AN ORIENTIFOLD OF THE SOLITONIC FIVEBRANE

We study an orientifold of the solitonic fivebrane of type II string t heory. The consideration is restricted to a space-time domain which ca n be described by an exact conformal field theory. There are no IR div ergent contributions to tadpole diagrams and thus no consistency condi tions arise. However, extrapolating the results to spatial infinity le ads to consistency conditions implying that there are four (physical) D-6-branes sitting at each of the two orientifold fixed planes. (C) 19 97 Elsevier Science B.V.