Thomas Van Riet
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View article: Visions in quantum gravity
Visions in quantum gravity Open
To deepen our understanding of Quantum Gravity and its connections with black holes and cosmology, building a common language and exchanging ideas across different approaches is crucial. The Nordita Program “Quantum Gravity: From gravitati…
Scale separation, rolling solutions, and entropy bounds Open
We revisit scale separation for compactifications of ten- and eleven-dimensional supergravity. For cosmological solutions rolling down flux-generated potentials, we observe that scale separation is achieved as time flows, and is fairly gen…
Warped G$_2$-throats in IIA and uplift dSillusions Open
Flux compactifications of IIA supergravity on orientifolded G$_2$-manifolds have been argued to allow for classical Minkowski$_3$ vacua with moduli and scale-separated AdS$_3$ vacua with full moduli stabilisation. To further uplift these v…
Scale separation, rolling solutions and entropy bounds Open
We revisit scale separation for compactifications of ten- and eleven-dimensional supergravity. For cosmological solutions rolling down flux-generated potentials, we observe that scale separation is achieved as time flows, and is fairly gen…
Black Holes, Moduli Stabilisation and the Swampland Open
In theories with moduli, extremal black holes behave such that for generic initial conditions, the distance traveled by the scalars from infinity to the horizon can grow with the size of the black hole. This, in turn, implies that larger b…
A distance conjecture beyond moduli? Open
A bstract The distance conjecture states that for theories with moduli coupled to gravity a tower of states becomes exponentially light in the geodesic distance in moduli space. This specifies how effective field theories break down for la…
View article: Visions in Quantum Gravity
Visions in Quantum Gravity Open
To deepen our understanding of Quantum Gravity and its connections with black holes and cosmology, building a common language and exchanging ideas across different approaches is crucial. The Nordita Program "Quantum Gravity: from gravitati…
Stability of axion-saxion wormholes Open
A bstract We reconsider the perturbative stability of Euclidean axion wormholes. The quadratic action that governs linear perturbations is derived directly in Euclidean gravity. We demonstrate explicitly that a stability analysis in which …
Supergravity solutions for D$p$-D$(6-p)$ bound states: from $p=7$ to $p=-1$ Open
Near horizon geometries of D$p$-branes with $p\neq 3$ are singular with a running dilaton. Bound states of D$p$ branes with their magnetic cousins, D$(6-p)$ branes, can stabilise the dilaton such that an AdS factor might appear in the near…
A distance conjecture beyond moduli? Open
The distance conjecture states that for theories with moduli coupled to gravity a tower of states becomes light exponentially in the geodesic distance in moduli space. This specifies how effective field theories break down for large field …
Stability of Axion-Saxion wormholes Open
We reconsider the perturbative stability of Euclidean axion wormholes. The quadratic action that governs linear perturbations is derived directly in Euclidean gravity. We demonstrate explicitly that a stability analysis in which one treats…
The Quantum Theory Of Gravitation, Effective Field Theories, and Strings: Yesterday And Today Open
This paper analyzes the effective field theory perspective on modern physics through the lens of the quantum theory of gravitational interaction. The historical part argues that the search for a theory of quantum gravity stimulated the cha…
Connecting flux vacua through scalar field excursions Open
We show how flux vacua that differ from each other in flux quanta can be seen as different vacua in a single scalar potential of an enlarged field space, which resolves the separation by thin domain walls. This observation, which is motiva…
Axion-de Sitter wormholes Open
A bstract We construct wormholes supported by axion flux in the presence of a positive cosmological constant. The solutions describe compact, one-handle bodies colloquially known as kettlebell geometries. The wormholes are perturbatively s…
Connecting flux vacua through scalar field excursions Open
We show how flux vacua that differ from each other in flux quanta can be seen as different vacua in a single scalar potential of an enlarged field space, which resolves the separation by thin domain walls. This observation, which is motiva…
No accelerating scaling cosmologies at string tree level? Open
We investigate the scalar potential of string compactifications in the parametric regime where string loops and higher derivative corrections to 10d supergravity can be ignored and where the fields are rolling down exponential slopes leadi…
Axion-de Sitter wormholes Open
We construct wormholes supported by axion flux in the presence of a positive cosmological constant. The solutions describe compact, one-handle bodies colloquially known as kettlebell geometries. The wormholes are perturbatively stable, but…
Beginners lectures on flux compactifications and related Swampland topics Open
These lecture notes provide a pedagogical introduction, with exercises, to the techniques used in attempts to construct vacua with stabilised moduli in string theory. The reader is only assumed to have a basic knowledge of general relativi…
Trustworthy de Sitter compactifications of string theory: a comprehensive review Open
We attempt to review all trustworthy and well-controlled de Sitter compactifications of string theory.
A 10d construction of Euclidean axion wormholes in flat and AdS space Open
Euclidean wormhole geometries sourced by axions and dilatons are puzzling objects in quantum gravity. From one side of the wormhole to the other, the scalar fields traverse a few Planck lengths in field space and so corrections from the UV…
AdS scale separation and the distance conjecture Open
It has been argued that orientifold vacua with fluxes in type IIA string theory can achieve moduli stabilisation and arbitrary decoupling between the AdS and KK scales upon sending certain unconstrained RR-flux quanta to infinity. In this …
Over-extremal brane shells from string theory? Open
We demonstrate that, if the usual phenomenological compactifications of IIB string theory with warped throats and anti-branes make sense, there must exist spherical brane shells in 4d that are overcharged. They correspond to classical over…
Axion wormholes with massive dilaton Open
If Euclidean wormholes contribute meaningfully to the path integral of quantum gravity they can have important implications for particle physics and cosmology. The dominant effects arise from wormholes whose sizes are comparable to the cut…
Towards an "AdS$_1/$CFT$_0$" correspondence from the D$(-1)/$D$7$ system? Open
We argue that a type IIB Euclidean supergravity solution of the form $\mathbb{R}\times S^1\times \mathbb{T}^8$ with imaginary self-dual $F_1$ flux through $\mathbb{R}\times S^1$ belongs to the chain of $AdS_d\times S^d\times \mathbb{T}^{10…
Over-extremal brane shells from string theory? Open
We demonstrate that, if the usual phenomenological compactifications of IIB string theory with warped throats and anti-branes make sense, there must exist spherical brane shells in 4d that are overcharged. They correspond to classical over…