Probing Gravitino Dark Matter with PAMELA and Fermi
  We analyze the cosmic-ray signatures of decaying gravitino dark matter in a
model independent way based on an operator analysis. Thermal leptogenesis and
universal boundary conditions at the GUT scale restrict the gravitino mass to
be below 600 GeV. Electron and positron fluxes from gravitino decays, together
with the standard GALPROP background, cannot explain both, the PAMELA positron
fraction and the electron + positron flux recently measured by Fermi LAT. For
gravitino dark matter, the observed fluxes require astrophysical sources. The
measured antiproton flux allows for a sizable contribution of decaying
gravitinos to the gamma-ray spectrum, in particular a line at an energy below
300 GeV. Future measurements of the gamma-ray flux will provide important
constraints on possible signatures of decaying gravitino dark matter at the
LHC.
