Strings2024 Conference

3 Jun 2024, 08:30 → 7 Jun 2024, 19:00 Europe/Zurich

500/1-001 - Main Auditorium (CERN)

CERN, EPFL, ETHZ, LAPTh, the University of Bern and the University of Geneva, are delighted to host the 34th instalment of Strings, the flagship annual conference for the extended string theory community. It brings together leading researchers from around the world to discuss the latest developments and explore cutting-edge ideas in the fields of string theory, quantum gravity and quantum field theory. As one of the most anticipated gatherings in theoretical physics, the conference serves as a platform for exchanging knowledge, fostering new collaborations, and pushing the boundaries of our understanding of the fundamental aspects of the physical laws of nature.

We invite participants of previous Strings conferences to provide feedback, which we can consider when planning the upcoming conference. Please provide your input here.

The conference will take place at two different locations at CERN: 1) Science Gateway Auditorium for the opening day on Monday, 2) CERN Main auditorium from Tuesday to Friday. 

Organisers: David Andriot (LAPTh, CNRS), Matthias Blau (U.Bern), Matthias Gaberdiel (ETHZ), Victor Gorbenko (EPFL), Alba Grassi (U.Genève and CERN), Monica Guica (EPFL and CERN), Shota Komatsu (CERN), Wolfgang Lerche (CERN), Kyriakos Papadodimas (CERN), Joao Penedones (EPFL), Susanne Reffert (U.Bern), Julian Sonner (U.Genève), Piotr Tourkine (LAPTh, CNRS), Irene Valenzuela (CERN), Alexander Zhiboedov (CERN)

Monday 3 June

08:30 → 09:35 Registration and coffee

09:35 → 09:50 Welcome

Speaker: Eliezer Rabinovici (Hebrew University, Jerusalem, Israel. President Cern Council)

RabinoviciV2.pdf

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09:50 → 10:50 String compactifications from top to bottom

To properly understand String Theory, we must understand its vast space of solutions -- the string Landscape --. The talk will review recent progress in this quest, starting with higher-dimensional supersymmetric vacua where a combination of top-down constructions and bottom-up consistency principles (Swampland constraints) have led to string universality -- a match between the set of low-energy EFT's satisfying bottom-up consistency conditions and those arising from top-down stringy constructions. We will then move on to less supersymmetric examples, ending in exciting new developments in the arena of non-supersymmetric string vacua.

Speaker: Miguel Montero (IFT UAM-CSIC)

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10:50 → 11:20 Constraints on the Species Scale and the Spectrum of States in Quantum Gravity

The species scale serves as a UV cutoff in the gravitational sector of an EFT which generically depends on the scalar fields in the theory. In this talk, I will show that the field-dependence of the species scale is determined by higher-derivative corrections to the Einstein-Hilbert action. I will further argue that the slope of the species scale as a function of scalar fields is bounded from above everywhere in moduli space. The emergent string conjecture, which gives a constraint on the possible spectrum of light states in gravitational weak-coupling limits, predicts an exact value for this upper bound which is indeed satisfied in all known examples. Using properties of black hole thermodynamics and gravitational scattering amplitudes I will further show that in gravitational weak-coupling limits the density of one-particle states has a universal behavior as a function of energy. Based on this, I will then provide bottom-up evidence for the emergent string conjecture by showing that any tower of weakly coupled, light states is either a KK-tower or features a spectrum of states with degeneracy growing exponentially in energy which resembles excitations of a perturbative string.

Speaker: Max Wiesner (Harvard University, USA)

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Weisner.pdf

11:20 → 12:00 Coffee Break

12:00 → 12:30 Real World Amplitudes from Curves on Surfaces

In this talk, I will begin by reviewing a new formulation of particle and string scattering amplitudes in terms of curves on surfaces, built around making the behavior near singularities manifest. I will then describe how this picture exposes qualitatively new features of real-world amplitudes: a novel pattern of factorizations away from poles, a direct kinematic connection between colored scalar, pion, and gluon amplitudes, and a surface generalization of kinematics allowing the determination of "perfect" loop integrands for the non-linear sigma model and non-supersymmetric Yang-Mills theory.

Speaker: Carolina Figueiredo (Princeton University, USA)

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12:30 → 13:00 Black Holes from Supercharge Cohomology

In this talk, I will introduce supercharge cohomology, which is semi-protected by supersymmetry and reveals much richer information beyond state counting. I will classify supercharge cohomologies in holographic conformal field theories into two categories: monotone (graviton) and fortuitous (black hole). Focusing on N=4 super-Yang-Mills theory, I will present explicit constructions of monotone and fortuitous cohomology classes and discuss their conjectural bulk duals as smooth horizonless geometries and black holes. Finally, I will examine the spectrum of near-BPS operators and near-BPS black holes.

Speaker: Chi-Ming Chang

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13:00 → 13:30 A matrix model for 2d de Sitter

I will introduce a new 2d gravity/matrix model duality. The bulk theory is a two-dimensional string theory defined by coupling two copies of Liouville CFT with central charges c = 13 \pm i \mathbb{R} on the worldsheet. The worldsheet theory may be recast semiclassically in terms of 2d dilaton gravity with a sine potential for the dilaton. Intriguingly, this dilaton gravity theory admits solutions with both signs of the cosmological constant. I will argue that this theory admits a dual description in terms of a double-scaled two-matrix integral. The duality holds for any value of the imaginary part of the central charge, and the perturbative string amplitudes may be computed exactly from topological recursion. Based on work in progress in collaboration with Lorenz Eberhardt, Beatrix Mühlmann and Victor Rodriguez.

Speaker: Scott Collier (Massachusetts Institute of Technology, USA)

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13:30 → 15:00 Lunch

15:00 → 15:30 The gravitational dual of double-scaled SYK

I will derive and discuss a new holographic duality between a double-scaling limit of the SYK model and a simple theory of quantum gravity in two dimensions. The gravitational theory in question is a model of dilaton gravity with a sine potential. Asides from deriving this duality, I will focus on certain aspects which may be surprising as compared to other examples of holography dualities, such as the distinction between temperature and fake temperature.

Speaker: Andreas Blommaert (SISSA)

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15:30 → 17:00 Lessons from JT gravity

The session will be divided into two parts. In the first part, we will provide an overview of JT gravity, go over recent applications and discuss some open questions. In the second part, Maxfield, Lin, Maldacena, Eberhardt, Sonner, and Jafferis will each make brief further comments.

Speakers: Douglas Stanford (Stanford University, USA), Joaquin Turiaci (University of Washington, USA)

Lessons_from_JT_and_SYK.pdf

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17:00 → 22:00 Reception and Poster Exhibition

Tuesday 4 June

09:20 → 10:20 The BFSS conjecture, a review

Speaker: Juan Maldacena (Institute for Advanced Study, USA)

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10:20 → 10:50 Asymptotic Symmetries for Logarithmic Soft Theorems

Gauge theories and perturbative gravity in four dimensions are governed by a tower of infinite-dimensional symmetries that arise from tree-level soft factorization theorems of the S-matrix. However, aside from the leading soft theorems which are all-loop exact, subleading ones receive loop corrections due to long-range infrared effects which result in new soft theorems with logarithmic dependence on the energy of the soft particle. In this talk I will initiate a program to compute long-range infrared corrections to the generators of asymptotic symmetries in scalar QED and gravity and show how the conservation law of the infrared corrected charges provides a symmetry interpretation for the leading logarithmic soft theorems. By virtue of being universal and all-loop exact, this is a key element for a holographic principle in spacetimes with flat asymptotics.

Speaker: Andrea Puhm (University of Amsterdam (NL))

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10:50 → 11:30 Coffee Break

11:30 → 12:00 A (non-)worldsheet description of string backgrounds

For string backgrounds with known exact worldsheet theory descriptions, ordinary string perturbation theory can be employed to study their observables such as string spectrum and scattering. However, many of interesting string backgrounds, including AdS and flux compactifications, lack such descriptions, posing challenges in understanding their stringy physics. Since these backgrounds are typically described as solutions to low-energy supergravity theory, having a string-theoretic counterpart to this field theory is desirable. In this talk, we discuss how string field theory provides such a framework, along with its limitations. Despite such limitations, we illustrate its practical utility in examining physical observables, particularly in examples such as AdS and flux compactifications.

Speaker: Minjae Cho (Princeton University, USA)

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12:00 → 13:30 String field theory: Past, Present, and Future

Xi Yin : I will review the formulation of closed (super-)string field theory, its application in string perturbation theory, RR flux backgrounds, D-instantons, quantum string vacua, and discuss some future prospects.

Ted Erler : We review a body of work, following the formulation of Sen's conjectures in the late 1990's, which endeavors to realize D-brane systems as nonperturbative vacuum solutions in open string field theory. We first sketch solutions derived numerically in the level truncation scheme, and later analytic solutions. If time permits I will sketch the status of analogous questions in closed string field theory.

Speakers: Ted Erler (FZU, Czechia), Xi Yin (Harvard University, USA)

Erler.pdf

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Xi Yin FINAL 2.pdf

13:30 → 14:30 Lunch

14:30 → 15:00 Coffee

15:00 → 15:30 Determinants and Branes in Twisted Holography

Twisted holography relates the 2d chiral algebra subsector of N=4 SYM to the B-model topological string theory on the complex manifold SL(2,C). In this talk, I will present the correspondence between determinant operators and “Giant Graviton” branes. In particular, the large N saddles of determinant correlation functions can be matched with semiclassical D-brane configurations and determinant modifications with brane excitations. I will also discuss twisted holography duals of 4d holomorphic theories and their analogous correspondence.

Speaker: Kasia Budzik (Perimeter Institute)

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15:30 → 16:00 Nonperturbative minimal (super)string / matrix integral duality

Worldsheet methods for doing string perturbation theory around D-instantons often yield answers that contain undetermined constants which need to be fixed using external assumptions, like duality. In this talk I will explain the basic string field theory idea that allows us to overcome the fundamental obstacle with string perturbation theory around D-instantons. Our setting will be minimal (super) string theory and we will show that the string field theory procedure produces instanton contributions that match perfectly with the dual matrix integrals.

Speaker: Raghu Mahajan (Stanford, USA)

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16:00 → 16:30 Gong Show

Speaker: Piotr Tourkine (CNRS, LAPTh, Annecy)

gongshow-all-speakers-strings2024.pdf

19:00 → 22:00 Conference Dinner

Wednesday 5 June

09:20 → 09:50 Emergence of kinetic terms in String Theory

The Emergence Proposal proposes that kinetic terms for fields in quantum gravity are emergent from integrating out towers of heavy states, and that this physics underlies some of the central Swampland constraints on effective theories. We provide evidence for this idea in the context of type IIA string theory on Calabi-Yau manifolds. We argue that the full kinetic terms for the vector multiplets, as controlled by the prepotential, arise from integrating out massive non-perturbative states at one-loop. The leading, tree-level, contribution to the prepotential arises from integrating out the ultraviolet modes of these states. At those energy scales, the degrees of freedom are strongly-coupled but can be captured in some cases by Fermi gas models.

Speaker: Eran Palti (Ben-Gurion University of the Negeva, Israel)

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09:50 → 10:20 Machine-learning in Calabi-Yau geometry

Calabi Yau (CY) manifolds are used ubiquitously in string theory. These spaces are central both to string phenomenology and formal developments. While CY manifolds can be constructed in large numbers, and much is known about their topological features, their geometry is still partly enigmatic. In particular, we lack an analytical expression for Ricci-flat metrics on CY n-folds for n>2. In this talk, I will review recent work on obtaining numerical approximations of CY metrics using machine learning, and how such metrics may be used string theory research.

Speaker: Magdalena Larfors (Uppsala university, Swedem)

Larfors-Strings-2024_v2.pdf

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10:20 → 10:50 de Sitter vacua at leading order?

In this talk I will present the first explicit example of a de Sitter vacuum as envisioned by Kachru, Kallosh, Linde and Trivedi 20 years ago, in the tree level approximation in both the string loop and $\alpha’$ expansion. I will begin by summarizing the construction of all the relevant components, from Calabi-Yau orientifolds, and a mechanism to generate exponentially small superpotentials from quantized fluxes, to the explicit stabilization of hundreds of Kähler moduli via non-perturbative D3-instantons on cycles that satisfy Witten’s rigidity conditions, and the construction of warped Randall-Sundrum throats that can host SUSY breaking uplifts. However, some corrections in the $\alpha’$ and $g_s$ expansions are potentially important but are not fully known, and I will comment on robustness against these.

This talk is based on upcoming work with Liam McAllister, Richard Nally, and Andreas Schachner.

Speaker: Jakob Ulrich Moritz (CERN)

JacobMoritz.pdf

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10:50 → 11:30 Coffee Break

11:30 → 12:00 Dynamical dark energy: from string theory to observations

I'll discuss some recent work towards stringy models of dynamical dark energy and how they stand against the most recent cosmological data

Speaker: Susha Louise Parameswaran (University of Liverpool, UK)

ParameswaranSusha.pdf

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12:00 → 13:30 Observational Prospects in Particle Physics and Cosmology

Mangano : Observational prospects in Colliders.

Simonovic : There is a large amount of cosmological data that will be collected during this decade. In this talk I will review some of the currently ongoing and planned observational programs, including several CMB experiments and different galaxy surveys. I will also discuss some science cases related to high energy physics that will be explored using these new data.

Van Riet: Discussion about the interplay between String Theory, Particle Physics and Cosmology.

Speakers: Marko Simonovic (Universita' di Firenze (IT)), Michelangelo Mangano (CERN), Thomas Van Riet (KU Leuven, Belgium)

Mangano_Strings24.pdf

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Simonovic.pdf

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13:30 → 14:30 Lunch

14:30 → 15:00 Coffee

15:00 → 16:00 Townhall meeting

Speaker: Alejandra Castro

Applicants.pdf

Employers.pdf

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townhall-2024.pdf

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16:00 → 16:30 Human Level AI by 2030? (on-line)

I will discuss recent AI progress and why it's plausible that AI systems will be better than humans at theoretical physics research by the end of the decade.

Speaker: Jared Kaplan

Kaplan.pdf

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16:30 → 18:00 CERN visits

Thursday 6 June

09:20 → 10:20 Light ray operators, detectors, and energy correlators

Light ray operators control many aspects of Lorentzian physics in quantum field theory. For example, they describe the behavior of correlators at large boost, and also provide a natural basis for collider measurements. Analyticity in spin connects these types of light-ray operators together into an intriguing but still mysterious unified structure. I will review aspects of light-ray operators and some of their applications.

Speaker: David Simmons-Duffin (CalTech)

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10:20 → 10:50 The ABJ anomaly as a U(1) symmetry and Noether's theorem

Haag duality is a simple property of algebras attached to regions in QFT that expresses a form of completeness of the theory. Violations of Haag duality are due to "non-local operators". These may be charged with respect to global symmetries. When this happens for a continuous symmetry there is an obstruction for the validity of Noether's theorem. This is behind all known examples when the Noether current is absent, including the ones covered by Weinberg-Witten theorem. An abstract classification of the simplest possibilities is divided into two classes. In the first one there are non compact sectors, which leads to free models. The other possibility, allowing interacting models, corresponds to the ABJ anomaly. This interpretation unifies the features of the anomaly --- anomaly matching, anomaly quantization, non-existence of the Noether current, and validity of Goldstone theorem --- from a symmetry based perspective.

Speaker: Horacio Casini (Instituto Balseiro, Argentina)

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10:50 → 11:30 Coffee Break

11:30 → 12:00 Confining strings and large N on the lattice (on-line)

Speaker: Mike Teper (Oxford University, UK)

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12:00 → 12:30 Bootstrapping Strings

The numerical S-matrix Bootstrap aims at establishing non-perturbative universal bounds on physical observables that can be extracted from scattering amplitudes in any dimension. In the first part of the talk, I will review our recent exploration of the space of supergravity amplitudes, and how String/M theory often appears close to the boundary of the allowed region. Even though this is encouraging, our conclusions would get sharper if we included multiparticle scattering amplitudes in the Bootstrap.
In the second part of the talk, I will report some recent progress on this scary problem. I will focus on the simplest non-integrable S-matrix describing the scattering of branons on the world sheet of confining strings in three dimensions, where multi-particle scattering seems treatable, and show our first multiparticle results.

Speaker: Andrea Guerrieri

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12:30 → 13:00 Integrated correlators and the bootstrap

In this talk, I will show some results obtained from combining the conformal bootstrap for maximally supersymmetric CFTs in three and four dimensions with exact results obtained from supersymmetric localization. The latter take the form of integral constraints on four-point functions of local operators in the CFTs. In N=4 super-Yang-Mills theory, I will present bounds on the low-lying CFT data that depend on the Yang-Mills coupling and that can be compared with integrability, weak coupling expansions, and holographic calculations.

Speaker: Silviu S. Pufu (Princeton University)

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13:00 → 13:30 Bootstrapping mesons at large N

Four-dimensional QCD has been known to simplify dramatically in the large N limit for decades. Yet, even in this limit, its solution still evades us. In this talk, I will discuss how one can instead proceed with a bootstrap approach to carve out the space of large N confining gauge theories that are compatible with a given set of assumptions. One expects to corner large N QCD once sufficiently many constraints are imposed. After motivating a certain set of assumptions, I will review the constraints that follow from 2→2 pion scattering for various meson couplings. We will see how some of these bounds lead to an extremal amplitude which is in uncanny agreement with real-world QCD.

Speaker: Jan Albert (Stony Brook University (USA))

AlbertJan.pdf

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13:30 → 14:30 Lunch

14:30 → 15:00 Coffee

15:00 → 15:30 3d gravity as a random ensemble

One of the major insights gained from holographic duality is the relation between the physics of black holes and quantum chaotic systems. This relation is made precise in the duality between two dimensional JT gravity and random matrix theory. In this work, we generalize this to a duality between AdS3 gravity and a random ensemble of approximate CFT's. The latter is described by a combined tensor and matrix model, describing the OPE coefficients and spectrum of a theory that approximately satisfies the bootstrap constraints. We will explain how the Feynman diagrams of the random ensemble produce a sum over 3 manifolds that agrees with the partition function of 3d gravity. Our model makes explicit the intriguing relation between the sum over topologies and the implementation of the bootstrap equations.

Speaker: Gabriel Wong (Oxford Math Institute, UK)

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Wongv4.pdf

15:30 → 16:00 Entanglement dynamics of Brownian models from universal low-lying modes

Information-theoretic quantities such as Renyi entropies show a remarkable universality in their late-time behaviour across a variety of chaotic systems. Understanding how such common features emerge from very different microscopic dynamics remains an important challenge. In this talk, I will address this question in a general class of Brownian models with a variety of different microscopic couplings. In any such model, the Lorentzian time-evolution of the n-th Renyi entropy can be mapped to a transition amplitude with a Euclidean Hamiltonian on 2n copies of the system. Using the structure of the ground states of the Euclidean Hamiltonian, we derive an expression for the saturation value of the n-th Renyi entropy in terms of an equilibrium density matrix, consistent with a general proposal called the equilibrium approximation. In non-integrable models without conserved quantities in (1+1) dimensions, we find that the spectrum of the Euclidean Hamiltonian relevant for the second Renyi entropy and OTOCs has two degenerate ground states, and a well-defined one-particle band consisting of plane waves of domain walls between them. The one-particle band gives rise to the membrane formula for entanglement dynamics, with the velocity-dependent membrane tension determined by its dispersion relation. This structure provides an understanding of entanglement dynamics in terms of a universal set of gapped modes, analogous to the gapless modes which govern hydrodynamic behaviour of conserved charge densities.

Speaker: Shreya Vardhan (Stanford University, USA)

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Vardhan.pdf

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16:00 → 16:30 Quantum Error Correction for Gravitational Algebras at large-N

Emergent gravitational von Neumann algebras, describing the observables of quantum gravity in various spacetime regions, embed naturally into some microscopic theory as a quantum error correcting code. The resulting mathematical structure naturally incorporates the large-N limit into the QEC program. I will discuss some applications including the computation of von Neumann entropies as well as constraining the stringy regime of AdS/CFT.

Speaker: Thomas Faulkner (University of Illinois, USA)

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16:30 → 17:00 Break

17:00 → 18:30 Black hole interiors

We review ideas for describing black hole interiors while retaining unitarity, and we mention a number of open questions for discussion

Speakers: Chris Akers (Institute for Advanced Study, USA), Daniel Jafferis (Harvard University, USA)

Akers.pdf

Jafferis.pdf

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19:30 → 21:30 Outreach

Friday 7 June

09:20 → 10:20 Recent developments in Generalized Symmetries

I will review recent progress on generalized symmetries, focusing on non-invertible (or higher categorial) symmetries and their properties.
Two questions have recently been the focus in this subject: What replaces the notion of "representation" for group-like symmetries, i.e. what are the generalized charges? What are the IR imprints of non-invertible symmetries? To answer these questions, it is crucial to study the Symmetry Topological Field Theory (SymTFT), which has close relations to string theoretic and holographic realizations of generalized symmetries. Generalized charges are the topological defects of the SymTFT, which also encodes the action of the symmetry. Using the SymTFT, a generalized or categorical Landau paradigm for phases and second order phase transitions in the presence of non-invertible symmetries can be formulated, leading to new phases in quantum systems in various space-time dimensions.

Speaker: Sakura Schafer-Nameki (University of Oxford, UK)

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Schafer-Nameki.pdf

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10:20 → 10:50 Higgs-Confinement Transitions in QCD from Symmetry Protected Topological Phases

In gauge theories with fundamental matter, such as QCD, there is typically no sharp way to distinguish confining and Higgs regimes because there are no suitable order parameters. It is standard lore that these two regimes are continuously connected. In this talk I will discuss simple examples in which Higgsing and confinement lead to different symmetry protected topological phases, which are necessarily separated by a phase transition. Finally, I will show that this phenomenon also occurs in QCD at finite baryon density, and comment on possible implications for the QCD phase diagram and neutron stars.

Speaker: Thomas Dumitrescu (UCLA, USA)

Dumitrescu.pdf

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10:50 → 11:25 Coffee Break

11:25 → 11:30 Announcement

Speaker: Monica Maria Guica (EPFL - Ecole Polytechnique Federale Lausanne (CH))

announcement.pdf

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11:30 → 12:00 Bootstrapping the AdS Virasoro-Shapiro amplitude

The formulation of the worldsheet theory for type IIB strings on AdS5xS5 remains an important open problem. Luckily, at least the corresponding AdS Virasoro-Shapiro amplitude can be bootstrapped in a small curvature expansion. I will describe how this is achieved by demanding consistency with both the OPE for the holographically dual CFT as well as worldsheet intuition. We explicitly constructed the first two curvature corrections, which take the form of a genus zero worldsheet integral involving single-valued multiple polylogarithms. Our answer reproduces the CFT data for unprotected operators in planar N=4 SYM theory at strong coupling available from integrability and the localization results for the low energy expansion. Furthermore, the high energy limit of the AdS Virasoro-Shapiro amplitude agrees with a classical scattering computation in AdS.

Speaker: Tobias Hansen (Durham University , UK)

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12:00 → 12:30 A Holographic Triptych at Large N

I will summarize recent results, obtained using supersymmetric localization, about the large N limit of path integrals of 3d SCFTs arising on the worldvolume of N M2-branes placed on compact Euclidean manifolds. The leading N^3/2 term in the large N expansion of these "free energies" receives 1/N, log(N), as well as exponentially suppressed corrections. I will describe how these corrections arise in the context of AdS/CFT and will show that in some instances they can be computed precisely and agree with the field theory results. The implications of these results for the physics of AdS_4 black holes and AdS_4 flux vacua in string and M-theory will also be discussed.

Speaker: Nikolay Bobev (KU Leuven)

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12:30 → 13:00 Nonsupersymmetric branes in heterotic string theories

I will talk about non-BPS branes in heterotic superstring theories. These branes are characterized by topologically nontrivial gauge field configurations on the sphere surrounding the branes. I discuss exact worldsheet theories for the near horizon limit. The worldvolume theories on the branes may be non-Lagrangian, nonsupersymmetric systems in higher dimensions, and they have very nontrivial properties related to anomalies and chiral fermions.

Speaker: Kazuya Yonekura (Tohoku University, Japan)

KazuyaYonekura.pdf

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13:00 → 13:30 The entropy of Holographic CFTs at large charge and angular momentum

Black holes in AdS$_d$ (with $d\ geq 4$) are always unstable at large angular momentum, and sometimes unstable at large charge. In this talk we
present proposals for the end point of these instabilities. Our constructions suggest new entropy formulae for ${\cal N}=4$ Yang MIlls in the neighbourhood of
extremality, and and in particular on the BPS manifold.

Speaker: Shiraz Minwalla (Tata Institute of Fundamental Research, Mumbai, India)

Minwalla.pdf

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13:30 → 14:15 Lunch

14:15 → 14:45 Coffee

14:45 → 15:15 Quantum Entanglement Entropy in String Theory

I discuss physical motivations from black hole physics and holography for expecting finite quantum entanglement entropy in quantum gravity. I describe recent and earlier results in defining such a notion in perturbative string theory by a stringy analog of the replica method using ZN orbifolds constructed for any odd positive integer N. The entropy so defined naturally includes a classical piece and is manifestly UV finite but has potential tachyonic IR divergences. I show that for several string compactifications as well as on black hole horizons in AdS3/CFT2 holography, the specific structure of the tachyonic spectrum allows for a re-summation and analytic continuation to the physical region 0 < N ≤ 1 where the IR divergences are absent and the resulting entropy is finite to one-loop order.

Speaker: Atish Dabholkar (ICTP)

Dabholkar.pdf

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15:15 → 15:45 Resurgence and non-perturbative topological strings

The string perturbative series diverges factorially, and it is expected that this behavior is related to the existence of non-perturbative effects due to D-branes. Although these ideas can be made precise in the case of non-critical strings, little is known in other situations. In this talk I summarize recent work showing that, in the case of topological strings on Calabi-Yau manifolds, one can use the theory of resurgence to describe its non-perturbative sectors. The main outcome is that the large order behavior of the genus expansion in topological string theory knows secretly about the spectrum of BPS D-branes on the Calabi-Yau, and non-perturbative amplitudes can be explicitly computed.

Speaker: Marcos Marino Beiras (University of Geneva, Switzerland)

MarinoStrings2024.pdf

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15:45 → 16:15 Future of Strings

Speakers: Ahmed Almheiri (NYUAD - United Arab Emirates), Alexander Zhiboedov (CERN), David Gross (KITP/UCSB)

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Strings 2025 2024.pdf

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16:15 → 17:15 The Future of String Theory: 100 Open Questions

Speakers: Andrew Strominger (Harvard University, USA), Hiroshi Ooguri (California Institute of Technology, USA)

Ooguriv2.pdf

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Strominger.pdf

The Future of String Theory - 100 Open Questions.pdf

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