Florian Gmeiner

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.

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 T 6 = Z6 and T 6 = Z 0 are presented in detail with the latter exhibiting the potential of supersymmetry breaking via a hidden sector gaugino condensate. The T 6 = Z 0 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.

Statistics of intersecting D-brane models on T6/Bbb Z6

We perform a statistical analysis of supersymmetric intersecting D-brane models on the type II orientifold T6/6. 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 T6/(2 × 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 3 × 1028.

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.

Gauge sector statistics of intersecting D-brane models

In this paper, which is based on the first part of the authors PhD thesis, we review the statistics of the open string sector in T6/(ℤ2 × ℤ2) orientifold compactifications of type IIA. After an introduction to the orientifold setup we discuss the two different techniques that have been developed, using either a saddle point approximation or a direct computer based method. We explain the two approaches by means of eight- and six-dimensional toy models and present the results for the four-dimensional models in detail. Special emphasis is placed on models containing phenomenologically interesting gauge groups, in particular those containing a standard model, Pati-Salam or SU(5) part.

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.