Welcome

Matilda Delgado - Global anomalies and Bordism of Non-Supersymmetric Strings Global anomalies and Bordism of Non-Supersymmetric Strings The three tachyon-free non-supersymmetric string theories in ten dimensions provide a handle on quantum gravity away from the supersymmetric lamppost. However, they have not been shown to be fully consistent; although local anomalies cancel due to versions of the Green-Schwarz mechanism, there could be global anomalies that could become fatal pathologies. We study these global anomalies in the three ten-dimensional non-supersymmetric, tachyon-free string theories. We demonstrate how they cancel by showing that the relevant bordism classes are trivial. An anomaly inflow argument allows us to shed light on the worldvolume degrees of freedom of the NS5 brane in the SO(16) x SO(16) theory. Finally, the bordism groups we compute can be used to predict the existence of new non-supersymmetric branes in these theories, by means of the cobordism conjecture.

Simon Schreyer - News on the anti-D3-brane uplift News on the anti-D3-brane uplift For the anti-D3-brane uplift one places p anti-D3-branes at the tip of a Klebanov-Strassler (KS) throat. This setup can only contribute positively to the vacuum energy if it is stable against the so called KPV decay where the anti-branes puff up into an NS5-brane which subsequently annihilates against flux and forms a supersymmetric state at zero vacuum energy. In this talk, I will discuss this setup of p anti-D3 branes at the tip of the KS throat at higher orders in alpha' from the perspective of a nonabelian stack of D3-branes and recap some earlier results from the puffed up NS5-brane perspective. I will point out advantages of both pictures and discuss implications for phenomenology.

Bruno de Luca - Can you hear the Planck mass? Can you hear the Planck mass? Upon compactification of higher-dimensional theories of gravity, a spectrum of spin 2 particles (Kaluza-Klein modes) is generated, whose masses depend on the details of warp factor and of the internal geometry. For the Laplacian of an n-Riemannian manifold X, the Weyl law states that the k-th eigenvalue is asymptotically proportional to (k/V)^{2/n}, where V is the volume of X. In this talk, I will show how this result can be derived via physical considerations by demanding that the gravitational potential for a compactification on X behaves in the expected (4+n)-dimensional way at short distances. In simple product compactifications, when particle motion on X is ergodic, for large k the eigenfunctions oscillate around a constant, and the argument is relatively straightforward. The Weyl law thus allows to reconstruct the four-dimensional Planck mass from the asymptotics of the masses of the spin 2 KK modes. For warped compactifications, a puzzle appears: the Weyl law still depends on the ordinary volume V, while the Planck mass famously depends on a weighted volume obtained as an integral of the warp factor. I will show how this apparent tension is resolved by arguing that in the ergodic case the eigenfunctions oscillate now around a power of the warping function rather than around a constant, leading to the notion of "weighted quantum ergodicity". This has implications for the problem of gravity localization, which I will discuss if time permits.

Damian van de Heisteeg - Landscapes of Moduli Spaces and Exact Flux Vacua Landscapes of Moduli Spaces and Exact Flux Vacua In this talk we explore the landscape of F-theory compactifications from two directions. In the first approach, we consider the simplest complex structure moduli space, the thrice-punctured sphere, and enumerate all corresponding Calabi-Yau fourfolds by monodromy considerations. In the second, we explore the landscape of flux vacua with a vanishing superpotential, both from a general Hodge-theoretic point of view and by considering explicit examples. Based on 2404.03456 and 2404.12422.

Hector Parra de Freitas - T-duality for non-critical heterotic strings T-duality for non-critical heterotic strings Non-critical heterotic strings with linear dilaton backgrounds are formally related to their critical non-supersymmetric counterparts. I will show that their T-duality symmetry groups upon circle compactification are of the form O(1,12+D/2,Z) for even dimension D. I will explain how the global structure of each moduli space is encoded in an extended Dynkin diagram, generalizing known results for critical supersymmetric and non-supersymmetric strings. In the context of subcritical strings, these moduli spaces represent deformations of heterotic brane backgrounds. These results suggest that the heterotic NS5 brane is related through T-duality to recently constructed non-supersymmetric heterotic branes. These backgrounds can also be obtained through the Hellerman-Swanson tachyon condensation process, suggesting that a pair of winding tachyons in a Scherk-Schwarz circle at self-dual radius can condense into a pair of coincident NS5-branes for a generic heterotic string.

Amineh Mohseni - Measuring Distances in the Quantum Gravity Landscape Measuring Distances in the Quantum Gravity Landscape We propose a notion of distance between vacua in the theory of a scalar field phi with scalar potential V(phi) coupled to gravity. We propose the normalized tension of domain wall connecting the vacua as a physically motivated one, where the normalization is relative to the local energy density. We show this definition reproduces the moduli space distance when the potential is zero as well as the proposed distance in the dS/AdS cases. In the case of large AdS we also obtain the expected exponent of mass versus distance if the mass of the light tower is m ~ sqrt{Lambda} and one extra dimension decompactifying.

Alvaro Herraez - On the origin of species thermodynamics and a black hole-tower correspondence On the origin of species thermodynamics and a black hole-tower correspondence We begin by studying configurations of particles at equilibrium at a temperature T inside a box in the presence of towers of species. By playing with the control parameters, we can obtain configurations that avoid gravitational collapse and fulfill the Covariant Entropy Bound (CEB). These interpolate between the usual dependence of the entropy with the volume (when T is low enough and the momentum modes available to massless particles dominate) and a dependence on the number of species that are “active” at a temperature T (when the T is high enough to “see" the towers of species). In the latter case, we recover the species entropy (and thus the area scaling of the entropy) in the limit in which the temperature approaches the maximum one, namely the species scale, which is also the point at which gravitational collapse and saturation of the CEB would occur for the smallest possible box. We then put this in the bigger picture of the black hole-tower correspondence, a generalization of the black hole-string correspondence that allows to qualitatively account for the scaling of the entropy of black holes with their area by adiabatically following them towards weak gravitational coupling regimes, up to the point where a transition to a system whose entropy is dominated by the towers of species should occur.

Alessandro Mininno - The Minimal Weak Gravity Conjecture The Minimal Weak Gravity Conjecture We examine the minimal constraints imposed by the Weak Gravity Conjecture (WGC) on the particle spectrum of quantum gravity theories. Recently, we argued for the existence of a minimal radius in circle reductions of generic quantum gravity theories. Consequently, whenever a minimal radius exists and the WGC is satisfied at the particle level below the black hole threshold by some states, these states are sufficient for consistency under dimensional reduction, even without a tower of super-extremal particles. Conversely, the absence of a minimal radius always coincides with the presence of a weakly coupled super-extremal tower of particle states. This observation motivates the Minimal Weak Gravity Conjecture, which posits that towers of super-extremal particles appear only when required for consistency of the WGC under dimensional reduction. The talk is based on [2312.04619].

Veronica Collazuol - Symmetric moduli spaces: boundaries, geodesics and the distance conjecture Symmetric moduli spaces: boundaries, geodesics and the distance conjecture In the context of the Swampland program, the Distance Conjecture predicts an infinite tower of states becoming massless at infinite distance in moduli spaces of string compactifications. This is widely believed to be a general feature of quantum gravity, but it is difficult to prove in full generality. On the other hand, the moduli spaces of toroidally compactified M- and string theories are coset spaces of symmetric type, which are mathematically fairly well understood. In this work, we provide a framework to study systematically the infinite distance limits for this class and use this knowledge to argue for the Distance Conjecture in this subset of theories, which could give insights for the case of more complicated moduli spaces with symmetric asymptotic regions.

Georges Obied - Festina Lente and branes Festina Lente and branes Extended objects are ubiquitous in string theory where they have special properties. Outside of string theory, there are relatively few insights into the nature of extended objects that are allowed by quantum gravity. In this talk, using the Festina Lente conjecture, I will argue for new universal bounds on the tension of branes coupled to gauge fields in de Sitter space. This bound is implied by cosmic censorship and can be derived by studying the evolution of large charged black holes in de Sitter space. Since this is a bottom-up argument, it should be obeyed by any de Sitter quantum gravity including stringy constructions.

Jeroen Monnee - Complexity of the Flux Landscape Complexity of the Flux Landscape The landscape of F-theory flux compactifications is expected to be remarkably constrained due to deep insights in Hodge theory and tame geometry. In this talk, I will first recall known finiteness theorems for the landscape of self-dual flux vacua and provide additional insights on this matter using asymptotic Hodge theory. In the remainder of the talk, I will present and motivate three new mathematical conjectures on the enumeration, dimensionality, and geometric complexity of the flux landscape, including a reformulation of the tadpole conjecture. Based on 2311.09295.

Andriana Makridou - Dynamical Cobordism and Codimension-2 End-of-the-world Branes Dynamical Cobordism and Codimension-2 End-of-the-world Branes Dynamical Cobordism is an implementation of the Cobordism Conjecture in the framework of Effective Field Theory, with End-of-the-World (ETW) Branes realized as codimension-1 solutions of the EFT becoming singular at infinite field distance and finite spacetime distance. In this talk, I will describe how codimension-2 ETW branes can be realized as intersecting solutions, providing both a general framework and specific examples for this description. From the cobordism perspective, the intersections can be regarded as describing the end of the world for end-of-the-world branes, or as boundary domain walls interpolating between different ETW brane boundary conditions for the same bulk theory.

Rafael Alvarez-Garcia - Non-minimal Elliptic Threefolds and the Distance Conjecture Non-minimal Elliptic Threefolds and the Distance Conjecture We analyze infinite-distance limits in the complex structure moduli space of six-dimensional F-theory, providing an algebro-geometric classification and a physical interpretation. From the point of view of the Swampland Program, the motivation is to understand the fate of open-moduli infinite-distance limits in relation with the Distance Conjecture. From an F-theory perspective, the infinite-distance limits correspond to degenerations of elliptic threefolds leading to non-minimal singularities in codimension one and higher. We show how such non-crepant singularities can be removed by a systematic sequence of blow-ups of the bases of the infinite-distance degenerations, making their central fibers a union of log Calabi-Yau spaces glued together along their boundaries. We interpret said central fibers as either the endpoints of decompactification limits with six-dimensional defects or as emergent string limits, providing further evidence for the Emergent String Conjecture.

Björn Friedrich - An EFT for end-of-the-world branes and the creation of universes from nothing An EFT for end-of-the-world branes and the creation of universes from nothing End-of-the-world (ETW) branes are expected to be a generic feature of string theory and may play an important role in cosmology. We explain how ETW branes can be described from a 4d EFT point of view and describe how their presence influences predictions in cosmology. We explicitly present a proposal for the creation of universes from nothing making use of the existence of ETW branes.

Jose Calderon-Infante - Tensionless Strings Limits in 4d Conformal Manifolds Tensionless Strings Limits in 4d Conformal Manifolds Three distinct infinite distance limits appear in the conformal manifolds of four-dimensional superconformal field theories admitting large N limit. They are distinguished by the CFT Distance Conjecture parameter, controlling the exponential behavior with the distance of the anomalous dimension of higher-spin currents. Borrowing lessons from the moduli spaces of flat space vacua in string theory, we argue that these three limits correspond to three different strings becoming tensionless in AdS. To support this claim, we show that the large N Hagedorn temperature of the CFT in these limits only depends on the CFT Distance Conjecture parameter. Thus, these three limits are physically distinguished by the density of states at high energies. Along the way, we build the first Distance Conjecture convex hull for a CFT and find a remarkable connection to no separation of scales in AdS.

Naomi Gendler - Axions in the Dark Dimension Axions in the Dark Dimension

Max Hübner - Generalized Symmetries and Global Models Generalized Symmetries and Global Models We consider compactifications of M-theory on purely geometric backgrounds. In many cases singularities of such top-down constructions support QFT degrees of freedom. Symmetries emerge when isolating these degrees of freedom via local limits. Conversely, completing a local model into a global model symmetries are broken or gauged. We explicitly discuss these processes in a number of orbifold geometries and characterize these using SymTrees.

Houri Tarazi - New Non-supersymmetric Tachyon-Free Strings New Non-supersymmetric Tachyon-Free Strings In four decades of string theory research only a handful of examples of non-supersymmetric, tachyon-free string models with only one neutral scalar at tree level are known. In this talk I will present new non-supersymmetric and tachyon-free string theories using asymmetric orbifolds that serve as the lower-dimensional counterparts to the O(16)xO(16) string in 4d, 6d, and 8d, each featuring only one neutral scalar at tree level.

Muthusamy Rajaguru - Stabilizing Massless Fields in Non-Geometric Landau-Ginzburg Models Stabilizing Massless Fields in Non-Geometric Landau-Ginzburg Models. The tadpole conjecture constrains the number of moduli that can be stabilized with fluxes in F-theory and type IIB flux compactifications. In this talk, I will discuss ongoing work that aims to test this assertion in non-geometric type IIB flux compactifications with no Kähler moduli. In particular, I will restrict to supersymmetric Minkowski vacua in orbifolds of the 1^9 and 2^6 Gepner models. Generically these Minkowski critical points have many massless directions. In principle, we are able to expand the flux superpotential around these Minkowski critical points upto arbitrary order. This allows us to ask if these massless directions are truly flat or if they get stabilized by some higher-than-quadratic order term in the superpotential.

Nicolo Petri - Exploring the AdS conjecture: a positive metric over DGKT vacua Exploring the AdS conjecture: a positive metric over DGKT vacua The AdS Distance conjecture proposes a notion of distance between AdS vacua in quantum gravity. Although the need for such a notion is evident, defining and computing this distance is challenging, both conceptually and technically. In my talk, I will address this challenge by proposing a consistent framework for defining and computing the metric over AdS vacua, establishing a well-defined distance. The key idea involves considering the off-shell quadratic variation of the string theory action and evaluating it over the space of on-shell solutions. I will particularly focus on DGKT vacua. Given the ongoing debate regarding whether these vacua exist as fully localized solutions, it is particularly intriguing to test our proposed metric over AdS vacua within this framework. I will show that DGKT vacua exhibit a positive metric, yielding a well-defined AdS distance. In conclusion, I will introduce a potential new Swampland criterion, suggesting that the metric over the space of vacua in quantum gravity, as defined by our proposed procedure, is positive definite.

Ivano Basile - Decoding Dualities at Divergent Distance Decoding Dualities at Divergent Distance String theory is quite picky: the only weakly coupled degrees of freedom that arise beyond effective quantum fields are encoded in a unique critical string, and dualities relate its various limits. Can we bootstrap this rigidity from general quantum gravity ideas? Combining insights on information theory, black holes and scattering amplitudes we build a swamplandish case for the emergent string conjecture. To this end, we leverage the properties of minimal black holes to indicate the emergence of geometry and strings from light towers of species, consistently with a complementary worldsheet conformal field theory analysis.