1,721,007 research outputs found
Electric and magnetic interaction of dyonic D-branes and odd spin structure
No full textWe present a general description of electromagnetic RR interactions between pairs of magnetically dual D-branes, focusing on the interaction of a magnetically charged brane with an electrically charged one. In the boundary state formalism, it turns out that while the electric-electric and/or magnetic-magnetic interaction corresponds to the usual RR even spin structure, the magnetic-electric interaction is described by the RR odd spin structure. As representative of the generic case of a dual pair of p and 6-p-branes, we discuss in detail the case of the self-dual 3-brane wrapped on a T-6/Z(3), which looks like an extremal dyonic black hole in four dimensions
Black holes as D-branes on Calabi-Yau threefolds
No full textWe show how an extremal Reissner-Nordstrom black hole can be obtained by wrapping a dyonic D3-brane on a Calabi-Yau manifold. In the orbifold limit T-6/Z(3), We explicitly show the correspondence between the solution of the supergravity equations of motion and the D-brane boundary state description of such a black hole
Anomalous couplings for D-branes and O-planes
Full text linkWe study anomalous Wess-Zumino couplings of D-branes and O-planes in a general background and derive them from a direct string computation by factorizing in the RR channel various one-loop amplitudes, In particular, we find that Op-planes present gravitational anomalous couplings involving the Hirzebruch polynomial (L) over cap, similarly to the roof genus (A) over cap encoding Dp-brane anomalous couplings, We determine, in each case, the precise dependence of these couplings on the curvature of the tangent and normal bundles. (C) 1999 Elsevier Science B.V. All rights reserved.GR-S
Open string models with Scherk-Schwarz SUSY breaking and localized anomalies
No full textWe study examples of chiral four-dimensional IIB orientifolds with Scherk-Schwarz supersymmetry breaking, based on freely acting orbifolds. We construct a new Z_3 x Z_3' model, containing only D9-branes, and rederive from a more geometric perspective the known Z_6' x Z_2' model, containing D9, D5 and \bar D 5 branes. The cancellation of anomalies in these models is then studied locally in the internal space. These are found to cancel through an interesting generalization of the Green-Schwarz mechanism involving twisted Ramond-Ramond axions and four-forms. The effect of the latter amounts to local counterterms from a low-energy effective field theory point of view.We study examples of chiral four-dimensional IIB orientifolds with Scherk–Schwarz supersymmetry breaking, based on freely acting orbifolds. We construct a new Z 3 × Z ′ 3 model, containing only D9-branes, and rederive from a more geometric perspective the known Z ′ 6 × Z ′ 2 model, containing D9, D5 and D 5 branes. The cancellation of anomalies in these models is then studied locally in the internal space. These are found to cancel through an interesting generalization of the Green–Schwarz mechanism involving twisted Ramond–Ramond axions and 4-forms. The effect of the latter amounts to local counterterms from a low-energy effective field theory point of view. We also point out that the number of spontaneously broken U (1) gauge fields is in general greater than what expected from a four-dimensional analysis of anomalies.We study examples of chiral four-dimensional IIB orientifolds with Scherk--Schwarz supersymmetry breaking, based on freely acting orbifolds. We construct a new Z3xZ3' model, containing only D9-branes, and rederive from a more geometric perspective the known Z6'xZ2' model, containing D9, D5 and \bar D 5 branes. The cancellation of anomalies in these models is then studied locally in the internal space. These are found to cancel through an interesting generalization of the Green--Schwarz mechanism involving twisted Ramond--Ramond axions and 4-forms. The effect of the latter amounts to local counterterms from a low-energy effective field theory point of view. We also point out that the number of spontaneously broken U(1) gauge fields is in general greater than what expected from a four-dimensional analysis of anomalies
A note on the torsion dependence of D-brane RR couplings
No full textThe dependence on the torsion H = db of the Wess-Zumino couplings of D-branes that are trivially embedded in space-time is studied. We show that even in this simple set-up some torsion components can be turned on, with a non-trivial effect on the RR couplings. In the special cases in which either the tangent or the normal bundle are trivial, the torsion dependence amounts to substitute the standard curvature with its generalization in the presence of torsion, in the usual couplings involving the roof genus Â. © 2001 Elsevier Science B. V
Non-local symmetry breaking in Kaluza-Klein theories
Full text linkScherk-Schwarz gauge symmetry breaking of a D-dimensional field theory model compactified on a circle is analyzed. It is explicitly shown that forbidden couplings in the unbroken theory appear in the one-loop effective action only in a non-local way, implying that they are finite at all orders in perturbation theory. This result can be understood as a consequence of the local gauge symmetry, but holds true also in the global limit. Similar results for Scherk-Schwarz supersymmetry breaking are expected to hold.Scherk-Schwarz gauge symmetry breaking of a D-dimensional field theory model compactified on a circle is analyzed. It is explicitly shown that forbidden couplings in the unbroken theory appear in the one-loop effective action only in a non-local way, implying that they are finite at all orders in perturbation theory. This result can be understood as a consequence of the local gauge symmetry, but it holds true also in the global limit
Black hole-D-brane correspondence: An example
Full text linkWe explore the connection between D-branes and black holes in one particular case: a D3-brane compactified to four dimensions on T-6/Z(3). Using the D-brane boundary state description, we show the equivalence with a double extremal N = 2 black hole solution of four-dimensional supergravity
Anomalies and inflow on D-branes and O-planes
Full text linkWe derive the general form of the anomaly for chiral spinors and self-dual antisymmetric tensors living on D-brane and O-plane intersections, using both path-integral and index theorem methods. We then show that the anomalous couplings to RR forms of D-branes and O-planes in a general background are precisely those required to cancel these anomalies through the inflow mechanism. This allows, for instance, for local anomaly cancellation in generic orientifold models, the relevant Green-Schwarz term being given by the sum of the anomalous couplings of all the D-branes and O-planes in the model
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