Type IIA superstrings, chiral symmetry, and N=1 4D gauge theory dualities

We study N = 1 four-dimensional gauge theories as the world-volume theory of D4-branes between NS 5-branes. We find constructions for a number of known field theory dualities involving SU(Nc) X SU(N'(c)) groups, coupled by matter fields F in the (N-c,(N) over bar(c)) representation, in terms of branes of type IIA string theory. The dual gauge group follows from simply reversing the ordering of the NS 5-branes and the D6-branes while conserving magnetic charge on the world-volume of the branes. We interpret many field theory phenomena such as deformation of the superpotential W = Tr(F (F) over tilde(k+1) in terms of the position of branes, By looking to D-branes for guidance, we find new N = 1 dualities involving arbitrary numbers of gauge groups. We propose a mechanism for enhanced chiral symmetry in the brane construction which, we conjecture, is associated with tensionless 3-branes in six dimensions. (C) 1997 Elsevier Science B.V.