihilation. Previous analyses have, in contrast, assumed a certain propagation scenario (or a small number of fixed benchmark scenarios) and thus a fixed antiproton background to then constrain a DM contribution in a second step (although, see [11] for an improved approach). Here, with a joint DM and C...

Dark matter physics, flavor physics and LHC constraints in the dark matter model with a bottom partner

“…The blue region is excluded by the bb + E miss T at the LHC, where the production cross section of the extra scalars at the LO exceeds the experimental upper bounds using the same data as the case of extra fermions. Note that the parameter region of figure 8 seems to face the stringent constraint from the latest AMS-02 result [12,13].…”

“…Note that one very strict exclusion limit on the annihilation cross section has been recently reported in refs. [12,13], based on the latest result of the AMS-02 experiment [11]. If we consider the other setups, as discussed in section 4, the upper bound on the annihilation cross section of DM to b b has already excluded the parameter space where the relic density can be explained.…”

“…For instance, the stringent bounds on the setup from the AMS-02 experiment [11] are recently suggested in refs. [12,13]. If the DM mass is below 1 TeV, the annihilation cross section associated with bb and W + W − in the final state should be below the required value for the thermal relic density.…”

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“…The former observes gamma rays coming from the dwarf spheroidal satellite galaxies (dSphs) of the Milky Way and the latter observes anti-protons coming from dark matter annihilations in the Milky Way. We refer the exclusion limit from the AMS-02 experiment obtained in the analysis [83]. 6 The Fermi-LAT experiment also observes gamma-rays coming from the galactic center and this potentially gives significant constraints on the dark matter annihilation rate.…”

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