Strings from orientifolds Original Research Article

We construct models in 1+1 dimensions with chiral (0, N) supersymmetry by taking orientifolds of type IIB on an eight-torus identified by different numbers of reflections. The resulting models have Dirichlet strings, 5-branes and 9-branes stretched along different directions. The cases we study in detail have residual chiral supersymmetry (0, 8), (0, 4) and (0, 2). The gravitational anomaly in all cases is shown to cancel.