Type IIB string

In theoretical physics, type IIB string theory is one of five consistent supersymmetric string theories in ten dimensions. It is based on oriented closed strings.

Orientifold of type IIB string theory leads to type I string theory.

At low energies, type IIB string theory is described by type IIB supergravity in ten dimensions which is a chiral (left-right asymmetric) theory with (2,0) d=10 supersymmetry; the fact that the anomalies in this theory cancel is therefore nontrivial.

In the late 1980s, if was realized that type IIB string theory is related to type IIA string theory by T-duality.

In the 1990s it was realized that type II string theory with the string coupling constant is equivalent to the same theory with the coupling . This equivalence is known as S-duality.