Hidden Dipole Dark Matter
  We consider models where a hidden U(1)' interacts with the Standard Model via kinetic mixing. We assume the dark matter is neutral under this U(1)', but interacts with it via higher dimension operators. In particular, we consider a hidden dipole operator for fermionic dark matter, and charge radius and Rayleigh operators for scalar dark matter. These models naturally explain the absence of direct detection signals, but allow for a thermal cosmology. LHC searches for the Z' represent a powerful probe. 
Aaron Pierce and Zhengkang Zhang
hep-ph