Papers by Joris Raeymaekers
The Journal of high energy physics/The journal of high energy physics, May 24, 2024
Superconformal 'type B' quantum mechanical sigma models arise in a variety of interesting context... more Superconformal 'type B' quantum mechanical sigma models arise in a variety of interesting contexts, such as the description of D-brane bound states in an AdS 2 decoupling limit. Focusing on N = 2B models, we study superconformal indices which count short multiplets and provide an alternative to the standard Witten index, as the latter suffers from infrared issues. We show that the basic index receives contributions from lowest Landau level states in an effective magnetic field and that, due to the noncompactness of the target space, it is typically divergent. Fortunately, the models of interest possess an additional target space isometry which allows for the definition of a well-behaved refined index. We compute this index using localization of the functional integral and find that the result agrees with a naive application of the Atiyah-Bott fixed point formula outside of it's starting assumptions. In the simplest examples, this formula can also be directly verified by explicitly computing the short multiplet spectrum.
arXiv (Cornell University), Jan 27, 2023
Nuclear Physics B, May 1, 1999
We present a convenient method for deriving the transformation of the dilaton under T-duality in ... more We present a convenient method for deriving the transformation of the dilaton under T-duality in the path-integral approach. Subtleties arising in performing the integral over the gauge fields are carefully analysed using Pauli-Villars regularization, thereby clarifying existing ambiguities in the literature. The formalism can not only be applied to the abelian case, but, and this for the first time, to the non-abelian case as well. Furthermore, by choosing a particular gauge, we directly obtain the target-space covariant expression for the dual geometry in the abelian case. Finally it is shown that the conditions for gauging non-abelian isometries are weaker than those generally found in the literature.
Journal of High Energy Physics, Apr 1, 2010
We give a simple nonsupersymmetric example in which chronology protection follows from unitarity ... more We give a simple nonsupersymmetric example in which chronology protection follows from unitarity and the AdS/CFT correspondence. We consider a ball of homogeneous, rotating dust in global AdS3 whose backreaction produces a region of Gödel space inside the ball. We solve the Israel matching conditions to find the geometry outside of the dust ball and compute its quantum numbers in the dual CFT. When the radius of the dust ball exceeds a certain critical value, the spacetime will contain closed timelike curves. Our main observation is that precisely when this critical radius is exceeded, a unitarity bound in the dual CFT is violated, leading to a holographic argument for chronology protection.
Journal of High Energy Physics, Apr 23, 2007
We present a simple example of a supersymmetric attractor mechanism in the purely open string con... more We present a simple example of a supersymmetric attractor mechanism in the purely open string context of D-branes embedded in curved space-time. Our example involves a class of D3-branes embedded in the 2-charge D1-D5 background of type IIB whose worldvolume contains a 2-sphere. Turning on worldvolume fluxes, these branes carry induced (p, q) string charges. Supersymmetric configurations display a flow of the open string moduli towards an attractor solution independent of their asymptotics. The equations governing this mechanism closely resemble the attractor flow equations for supersymmetric black holes in closed string theory. The BPS equations take the form of a gradient flow and describe worldvolume solitons interpolating between an AdS 2 geometry where the two-sphere has collapsed, and an attractor solution with AdS 2 × S 2 geometry. In these limiting solutions, the preserved supersymmetry is enhanced from 4 to 8 supercharges. We also discuss the interpretation of our solutions as intersecting brane configurations placed in the D1-D5 background, as well as the S-duality transformation to the F1-NS5 background.
Journal of High Energy Physics, Oct 10, 2008
Journal of High Energy Physics, Dec 6, 2006
We construct supersymmetric D-brane probe solutions in the background of the 2-charge D1-D5 syste... more We construct supersymmetric D-brane probe solutions in the background of the 2-charge D1-D5 system on M, where M is either K3 or T 4. We focus on 'nearhorizon bound states' that preserve supersymmetries of the near-horizon AdS 3 ×S 3 ×M geometry and are static with respect to the global time coordinate. We find a variety of half-BPS solutions that span an AdS 2 subspace in AdS 3 , carry worldvolume flux and can wrap an S 2 within S 3 and/or supersymmetric cycles in M.
Journal of High Energy Physics, Feb 18, 2005
The C/Z N orbifold of type II string theory has localized tachyons with m 2 ranging from −1 + 1/N... more The C/Z N orbifold of type II string theory has localized tachyons with m 2 ranging from −1 + 1/N to −2/N in units of 2/α ′. We show that by restricting attention to the lightest tachyons it is possible to take a zero-slope limit where N is taken to infinity while N α ′ is held fixed. This is done by applying Buscher duality in the angular direction of the cone to obtain a supergravity solution on which the tachyons are gravitational instabilities. In this picture, supergravity provides a natural off-shell description of the tachyonic interactions. For example, the three-point couplings can be read off easily (to leading order in 1/N) from the supergravity action, and are in agreement with the on-shell couplings computed using CFT techniques.
Journal of High Energy Physics, Oct 23, 2004
Journal of High Energy Physics, Feb 1, 2008
We construct probe solutions in the attractor background of the fivedimensional D1-D5-P black hol... more We construct probe solutions in the attractor background of the fivedimensional D1-D5-P black hole which represent near-horizon microstates in the limit of large D1-charge. These generalize the corresponding solutions considered by Gaiotto, Strominger and Yin for the 4-dimensional D0-D4 black hole. Using U-duality and a 4D-5D connection, we argue that the relevant configurations are bound states of D1branes that have expanded through the Myers effect to form a Kaluza-Klein monopole wrapping the black hole horizon. We show that these branes experience a magnetic field on their moduli space, and that the degeneracy of lowest Landau levels reproduces the Bekenstein-Hawking entropy. Contents 1. Introduction and summary 1 2. The D0-D4 black hole in type IIA 4 2.1 Background 4 2.2 Horizon-wrapping membranes and their symmetries 5 2.3 Landau levels on moduli space and microstate counting 7 3. U-duality and the D1-D5-P-KK black hole 9 3.1 Duality chain 9 3.2 The worldvolume action for a KK monopole 11 3.3 Horizon-wrapping KK-monopoles and their symmetries 13 3.4 Moduli space dynamics and state counting 14 4. 4D-5D connection and the D1-D5-P black hole 15 5. Discussion and outlook 17
Journal of High Energy Physics, 2010
We show that M-theory admits a supersymmetric compactification to the Gödel universe of the form ... more We show that M-theory admits a supersymmetric compactification to the Gödel universe of the form Gödel 3 ×S 2 ×CY 3. We interpret this geometry as coming from the backreaction of M2-branes wrapping the S 2 in an AdS 3 ×S 2 ×CY 3 flux compactification. In the black hole deconstruction proposal similar states give rise to the entropy of a D4-D0 black hole. The system is effectively described by a three-dimensional theory consisting of an axion-dilaton coupled to gravity with a negative cosmological constant. Other embeddings of the three-dimensional theory imply similar supersymmetric Gödel compactifications of type IIA/IIB string theory and F-theory.
We present a brief historical overview of the classical theory of a radiating point charge, descr... more We present a brief historical overview of the classical theory of a radiating point charge, described by the Lorentz-Dirac equation. A recent development is the discovery of tunnelling of a charge through a potential barrier, in a completely classical context. Also, a concrete example is discussed of the existence of several physically acceptable solutions for a range of initial data. We end by pointing out some open problems in connection with D-brane and monopole physics.
Fortschritte der Physik, May 1, 2007
In [1], Gaiotto, Strominger and Yin proposed a novel way of counting black hole microstates by co... more In [1], Gaiotto, Strominger and Yin proposed a novel way of counting black hole microstates by counting the quantum mechanical ground states of probe branes placed in the near-horizon black hole background. We discuss the generalization of this proposal to the case of two-charge D0-D4 'small' black holes in type IIA. We also describe the construction of BPS D-brane probes in the near-horizon region of the 2-charge D1-D5 system in type IIB. Based on [5],[6].
Journal of High Energy Physics, May 22, 2004
Off-shell interactions for localized closed-string tachyons in C/Z N superstring backgrounds are ... more Off-shell interactions for localized closed-string tachyons in C/Z N superstring backgrounds are analyzed and a conjecture for the effective height of the tachyon potential is elaborated. At large N, some of the relevant tachyons are nearly massless and their interactions can be deduced from the S-matrix. The cubic interactions between these tachyons and the massless fields are computed in a closed form using orbifold CFT techniques. The cubic interaction between nearly-massless tachyons with different charges is shown to vanish and thus condensation of one tachyon does not source the others. It is shown that to leading order in N, the quartic contact interaction vanishes and the massless exchanges completely account for the four point scattering amplitude. This indicates that it is necessary to go beyond quartic interactions or to include other fields to test the conjecture for the height of the tachyon potential.
SciPost Physics
In this work we discuss the holographic description of states in the Hilbert space of (2+1)-dimen... more In this work we discuss the holographic description of states in the Hilbert space of (2+1)-dimensional quantum gravity, living on a time slice in the bulk. We focus on pure gravity coupled to pointlike sources for heavy spinning particles. We develop a formulation where the equations for the backreacted metric reduce to two decoupled Liouville equations with delta-function sources under pseudosphere boundary conditions. We show that both the semiclassical wavefunction and the gravity solution are determined by a universal object, namely a classical Virasoro vacuum block on the sphere. In doing so we derive a version of Polyakov’s conjecture, as well as an existence criterion, for classical Liouville theory on the pseudosphere. We also discuss how some of these results are modified when considering closed universes with compact spatial slices.
Journal of High Energy Physics
We perform a nontrivial check of Witten’s recently proposed admissibility criterion for complex m... more We perform a nontrivial check of Witten’s recently proposed admissibility criterion for complex metrics. We consider the ‘quasi-Euclidean’ metrics obtained from continuing the BTZ class of metrics to imaginary time. Of special interest are the overspinning metrics, which are smooth in this three-dimensional context. Their inclusion as saddle points in the gravitational path integral would lead to puzzling results in conflict with those obtained using other methods. It is therefore encouraging that the admissibility criterion discards them. For completeness, we perform an analysis of smoothness and admissibility for the family of quasi-Euclidean BTZ metrics at all values of the mass and angular momentum.
Cornell University - arXiv, Nov 10, 2022
In this work we discuss the holographic description of states in the Hilbert space of (2+1)-dimen... more In this work we discuss the holographic description of states in the Hilbert space of (2+1)-dimensional quantum gravity, living on a time slice in the bulk. We focus on pure gravity coupled to pointlike sources for heavy spinning particles. We develop a formulation where the equations for the backreacted metric reduce to two decoupled Liouville equations with delta-function sources under pseudosphere boundary conditions. We show that both the semiclassical wavefunction and the gravity solution are determined by a universal object, namely a classical Virasoro vacuum block on the sphere. In doing so we derive a version of Polyakov's conjecture, as well as an existence criterion, for classical Liouville theory on the pseudosphere. We also discuss how some of these results are modified when considering closed universes with compact spatial slices.
Journal of High Energy Physics, 2015
We present a new family of asymptotic AdS 3 × S 2 solutions to eleven dimensional supergravity co... more We present a new family of asymptotic AdS 3 × S 2 solutions to eleven dimensional supergravity compactified on a Calabi-Yau threefold. They originate from the backreaction of S 2-wrapped M2-branes, which play a central role in the deconstruction proposal for the microscopic interpretation of the D4-D0 black hole entropy. We show that they are free of possible pathologies such as closed timelike curves and discuss their holographic interpretation.
Journal of High Energy Physics
Motivated by recently explored examples, we undertake a systematic study of conformal invariance ... more Motivated by recently explored examples, we undertake a systematic study of conformal invariance in one-dimensional sigma models where an isometry group has been gauged. Perhaps surprisingly, we uncover classes of sigma models which are only scale invariant in their ungauged form and become fully conformally invariant only after gauging. In these cases the target space of the gauged sigma model satisfies a deformation of the well-known conformal geometry constraints. We consider bosonic models as well as their $$ \mathcal{N} $$ N = 1, 2, 4 supersymmetric extensions. We solve the quantum ordering ambiguities in implementing (super-) conformal symmetry on the physical Hilbert space. Examples of our general results are furnished by the D(2, 1; 0)-invariant Coulomb branch quiver models relevant for black hole physics.
Journal of High Energy Physics, 2021
We study simple examples of ensemble-averaged holography in free compact boson CFTs with rational... more We study simple examples of ensemble-averaged holography in free compact boson CFTs with rational values of the radius squared. These well-known rational CFTs have an extended chiral algebra generated by three currents. We consider the modular average of the vacuum character in these theories, which results in a weighted average over all modular invariants. In the simplest case, when the chiral algebra is primitive (in a sense we explain), the weights in this ensemble average are all equal. In the non-primitive case the ensemble weights are governed by a semigroup structure on the space of modular invariants.These observations can be viewed as evidence for a holographic duality between the ensemble of CFTs and an exotic gravity theory based on a compact U(1) × U(1) Chern-Simons action. In the bulk description, the extended chiral algebra arises from soliton sectors, and including these in the path integral on thermal AdS3 leads to the vacuum character of the chiral algebra. We also ...
Uploads
Papers by Joris Raeymaekers