Continuum photon spectrum from Z^1 Z^1 annihilations in universal extra
  dimensions
  We calculate the continuum photon spectrum from the pair annihilation of a
Z^1 LKP in non-minimal universal extra dimensions. We find that, due to the
preferred annihilation into W^+ W^- pairs, the continuum flux of collinear
photons is relatively small compared to the standard case of the B1 as the LKP.
This conclusion applies in particular to the spectral endpoint, where also the
additional fermionic contributions are not large enough to increase the flux
significantly. When searching for the line signal originating from Z^1 Z^1
annihilations, this is actually a perfect situation, since the continuum signal
can be regarded as background to the smoking gun signature of a peak in the
photon flux at an energy that is nearly equal to the mass of the dark matter
particle. This signal, in combination with (probably) a non-observation of the
continuum signal at lower photon energies, constitutes a perfect handle to
probe the hypothesis of the Z1 LKP being the dominant component of the dark
matter observed in the Universe.
