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Search: authors:"Andreas P. Braun"

10 papers found.
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Spin(7)-manifolds as generalized connected sums and 3d \( \mathcal{N}=1 \) theories

Abstract M-theory on compact eight-manifolds with Spin(7)-holonomy is a framework for geometric engineering of 3d \( \mathcal{N}=1 \) gauge theories coupled to gravity. We propose a new construction of such Spin(7)-manifolds, based on a generalized connected sum, where the building blocks are a Calabi-Yau four-fold and a G2-holonomy manifold times a circle, respectively, which...

Tops as building blocks for G 2 manifolds

A large number of examples of compact G 2 manifolds, relevant to supersymmetric compactifications of M-Theory to four dimensions, can be constructed by forming a twisted connected sum of two building blocks times a circle. These building blocks, which are appropriate K3-fibred threefolds, are shown to have a natural and elegant construction in terms of tops, which parallels the...

Heterotic line bundle models on elliptically fibered Calabi-Yau three-folds

AbstractWe analyze heterotic line bundle models on elliptically fibered Calabi-Yau three-folds over weak Fano bases. In order to facilitate Wilson line breaking to the standard model group, we focus on elliptically fibered three-folds with a second section and a freely-acting involution. Specifically, we consider toric weak Fano surfaces as base manifolds and identify six such...

Discrete Symmetries of Calabi–Yau Hypersurfaces in Toric Four-Folds

We analyze freely-acting discrete symmetries of Calabi–Yau three-folds defined as hypersurfaces in ambient toric four-folds. An algorithm that allows the systematic classification of such symmetries which are linearly realised on the toric ambient space is devised. This algorithm is applied to all Calabi–Yau manifolds with \({h^{1,1}(X)\leq 3}\) obtained by triangulation from the...

Mirror symmetry for G 2-manifolds: twisted connected sums and dual tops

Recently, at least 50 million of novel examples of compact G 2 holonomy manifolds have been constructed as twisted connected sums of asymptotically cylindrical Calabi-Yau threefolds. The purpose of this paper is to study mirror symmetry for compactifications of Type II superstrings in this context. We focus on G 2 manifolds obtained from building blocks constructed from dual...

De Sitter vacua from a D-term generated racetrack potential in hypersurface Calabi-Yau compactifications

In [1] a mechanism to fix the closed string moduli in a de Sitter minimum was proposed: a D-term potential generates a linear relation between the volumes of two rigid divisors which in turn produces at lower energies a race-track potential with de Sitter minima at exponentially large volume. In this paper, we systematically search for implementations of this mechanism among all...

Hypercharge flux in F-theory and the stable Sen limit

IIB compactifications enjoy the possibility to break GUT groups via fluxes without giving mass to the hypercharge gauge field. Although this important advantage has greatly motivated F-theory constructions, no such fluxes have been constructed directly in terms of the M-theory G 4-form. In this note, we give a general prescription for constructing hypercharge G-fluxes. By using a...

The fate of U(1)’s at strong coupling in F-theory

U(1) gauge symmetries in F-theory are expected to manifest themselves as codimension three singularities of Calabi-Yau fourfolds. However, some of these are known to become massive at strong coupling via the Stückelberg mechanism. In this note, we propose a geometric picture for detecting all U(1)’s, and determining which ones are massive and which ones are massless. We find that...