Decoding the geometry of conformal field theories

To certain geometries, string theory associates conformal field theories. We discuss techniques to perform the reverse procedure: To recover geometrical data from abstractly defined conformal field theories. This is done by introducing appropriate notions of limits of conformal field theories and their degenerations, and by applying techniques from noncommutative geometry. This note is a summary of our work hep-th/0308143 , aimed to be less technical than the original paper, along with some new calculations confirming our interpretation of the rescaled limiting zero mode of the Virasoro field.Comment: 12 pages, contribution to the Proceedings of the 7th International Workshop "Lie Theory and Its Applications in Physics", Varna, Bulgari

String Corrected Spacetimes and SU(N)-Structure Manifolds

Using an effective field theory approach and the language of SU(N)-structures, we study higher derivative corrections to the supersymmetry constraints for compactifications of string or M-theory to Minkowski space. Our analysis is done entirely in the target space and is thus very general, and does not rely on theory-dependent details such as the amount of worldsheet supersymmetry. For manifolds of real dimension n<4 we show that the internal geometry remains flat and uncorrected. For n=4, 6, Kahler manifolds with SU(N)-holonomy can become corrected to SU(N)-structure, while preserving supersymmetry, once corrections are included.Comment: 27 page

Kaluza-Klein Theories Without Truncation

In this note we present a closed expression for the space-time effective action for all bosonic fields (massless and massive) obtained from the compactification of gravity or supergravity theories (such as type II or eleven-dimensional supergravities) from $D$ to $d$ space-time dimensions.Comment: 20 page

Three-Point Disc Amplitudes in the RNS Formalism

We calculate all tree level string theory vacuum to Dp-brane disc amplitudes involving an arbitrary RR-state and two NS-NS vertex operators. This computation was earlier performed by K. Becker, Guo, and Robbins for the simplest case of a RR-state of type C_{p-3}. Here we use the aid of a computer to calculate all possible three-point amplitudes involving a RR-vertex operator of type C_{p+1+2k}.Comment: 40 page

Chern-Simons Actions and Their Gaugings in 4D, N=1 Superspace

We gauge the abelian hierarchy of tensor fields in 4D by a Lie algebra. The resulting non-abelian tensor hierarchy can be interpreted via an equivariant chain complex. We lift this structure to N=1 superspace by constructing superfield analogs for the tensor fields, along with covariant superfield strengths. Next we construct Chern-Simons actions, for both the bosonic and N=1 cases, and note that the condition of gauge invariance can be presented cohomologically. Finally, we provide an explicit realization of these structures by dimensional reduction, for example by reducing the three-form of eleven-dimensional supergravity into a superspace with manifest 4D, N=1 supersymmetry.Comment: 40pp, v2 added reference

Abelian Tensor Hierarchy in 4D, N=1 Superspace

With the goal of constructing the supersymmetric action for all fields, massless and massive, obtained by Kaluza-Klein compactification from type II theory or M-theory in a closed form, we embed the (Abelian) tensor hierarchy of p-forms in four-dimensional, N=1 superspace and construct its Chern-Simons-like invariants. When specialized to the case in which the tensors arise from a higher-dimensional theory, the invariants may be interpreted as higher-dimensional Chern-Simons forms reduced to four dimensions. As an application of the formalism, we construct the eleven-dimensional Chern-Simons form in terms of four-dimensional, N=1 superfields.Comment: 31 page

Untersuchungen zur Nutzung der Esparsette (Onobrychis viciifolia) im Ökologischen Landbau

Field trials with four sainfoin cultivars as well as lucerne were carried out on two sites in southern Northrhine - Westphalia from 2003 to 2005. The objective of the experi-ments was to gain experience with the organic cultivation of sainfoin, an old fodder legume known for low yields but a high feeding value, particularly for horses. Crop development, dry matter yield and hay quality were determined. Crop dm yield on a loess soil site with a total lime content of 3207 mg kg-1 was very low (about 1t ha-1) in 2005. Dry matter yield on a loess soil site rich in lime (total lime content = 13974 mg kg-1) was comparatively high in 2004 (first cut: = 7.5 t ha-1), but decreased in 2005 (first cut: 1.6 t ha-1) mainly due to increasing weed infestation. Dry matter yield of sainfoin cv. Visnowsky was always lower compared with Lucerne, while digestable energy content tended to be higher in sainfoin. Sainfoin production may be an interest-ing option for organic horse fodder production, if soils are rich in lime and if weed pressure is manageable

Spatial scales of interactions among bacteria and between bacteria and the leaf surface.

Microbial life on plant leaves is characterized by a multitude of interactions between leaf colonizers and their environment. While the existence of many of these interactions has been confirmed, their spatial scale or reach often remained unknown. In this study, we applied spatial point pattern analysis to 244 distribution patterns of Pantoea agglomerans and Pseudomonas syringae on bean leaves. The results showed that bacterial colonizers of leaves interact with their environment at different spatial scales. Interactions among bacteria were often confined to small spatial scales up to 5-20 μm, compared to interactions between bacteria and leaf surface structures such as trichomes which could be observed in excess of 100 μm. Spatial point-pattern analyses prove a comprehensive tool to determine the different spatial scales of bacterial interactions on plant leaves and will help microbiologists to better understand the interplay between these interactions