Program

Talks will take place from 10.30 EST to 12.45 EST (Boston time). There will be three talks per day.

Titles and abstracts

Speakers: Timo Weigand and Daniel Klaewer

Title: Emergent Heterotic Strings, the Weak Gravity Conjecture and Quantum Corrections

Abstract: We prove the Weak Gravity Conjecture in F-theory compactifications to four dimensions with fluxes, in the limit of asymptotically small gauge couplings. This regime corresponds to infinite distance limits in the Kahler moduli space of elliptic fourfolds (in the F-theory limit) with an emergent heterotic string. The non-BPS spectrum of heterotic string excitations contains a sublattice of states which marginally satisfy the Weak Gravity Conjecture bound, to leading order. $alpha’$-corrections in the F-theory frame are interpreted as heterotic gauge threshold corrections, which modify the super-extremality bound. We propose how the Weak Gravity Conjecture can nonetheless be satisfied including these quantum corrections. From the mathematics perspective, the existence of the super-extremal sub-lattice follows from the transformation of the four-dimensional heterotic elliptic genus as a quasi-Jacobi, rather than as a Jacobi, form, in contradistinction to the situation in six dimensions. This is reflected in a set of modular and elliptic anomaly equations governing the properties of BPS invariants on fourfolds with fluxes, which we derive from the topological A-model on four-folds.

Speakers: Thomas Grimm and Damian van de Heisteeg

Title: Reconstructing a finite flux landscape

Abstract: In this talk we discuss a new holographic perspective to uncover the structure of the flux landscape. It is motivated by a general description of the asymptotic, near-boundary regions in complex structure moduli spaces using asymptotic Hodge theory. For the one modulus case we solve an auxiliary bulk theory with associated sl(2) boundary data. The classical bulk reconstruction is provided by the famous sl(2)-orbit theorem. Applied to the flux landscape of Calabi-Yau fourfold compactifications we discuss how these results allow us to prove that the number of self-dual flux vacua is finite. We then show how the reconstruction works in practice for all possible one-modulus CY3 examples, covering well-known special points in moduli space such as the conifold point. As a further consequence we find that the boundary structure requires the presence of instanton terms for any boundary not of large complex structure type.

Speaker: Fernando Marchesano

Title: The String at the End of the Swampland

Abstract: There is a direct relation between the existence of fundamental axionic strings, dubbed EFT strings in this talk, and infinite distance limits in 4d N=1 EFTs. The physics of EFT strings is encoded in their backreaction, which can be interpreted as an RG flow of their couplings, and allows to probe large distance limits in the EFT field space. One may then conjecture that any infinite distance limit of a 4d EFT is realised by the backreaction of EFT strings, with the string tension tied up to the scale at which the EFT breaks down. We will discuss some implications of this conjecture and its relation with other Swampland criteria.

Speakers: Gary Shiu and Lars Aalsma

Title: Quantum Information Bounds on de Sitter Space

Abstract: It is generally accepted that de Sitter space in quantum gravity has a finite lifetime, but the precise value has been debated. In this talk, we will use ideas from quantum information theory to bound the validity of EFTs in de Sitter space. We consider two different thought experiments in which an observer probes the de Sitter entropy by only using resources available to them in a single static patch. We show that in semi-classical gravity to avoid large backreaction these experiments can last at most for a time proportional to the de Sitter entropy.

Speaker: Ben Heidenreich

Title: The Weak Gravity Conjecture and BPS particles

Abstract: I discuss non-perturbative evidence for the tower / sublattice WGC from the spectrum of BPS particles in M-theory compactified on a Calabi-Yau threefold. A central theme of my talk is the question: when are extremal black holes BPS? I provide a partial answer that is broadly applicable as well as a complete answer in certain examples. With this knowledge in hand, I formulate a sharp prediction of the T/sLWGC that has been verified in many examples using the GV invariants. I explain a novel way to compute the cone of effective divisors that falls out as an unexpected byproduct of this analysis.

Speakers: Timm Wrase and Niccolo Cribiori

Title: Non-SUSY strings and the swampland

Abstract: While supersymmetry has been a remarkable tool in theoretical physics it is unclear whether it is actually realized in our universe. This motivates the exploration of non-supersymmetric string theories and their properties. In this talk we will discuss anti-branes that break supersymmetry at the string scale and the genuinely non-supersymmetric SO(16)xSO(16) string theory. We show that both of these have a spectrum that oscillates between bosonic and fermionic degrees of freedoms at higher and higher mass levels. This oscillation was dubbed misaligned supersymmetry and is a generic feature of tachyon free, non-supersymmetric string theories. Misaligned supersymmetry is closely connected to the conformal symmetry on the worldsheet and it appears to be the reason for finite string amplitudes and the vanishing of certain supertraces in genuinely non-supersymmetric string theories.

Speaker: Lavinia Heisenberg

Title: Wealth of EFTs and the constraining power of the Swampland

Abstract: After introducing some of the prominent effective field theories that have been constructed for direct cosmological implications, I will discuss how different theoretical consistency checks can be applied on them for their scrutiny. I will then discuss how the Swampland program could be combined with different cosmological observations in order to disentangle between different dark energy models.

Speakers: Luis Ibañez and Eduardo Gonzalo

Title: Pair production and gravity as the weakest force/Constraints on SM from AdS conjectures

Abstract: In a first part we propose to impose the principle of gravity as the weakest force to purely scalar interactions as a swampland constraint, in terms of pair production of massive particles. One obtains a diferential constraint  with a  built-in duality symmetry. BPS states in N=2 string compactifications  saturate the bounds. One also obtains conditions on moduli potentials consistent with the dS conjecture. Other possible applications  of the conditions to examples like the axion or Higgs potential are briefly discussed. In a second part we discuss how the  AdS distance conjecture  applied to the dimensional reduction of the SM lead to constraints on the mass of the lightest neutrino. We also consider a generalization of the SM including a quintessence field and show how the generalization of the dS conjecture to AdS vacua leads again to similar constraints on neutrino masses. Both constraints can also shed light on the hierarchy problem.

Speaker: Claudia de Rham

Title: Positivity with Gravity

Abstract: In standard effective field theories, the notion of causality is intrinsically linked with that of subluminality and with a set of positivity constraints to be imposed on the low-energy scattering amplitudes. I will highlight how the presence of gravity leads to a more subtle relation between causality, (sub)luminality and positivity bounds pertinent to the Weak Gravity Conjecture. These considerations are relevant for putting constraints on cosmological and gravitational effective field theories and I will provide explicit criteria to be satisfied so as to ensure causality and a standard high energy completion in gravitational effective field theories.