Suchergebnisse

24 páginas, 1 tabla.-- El PDF es la versión pre-print (UG-00-15 SU-ITP-01/09 IFT-UAM/CSIC-00-35 KUL-TF-01/06 hep-th/0103233). ; We discuss a generalized form of IIA/IIB supergravity depending on all R-R potentials C(p) (p = 0,1,.,9) as the effective field theory of type IIA/IIB superstring theory. For the IIA case we explicitly break this R-R democracy to either p≤3 or p≥5, which allows us to write a new bulk action that can be coupled to N = 1 supersymmetric brane actions. The case of eight-branes is studied in detail using the new bulk & brane action. The supersymmetric negative-tension branes without matter excitations can be viewed as orientifolds in the effective action. These D8-branes and \mbox{O$8$-planes} are fundamental in type I' string theory. A BPS eight-brane solution is given which satisfies the jump conditions on the wall. It implies a quantization of the mass parameter in string units. Also, we find a maximal distance between the two walls, depending on the string coupling and the mass parameter. We derive the same results via supersymmetric flow equations. ; This work was supported by the European Commission RTN program HPRN-CT-2000- 00131, in which E B is associated with Utrecht University. The work of R K was supported by NSF grant PHY-9870115. The work of T O has been supported in part by the Spanish grant FPA2000-1584. T O would like to thank the CERN Theory Division and the ITP of the University of Groningen for their financial support. ; Peer reviewed