Ramond-Ramond couplings of D-branes

Applying supersymmetric localization for superstring worldsheet theory with N=(1,1) supersymmetries on a cylinder and with arbitrary boundary interactions, we find the most general formula for the Ramond-Ramond (RR) coupling of D-branes. We allow all massive excitations of open superstrings, and find that only a finite number of them can contribute to the formula. The formula is written by Quillen's superconnection which includes higher form gauge fields, and the resultant general Chern-Simons terms are consistent with RR charge quantization. Applying the formula to boundary string field theory of a BPS D9-brane or a D9-antiD9 brane system, we find that any D9-brane creation via massive mode condensation is impossible.Comment: 24 pages, 1 figur

Type IIA D-Branes, K-Theory, and Matrix Theory

We show that all supersymmetric Type IIA D-branes can be constructed as bound states of a certain number of unstable non-supersymmetric Type IIA D9-branes. This string-theoretical construction demonstrates that D-brane charges in Type IIA theory on spacetime manifold $X$ are classified by the higher K-theory group $K^{-1}(X)$, as suggested recently by Witten. In particular, the system of $N$ D0-branes can be obtained, for any $N$, in terms of sixteen Type IIA D9-branes. This suggests that the dynamics of Matrix theory is contained in the physics of magnetic vortices on the worldvolume of sixteen unstable D9-branes, described at low energies by a U(16) gauge theory.Comment: 32 pages (published version

NS Fivebrane and Tachyon Condensation

We argue that a semi-infinite D6-brane ending on an NS5-brane can be obtained from the condensation of the tachyon on the unstable D9-brane of type IIA theory. The construction uses a combination of the descriptions of these branes as solitons of the worldvolume theory of the D9-brane. The NS5-brane, in particular, involves a gauge bundle which is operator valued, and hence is better thought of as a gerbe.Comment: 20 pages, harvma

Anomaly Cancellations in the Type I D9-anti-D9 System and the USp(32) String Theory

We check some consistency conditions for the D9-anti-D9 system in type I string theory. The gravitational anomaly and gauge anomaly for SO(n) x SO(m) gauge symmetry are shown to be cancelled when n-m=32. In addition, we find that a string theory with USp(n) x USp(m) gauge symmetry also satisfies the anomaly cancellation conditions. After tachyon condensation, the theory reduces to a tachyon-free USp(32) string theory, though there is no spacetime supersymmetry.Comment: 17 pages + 10 eps figures, LaTeX; minor corrections, reference added, version to appear in Prog. Theor. Phy

Non-BPS D9-branes in the Early Universe

We have investigated the finite temperature systems of non-BPS D-branes and D-brane-anti-D-brane pairs in the previous papers. It has been shown that non-BPS D9-branes and D9-anti-D9 pairs become stable near the Hagedorn temperature on the basis of boundary string field theory. This implies that there is a possibility that these spacetime-filling branes exist in the early universe. We study the time evolution of the universe in the presence of non-BPS D9-branes on the basis of boundary string field theory in this paper. We try to construct the following scenario for the early universe: The universe expands at high temperature and the open string gas on the non-BPS D9-branes dominates the total energy of the system at first. The temperature decreases as the universe expands. Then the non-BPS D9-branes become unstable at low temperature and decay through tachyon condensation. We obtain some classical solutions for Einstein gravity and dilaton gravity in the very simple cases.Comment: 26 pages, 9 figures, comments and references added, minor errors corrected, version to appear in JHE

D-brane annihilation, renormalization-group flow and non-linear σ\sigma-model for the ADHM construction

In this note $D9$- and anti-$D9$-brane annihilation in type I string theory is probed by a $D1$-brane. We consider the covariant Green-Schwarz or twistor formulation of the probe theory. We expect the theory to be $\kappa$-invariant after the annihilation is completed. Conditions of the $\kappa$-invariance of the theory impose constraints on the background tachyon field. Solutions to the constraints define tachyon values which correspond to type I $D5$-branes as remnants of the annihilation. As a byproduct we get a theory which lies in the same universality class as the non-linear $\sigma$-model for the Atiyah-Drinfeld-Hitchin-Manin construction.Comment: 11pages, Latex, Language of the text is considerably improve

Superstring 'ending' on super-D9-brane: a supersymmetric action functional for the coupled brane system

A supersymmetric action functional describing the interaction of the fundamental superstring with the D=10, type IIB Dirichlet super-9-brane is presented. A set of supersymmetric equations for the coupled system is obtained from the action principle. It is found that the interaction of the string endpoints with the super-D9-brane gauge field requires some restrictions for the image of the gauge field strength. When those restrictions are not imposed, the equations imply the absence of the endpoints, and the equations coincide either with the ones of the free super-D9-brane or with the ones for the free closed type IIB superstring. Different phases of the coupled system are described. A generalization to an arbitrary system of intersecting branes is discussed.Comment: 44 pages, latex, no figure

Ghost D-branes

We define a ghost D-brane in superstring theories as an object that cancels the effects of an ordinary D-brane. The supergroups U(N|M) and OSp(N|M) arise as gauge symmetries in the supersymmetric world-volume theory of D-branes and ghost D-branes. A system with a pair of D-brane and ghost D-brane located at the same location is physically equivalent to the closed string vacuum. When they are separated, the system becomes a new brane configuration. We generalize the type I/heterotic duality by including n ghost D9-branes on the type I side and by considering the heterotic string whose gauge group is OSp(32+2n|2n). Motivated by the type IIB S-duality applied to D9- and ghost D9-branes, we also find type II-like closed superstrings with U(n|n) gauge symmetry.Comment: 49 pages, 6 figures, harvmac. v2: references and acknowledgements adde