Strings and Geometry 2026

Contribution List

1. Shiu

19/05/2026, 09:00

2. Castellano: New Insights on Non-Perturbative BPS Black Hole Entropy

19/05/2026, 09:30

Black holes exhibit a non-vanishing entropy which, at leading order, is proportional to the horizon area in Planck units. A microscopic interpretation in quantum gravity requires this quantity to arise as the logarithm of an integer degeneracy, necessitating the inclusion of both perturbative and non-perturbative corrections. In this talk, we will review recent progress in understanding...

3. Rudelius: Swampland and Cone Conjectures in Calabi-Yau Moduli Spaces

19/05/2026, 10:00

Various swampland conjectures predict the existence of light particles and strings in infinite-distance limits of moduli space. In this talk, we will see that these swampland conjectures are intimately linked with the cone conjectures of Morrison in the context of M-theory compactifications on Calabi-Yau threefolds. In the process, we will clarify the subtle geometric distinction between...

4. Tomasiello: New punctures for six-dimensional CFT compactifications

19/05/2026, 11:00

Compactifying 6D SCFTs with N=(1,0) supersymmetry on Riemann surfaces is expected to produce N=1 analogues of the famous Class S models. I will study holographic defects in massive IIA string theory AdS7 solutions, and use the results to obtain information about the punctures of these N=1 models, and their contribution to central charges.

5. Delgado: Constraints on Spacetime from Worldsheet Anomaly Cancellation

19/05/2026, 11:30

I will discuss recent progress in understanding non-supersymmetric string backgrounds through anomaly cancellation. Worldsheet anomaly cancellation imposes restrictions on the two-dimensional theory describing string propagation and, in turn, constrains the allowed target-space backgrounds. I will explain how these worldsheet anomaly-cancellation conditions can be used to identify and...

6. Lockhart: String probes and the supergravity landscape

19/05/2026, 14:00

String probes are a useful tool for studying the consistency conditions and properties of supergravity theories. I will present two novel applications along these lines. The first is a new link between the global form of gauge groups in the bulk and holomorphic simple current extensions of the worldsheet CFT of string probes, which gives a worldsheet explanation for the absence of global...

7. Heckman: On Physical Discretization and Arithmetic Geometry

19/05/2026, 14:30

We discuss a speculative formulation of quantum field theories and string theories with fields viewed as maps between mod p, p-adic geometries, and "smoother" analytifications. This provides a physical interpretation and refinement of discretization over lattice truncation schemes and motivates some natural generalizations of p-adic strings.

8. Lawrie: Algebro-Geometric Bootstrapping from OPE Decoupling

19/05/2026, 15:30

In recent work, with M. J. Kang and J. Song, we conjecture that the Macdonald index (thus the Schur index) and the Higgs branch of a 4d N=2 SCFT can be obtained from an algebro-geometric object: a bifiltered affine scheme. This scheme, in practice a by-word for a collection of polynomial equations, is determined from nilpotency/decoupling relations in the operator product expansion of the...

9. Dierigl: A missing link

19/05/2026, 16:00

In this talk we will explore how symmetry-breaking defects, predicted by the Cobordism Conjecture, can appear in brane networks. We will focus on theories with discrete symmetry groups, which naturally come with codimension-two branes defined by the gauge monodromy around them. Their second bordism group generically encodes generators described by discrete gauge bundles on genus g Riemann...

10. Acharya: Spacetime Geometry in Geometric Engineering

19/05/2026, 16:45

11. Lin: SymTFTs with Interfaces in Geometric Engineering

19/05/2026, 17:15

I will show that torsion (co-)homology in the internal space of M-theory geometric engineering leads to topological interfaces in the Symmetry TFT (SymTFT) — a setup also known as the “club sandwich” in the literature. As a concrete example I will discuss geometries leading to 6d supersymmetric sp(n) gauge theories. By duality, I will further argue that also 7d and 8d frozen compactifications...

12. Grimminger: 5d SCFTs on Brane Webs and CY3s -- non-toric

20/05/2026, 09:00

I will address some recent progress in the study of 5 dimensional SCFTs which can be engineered in M-theory on CY3s as well as fivebrane webs in Type IIB String Theory. Especially how the two approaches compare in the non-toric case.

13. Collinucci: 5d SCFT’s from Pagoda geometries

20/05/2026, 09:30

Geometric engineering constructs 5d SCFT from Calabi-Yau manifolds. The most studied case is the toric world, SCFT’s are defined implicitly as UV limits of standard Lagrangian theories like SYM with hypermultiplet matter.

In this talk I will introduce what I call Pagoda Theories. These are defined via M-theory on non-toric CY threefolds. They contain a SYM sector, and a non-conventional...

14. Prieto: Complexity of Effective Field Theories in the Quantum Gravity Landscape

20/05/2026, 10:00

In this talk, I will present the recently developed mathematical framework of tameness as a candidate for a unifying finiteness principle underlying effective field theories. After introducing the central ideas of the formalism, I will show how it gives rise to a quantitative notion of complexity for EFTs, capturing the information required to specify a given theory. I will illustrate this...

15. Wiesner: Geometry and Physics of Degenerating Calabi-Yau three- and fourfolds

20/05/2026, 11:00

In this talk, I will discuss the physics of Type IIB and F-theory compactifications on Calabi–Yau 3- and 4-folds undergoing semi-stable degeneration. In the resulting 4d effective theory, these degenerations give rise to solitonic string solutions. I will describe how the worldsheet theory of these strings can be inferred from the degeneration geometry and how it encodes the effective physics...

16. Montero

20/05/2026, 11:30

17. Graña: Effective theories with symmetric moduli spaces: the landscape and the swampland

20/05/2026, 14:00

We will show that effective theories with symmetric moduli spaces satisfy the Swampland Distance Conjecture, namely for any infinite distance limit there is a tower of states becoming exponentially light. The mass decay rates of the states are entirely encoded in the Weyl polytope of the representation under which they transform. Imposing these rates to be those of either tensionless strings...

18. Apruzzi: Gaillard-Zumino non-invertible symmetries

20/05/2026, 14:30

In this talk I will discuss an infinite class of novel zero-form non-invertible symmetries in a broad family of four-dimensional field theoretical models, studied years ago by Gaillard and Zumino (GZ). The GZ models consist of abelian gauge fields coupled to a neutral sector, typically including a set of scalars, whose equations of motion are classically invariant under a continuous group G...

19. Weigand: Infinity and Finiteness in Strings and Geometry

21/05/2026, 09:00

Two key properties of quantum gravity concern its universal behaviour linked to infinite towers of states that appear asymptotically in moduli space on the one hand, and the boundedness of its light degrees of freedom in the interior of moduli space on the other hand. We will report on recent results regarding these two hallmarks of quantum gravity: We will analyze the nature of towers of...

20. Valenzuela: Limits in Warpland and CFTs

21/05/2026, 09:30

21. Marchesano: Six Lessons on Gravity Decoupling

21/05/2026, 10:00

22. Vafa: Non-Supersymmetric Strings and Geometry

21/05/2026, 11:00

I discuss aspects of non-supersymmetric string vacua emphasizing both the geometry of target space as well as the moduli space of light fields. This will include the geometry of tachyon and dilaton fields in 0A and 0B strings.

23. Parra de Freitas: A Duality Web for Non-Supersymmetric Strings

21/05/2026, 11:30

I will describe a proposed duality web relating several non-supersymmetric string theories. Using recent M-theory and F-theory geometric descriptions of type 0 strings, I will show how suitable Z2​ quotients produce 0A/0B orientifolds. This perspective also gives new evidence for the Bergman–Gaberdiel and DMS duality conjectures relating type 0 orientifolds to bosonic string compactifications.

24. Cvetic: Symmetry Theories, Anomalies and η Invariants (Geometric Engineering and Quiver Approaches)

21/05/2026, 14:00

25. García Etxebarria: Anomaly-induced vanishing of brane partition functions

21/05/2026, 14:30

In the presence of ’t Hooft anomalies, backgrounds for the
symmetries of a quantum field theory can lead to non-conservation of
Noether currents. When there is a net background charge, the partition
function evaluated on closed manifolds will vanish. For anomalous
symmetries, this statement can also be understood as the anomaly theory
giving rise to a non-trivial anomalous phase for the...

26. Kim: 6d Supergravity Blocks

21/05/2026, 15:30

I will present a bottom-up framework for constructing 6d (1,0) supergravity theories from supergravity blocks. Each block is a basic unit built from a little string theory sector associated with the H-string, together with the external BPS generators attached to it, and is characterized by carrying intrinsic gravitational tensors. As a first application, I will give the classification of...

27. Moritz: Calabi-Yau Orientifold Hypersurfaces and Their F-theory Uplifts

21/05/2026, 16:00

I will describe a systematic combinatorial construction of O3/O7 orientifolds of Calabi-Yau hypersurfaces in toric varieties and of their corresponding F-theory uplifts. Starting from toric fourfolds associated to four-dimensional reflexive polytopes, the orientifold involutions can be classified combinatorially, while the F-theory uplifts arise as codimension-two complete intersections in...

28. Tarazi: Toward a Universality Principle for Matter in String Theory

22/05/2026, 09:00

In this talk, I will discuss the classification of exotic matter representations arising in toroidal heterotic orbifolds that cannot be obtained through geometric engineering. We show that every such representation admits an interpretation as an embedding into the adjoint representation of a simple Lie algebra. Motivated by this, we argue more generally that consistent matter in string theory...

29. Valandro: D2-brane probes of non-toric cDV threefolds via monopole superpotentials

22/05/2026, 09:30

Abstract: D-branes probing singular Calabi–Yau threefolds give rise to supersymmetric quiver gauge theories whose moduli space reproduces the local geometry. While powerful techniques exist for toric singularities, no systematic method has been available for the non-toric case. I will present a framework to construct probe-brane theories for compound Du Val (cDV) singularities, based on a...

30. Lüst: Continuity on the Boundary of Moduli Space

22/05/2026, 10:00

I discuss whether period maps and their Kähler-covariant derivatives can be continuously extended to the boundary of the complex structure moduli space of a Calabi-Yau fourfold. This continuity makes it possible to define a topological contour integral along the boundary, which in turn yields a sufficient condition for the existence of flux vacua in the interior of moduli space.

31. Wang: Higgs branch and VOA of 4d N=2 SCFTs from IIB

22/05/2026, 11:00

We study the Higgs branch and VOA of 4d N=2 SCFTs from the geometric engineering of IIB superstring on canonical threefold singularities. We cover examples of terminal singularities as well as hypersurface singularities with smooth or singular exceptional divisors in their crepant resolution. We found many new VOAs with no known W-algebra descriptions, as well as examples of 4d N=2 SCFTs with...

32. De Marco: Discrete gauging in theories with 8 supercharges

22/05/2026, 11:30

I will discuss how gauging 0-form discrete symmetries modifies the Higgs and Coulomb branches of theories with eight supercharges. I will focus on two classes of examples: 4d N = 2 SQCD and 5d rank-one SCFTs. In the latter case, I will discuss how string theory connects the HB and CB realizations of these symmetries, and how the construction suggests the existence of 5d rank-one SCFTs with...