arXiv subjects

Ruud Siebelink

Publications and source records attributed to Ruud Siebelink.

3 recordsLinked to original sources

arXiv1999

The Gravitational Action in Asymptotically AdS and Flat Spacetimes

The divergences of the gravitational action are analyzed for spacetimes that are asymptotically anti-de Sitter and asymptotically flat. The gravitational action is rendered finite using a local counterterm prescription, and the relation of this method to the traditional reference spacetime is discussed. For AdS, an iterative procedure is devised that determines the counterterms efficiently. For asymptotically flat space, we use a different method to derive counterterms which are sufficient to remove divergences in most cases.

hep-th↗

arXiv1999

The D2-D6 System and a Fibered AdS Geometry

The system of D2 branes localized on or near D6 branes is considered. The world-volume theory on the D2 branes is investigated, using its conjectured relation to the near-horizon geometry. The results are in agreement with known facts and expectations for the corresponding field theory and a rich phase structure is obtained as a function of the energy scale and the number of branes. In particular, for an intermediate range of the number of D6 branes, the IR geometry is that of an AdS_4 space fibered over a compact space. This D2-D6 system is compared to other systems, related to it by compactification and duality and it is shown that the qualitative differences have compatible explanations in the geometric and field-theoretic descriptions. Another system -- that of NS5 branes located at D6 branes -- is also briefly studied, leading to a similar phase structure.

hep-th↗

arXiv1994

On the Lagrangian Realization of Non-Critical ${\cal W}$-Strings

A large class of non-critical string theories with extended worldsheet gauge symmetry are described by two coupled, gauged Wess-Zumino-Witten Models. We give a detailed analysis of the gauge invariant action and in particular the gauge fixing procedure and the resulting BRST symmetries. The results are applied to the example of ${\cal W}_3$ strings.

hep-th↗