Cosmic Antiprotons as a Probe for Supersymmetric Dark Matter?

Abstract

The Ñux of cosmic-ray antiprotons from neutralino annihilations in the Galactic halo is computed for a large sample of models in the minimal supersymmetric extension of the standard model (MSSM). We also revisit the problem of estimating the background of low-energy cosmic-rayÈinduced secondary antiprotons, taking into account their subsequent interactions (and energy loss) and the presence of nuclei in the interstellar matter. We consider a two-zone di †usion model, with and without a Galactic wind. We Ðnd that, given the uncertainties in the background predictions, there is no need for a primary (exotic) component to explain current data. However, allowing for a signal by playing with the uncertainties in the background estimate, we discuss the characteristic features of the supersymmetric models that give a satisfactory description of the data. We point out that in some cases, the optimal kinetic energy to search for a signal from supersymmetric dark matter is above several GeV, rather than the traditional sub-GeV region. The large astrophysical uncertainties involved do not, on the other hand, allow the exclusion of any of the MSSM models we consider on the basis of data. In addition to numerical results, we also present convenient parameterizations of the antiproton yields of all "" basic ÏÏ two-body Ðnal states. We also give examples of the yield and di †erential energy spectrum for a set of supersymmetric models with high rates. We also remark that it is difficult to set a limit on the antiproton lifetime from present measurements, since the injection of antiprotons from neutralino annihilation can compensate for the loss from decay.

Antiprotons from dark matter: Effects of a position-dependent diffusion coefficient

“…This parameterization fits the results of the PYTHIA Monte-Carlo code [18]. The parameters p i depend on the WIMP mass m χ and, for annihilation into W + W − , can be written as [8] p 1 = (306.0m 0.28…”

“…where n H ∼ 1 cm −3 and n He ∼ 0.07n H are the hydrogen and helium number densities, and σ ann pp (T ) is given by [7,8] …”

The Alpha Magnetic Spectrometer (AMS) on the International Space Station: Part I – results from the test flight on the space shuttle

“…Conventional sources predicted a relatively low ux of antiprotons below 1 GeV whereas the signal expected from neutralino annihilations was relatively high at these energies. However, as was recently demonstrated [4,69], the conventional sources contribute considerable antiproton ux at low energy if one takes into account proton-helium collisions, fermi motion e ects and the so called "tertiary" antiproton component, i.e. the interactions of produced antiprotons.…”

The soft supersymmetry-breaking Lagrangian: theory and applications

“…Unfortunately, the positron signal-to-background ratio is generically extremely low, typically less than 0.01 [441]. An antiproton signal also must fight a large background [548,549,526,550].…”