  We propose a method for constructing pairs of nonsupersymmetric gauge
theories related by S-duality. Starting from a known S-duality of
supersymmetric theories realized on the worldvolume of D3 branes in type IIB
string theory, a new duality is obtained by replacing the D3-branes with
antibranes. Large classes of dual pairs of nonsupersymmetric theories can be
obtained in this way, with different interactions and matter content (chiral
and vector-like). The approach is illustrated on gauge theories realized on
three-branes and fractional branes probing orbifold singularities. The duality
sheds light on the dynamics of gauge theories and their possible infrared
phases by providing concrete magnetic dual descriptions of strongly coupled
theories. Some of the models share various properties with QCD, including
confinement and chiral symmetry breaking. More generally, these theories
feature fermions in multiple two-index representations and could realize
intriguing phases such as a free magnetic phase with chiral symmetry breaking
or mixed phases where an interacting fixed point coexists with a confining
phase.
