Type-B/-O bosonic string σ-models

We provide world-sheet non-supersymmetrical actions that describe the coupling of a bosonic string to the tachyon and massless states of both the type-B and type-O theories. The type-B theory is derived as a truncation and chiral doubling of the Ramond-Ramond sector in our previous model that connected the (1, 0) heterotic string to a 10D, type-IIB supergravity backgroud.. The type-O theory then follows from a “fermionization” of the type-B theory.