Related papers: Brane compactifications and 4-dimensional geometry…
We investigate gravitational perturbations in a compact six-dimensional self-tuning brane model. We specifically look for analytic solutions to the perturbed Einstein equations that correspond in four-dimensions to massless or approximately…
In this paper we present a classification of possible dynamics of closed string moduli within specific toroidal compactifications of Type II string theories due to the NS-NS tadpole terms in the reduced action. They appear as potential…
In this note, we present a scenario in which the existence of dS vacua is jeopardized by topological transitions between non-BPS branes and fluxes in type IIB toroidal compactifications. We focus our study on a six-dimensional torus…
The localization of metric fluctuations on scalar brane configurations breaking spontaneously five-dimensional Poincar\'e invariance is discussed. Assuming that the four-dimensional Planck mass is finite and that the geometry is regular, it…
We compute the matching conditions for a general thick codimension 2 brane, a necessary previous step towards the investigation of gravitational phenomena in codimension 2 braneworlds. We show that, provided the brane is weakly curved, they…
We have recently proposed a dynamical mechanism that may realize a flat four-dimensional space time as a brane in type IIB superstring theory. A crucial role is played by the phase of the chiral fermion integral associated with the IKKT…
We consider a 4+N-dimensional brane world with 2 co-dimension 1 branes in an empty bulk. The two branes have N-1 of their extra dimensions compactified on a sphere S^(N-1), whereas the ordinary 4 spacetime directions are Poincare invariant.…
We study a generalization of the Randall-Sundrum mechanism for generating the weak/Planck hierarchy, which uses two rather than one warped extra dimension, and which requires no negative tension branes. A 4-brane with one exponentially…
We provide a general overview of the current state of the art in four dimensional three generation model building proposals - using intersecting D-brane toroidal compactifications [without fluxes] of IIA, IIB string theories - which have…
Configurations of two or more branes wrapping different homology cycles of space-time are considered and the amount of supersymmetry preserved is analysed, generalising the analysis of multiple branes in flat space. For K3…
A T6 orbifold compactification is discussed from the somewhat unconventional perspective as the large radius limit of a Landau-Ginzburg model. The features of the model are in principle familiar, but the way they enter here is different…
We discuss the non-linear gravitational interactions in the Randall-Sundrum single brane model. If we naively write down the 4-dimensional effective action integrating over the fifth dimension with the aid of the decomposition with respect…
In the construction of a classical smoothed out brane world model in five dimensions, one uses a dynamically generated domain wall (a kink) to localise an effective four dimensional theory. At the level of the Euler-Lagrange equations the…
We look at general braneworlds in six-dimensional Einstein-Gauss-Bonnet gravity. We find the general matching conditions for the Einstein-Gauss-Bonnet braneworld, which remarkably turn out to give precisely the four-dimensional Einstein…
We present a systematical study of brane worlds in string theory on $S^{1}/Z_{2}$. Starting with the toroidal compactification of the NS/NS sector in (D+d) dimensions, we first obtain an effective $D$-dimensional action, and then compactify…
We study perturbations of 4-dimensional fuzzy spheres as backgrounds in the IKKT or IIB matrix model. Gauge fields and metric fluctuations are identified among the excitation modes with lowest spin, supplemented by a tower of higher-spin…
A detailed derivation of $3+1$ dimensional induced or emergent gravity in the IKKT matrix model at one loop is given, as announced in [1]. The mechanism requires a brane configuration with structure ${\cal M}^{3,1}\times {\cal K} \subset…
Many existing models of brane inflation suffer from a steep irreducible gravitational potential between the branes that causes inflation to end too early. Inspired by the fact that point masses in 2+1 D exert no gravitational force, we…
We perform a Hodge theoretic study of parameter dependent families of D-branes on compact Calabi-Yau manifolds in type II and F-theory compactifcations. Starting from a geometric Gauss-Manin connection for B type branes we study the…
We investigate the scalar metric perturbations about a de Sitter brane universe in a 5-dimensional anti de Sitter bulk. We compare the master-variable formalism, describing metric perturbations in a 5-dimensional longitudinal gauge, with…