Constraints on the Dark Photon Parameter Space from Leptonic Rare Kaon   Decays
  With anomalies found in cosmic ray observations and unsolved questions of the Standard Model of particle physics like the discrepancy in the muon's anomalous magnetic moment, the idea of an U(1) extension of the Standard Model arose. This extension allows for the interaction of Dark Matter by exchange of a photon-like massive force carrier $A'$ not included in the Standard Model. We discuss the possibility to constrain the dark photon parameter space by using data taken from rare kaon decays. Therefore we analyze the decay $K\rightarrow \mu \nu A'$ as a signal process and calculate the expected Standard Model background. Using these results we calculate new limits on the $A'$ parameter space, providing motivations for new rare kaon decay experiments to extend the existing $A'$ bounds. 
T. Beranek, M. Vanderhaeghen
hep-ph hep-ex