Testing GeV-Scale Dark Matter with Fixed-Target Missing Momentum   Experiments
  We describe an approach to detect dark matter and other invisible particles with mass below a GeV, exploiting missing energy-momentum measurements and other kinematic features of fixed-target production. In the case of an invisibly decaying MeV-GeV-scale dark photon, this approach can improve on present constraints by 2-6 orders of magnitude over the entire mass range, reaching sensitivity as low as $\epsilon^2\sim 10^{-14}$. Moreover, the approach can explore essentially all of the viable parameter space for thermal or asymmetric dark matter annihilating through the vector portal. 
Eder Izaguirre, Gordan Krnjaic, Philip Schuster, and Natalia Toro
hep-ph astro-ph.CO hep-ex nucl-ex