Abstract

I will describe recent work on a new class of dualities, directly inherited from IIB S -duality, in 4d theories with 4 supercharges.

I will focus on the microscopic description of the duality, when realized in terms of system of branes at singularities in string theory. The theories in question are obtained by considering, in addition to the fractional branes, orientifold planes wrapping vanishing 4-cycles.

I will discuss the system from the point of view of large volume branes, focusing in particular on the relevant issues when continuing orientifolds of quiver gauge theories to large volume. This discussion provides a first principles derivation of the relevant orientifolded quivers. By studying the strongly coupled behavior of the resulting orientifold+brane configuration, I will argue for the existance of a dual, weakly coupled description of the strongly coupled quiver theory at the singularity.