Towards complete string effective actions beyond leading order
We review the current knowledge of higher-derivative terms in string effective actions, the various approaches that have been used to obtain them and their applications.
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arXiv subjects
Anders Westerberg
Publications and source records attributed to Anders Westerberg.
The Ramond-Ramond sector of string theory beyond leading order
Present knowledge of higher-derivative terms in string effective actions is, with a few exceptions, restricted to the NS-NS sector, a situation which prevents the development of a variety of interesting applications for which the RR terms are relevant. We here provide the formalism as well as efficient techniques to determine the latter directly from string-amplitude calculations. As an illustration of these methods, we compute the dependence of the type-IIB action on the three- and five-form RR field strengths at four-point, genus-one, order-(alpha')^3 level. We explicitly verify that our results are in accord with the SL(2,Z) S-duality invariance of type-IIB string theory. Extensions of our method to other bosonic terms in the type-II effective actions are discussed as well.
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Supersymmetric higher-derivative actions in ten and eleven dimensions, the associated superalgebras and their formulation in superspace
Higher-derivative terms in the string and M-theory effective actions are strongly constrained by supersymmetry. Using a mixture of techniques, involving both string amplitude calculations and an analysis of supersymmetry requirements, we determine the supersymmetric completion of the R^4 action in eleven dimensions to second order in the fermions, in a form compact enough for explicit further calculations. Using these results, we obtain the modifications to the field transformation rules and determine the resulting field-dependent modifications to the coefficients in the supersymmetry algebra. We then make the link to the superspace formulation of the theory and discuss the mechanism by which higher-derivative interactions lead to modifications to the supertorsion constraints. For the particular interactions under discussion we find that no such modifications are induced.
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Chiral splitting and world-sheet gravitinos in higher-derivative string amplitudes
We report on progress made in the construction of higher-derivative superinvariants for type-II theories in ten dimensions. The string amplitude calculations required for this analysis exhibit interesting features which have received little attention in the literature so far. We discuss two examples from a forthcoming publication: the construction of the (H_{NS})^2 R^3 terms and the fermionic completion of the εεR^4 terms. We show that a correct answer requires very careful treatment of the chiral splitting theorem, implies unexpected new relations between fermionic correlators, and most interestingly, necessitates the use of worldsheet gravitino zero modes in the string vertex operators. In addition, we discuss the relation of our results to the predictions of the linear scalar superfield of the type-IIB theory and find (and explain) an interesting discrepancy.
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Supersymmetric R^4 actions and quantum corrections to superspace torsion constraints
We present the supersymmetrisation of the anomaly-related R^4 term in eleven dimensions and show that it induces no non-trivial modifications to the on-shell supertranslation algebra and the superspace torsion constraints before inclusion of gauge-field terms.
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Super-p-brane actions from interpolating dualisations
We review a recently proposed method for constructing super-p-brane world-volume actions. In this approach, starting from a democratic choice of world-volume gauge-fields guided by p-brane intersection rules, the requirements of kappa-symmetry and gauge invariance can be used to determine the corresponding action. We discuss the application of the method to some cases of interest, notably the (p,q)-5-branes of type-IIB string theory in a manifestly S-duality covariant formulation.
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Supersymmetric brane actions from interpolating dualisations
We explore the possibility of constructing p-brane world-volume actions with the requirements of kappa-symmetry and gauge invariance as the only input. In the process, we develop a general framework which leads to actions interpolating between Poincare-dual descriptions of the world-volume theories. The method does not require any restrictions on the on-shell background configurations or on the dimensions of the branes. After some preliminary studies of low-dimensional cases we apply the method to the type IIB five-branes and, in particular, construct a kappa-symmetric action for the type IIB NS5-brane with a world-volume field content reflecting the fact that the D1-, D3- and D5-branes can end on it.
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Towards a manifestly SL(2,Z)-covariant action for the type IIB (p,q) super-five-branes
We determine a manifestly SL(2,Z)-covariant kappa-symmetric action for the type IIB (p,q) five-branes as a perturbative expansion in the world-volume field strengths within the framework where the brane tension is generated by a world-volume field. In this formulation the Lagrangian is expected to be polynomial; we construct the kappa-invariant action to fourth order in the world-volume field strengths.
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World-volume fields, SL(2;Z) and duality: The type IIB 3-brane
We propose a method for constructing super-brane actions where every background tensor potential corresponds to a world-volume field strength. The procedure provides a natural coupling to the background and automatically displays the SL(2;Z) symmetry of the IIB string theory. The Dirichlet 3-brane is used as a test ground for these ideas. A polynomial action consistent with non-linear self-duality is presented. Invariance of the action under kappa-symmetry is demonstrated for arbitrary on-shell type IIB supergravity backgrounds and is shown to require self-duality.
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On higher-dimensional loop algebras, pseudodifferential operators and Fock space realizations
We discuss a previously discovered [hep-th/9401027] extension of the infinite-dimensional Lie algebras Map(M,g) which generalizes the Kac-Moody algebras in 1+1 dimensions and the Mickelsson-Faddeev algebras in 3+1 dimensions to manifolds M of general dimensions. Furthermore, we review the method of regularizing current algebras in higher dimensions using pseudodifferential operator (PSDO) symbol calculus. In particular, we discuss the issue of Lie algebra cohomology of PSDOs and its relation to the Schwinger terms arising in the quantization process. Finally, we apply this regularization method to the algebra of the above reference with partial success, and discuss the remaining obstacles to the construction of a Fock space representation.
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The Dirichlet Super-p-Branes in Ten-Dimensional Type IIA and IIB Supergravity
We give the full supersymmetric and kappa-symmetric actions for the Dirichlet p-branes, including their coupling to background superfields of ten-dimensional type IIA and IIB supergravity.
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The Dirichlet Super-Three-Brane in Ten-Dimensional Type IIB Supergravity
We give the full supersymmetric and kappa-symmetric action for the Dirichlet three-brane, including its coupling to background superfields of ten-dimensional type IIB supergravity.
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On the Dirac-Born-Infeld Action for D-branes
In this note, we consider the reformulation of the Dirac-Born-Infeld action for a Dirichlet p-brane in Brink-Di Vecchia-Howe-Tucker form, i.e., including an independent non-propagating world-volume metric. When p>2, the action becomes non-polynomial. A closed expression is derived for p=3. For selfdual field-strengths, the DBI action is reproduced by an action with a simple F^2 term. We speculate on supersymmetrization of the D_3-brane action. We also give the governing equations for arbitrary p, and derive an implicit expression for the D_4-brane lagrangian.
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Schwinger Terms and Cohomology of Pseudodifferential Operators
We study the cohomology of the Schwinger term arising in second quantization of the class of observables belonging to the restricted general linear algebra. We prove that, for all pseudodifferential operators in 3+1 dimensions of this type, the Schwinger term is equivalent to the ``twisted'' Radul cocycle, a modified version of the Radul cocycle arising in non-commutative differential geometry. In the process we also show how the ordinary Radul cocycle for any pair of pseudodifferential operators in any dimension can be written as the phase space integral of the star commutator of their symbols projected to the appropriate asymptotic component.
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The Twisted String Vertex Algorithm Applied to the $Z_2$-Twisted Scalar String Four Vertex
Recently an algorithm was found by means of which one can calculate terms at arbitrary oscillator level in the four-Ramond vertex obtained by sewing. Here we show that this algorithm is applicable also to the case of ${\bf Z}_2$-twisted scalars and derive the full propagator for scalars on the Riemann sphere with two branch cuts. The relation to similar results previously derived in the literature by other means is discussed briefly.
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