Hidden dipole dark matter

Abstract

We consider models where a hidden $U(1{)}^{\ensuremath{'}}$ interacts with the Standard Model via kinetic mixing. We assume the dark matter is neutral under this $U(1{)}^{\ensuremath{'}}$, but interacts with it via higher-dimensional 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 ${Z}^{\ensuremath{'}}$ represent a powerful probe.