X-ray lines from R-parity violating decays of keV sparticles
  If R-parity is only mildly violated then the lightest supersymmetric particle
(LSP) can be stable over cosmologically time-scales and still account for the
dark matter relic density. We examine the possibility of generating detectable
X-ray lines from R-parity violating decays of keV-scale LSP dark matter to
neutrino-photon pairs. Specifically, we consider scenarios in which the LSP is
a light gravitino, bino, or hidden sector photino. Potential signals are
discussed in the context of recent claims of an unidentified 3.5 keV X-ray line
in studies of stacked galaxy clusters. We comment on the difficulties in
obtaining the observed relic density for keV scale bino or hidden photino dark
matter and some possible resolutions.
