Supergravity and “new” six-dimensional gauge theories

In the first part of this Letter, we analyse the supergravity dual descriptions of six-dimensional field theories realized on the worldvolume of (p,q) five-branes (OD5 theory). We show that in order for the low-energy gauge theory description to be valid the θ parameter must be rational. Irrational values of θ require a strongly coupled string description of the system at low-energy. We discuss the phase structure and deduce some properties of these theories. In the second part we construct and study the supergravity description of NS5-branes with two electric RR field, which provides a dual description of six-dimensional theories with several light open D-brane excitations.