Publications (97)
One in a Billion: MSSM-like D-Brane Statistics
Florian Gmeiner, Ralph Blumenhagen, Gabriele Honecker +2
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 per…
The Green-Schwarz Mechanism and Geometric Anomaly Relations in 2d (0,2) F-theory Vacua
Timo Weigand, Fengjun Xu
We study the structure of gauge and gravitational anomalies in 2d N=(0,2) theories obtained by compactification of F-theory on elliptically fibered Calabi-Yau 5-folds. Abelian gaug…
Computation of D-brane instanton induced superpotential couplings - Majorana masses from string theory
Mirjam Cvetic, Robert Richter, Timo Weigand
We perform a detailed conformal field theory analysis of D2-brane instanton effects in four-dimensional type IIA string vacua with intersecting D6-branes. In particular, we explici…
Quantum obstructions for infinite distance limits -- Part I: obstructions
Lukas Kaufmann, Jeroen Monnee, Timo Weigand +1
We analyse quantum obstructions to classical infinite distance limits in four-dimensional string compactifications with N=1 supersymmetry. Such quantum effects signal a severe depa…
Non-perturbative Yukawa Couplings from String Instantons
Ralph Blumenhagen, Mirjam Cvetic, Dieter Lust +2
Non-perturbative D-brane instantons can generate perturbatively absent though phenomenologically relevant couplings for Type II orientifold compactifications with D-branes. We disc…
Emergent Strings in Type IIB Calabi--Yau Compactifications
Bjoern Hassfeld, Jeroen Monnee, Timo Weigand +1
We study infinite distance limits in the complex structure moduli space of Type IIB compactifications on Calabi--Yau threefolds, in light of the Emergent String Conjecture. We focu…
Massive Abelian Gauge Symmetries and Fluxes in F-theory
Thomas W. Grimm, Max Kerstan, Eran Palti +1
F-theory compactified on a Calabi-Yau fourfold naturally describes non-Abelian gauge symmetries through the singularity structure of the elliptic fibration. In contrast Abelian sym…
A string theoretic model of gauge mediated supersymmetry beaking
Mirjam Cvetic, Timo Weigand
We propose a robust supergravity model of dynamical supersymmetry breaking and gauge mediation, and a natural embedding in non-perturbative string theory with D-branes. A chiral fi…
Global F-theory GUTs
Ralph Blumenhagen, Thomas W. Grimm, Benjamin Jurke +1
We construct global F-theory GUT models on del Pezzo surfaces in compact Calabi-Yau fourfolds realized as complete intersections of two hypersurface constraints. The intersections…
Physics and Geometry of Complex Structure Limits in Type IIB Calabi-Yau Compactifications
Jeroen Monnee, Timo Weigand, Max Wiesner
We provide a detailed geometric and physical interpretation of infinite distance limits in the complex structure moduli space of Type IIB compactifications on Calabi-Yau threefolds…
On Quantum Obstructions in Type IIA Orientifolds
Lukas Kaufmann, Timo Weigand, Max Wiesner
Quantum corrections can severely modify or even remove classical infinite distance limits in four-dimensional gravity theories with minimal N=1 supersymmetry. In this note we study…
On Discrete Symmetries and Torsion Homology in F-Theory
Christoph Mayrhofer, Eran Palti, Oskar Till +1
We study the relation between discrete gauge symmetries in F-theory compactifications and torsion homology on the associated Calabi-Yau manifold. Focusing on the simplest example o…
D7-Brane Moduli Space in Axion Monodromy and Fluxbrane Inflation
Maximilian Arends, Arthur Hebecker, Konrad Heimpel +5
We analyze the quantum-corrected moduli space of D7-brane position moduli with special emphasis on inflationary model building. D7-brane deformation moduli are key players in two r…
Quasi-Jacobi Forms, Elliptic Genera and Strings in Four Dimensions
Seung-Joo Lee, Wolfgang Lerche, Guglielmo Lockhart +1
We investigate the interplay between the enumerative geometry of Calabi-Yau fourfolds with fluxes and the modularity of elliptic genera in four-dimensional string theories. We argu…
TASI Lectures on F-theory
Timo Weigand
F-theory is perhaps the most general currently available approach to study non-perturbative string compactifications in their geometric, large radius regime. It opens up a wide and…
Comments on Orientifolds without Vector Structure
Constantin Bachas, Massimo Bianchi, Ralph Blumenhagen +2
We revisit type I compactifications with a Spin(32)/Z2 gauge bundle that admits no vector structure. We elucidate the relation of this Z2 obstruction to discrete B-field flux and t…
The Minimal Weak Gravity Conjecture
Cesar Fierro Cota, Alessandro Mininno, Timo Weigand +1
We examine the minimal constraints imposed by the Weak Gravity Conjecture (WGC) on the particle spectrum of a quantum gravity theory. Towers of super-extremal states have previousl…
Non-Abelian Brane Worlds: The Heterotic String Story
Ralph Blumenhagen, Gabriele Honecker, Timo Weigand
We discuss chiral supersymmetric compactifications of the SO(32) heterotic string on Calabi-Yau manifolds equipped with direct sums of stable bundles with structure group U(n). In…
Bounds on the Mordell-Weil rank of elliptic fibrations
Antonella Grassi, Rick Miranda, Kapil Paranjape +2
We present two proofs for a bound on the rank of the Mordell-Weil group of some elliptic fibrations. The bounds apply to Calabi-Yau varieties, which are also of interest to the phy…
Non-minimal Elliptic Threefolds at Infinite Distance II: Asymptotic Physics
Rafael Ãlvarez-GarcÃa, Seung-Joo Lee, Timo Weigand
We interpret infinite-distance limits in the complex structure moduli space of F-theory compactifications to six dimensions in the light of general ideas in quantum gravity. The li…
On topological invariants of algebraic threefolds with (-factorial) singularities
Antonella Grassi, Timo Weigand, with an Appendix by V. Srinivas
We study local, global and local-to-global properties of threefolds with certain singularities. We prove criteria for these threefolds to be rational homology manifolds and conditi…
Membrane Limits in Quantum Gravity
Rafael Ãlvarez-GarcÃa, Daniel Kläwer, Timo Weigand
It is expected that infinite distance limits in the moduli space of quantum gravity are accompanied by a tower of light states. In view of the emergent string conjecture, this towe…
Non-Abelian Brane Worlds: The Open String Story
Ralph Blumenhagen, Gabriele Honecker, Timo Weigand
We extend the string model building rules for the construction of chiral supersymmetric Type I compactifications on smooth Calabi-Yau manifolds. These models contain stacks of D9-b…
GUTs in Type IIB Orientifold Compactifications
Ralph Blumenhagen, Volker Braun, Thomas W. Grimm +1
We systematically analyse globally consistent SU(5) GUT models on intersecting D7-branes in genuine Calabi-Yau orientifolds with O3- and O7-planes. Beyond the well-known tadpole an…
The Statistics of Supersymmetric D-brane Models
Ralph Blumenhagen, Florian Gmeiner, Gabriele Honecker +2
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 general…
Elliptic fibrations for SU(5) x U(1) x U(1) F-theory vacua
Jan Borchmann, Christoph Mayrhofer, Eran Palti +1
Elliptic Calabi-Yau fibrations with Mordell-Weil group of rank two are constructed. Such geometries are the basis for F-theory compactifications with two abelian gauge groups in ad…
Hidden Selection Rules, M5-instantons and Fluxes in F-theory
Luca Martucci, Timo Weigand
We introduce a new approach to investigate the selection rules governing the contributions of fluxed M5-instantons to the F-theory four-dimensional effective action, with emphasis…
Non-perturbative selection rules in F-theory
Luca Martucci, Timo Weigand
We discuss the structure of charged matter couplings in 4-dimensional F-theory compactifications. Charged matter is known to arise from M2-branes wrapping fibral curves on an ellip…
Quantum obstructions for infinite distance limits -- Part II: Kähler obstructions
Lukas Kaufmann, Jeroen Monnee, Timo Weigand +1
We continue our analysis of quantum corrections in the complex structure moduli space of four-dimensional Type IIB/F-theory compactifications with N=1 supersymmetry. We find that l…
6d SCFTs and U(1) Flavour Symmetries
Seung-Joo Lee, Diego Regalado, Timo Weigand
We study the behaviour of abelian gauge symmetries in six-dimensional N=(1,0) theories upon decoupling gravity and investigate abelian flavour symmetries in the context of 6d N=(1,…
Hierarchies from D-brane instantons in globally defined Calabi-Yau Orientifolds
Mirjam Cvetic, Timo Weigand
We construct the first globally consistent semi-realistic Type I string vacua on an elliptically fibered manifold where the zero modes of the Euclidean D1-instanton sector allow fo…
The Dark Dimension and the Grand Unification of Forces
Jonathan J. Heckman, Cumrun Vafa, Timo Weigand +1
The dark dimension scenario, predicting one extra mesoscopic dimension in the micron range, has emerged by applying various Swampland principles to the dark energy. In this note we…
D-brane and F-theory Model Building
Fernando Marchesano, Bert Schellekens, Timo Weigand
We review recent progress in the construction of four-dimensional vacua of Type II string theory and F-theory which yield the Standard Model of particle physics (SM) or extensions…
Emergent Strings, Duality and Weak Coupling Limits for Two-Form Fields
Seung-Joo Lee, Wolfgang Lerche, Timo Weigand
We systematically analyse weak coupling limits for 2-form tensor fields in the presence of gravity. Such limits are significant for testing various versions of the Weak Gravity and…
On Abelian Gauge Symmetries and Proton Decay in Global F-theory GUTs
Thomas W. Grimm, Timo Weigand
The existence of abelian gauge symmetries in four-dimensional F-theory compactifications depends on the global geometry of the internal Calabi-Yau fourfold and has important phenom…
F-theory and 2d (0,2) Theories
Sakura Schafer-Nameki, Timo Weigand
F-theory compactified on singular, elliptically fibered Calabi-Yau five-folds gives rise to two-dimensional gauge theories preserving N=(0,2) supersymmetry. In this paper we initia…
SU(5) Tops with Multiple U(1)s in F-theory
Jan Borchmann, Christoph Mayrhofer, Eran Palti +1
We study F-theory compactifications with up to two Abelian gauge group factors that are based on elliptically fibered Calabi-Yau 4-folds describable as generic hypersurfaces. Speci…
Swampland Bounds on the Abelian Gauge Sector
Seung-Joo Lee, Timo Weigand
We derive bounds on the number of abelian gauge group factors in six-dimensional gravitational theories with minimal supersymmetry and in their F-theoretic realisations. These boun…
Supersymmetric (non-)Abelian Bundles in the Type I and SO(32) Heterotic String
Ralph Blumenhagen, Gabriele Honecker, Timo Weigand
We discuss perturbative four-dimensional compactifications of both the SO(32) heterotic and the Type I string on smooth Calabi-Yau manifolds endowed with general non-abelian and ab…
(Non-)BPS bound states and D-brane instantons
Mirjam Cvetic, Robert Richter, Timo Weigand
We study non-perturbative effects in four-dimensional N=1 supersymmetric orientifold compactifications due to D-brane instantons which are generically not invariant under the orien…
G4-Flux and Standard Model Vacua in F-theory
Ling Lin, Timo Weigand
We study the geometry of gauge fluxes in four-dimensional F-theory vacua with gauge group SU(3)xSU(2)xU(1)xU(1) and its implications for phenomenology. The models are defined by a…
D-brane Instantons in Type II String Theory
Ralph Blumenhagen, Mirjam Cvetic, Shamit Kachru +1
We review recent progress in determining the effects of D-brane instantons in N=1 supersymmetric compactifications of Type II string theory to four dimensions. We describe the abst…
Heterotic Vacua from general (non-) Abelian Bundles
Timo Weigand
We report on the construction of four-dimensional string vacua by considering general abelian and non-abelian bundles on an internal Calabi-Yau for both heterotic theories. The str…
Elliptic K3 Surfaces at Infinite Complex Structure and their Refined Kulikov models
Seung-Joo Lee, Timo Weigand
Motivated by the Swampland Distance and the Emergent String Conjecture of Quantum Gravity, we analyse the infinite distance degenerations in the complex structure moduli space of e…
Gauge Backgrounds and Zero-Mode Counting in F-Theory
Martin Bies, Christoph Mayrhofer, Timo Weigand
Computing the exact spectrum of charged massless matter is a crucial step towards understanding the effective field theory describing F-theory vacua in four dimensions. In this wor…
The Higgs mass from a String-Theoretic Perspective
Arthur Hebecker, Alexander K. Knochel, Timo Weigand
The Higgs quartic coupling has now been indirectly measured at the electroweak scale. Assuming no new low-scale physics, its running is known and, together with gauge and Yukawa co…
Terminal Singularities, Milnor Numbers, and Matter in F-theory
Philipp Arras, Antonella Grassi, Timo Weigand
We initiate a systematic investigation of F-theory on elliptic fibrations with singularities which cannot be resolved without breaking the Calabi-Yau condition, corresponding to $\…
Heterotic GUT and Standard Model Vacua from simply connected Calabi-Yau Manifolds
Ralph Blumenhagen, Sebastian Moster, Timo Weigand
We consider four-dimensional supersymmetric compactifications of the E8 x E8 heterotic string on Calabi-Yau manifolds endowed with vector bundles with structure group SU(N) x U(1)…
The effective action of D6-branes in N=1 type IIA orientifolds
Max Kerstan, Timo Weigand
We use a Kaluza-Klein reduction to compute the low-energy effective action for the massless modes of a spacetime-filling D6-brane wrapped on a special Lagrangian 3-cycle of a type…
Retrofitting and the mu Problem
Daniel Green, Timo Weigand
One of the challenges of supersymmetry (SUSY) breaking and mediation is generating a mu term consistent with the requirements of electro-weak symmetry breaking. The most common app…
On Fluxed Instantons and Moduli Stabilisation in IIB Orientifolds and F-theory
Thomas W. Grimm, Max Kerstan, Eran Palti +1
We study the superpotential induced by Euclidean D3-brane instantons carrying instanton flux, with special emphasis on its significance for the stabilisation of Kahler moduli and N…
Lectures on F-theory compactifications and model building
Timo Weigand
These lecture notes are devoted to formal and phenomenological aspects of F-theory. We begin with a pedagogical introduction to the general concepts of F-theory, covering classic t…
Spacetime Instanton Corrections in 4D String Vacua - The Seesaw Mechanism for D-Brane Models
Ralph Blumenhagen, Mirjam Cvetic, Timo Weigand
We systematically investigate instanton corrections from wrapped Euclidean D-branes to the matter field superpotential of various classes of N=1 supersymmetric D-brane models in fo…
Chiral 2d Theories from N=4 SYM with Varying Coupling
Craig Lawrie, Sakura Schafer-Nameki, Timo Weigand
We study 2d chiral theories arising from 4d N=4 Super-Yang Mills (SYM) with varying coupling tau. The 2d theory is obtained by dimensional reduction of N=4 SYM on a complex curve w…
A Shift Symmetry in the Higgs Sector: Experimental Hints and Stringy Realizations
Arthur Hebecker, Alexander K. Knochel, Timo Weigand
We interpret reported hints of a Standard Model Higgs boson at ~ 125 GeV in terms of high-scale supersymmetry breaking with a shift symmetry in the Higgs sector. More specifically,…
Testing F-theory GUTs with the Axiverse
Michael Nee, Mario Reig, Timo Weigand
We show that axions coupled to photons in F-theory Grand Unified Theories (GUTs) satisfy the coupling-to-mass relation $g_{aγ}/m_a \leq C\, \frac{α_{\rm em}}{2Ï}\frac{1}{m_Ïf_Ï…
Holomorphic Anomalies, Fourfolds and Fluxes
Seung-Joo Lee, Wolfgang Lerche, Guglielmo Lockhart +1
We investigate holomorphic anomalies of partition functions underlying string compactifications on Calabi-Yau fourfolds with background fluxes. For elliptic fourfolds the partition…
Non-minimal Elliptic Threefolds at Infinite Distance I: Log Calabi-Yau Resolutions
Rafael Ãlvarez-GarcÃa, Seung-Joo Lee, Timo Weigand
We study infinite-distance limits in the complex structure moduli space of elliptic Calabi-Yau threefolds. In F-theory compactifications to six dimensions, such limits include infi…
Fluxes in F-theory Compactifications on Genus-One Fibrations
Ling Lin, Christoph Mayrhofer, Oskar Till +1
We initiate the construction of gauge fluxes in F-theory compactifications on genus-one fibrations which only have a multi-section as opposed to a section. F-theory on such spaces…
Towards the Standard Model in F-theory
Ling Lin, Timo Weigand
This article explores possible embeddings of the Standard Model gauge group and its matter representations into F-theory. To this end we construct elliptic fibrations with gauge gr…
Fluxbrane Inflation
Arthur Hebecker, Sebastian C. Kraus, Dieter Lust +2
As a first step towards inflation in genuinely F-theoretic setups, we propose a scenario where the inflaton is the relative position of two 7-branes on holomorphic 4-cycles. Non-su…
Quantum Gravity Bounds on N=1 Effective Theories in Four Dimensions
Luca Martucci, Nicolo Risso, Timo Weigand
We propose quantum gravitational constraints on effective four-dimensional theories with N=1 supersymmetry. These Swampland constraints arise by demanding consistency of the worlds…
Hypercharge Flux in IIB and F-theory: Anomalies and Gauge Coupling Unification
Christoph Mayrhofer, Eran Palti, Timo Weigand
We analyse hypercharge flux GUT breaking in F-theory/Type IIB GUT models with regards to its implications for anomaly cancellation and gauge coupling unification. To this aim we ex…
Towards large r from [p,q]-inflation
Eran Palti, Timo Weigand
The recent discovery of B-mode polarizations in the CMB by the BICEP2 collaboration motivates the study of large-field inflation models which can naturally lead to significant tens…
A Stringy Test of the Scalar Weak Gravity Conjecture
Seung-Joo Lee, Wolfgang Lerche, Timo Weigand
We prove a version of the Weak Gravity Conjecture for 6d F-theory or heterotic string compactifications with 8 supercharges. This sharpens our previous analysis by including massle…
G_4 flux, chiral matter and singularity resolution in F-theory compactifications
Sven Krause, Christoph Mayrhofer, Timo Weigand
We construct a set of chirality inducing G_4-fluxes in global F-theory compactifications on Calabi-Yau four-folds. Special emphasis is put on models with gauge group SU(5) x U(1)_X…
Massless Spectra of Three Generation U(N) Heterotic String Vacua
Ralph Blumenhagen, Sebastian Moster, Rene Reinbacher +1
We provide the methods to compute the complete massless spectra of a class of recently introduced supersymmetric E8 x E8 heterotic string models which invoke vector bundles with U(…
The Standard Model from String Theory: What Have We Learned?
Fernando Marchesano, Gary Shiu, Timo Weigand
Amidst all candidates of physics beyond the Standard Model, string theory provides a unique proposal for incorporating gauge and gravitational interactions. In string theory, a fou…
D-brane instanton effects in Type II orientifolds: local and global issues
Mirjam Cvetic, Robert Richter, Timo Weigand
We review how D-brane instantons can generate open string couplings of stringy hierarchy in the superpotential which violate global abelian symmetries and are therefore perturbativ…
K-Points and Type IIB/Heterotic Duality with NS5-Branes
Jeroen Monnee, Timo Weigand, Max Wiesner
We revisit type II limits in the vector multiplet moduli space of compactifications of Type IIB string theory on Calabi-Yau threefolds. These limits are special because they ca…
Multiplet Recombination and the CFT Distance Conjecture
Fabio Mantegazza, Enrico Marchetto, Elli Pomoni +2
Motivated by quantum gravity and the CFT Distance Conjecture, we study infinite-distance limits in four-dimensional superconformal field theories with higher-dimension…
Loop-Corrected Compactifications of the Heterotic String with Line Bundles
Ralph Blumenhagen, Gabriele Honecker, Timo Weigand
We consider the E8 x E8 heterotic string theory compactified on Calabi-Yau manifolds with bundles containing abelian factors in their structure group. Generic low energy consequenc…
F-theory uplifts and GUTs
Ralph Blumenhagen, Thomas W. Grimm, Benjamin Jurke +1
We study the F-theory uplift of Type IIB orientifold models on compact Calabi-Yau threefolds containing divisors which are del Pezzo surfaces. We consider two examples defined via…
Discrete Gauge Symmetries by Higgsing in four-dimensional F-Theory Compactifications
Christoph Mayrhofer, Eran Palti, Oskar Till +1
We study F-Theory compactifications to four dimensions that exhibit discrete gauge symmetries. Geometrically these arise by deforming elliptic fibrations with two sections to a gen…
Chiral Supersymmetric Gepner Model Orientifolds
Ralph Blumenhagen, Timo Weigand
We explicitly construct A-type orientifolds of supersymmetric Gepner models. In order to reduce the tadpole cancellation conditions to a treatable number we explicitly work out the…
Elliptic threefolds with high Mordell-Weil rank
Antonella Grassi, Timo Weigand
We present the first examples of smooth elliptic Calabi-Yau threefolds with Mordell-Weil rank 10, the highest currently known value. They are given by the Schoen threefolds introdu…
Mordell-Weil Torsion and the Global Structure of Gauge Groups in F-theory
Christoph Mayrhofer, David R. Morrison, Oskar Till +1
We study the global structure of the gauge group of F-theory compactified on an elliptic fibration . The global properties of are encoded in the torsion subgroup of the…
Supersymmetric Protection and the Swampland
Eran Palti, Cumrun Vafa, Timo Weigand
For certain terms in the action, supersymmetry can forbid an infinite number of possible contributions. We study whether such protection can occur in quantum gravity even without s…
F-Theory GUT Vacua on Compact Calabi-Yau Fourfolds
Thomas W. Grimm, Sven Krause, Timo Weigand
We present compact three-generation F-theory GUT models meeting in particular the constraints of D3-tadpole cancellation and D-term supersymmetry. To this end we explicitly constru…
Algebraic Cycles and Local Anomalies in F-Theory
Martin Bies, Christoph Mayrhofer, Timo Weigand
We introduce a set of identities in the cohomology ring of elliptic fibrations which are equivalent to the cancellation of gauge and mixed gauge-gravitational anomalies in F-theory…
A Note on Partition Functions of Gepner Model Orientifolds
Ralph Blumenhagen, Timo Weigand
In this note we generalize the description of simple current extended Gepner Model orientifolds as presented in hep-th/0401148 to the case of even levels and non-trivial dressings…
Emergent Strings from Infinite Distance Limits
Seung-Joo Lee, Wolfgang Lerche, Timo Weigand
As a refinement of the Swampland Distance Conjecture, we propose that a quantum gravitational theory in an infinite distance limit of its moduli space either decompactifies, or red…
Modular Fluxes, Elliptic Genera, and Weak Gravity Conjectures in Four Dimensions
Seung-Joo Lee, Wolfgang Lerche, Timo Weigand
We analyse the Weak Gravity Conjecture for chiral four-dimensional F-theory compactifications with N=1 supersymmetry. Extending our previous work on nearly tensionless heterotic st…
Chow groups, Deligne cohomology and massless matter in F-theory
Martin Bies, Christoph Mayrhofer, Christian Pehle +1
We propose a method to compute the exact number of charged localized massless matter states in an F-theory compactification on a Calabi-Yau 4-fold with non-trivial 3-form data. Our…
The Gravitational Sector of 2d (0,2) F-theory Vacua
Craig Lawrie, Sakura Schafer-Nameki, Timo Weigand
F-theory compactifications on Calabi-Yau fivefolds give rise to two-dimensional N=(0,2) supersymmetric field theories coupled to gravity. We explore the dilaton supergravity define…
Asymptotics of 5d Supergravity Theories and the Emergent String Conjecture
Lukas Kaufmann, Stefano Lanza, Timo Weigand
We invoke probe brane arguments to classify the asymptotic behavior of general five-dimensional supergravity theories with eight supercharges near infinite distance boundaries of t…
The Asymptotic Weak Gravity Conjecture for Open Strings
Cesar Fierro Cota, Alessandro Mininno, Timo Weigand +1
We investigate the asymptotic Tower Weak Gravity Conjecture in weak coupling limits of open string theories with minimal supersymmetry in four dimensions, focusing for definiteness…
Fluxed M5-instantons in F-theory
Max Kerstan, Timo Weigand
We analyse the non-perturbative superpotential due to M5-brane instantons in F-theory compactifications on Calabi-Yau fourfolds. The M5 partition function is obtained via holomorph…
Lifting D-Instanton Zero Modes by Recombination and Background Fluxes
Ralph Blumenhagen, Mirjam Cvetic, Robert Richter +1
We study the conditions under which D-brane instantons in Type II orientifold compactifications generate a non-perturbative superpotential. If the instanton is non-invariant under…
Physics of Infinite Complex Structure Limits in eight Dimensions
Seung-Joo Lee, Wolfgang Lerche, Timo Weigand
We investigate infinite distance limits in the complex structure moduli space of F-theory compactified on K3 to eight dimensions. While this is among the simplest possible arenas t…
The Asymptotic Weak Gravity Conjecture in M-theory
Cesar Fierro Cota, Alessandro Mininno, Timo Weigand +1
The tower Weak Gravity Conjecture predicts infinitely many super-extremal states along every ray in the charge lattice of a consistent quantum gravity theory. We show this far-reac…
Tensionless Strings and the Weak Gravity Conjecture
Seung-Joo Lee, Wolfgang Lerche, Timo Weigand
We test various conjectures about quantum gravity for six-dimensional string compactifications in the framework of F-theory. Starting with a gauge theory coupled to gravity, we ana…
Quantum Corrections in 4d N=1 Infinite Distance Limits and the Weak Gravity Conjecture
Daniel Klaewer, Seung-Joo Lee, Timo Weigand +1
We study quantum corrections in four-dimensional theories with supersymmetry in the context of Quantum Gravity Conjectures. According to the Emergent String Conjecture, infin…
Gauge Fluxes in F-theory and Type IIB Orientifolds
Sven Krause, Christoph Mayrhofer, Timo Weigand
We provide a detailed correspondence between G_4 gauge fluxes in F-theory compactifications with SU(n) and SU(n)x(1) gauge symmetry and their Type IIB orientifold limit. Based on t…
Fluxbranes: Moduli Stabilisation and Inflation
Arthur Hebecker, Sebastian C. Kraus, Moritz Kuntzler +2
Fluxbrane inflation is a stringy version of D-term inflation in which two fluxed D7-branes move towards each other until their (relative) gauge flux annihilates. Compared to brane-…
Testing the Heterotic String with the Axion-Photon Coupling
Mario Reig, Timo Weigand
The discovery of an axion-like particle above the QCD line would rule out Grand Unified Theories, including the perturbative heterotic string with the Standard Model embedded in a…
U(1) symmetries in F-theory GUTs with multiple sections
Christoph Mayrhofer, Eran Palti, Timo Weigand
We present a systematic construction of F-theory compactifications with Abelian gauge symmetries in addition to a non-Abelian gauge group G. The formalism is generally applicable t…