arXiv subjects

Florian Gmeiner

Publications and source records attributed to Florian Gmeiner.

16 recordsLinked to original sources

arXiv2009

Complete Gauge Threshold Corrections for Intersecting Fractional D6-Branes: The Z6 and Z6' Standard Models

We perform a complete analysis of one-loop threshold corrections to the gauge couplings of fractional D6-branes. This includes besides SU(N) also symplectic, orthogonal and massless Abelian gauge factors and the full computation of contributions from discrete and continuous Wilson lines and brane displacements. Two classes of globally consistent supersymmetric compactifications with Standard Model spectra on T6/Z6 and T6/Z6' are presented in detail with the latter exhibiting the potential of supersymmetry breaking via a hidden sector gaugino condensate. The T6/Z6' Standard Models are completely classified, and it turns out that out of 768 distinct D6-brane configurations only 16 different sets of massless spectra and ten distinct values of gauge couplings at one-loop arise. The gauge threshold corrections enhance the diversity to 196 nonequivalent models.

hep-th↗

arXiv2008

Statistical analysis of a subset of the string theory landscape

An analysis of a special class of type II string theory compactifications is presented. We focus on recent work in one particular orientifold background of intersecting brane models and the resulting four dimensional gauge group and matter content. Special attention is paid to solutions that resemble the gauge group of the MSSM. Statistical correlations between properties of the models are analysed and compared to results on different backgrounds.

hep-th↗

arXiv2008

Calibrated cycles and T-duality

For Hitchin's generalised geometries we introduce and analyse the concept of a structured submanifold which encapsulates the classical notion of a calibrated submanifold. Under a suitable integrability condition on the ambient geometry, these generalised calibrated cycles minimise a functional occurring as D-brane energy in type II string theories, involving both so-called NS-NS- and R-R-fields. Further, we investigate the behaviour of calibrated cycles under T-duality and construct non-trivial examples.

math.DG↗

arXiv2008

Millions of Standard Models on Z6-prime?

Using previous results on the statistics of intersecting D6-brane models on T^6/Z_6' we analyse solutions that resemble the gauge group and matter content of the supersymmetric standard model. In particular the structure of the hidden sector, the gauge coupling constants and chiral exotic matter content are computed and classified for all possible standard model-like configurations on this background. It turns out that the number of chiral exotics, Higgses and values of gauge couplings are strongly correlated. Some examples with the chiral spectrum of the supersymmetric standard model plus vector-like states and a massless U(1) B-L are discussed in detail.

hep-th↗

arXiv2008

DBI Inflation using a One-Parameter Family of Throat Geometries

We demonstrate the possibility of examining cosmological signatures in the DBI inflation setup using the BGMPZ solution, a one-parameter family of geometries for the warped throat which interpolate between the Maldacena-Nunez and Klebanov-Strassler solutions. The warp factor is determined numerically and subsequently used to calculate cosmological observables including the scalar and tensor spectral indices, for a sample point in the parameter space. As one moves away from the KS solution for the throat the warp factor is qualitatively different, which leads to a significant change for the observables, but also generically increases the non-Gaussianity of the models. We argue that the different models can potentially be differentiated by current and future experiments.

hep-th↗

arXiv2008

Statistics in the Landscape of Intersecting Brane Models

An approach towards a statistical survey of four dimensional supersymmetric vacua in the string theory landscape is described and illustrated with three examples of ensembles of intersecting D-brane models. The question whether it is conceivable to make predictions based on statistical distributions is discussed. Especially interesting in this context are possible correlations between low energy observables. As an example we look at correlations between properties of the gauge sector of intersecting D-brane models and Gepner model constructions.

hep-th↗

arXiv2007

Mapping an Island in the Landscape

We provide a complete classification and statistical analysis of all type IIA orientifold compactifications with intersecting D6-branes on the orbifold T^6/Z'_6. The total number of four dimensional N=1 supersymmetric models is found to be O(10^23). After a statistical analysis of the gauge sector properties of all possible solutions, we study three subsets of configurations which contain the chiral matter sector of the standard model, a Pati-Salam or SU(5) GUT model, respectively. We find O(10^15) compactifications with an MSSM and O(10^11) models with a Pati-Salam sector. Along the way we derive an explicit algebraic formulation for the computation of the non-chiral matter spectrum for all Z_N orbifolds.

hep-th↗

arXiv2007

Statistics of intersecting D-brane models on T^6/Z_6

We perform a statistical analysis of supersymmetric intersecting D-brane models on the type II orientifold T^6/Z_6. After providing an analytic proof of the finiteness of the number of possible solutions in this setup we study the frequency distributions of properties of the gauge group and the chiral matter content. In particular we search for models with a standard model gauge group and discuss their statistical suppression. The results are compared with the recent studies on T^6/Z_2xZ_2. The analysis is conducted using a statistical method, based on the choice of random subsets of the full ensemble of solutions. This method allows to calculate the total number of models with high precision to 3x10^28.

hep-th↗

arXiv2007

Gauge sector statistics of intersecting D-brane models

In this article, which is based on the first part of my PhD thesis, I review the statistics of the open string sector in T^6/(Z_2xZ_2) orientifold compactifications of the type IIA string. After an introduction to the orientifold setup, I discuss the two different techniques that have been developed to analyse the gauge sector statistics, using either a saddle point approximation or a direct computer based method. The two approaches are explained and compared by means of eight- and six-dimensional toy models. In the four-dimensional case the results are presented in detail. Special emphasis is put on models containing phenomenologically interesting gauge groups and chiral matter, in particular those containing a standard model or SU(5) part.

hep-th↗

arXiv2007

Calibrations on spaces with GxG-structure

In these notes we give an introduction to the concept of spaces with GxG-structure and their structured submanifolds. These objects generalise the classical notion of a calibrated submanifold. Therefore, they are interesting from a string theory viewpoint as they are relevant to describe D-branes in string compactifications on backgrounds with fluxes.

hep-th↗

arXiv2006

Statistics of SU(5) D-Brane Models on a Type II Orientifold

We perform a statistical analysis of models with SU(5) and flipped SU(5) gauge group in a type II orientifold setup. We investigate the distribution and correlation of properties of these models, including the number of generations and the hidden sector gauge group. Compared to the recent analysis hep-th/0510170 of models with a standard model-like gauge group, we find very similar results.

hep-th↗

arXiv2005

Standard Model statistics of a Type II orientifold

We analyse four-dimensional, supersymmetric intersecting D-brane models in a toroidal orientifold background from a statistical perspective. The distribution and correlation of observables, like gauge groups and couplings, are discussed. We focus on models with a Standard Model-like gauge sector, derive frequency distributions for their occurence and analyse the properties of the hidden sector.

hep-th↗

arXiv2005

One in a Billion: MSSM-like D-Brane Statistics

Continuing our recent work hep-th/0411173, we study the statistics of four-dimensional, supersymmetric intersecting D-brane models in a toroidal orientifold background. We have performed a vast computer survey of solutions to the stringy consistency conditions and present their statistical implications with special emphasis on the frequency of Standard Model features. Among the topics we discuss are the implications of the K-theory constraints, statistical correlations among physical quantities and an investigation of the various statistical suppression factors arising once certain Standard Model features are required. We estimate the frequency of an MSSM like gauge group with three generations to be one in a billion.

hep-th↗

arXiv2004

The Statistics of Supersymmetric D-brane Models

We investigate the statistics of the phenomenologically important D-brane sector of string compactifications. In particular for the class of intersecting D-brane models, we generalise methods known from number theory to determine the asymptotic statistical distribution of solutions to the tadpole cancellation conditions. Our approach allows us to compute the statistical distribution of gauge theoretic observables like the rank of the gauge group, the number of chiral generations or the probability of an SU(N) gauge factor. Concretely, we study the statistics of intersecting branes on T^2 and T^4/Z_2 and T^6/Z_2 x Z_2 orientifolds. Intriguingly, we find a statistical correlation between the rank of the gauge group and the number of chiral generations. Finally, we combine the statistics of the gauge theory sector with the statistics of the flux sector and study how distributions of gauge theoretic quantities are affected.

hep-th↗

arXiv2004

Mirror symmetry for topological sigma models with generalized Kahler geometry

We consider topological sigma models with generalized Kahler target spaces. The mirror map is constructed explicitly for a special class of target spaces and the topological A and B model are shown to be mirror pairs in the sense that the observables, the instantons and the anomalies are mapped to each other. We also apply the construction to open topological models and show that A branes are mapped to B branes. Furthermore, we demonstrate a relation between the field strength on the brane and a two-vector on the mirror manifold.

hep-th↗

arXiv2002

Localized nonabelian anomalies at orbifold fixed points

Orbifold compactifications of 10D heterotic strings do allow different sets of chiral fermions at different fixed points. Even if the effective 4D theory is anomaly free by including the bulk fermions, there arise abelian and nonabelian fixed point anomalies from these chiral fermions. As the underlying string theory is well defined these localized fixed point anomalies of the chiral fermions are to be cancelled by a variant of the Green-Schwarz mechanism.

hep-th↗