Gamma-ray line from radiative decay of gravitino dark matter
  We study radiative decay of gravitino dark matter with trilinear R-parity
violations. We show that the branching ratio of the decay of gravitino into
monochromatic photon can be large enough to explain the observed gamma-ray line
from the Galactic centre in the Fermi-LAT data without producing too much
continuum gamma-ray and anti-proton flux. This scenario is realized when the
mass of sfermions and the trilinear R-parity violating coupling are $O(1-10)$
TeV and $O(10^{-7}-10^{-6})$ respectively.
