M theory fivebrane interpretation for strong coupling dynamics of SO(Nc) gauge theories

We study M theory fivebranes to understand the moduli space of vacua of N=1 supersymmetric SO(Nc) gauge theory with Nf flavors in four dimensions. We discuss how the various branches of this theory arise in the string/M theory brane configurations and compare our results with the ones obtained earlier by Intriligator and Seiberg in the context of field theory. In the M theory approach, we explain the various branches from the asymptotic position of semi-infinite D4 branes in the w=x8+ix9 direction, which is closely related to the eigenvalues of the meson matrix Mij=QiaQja where Qia is a squark multiplet(i=1,⋯,2Nf and a=1,⋯,Nc). In M theory, these branches are explained by observing a new phenomena which did not occur for the gauge groups SU(Nc) or Sp(Nc).