Constrained superfields from an anti-D3-brane in KKLT

The KKLT construction of dS vacua relies on an uplift term that arises from an anti-D3-brane. It was argued by Kachru, Pearson and Verlinde that this anti-D3-brane is an excited state in a supersymmetric theory since it can decay to a supersymmetric ground state. Hence the anti-D3-brane breaks supersymmetry spontaneously and one should be able to package all the world-volume fields on the anti-D3-brane into a four dimensional $\cal{N}=1$ supersymmetric action. Here we extend previous results and identify the constrained superfields that correspond to all the degrees of freedom on the anti-D3-brane. In particular, we show explicitly that the four 4D worldvolume spinors give rise to constrained chiral multiplets $S$ and $Y^i$, $i=1,2,3$ that satisfy $S^2=SY^i=0$. We also conjecture (and provide evidence in a forthcoming publication) that the vector field $A_\mu$ and the three scalars $\phi^i$ give rise to a field strength multiplet $W_\alpha$ and three chiral multiplets $H^i$ that satisfy the constraints $S W_\alpha= \bar{D}_{\dot \alpha} (S \bar H^i)=0$. This is the first time that such constrained multiplets appear in string theory constructions.Comment: 20 pages, v2: references adde

Efficiently Parsable Extensions to Tree-Local Multicomponent TAG

Recent applications of Tree-Adjoining Grammar (TAG) to the domain of semantics as well as new attention to syntactic phenomena have given rise to increased interested in more expressive and complex multicomponent TAG formalisms (MCTAG). Although many constructions can be modeled using tree-local MCTAG (TL-MCTAG), certain applications require even more flexibility. In this paper we suggest a shift in focus from constraining locality and complexity through tree- and set-locality to constraining locality and complexity through restrictions on the derivational distance between trees in the same tree set in a valid derivation. We examine three formalisms, restricted NS-MCTAG, restricted Vector-TAG and delayed TL-MCTAG, that use notions of derivational distance to constrain locality and demonstrate how they permit additional expressivity beyond TL-MCTAG without increasing complexity to the level of set local MCTAG.Engineering and Applied Science

Nueva especie de Nebria Latreille, 1802 de los Montes de León, noroeste de España (Coleoptera, Carabidae: Nebriinae)

Nebria leonensis sp. n. from the Sierras de la Cabrera Baja and del Teleno (southern Montes de León) is described. This species, related to N. lafresnayei Serville, 1821, is characterised by its slender body, long and light brown extremities, the form of its pronotum, and evenly rounded elytra, which are conspicuously flattened on the discus. The differentiating characters and the habitat are described. A determination key to the species and subspecies of the group to which the new species belongs is presented.Se describe Nebria leonensis sp. n. de las sierras de la Cabrera Baja y del Teleno (sur de los Montes de León). Esta especie, relacionada con Nebria lafresnayei Serville, 1821, se caracteriza especialmente por su cuerpo delgado, largas extremidades de color marrón claro, forma del pronoto, y élitros uniformemente redondeados y claramente deprimidos en el disco. Además de describir los caracteres que la definen y el hábitat, se presentan unas breves notas sobre la historia faunística de los montes de León, y una clave de determinación de las especies y subespecies del grupo al que pertenece la nueva especie

D-Terms from Generalized NS-NS Fluxes in Type II

Orientifolds of type II string theory admit a certain set of generalized NS-NS fluxes, including not only the three-form field strength H, but also metric and non-geometric fluxes, which are related to H by T-duality. We describe in general how these fluxes appear as parameters of an effective N=1 supergravity theory in four dimensions, and in particular how certain generalized NS-NS fluxes can act as charges for R-R axions, leading to D-term contributions to the effective scalar potential. We illustrate these phenomena in type IIB with the example of a certain orientifold of T^6/Z_4.Comment: 31+1 pages, uses utarticle.cls; v2: references adde

The problematic backreaction of SUSY-breaking branes

In this paper we investigate the localisation of SUSY-breaking branes which, in the smeared approximation, support specific non-BPS vacua. We show, for a wide class of boundary conditions, that there is no flux vacuum when the branes are described by a genuine delta-function. Even more, we find that the smeared solution is the unique solution with a regular brane profile. Our setup consists of a non-BPS AdS_7 solution in massive IIA supergravity with smeared anti-D6-branes and fluxes T-dual to ISD fluxes in IIB supergravity.Comment: 27 pages, Latex2e, 5 figure

Supersymmetric Vacua in Random Supergravity

We determine the spectrum of scalar masses in a supersymmetric vacuum of a general N=1 supergravity theory, with the Kahler potential and superpotential taken to be random functions of N complex scalar fields. We derive a random matrix model for the Hessian matrix and compute the eigenvalue spectrum. Tachyons consistent with the Breitenlohner-Freedman bound are generically present, and although these tachyons cannot destabilize the supersymmetric vacuum, they do influence the likelihood of the existence of an `uplift' to a metastable vacuum with positive cosmological constant. We show that the probability that a supersymmetric AdS vacuum has no tachyons is formally equivalent to the probability of a large fluctuation of the smallest eigenvalue of a certain real Wishart matrix. For normally-distributed matrix entries and any N, this probability is given exactly by P = exp(-2N^2|W|^2/m_{susy}^2), with W denoting the superpotential and m_{susy} the supersymmetric mass scale; for more general distributions of the entries, our result is accurate when N >> 1. We conclude that for |W| \gtrsim m_{susy}/N, tachyonic instabilities are ubiquitous in configurations obtained by uplifting supersymmetric vacua.Comment: 26 pages, 6 figure

New Supergravity Backgrounds Dual to N=1 SQCD-like Theories with N_f=2N_c

We present new supergravity backgrounds generated by N_c D5-branes, wrapping the S^2 of the resolved conifold, in the presence of N_f = 2 N_c smeared flavor D5-branes. The smearing allows us to take their backreaction on the geometry into account. We discuss the consistency, stability, and supersymmetry of these types of setups. We find near horizon geometries that we expect to be supergravity duals of SQCD-like theories with N_f= 2N_c. From these backgrounds we numerically extract rectangular Wilson loops and beta functions of the dual field theory for the regime where our approximations are valid.Comment: 22+24 pages, 17 figures, Figure 12 replace

Challenges for String Cosmology

We critically assess the twin prospects of describing the observed universe in string theory, and using cosmological experiments to probe string theory. For the purposes of this short review, we focus on the limitations imposed by our incomplete understanding of string theory. After presenting an array of significant obstacles, we indicate a few areas that may admit theoretical progress in the near future.Comment: 18 pages; contribution to a focus issue on string cosmology for Classical and Quantum Gravit