Branes and Theta Dependence
  We use the fivebrane of M theory to study the $\theta$ dependence of four dimensional $SU(N_c)$ super Yang-Mills and super QCD softly broken by a gaugino mass. We compute the energy of the vacuum in the supergravity approximation. The results obtained are in qualitative agreement with field theory. We also study the $\theta$ dependence of the QCD string tension via the fivebrane. 
Yaron Oz and Andrea Pasquinucci