Microlensing Constraints on the Frequency of Jupiter Mass Planets
  Microlensing is the only technique likely, within the next 5 years, to constrain the frequency of Jupiter-analogs. The PLANET collaboration has monitored nearly 100 microlensing events of which more than 20 have sensitivity to the perturbations that would be caused by a Jovian-mass companion to the primary lens. No clear signatures of such planets have been detected. These null results indicate that Jupiter mass planets with separations of 1.5-3 AU occur in less than 1/3 of systems. A similar limit applies to planets of 3 Jupiter masses between 1-4 AU. 
B. Scott Gaudi, M.D. Albrow, Jin H. An, J.-P. Beaulieu, J.A.R.   Caldwell, D.L. Depoy, M. Dominik, A. Gould, J. Greenhill, K...