The large level limit of Kazama-Suzuki models

Limits of families of conformal field theories are of interest in the context of AdS/CFT dualities. We explore here the large level limit of the two-dimensional N = 2 , 2 $$\mathcal{N}=\left(2,\ 2\right)$$ superconformal W n + 1 $${\mathcal{W}}_{n+1}$$ minimal models that appear in the context of the supersymmetric higher-spin AdS 3 /CFT 2 duality. These models are constructed as Kazama-Suzuki coset models of the form SU( n + 1) / U( n ). We determine a family of boundary conditions in the limit theories, and use the modular bootstrap to obtain the full bulk spectrum of N = 2 $$\mathcal{N}=2$$ super- W n + 1 $${\mathcal{W}}_{n+1}$$ primaries in the theory. We also confirm the identification of this limit theory as the continuous orbifold ℂ n / U n $${\mathbb{C}}^n/\mathrm{U}(n)$$ that was discussed recently

On conformal higher spin wave operators

We analyze free conformal higher spin actions and the corresponding wave operators in arbitrary even dimensions and backgrounds. We show that the wave operators do not factorize in general, and identify the Weyl tensor and its derivatives as the obstruction to factorization. We give a manifestly factorized form for them on (A)dS backgrounds for arbitrary spin and on Einstein backgrounds for spin 2. We are also able to fix the conformal wave operator in d = 4 for s = 3 up to linear order in the Riemann tensor on generic Bach-flat backgrounds

An inverse scattering construction of the JMaRT fuzzball

We present an inverse scattering construction in STU supergravity of the twocharge single-rotation JMaRT fuzzball. The key element in our construction is the fact that with appropriate changes in the parameters, the JMaRT fuzzball can be smoothly connected to the Myers-Perry instanton

Integrable properties of σ -models with non-symmetric target spaces

It is well known that σ -models with symmetric target spaces are classically integrable. With the example of the model with target space the flag manifold U(3)U(1)3 – a non-symmetric space – we show that the introduction of torsion allows to cast the equations of motion in the form of a zero-curvature condition for a one-parameter family of connections, which can be a sign of integrability of the theory. We also elaborate on geometric aspects of the proposed model

An inverse scattering formalism for STU supergravity

STU supergravity becomes an integrable system for solutions that effectively only depend on two variables. This class of solutions includes the Kerr solution and its charged generalizations that have been studied in the literature. We here present an inverse scattering method that allows to systematically construct solutions of this integrable system. The method is similar to the one of Belinski and Zakharov for pure gravity but uses a different linear system due to Breitenlohner and Maison and here requires some technical modifications. We illustrate this method by constructing a four-charge rotating solution from flat space. A generalization to other set-ups is also discussed

Generalised geometry from the ground up

Extending previous work on generalised geometry, we explicitly construct an E 7(7) -valued vielbein in eleven dimensions that encompasses the would be scalar bosonic degrees of freedom after reduction to four dimensions of D = 11 supergravity, by identifying new “generalised vielbeine” in eleven dimensions associated with the dual 6-form potential and the dual graviton. By maintaining full on-shell equivalence with the original theory at every step our construction furnishes the non-linear ansatz for the dual (magnetic) 7-form flux for any non-trivial compactification of D = 11 supergravity, complementing the known non-linear ansätze for the metric and the 4-form flux. A preliminary analysis of the generalised vielbein postulate for the new vielbein components reveals tantalising hints of new structures beyond D = 11 supergravity and ordinary space-time covariancxe, and also points to the possible D = 11 origins of the embedding tensor. We discuss the extension of these results to E 8(8)

On the no-boundary proposal for ekpyrotic and cyclic cosmologies

The no-boundary proposal provides a compelling theory for the initial conditions of our universe. We study the implications of such initial conditions for ekpyrotic and cyclic cosmologies. These cosmologies allow for the existence of a new type of ``ekpyrotic instanton'', which describes the creation of a universe in the ekpyrotic contraction phase. Remarkably, we find that the ekpyrotic attractor can explain how the universe became classical. In a cyclic context, in addition to the ekpyrotic instantons there exist de Sitter-like instantons describing the emergence of the universe in the dark energy phase. Our results show that typically the ekpyrotic instantons yield a higher probability. In fact, in a potential energy landscape allowing both inflationary and cyclic cosmologies, the no-boundary proposal implies that the probability for ekpyrotic and cyclic initial conditions is vastly higher than that for inflationary ones

Cosmological perturbations through a non-singular ghost-condensate/Galileon bounce

We study the propagation of super-horizon cosmological perturbations in a non-singular bounce spacetime. The model we consider combines a ghost condensate with a Galileon term in order to induce a ghost-free bounce. Our calculation is performed in harmonic gauge, which ensures that the linearized equations of motion remain well-defined and non-singular throughout. We find that, despite the fact that near the bounce the speed of sound becomes imaginary, super-horizon curvature perturbations remain essentially constant across the bounce. In fact, we show that there is a time close to the bounce where curvature perturbations of all wavelengths are required to be momentarily exactly constant. We relate our calculations to those performed in other gauges, and comment on the relation to previous results in the literature

Heterotic flux backgrounds and their IIA duals

We study four-dimensional heterotic flux vacua with N = 2 spacetime supersymmetry. A worldsheet perspective is used to clarify quantization conditions associated to the fluxes and the constraints these place on the moduli spaces of resulting compactifications. We propose that these vacua fit naturally in the context of heterotic/IIA duality as heterotic duals to compactifications on K3-fibered but not elliptically fibered Calabi-Yau three-folds. We present some examples of such potential dual pairs

Standard model fermions and K(E10)

In recent work [1] it was shown how to rectify Gell-Mann's proposal for identifying the 48 quarks and leptons of the Standard Model with the 48 spin- 12 fermions of maximal SO(8) gauged supergravity remaining after the removal of eight Goldstinos, by deforming the residual U(1) symmetry at the SU(3) × U(1) stationary point of N=8 supergravity, so as to also achieve agreement of the electric charge assignments. In this Letter we show that the required deformation, while not in SU(8), does belong to K(E10) , the ‘maximal compact’ subgroup of E10 which is a possible candidate symmetry underlying M theory. The incorporation of infinite-dimensional Kac–Moody symmetries of hyperbolic type, apparently unavoidable for the present scheme to work, opens up completely new perspectives on embedding Standard Model physics into a Planck scale theory of quantum gravity