Searcharxiv⌕ Search

arXiv subjects

Douglas J. Smith

Publications and source records attributed to Douglas J. Smith.

At least 37 records · Page 2Linked to original sources
arXiv2012

Supersymmetric Chern-Simons Theory in Presence of a Boundary

In this paper we analyse super-Chern-Simons theory in $\mathcal{N} =1$ superspace formalism, in the presence of a boundary. We modify the Lagrangian for the Chern-Simons theory in such a way that it is supersymmetric even in the presence of a boundary. Also, even though the Chern-Simons theory is not gauge invariant in the presence of a boundary, if it is suitable coupled to a gauged Wess-Zumino-Witten model, then the resultant theory can be made gauge invariant. Thus, by suitably adding extra boundary degrees of freedom, the gauge and supersymmetry variations of the boundary theory exactly cancel the boundary terms generated by the variations of the bulk Chern-Simons theory. We also discuss how this can be applied to the ABJM model in $\mathcal{N} =1$ superspace, and we then describe the BRST and anti-BRST symmetries of the resultant gauge invariant supersymmetric theory.

hep-th↗
arXiv2009

Multiple Self-Dual Strings on M5-Branes

We show how to define Chern-Simons matter theories with boundary. Rather than imposing boundary conditions, we introduce new boundary degrees of freedom from the beginning and show how they can be used to cancel the gauge non-invariance of the Chern-Simons action. We apply this method to the ABJM theory with boundary. By imposing also boundary conformal invariance, we determine the required boundary action. This result allows us to derive the action for the multiple self-dual strings living on M5-branes.

hep-th↗
arXiv2009

Topological charges in SL(2,R) covariant massive 11-dimensional and Type IIB SUGRA

In this paper we construct closed expressions that correspond to the topological charges of the various 1/2-BPS states of the maximal 10 and 11-dimensional supergravity theories. These expressions are related to the structure of the SUSY algebras in curved spacetimes. We mainly focus on IIB SUGRA and 11-dimensional SUGRA in a double M9-brane background, with an emphasis on the SL(2,R) multiplet structure of the charges and how these map between theories. This includes the charges corresponding to the multiplets of 7- and 9-branes in IIB. We find that examining the possible multiplet structures of the charges provides another tool for exploring the spectrum of BPS states that appear in these theories. As a prerequisite to constructing the charges we determine the field equations and multiplet structure of the 11-dimensional gauge potentials, extending previous results on the subject. The massive gauge transformations of the fields are also discussed. We also demonstrate how these massive gauge transformations are compatible with the construction of an SL(2,R) covariant kinetic term in the 11-dimensional Kaluza-Klein monopole worldvolume action.

hep-th↗
arXiv2008

AdS/CFT Duality for Non-Anticommutative Supersymmetric Gauge Theory

We construct type IIB supergravity duals of non-anticommutative deformed N = 4 SU(N) gauge theories. We consider in particular deformations preserving N = (1,0) and N = (1/2,0) supersymmetry. Such theories can be realised on N D3-branes in specific self-dual 5-form backgrounds. We show that the required 5-form field strengths can be produced by configurations of intersecting D3-branes and we are then able to construct the supergravity solutions in the near-horizon limit. We consider some consequences of this duality, in particular showing that the gravity duals predict that the dimensions of a subset of BPS operators are not modified by the deformation.

hep-th↗
arXiv2008

Topological BPS charges in 10 and 11-dimensional supergravity

We consider the supersymmetry algebras of the 10 and 11 dimensional maximal supergravities. We construct expressions from which the topological charge structure of the algebras can be determined in supersymmetric curved backgrounds. These are interpreted as the topological charges of the 1/2-BPS states that are found in the theories. We consider charges for all the M-, NS- and D-branes as well as the Kaluza Klein monopoles. We also show that the dimensional reduction relations between the 11-d and IIA charges, and T-duality relations of the IIA and IIB charges match those found for the branes themselves. Finally we consider the massive versions of the IIA and 11-d theories and find that the expressions for the charges, with a slight modification, are still valid in those instances.

hep-th↗
arXiv2006

Central charges of wrapped M5-brane backgrounds

We study the central charges of the supersymmetry algebra of branes in backgrounds corresponding to wrapped M5-branes. In the case of M5-branes wrapping a holomorphic 2-cycle in two complex-dimensional space, we find this allows for a supersymmetric M5-brane probe which is related to the M2-brane probe which describes the BPS spectra of the corresponding N=2 worldvolume gauge theory. For the case of M5-branes wrapping a holomorphic 2-cycle in three complex-dimensional space, we find that the central charges allow for a supersymmetric M5-brane probe wrapping a Cayley calibrated 4-cycle, which has an intersecting BPS domain wall interpretation in the corresponding N=1 MQCD gauge theory. The domain wall is constructed explicitly as an M5-brane wrapping an associative 3-cycle. The tension is found to be the integral of a calibrating form. These wrapped M5-brane backgrounds provide a clear and interesting geometrical realisation of structure groups of M-theory vacua with fluxes.

hep-th↗
arXiv2005

Four-dimensional SYM probes in wrapped M5-brane backgrounds

We study the worldvolume supersymmetric gauge theory of M-branes probing backgrounds corresponding to wrapped M5-branes. In the case of M5-branes wrapping a 2-cycle in two-dimensional complex space, we use M2-brane probes to compute the BPS spectra of the corresponding N=2 gauge theory as well as M5-brane probes to calculate field theory parameters such as the gauge coupling, theta angle and complex scalar moduli space metric. This background describes a large class of Hanany-Witten type models when dimensionally reduced to Type IIA 10d string theory. We calculate the instanton action using a D0-brane probe in this limit. For the case of M5-branes wrapping a 2-cycle in three-dimensional complex space, we firstly show an alternative method to derive this solution involving the projection conditions and certain spinor bilinear differential equations. We also consider M5-brane probes of this background, and analyse the corresponding N=1 MQCD gauge theory parameters. In general there were no supergravity corrections to field theory parameters when compared to previous flat-space field theory analysis.

hep-th↗
arXiv2004

On Gauss-Bonnet black hole entropy

We investigate the entropy of black holes in Gauss-Bonnet and Lovelock gravity using the Noether charge approach, in which the entropy is given as the integral of a suitable (n-2) form charge over the event horizon. We compare the results to those obtained in other approaches. We also comment on the appearance of negative entropies in some cases, and show that there is an additive ambiguity in the definition of the entropy which can be appropriately chosen to avoid this problem.

gr-qc↗
arXiv2004

On the non-existence of totally localised intersections of D3/D5 branes in type IIB SUGRA

In the present paper we study the most general configuration of intersecting D3/D5 branes in type IIB supergravity satisfying Poincare invariance in the directions common to the branes and SO(3) symmetry in the totally perpendicular directions. The form of these configurations is greatly restricted by the Killing spinor equations and the equations of motion, which among other things, force the Ramond-Ramond scalar to be zero and do not permit the existence of totally localised intersections of this kind.

hep-th↗
arXiv2004

Type IIB Killing spinors and calibrations

In this paper we derive the full set of differential equations and some algebraic relations for p-forms constructed from type IIB Killing spinors. These equations are valid for the most general type IIB supersymmetric backgrounds which have a non-zero NS-NS 3-form field strength, H, and non-zero R-R field strengths, G^{(1)}, G^{(3)} and G^{(5)}. Our motivation is to use these equations to obtain generalised calibrations for branes in supersymmetric backgrounds. In particular, we consider giant gravitons in AdS_5 x S^5. These non-static branes have an interesting construction via holomorphic surfaces in C^{1,2} x C^3. We construct the p-forms corresponding to these branes and show that they satisfy the correct differential equations. Moreover, we interpret the equations as calibration conditions and derive the calibration bound. We find that giant gravitons minimise ``energy minus momentum''.

hep-th↗
arXiv2003

Topological charges for branes in M-theory

We propose a simple form for the superalgebra of M2 and M5-brane probes in arbitrary supersymmetric backgrounds of 11D supergravity, extending previous results in the literature. In particular, we identify the topological charges in the algebras and find BPS bounds for the energies. The charges are given by the integral over a brane's spatial worldvolume of a certain closed form built out of the Killing spinors and background fields. The existence of such closed forms for arbitrary supersymmetric backgrounds generalises the existence of calibration forms for special holonomy manifolds.

hep-th↗
arXiv2003

Intersecting brane solutions in string and M-theory

We review various aspects of configurations of intersecting branes, including the conditions for preservation of supersymmetry. In particular, we discuss the projection conditions on the Killing spinors for given brane configurations and the relation to calibrations. This highlights the close connection between intersecting branes and branes wrapping supersymmetric cycles as well as special holonomy manifolds. We also explain how these conditions can be used to find supergravity solutions without directly solving the Einstein equations. The description of intersecting branes is considered both in terms of the brane worldvolume theories and as supergravity solutions. There are well-known simple procedures (harmonic function rules) for writing down the supergravity solutions for supersymmetric configurations of orthogonally intersecting branes. However, such solutions involve smeared or delocalised branes. We describe several methods of constructing solutions with less smearing, including some fully localised solutions. Some applications of these supergravity solutions are also considered - in particular the study of black holes and gauge theories.

hep-th↗
arXiv2002

Giant gravitons as probes of gauged supergravity

We consider giant graviton probes of 11-dimensional supergravity solutions which are lifts of arbitrary solutions of 4-dimensional U(1)^4 and 7-dimensional U(1)^2 gauged supergravities. We show that the structure of the lift ansatze is sufficient to explicitly find a solution for the embedding and motion of the M5- or M2-brane in the internal space. The brane probe action then reduces to that of a massive charged particle in the gauged supergravity, demonstrating that probing the gauged supergravity with such particles is equivalent to the more involved 11-dimensional brane probe calculation. As an application of this we use these particles to probe superstar geometries which are conjectured to be sourced by giant gravitons.

hep-th↗
arXiv2002

Giant gravitons in non-supersymmetric backgrounds

We consider giant gravitons as probes of a class of ten-dimensional solutions of type IIB supergravity which arise as lifts of solutions of U(1)^3 gauged N=2 supergravity in five-dimensions. Surprisingly it is possible to solve exactly for minimum energy configurations of these spherical D3-brane probes in the compact directions, even in backgrounds which preserve no supersymmetry. The branes behave as massive charged particles in the five non-compact dimensions. As an example we probe geometries which are believed to represent the supergravity background of coherent states of giant gravitons. We comment on the apparently repulsive nature of the naked singularities in these geometries.

hep-th↗
arXiv2001

N=1 M5-brane geometries

We describe how to construct solutions to 11-dimensional supergravity corresponding to M5-branes wrapped on holomorphic 2-cycles embedded in C^3. These solutions preserve N=1 supersymmetry in four dimensions. In the near-horizon limit they are expected to be dual to N=1 large N gauge theories in four dimensions by Maldacena's duality.

hep-th↗
arXiv2000

Supergravity M5-branes wrapped on Riemann surfaces and their QFT duals

We find solutions of 11-dimensional supergravity for M5-branes wrapped on Riemann surfaces. These solutions preserve ${\cal N} = 2$ four-dimensional supersymmetry. They are dual to ${\cal N} = 2$ gauge theories, including non-conformal field theories. We work out the case of ${\cal N} = 2$ Yang-Mills in detail.

hep-th↗
arXiv1999

Localized intersections of M5-branes and four-dimensional superconformal field theories

We write supersymmetry preserving conditions for infinite M5-branes intersecting on a (3+1)-dimensional space. In contrast to previously known solutions, these intersections are completely localized. We solve the equations for a particular class of configurations which in the near-horizon decoupling limit are dual to N_f = 2N_c Seiberg-Witten superconformal field theories with gauge group SU(N) and generalisations to SU(N)^n. We also discuss the relationship to D3-branes in the presence of an A_k singularity.

hep-th↗