arXiv subjects

M. de Roo

Publications and source records attributed to M. de Roo.

At least 19 recordsLinked to original sources

arXiv2011

Newtonian Gravity and the Bargmann Algebra

We show how the Newton-Cartan formulation of Newtonian gravity can be obtained from gauging the Bargmann algebra, i.e., the centrally extended Galilean algebra. In this gauging procedure several curvature constraints are imposed. These convert the spatial (time) translational symmetries of the algebra into spatial (time) general coordinate transformations, and make the spin connection gauge fields dependent. In addition we require two independent Vielbein postulates for the temporal and spatial directions. In the final step we impose an additional curvature constraint to establish the connection with (on-shell) Newton-Cartan theory. We discuss a few extensions of our work that are relevant in the context of the AdS-CFT correspondence.

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arXiv2003

Potential and mass-matrix in gauged N=4 supergravity

We discuss the potential and mass-matrix of gauged N=4 matter coupled supergravity for the case of six matter multiplets, extending previous work by considering the dependence on all scalars. We consider all semi-simple gauge groups and analyse the potential and its first and second derivatives in the origin of the scalar manifold. Although we find in a number of cases an extremum with a positive cosmological constant, these are not stable under fluctuations of all scalar fields.

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arXiv2002

De Sitter solutions in N=4 matter coupled supergravity

We investigate the scalar potential of gauged N=4 supergravity with matter. The extremum in the SU(1,1)/U(1) scalars is obtained for an arbitrary number of matter multiplets. The constraints on the matter scalars are solved in terms of an explicit parametrisation of an SO(6,6+n) element. For the case of six matter multiplets we discuss both compact and noncompact gauge groups. In an example involving noncompact groups and four scalars we find a potential with an absolute minimum and a positive cosmological constant.

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arXiv2002

Supersymmetric Yang-Mills theory at order alpha'^3

We construct the order alpha'^3 terms in the supersymmetric Yang-Mills action in ten dimensions for an arbitrary gauge group. The result can be expressed in terms of the structure constants of the Yang-Mills group, and is therefore independent of abelian factors. The alpha'^3 invariant obtained here is independent of the alpha'^2 invariant, and we argue that additional superinvariants will occur at all odd orders of alpha'.

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arXiv2001

Supersymmetric non-abelian Born-Infeld revisited

We determine the non-abelian Born-Infeld action, including fermions, as it results from the four-point tree-level open superstring scattering amplitudes at order alpha'^2. We find that, after an appropriate field redefinition all terms at this order can be written as a symmetrised trace. We confront this action with the results that follow from kappa-symmetry and conclude that the recently proposed non-abelian kappa-symmetry cannot be extended to cubic orders in the Born-Infeld curvature.

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arXiv2000

On the supersymmetric non-abelian Born-Infeld action

We review an iterative construction of the supersymmetric non-abelian Born-Infeld action. We obtain the action through second order in the fieldstrength. Kappa-invariance fixes the ordenings which turn out to deviate from the symmetrized trace proposal.

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arXiv2000

Non-abelian Born-Infeld and kappa-symmetry

We define an iterative procedure to obtain a non-abelian generalization of the Born-Infeld action. This construction is made possible by the use of the severe restrictions imposed by kappa-symmetry. In this paper we will present all bosonic terms in the action up to terms quartic in the Yang-Mills field strength and all fermion bilinear terms up to terms cubic in the field strength. Already at this order the fermionic terms do not satisfy the symmetric trace-prescription.

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arXiv2000

Towards a supersymmetric non-abelian Born-Infeld theory

We define an iterative procedure to obtain a non-abelian generalization of the Born-Infeld action. This construction is made possible by the use of the severe restrictions imposed by kappa-symmetry. We have calculated all bosonic terms in the action up to terms quartic in the Yang-Mills field strength and all fermion bilinear terms up to terms cubic in the field strength. Already at this order the fermionic terms do not satisfy the symmetric trace-prescription.

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arXiv2000

T-duality and Actions for Non-BPS D-branes

We employ T-duality to restrict the tachyon dependence of effective actions for non-BPS D-branes. For the Born-Infeld part the criteria of T-duality and supersymmetry are satisfied by a simple extension of the D-brane Born-Infeld action.

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arXiv1998

Intersecting Branes in Matrix Theory

We construct BPS states in the matrix description of M-theory. Starting from a set of basic M-theory branes, we study pair intersections which preserve supersymmetry. The fractions of the maximal supersymmetry obtained in this way are 1/2, 1/4, 1/8, 3/16 and 1/16. In explicit examples we establish that the matrix BPS states correspond to (intersecting) brane configurations that are obtained from the d=11 supersymmetry algebra. This correspondence for the 1/2 supersymmetric branes includes the precise relations between the charges.

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arXiv1998

Unstable vortices do not confine

Recently, a geometric model for the confinement of magnetic charges in the context of type II string compactifications was constructed by Greene, Morrison and Vafa. This model assumes the existence of stable magnetic vortices with quantized flux in the low energy theory. However, quantization of flux alone does not imply that the vortex is stable, since the flux may not be confined to a tube of definite size. We show that in the field theoretical model which underlies the geometric model of confinement, static, cylindrically symmetric magnetic vortices do not exist. While our results do not preclude the existence of confinement in a different low-energy regime of string theory, they show that confinement is not a universal outcome of the string picture, and its origin in the low energy theory remains to be understood.

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arXiv1997

Intersections involving waves and monopoles in eleven dimensions

We consider intersections in eleven dimensions involving Kaluza-Klein monopoles and Brinkmann waves. Besides these purely gravitational configurations we also construct solutions to the equations of motion that involve additional M2- and M5-branes. The maximal number of independent objects in these intersections is nine, and such maximal configurations, when reduced to two dimensions, give rise to a 0-brane solution with dilaton coupling a=-4/9.

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arXiv1997

Gauged Supergravity from Dimensional Reduction

We perform a generalised Scherk-Schwarz reduction of the effective action of the heterotic string on T^6 to obtain a massive N=4 supergravity theory in four dimensions. The local symmetry-group of the resulting d=4 theory includes a Heisenberg group, which is a subgroup of the global O(6,6+n) obtained in the standard reduction. We show explicitly that the same theory can be obtained by gauging this Heisenberg group in d=4, N=4 supergravity.

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arXiv1997

Intersecting branes and Supersymmetry

We consider intersecting M-brane solutions of supergravity in eleven dimensions. Supersymmetry turns out to be a powerful tool in obtaining such solutions and their generalizations.

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arXiv1997

Multiple Intersections of D-branes and M-branes

We give a classification of all multiple intersections of D-branes in ten dimensions and M-branes in eleven dimensions that corresponds to threshold BPS bound states. The residual supersymmetry of these composite branes is determined. By dimensional reduction composite p-branes in lower dimensions can be constructed. We emphasize in dimensions D greater or equal than two, those solutions which involve a single scalar and depend on a single harmonic function. For these extremal branes we obtain the strength of the coupling between the scalar and the gauge field. In particular we give a D-brane and M-brane interpretation of extreme p-branes in two, three and four dimensions.

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arXiv1996

Four-dimensional High-Branes as Intersecting D-Branes

We show that a class of extremal four-dimensional supersymmetric ``high-branes'', i.e. string and domain wall solutions, can be interpreted as intersections of four ten-dimensional Dirichlet branes. These $d=4$ solutions are related, via $T$-duality in ten dimensions, to the four-dimensional extremal Maxwell/scalar black holes that are characterized by a scalar coupling parameter $a$ with $a=0,1/\sqrt{3}, 1, \sqrt{3}$.

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arXiv1996

Duality of Type II 7-branes and 8-branes

We present a version of ten-dimensional IIA supergravity containing a 9-form potential for which the field equations are equivalent to those of the standard, massless, IIA theory for vanishing 10-form field strength, $F_{10}$, and to those of the `massive' IIA theory for non-vanishing $F_{10}$. We present a multi 8-brane solution of these equations that generalizes the 8-brane of Polchinski and Witten. We show that this solution is T-dual to a new multi 7-brane solution of $S^1$ compactified IIB supergravity, and that the latter is T-dual to the IIA 6-brane. When combined with the $Sl(2;\Z)$ U-duality of the type IIB superstring, the T-duality between type II 7-branes and 8-branes implies a quantization of the cosmological constant of type IIA superstring theory. These results are made possible by the construction of a new {\it massive} N=2 D=9 supergravity theory. We also discuss the 11-dimensional interpretation of these type II p-branes.

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arXiv1996

D-branes and T-duality

We show how the $T$--duality between $D$--branes is realized (i) on $p$--brane solutions $(p=0,\cdots ,9)$ of IIA/IIB supergravity and (ii) on the $D$--brane actions ($p=0,\cdots ,3)$ that act as source terms for the $p$--brane solutions. We point out that the presence of a cosmological constant in the IIA theory leads, by the requirement of gauge invariance, to a topological mass term for the worldvolume gauge field in the 2--brane case.

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