M Theory Fivebrane Interpretation for Strong Coupling Dynamics of $SO(N_{c})$ Gauge Theories

We study M theory fivebrane to understand the moduli space of vacua of $N=1$ supersymmetric $SO(N_c)$ gauge theory with $N_f$ flavors in four dimensions. We discuss how the various branches of this theory arise in string/M theory brane configuration and compare our results with the ones obtained earlier by Intriligator and Seiberg in the context of field theory. In M theory approach, we explain their appearance by finding the asymptotic position of the semiinfinite D4 branes in the $w = x^{8}+i x^{9}$ directions which is closely related to the eigenvalues of meson matrix $M^{ij} = Q^{i}_a Q^{j}_a$ where $Q^{i}_a$ is a squark multiplet ($i=1, \cdots, 2N_f$ and a=1, \cdots, N_c$). In M theory, these branches are explained by observing a new phenomenon which did not occur for the gauge groups $SU(N_c)$ or $Sp(N_c)$