Strings 2023

24 Jul 2023, 08:30 → 29 Jul 2023, 17:00 America/Toronto

PI/1-100 - Theatre (Perimeter Institute for Theoretical Physics)

Sabrina Pasterski (Perimeter Institute)

The Perimeter Institute for Theoretical Physics is delighted to host the 34th installment of Strings, the flagship annual conference for the extended string theory community.

Strings 2023 will take place at PI July 24-29. Capacity is limited to 200 in-person attendees. The programming will incorporate an interactive simulcast for virtual attendees.

Recorded talks: https://pirsa.org/C23001

 

Organizing Committee: Sabrina Pasterski,* Freddy Cachazo, Kevin Costello, Davide Gaiotto, Jaume Gomis, Rob Myers, Pedro Vieira, & Alex Buchel.

 

 

 

 

Territorial Land Acknowledgement

Perimeter Institute acknowledges that it is situated on the traditional territory of the Anishinaabe, Haudenosaunee, and Neutral peoples.

Perimeter Institute is located on the Haldimand Tract. After the American Revolution, the tract was granted by the British to the Six Nations of the Grand River and the Mississaugas of the Credit First Nation as compensation for their role in the war and for the loss of their traditional lands in upstate New York. Of the 950,000 acres granted to the Haudenosaunee, less than 5 percent remains Six Nations land. Only 6,100 acres remain Mississaugas of the Credit land. 

gather.town.pdf

Monday, 24 July

08:30 → 10:00 Registration+Breakfast

10:00 → 10:15 Remarks: Welcome to Strings 2023

10:00 Opening Remarks

Speaker: Robert Myers (Perimeter Institute)

10:15 → 11:15 Research Talks

10:15 Research Talk 1 - Cosmic ER=EPR

Speaker: Andrew Strominger (Harvard University)

10:45 Research Talk 2 - Burns holography

I will describe a complete, top-down example of celestial holography, based on recent work with Costello and Paquette. Our duality relates certain models of self-dual gauge theory and conformal gravity, placed on an asymptotically flat four-dimensional spacetime called Burns space, to a two-dimensional chiral algebra living on D1 branes in a topological string theory on twistor space.

Speaker: Atul Sharma (Harvard University)

Burns holography.pdf

11:15 → 12:15 Research Talks

11:15 Research Talk 3 - Swampland and a Unification of the Dark Sector

Speaker: Cumrun Vafa (Harvard University)

Vafa.pdf

11:45 Research Talk 4 - A universal pattern at infinite field distance

Speaker: Irene Valenzuela (CERN)

12:15 → 13:45 Lunch

Buffet stations will be set up in the 1st FL and 2nd FL Bistro areas, with additional seating in the Atrium.

13:45 → 14:30 Challenge Talks

13:45 Challenge Talk 1 - The Cosmic Neutrino Background: Its distribution on the surface of the Earth and its manipulation on laboratory scales

Speaker: Savas Dimopoulos (Stanford University)

14:30 → 15:00 Coffee Break

15:00 → 16:00 Research Talks

15:00 Research Talk 5 - Crossing beyond scattering amplitudes

What can be measured asymptotically in quantum field theory? Among the answers to this question are scattering amplitudes, but also a whole compendium of inclusive measurements, such as expectation values of gravitational radiation and out-of-time-ordered amplitudes. We show that these asymptotic observables can be related to one another through new versions of crossing symmetry. Assuming analyticity, we propose generalized crossing relations and corresponding paths of analytic continuation. Throughout the talk, we show how to apply crossing in practice, using various tree- and loop-level examples.

Speaker: Hofie Hannesdottir (Institute for Advanced Study)

Hannesdottir_Strings_2023.pdf

15:30 Research Talk 6 - Soft theorems: symmetry and geometry

Speaker: Julio Parra-Martinez (Caltech)

23-07_Strings2023.pdf

Tuesday, 25 July

08:30 → 09:30 Discussion Session

08:30 Discussion Session 1 - The Future of the S-matrix

Speakers: Sebastian Mizera (Institute for Advanced Study), Simon Caron-Huot (McGill University)

The future of the S-matrix (merged).pdf

09:30 → 10:15 Coffee+Breakfast Available 8:30-11 Monday-Friday

Breakfast Available 8:30-11 Monday-Friday

10:15 → 11:00 Challenge Talks

10:15 Challenge Talk 2 - Feynman's Last Blackboard: From Bethe Ansatz to Langlands Duality

Richard Feynman's last blackboard at Caltech contains a number of tantalizing inscriptions about Bethe Ansatz in quantum integrable models, which fascinated him in the last years of his life. After reviewing some basic examples, I will present a modern perspective on the subject, linking it to dualities in QFT and String Theory, as well as the Langlands duality in mathematics. I will then discuss some recent developments that lend support to Feynman's intuition that these ideas could be useful in the study of 4d gauge theory, and formulate some open questions.

Speaker: Edward Frenkel (UC Berkeley)

Frenkel-strings.pdf

11:00 → 12:00 Research Talks

11:00 Research Talk 7 - Revisiting logarithmic corrections to supersymmetric black hole entropy

Speaker: Ashoke Sen (Harish-Chandra Research Institute)

logfull.pdf

11:30 Research Talk 8 - The Virasoro Minimal String

I will explain a new 2d gravity/matrix model duality. The bulk theory can be defined as a minimal string theory whose matter sector is given by timelike Liouville theory instead of a minimal model. The theory admits a dual description in terms of a double-scaled matrix integral whose leading density of states is given by the universal Cardy density of states in a 2d CFT of central charge c, thus motivating us to call the bulk theory the Virasoro minimal string. The duality can be derived by exploiting a certain relation to 3d gravity compactified on a circle. For large central charge, it reduces to the duality between JT-gravity and the corresponding double-scaled matrix integral. Based on work in collaboration with Scott Collier, Beatrix Mühlmann and Victor Rodriguez.

Speaker: Lorenz Eberhardt (Institute for Advanced Study)

12:00 → 13:30 Lunch

Buffet stations will be set up in the 1st FL and 2nd FL Bistro areas, with additional seating in the Atrium.

13:30 → 14:30 Research Talks

13:30 Research Talk 9 - Black hole cohomologies in N=4 Yang-Mills

I will explain a cohomology problem in the SU(N) maximal super-Yang-Mills theory which we expect to capture BPS black holes in AdS. I also explain the recent progress for the SU(2) theory.

Speaker: Seok Kim (Seoul National University)

strings-2023.pdf

14:00 Research Talk 10 - A tensor model for approximate CFTs

Speaker: Daniel Jafferis (Harvard University)

14:30 → 15:00 Coffee Break

15:00 → 16:00 Research Talks

15:00 Research Talk 11 - Emanant symmetries

Speaker: Nathan Seiberg (Institute for Advanced Study)

Emanant symmetries Seiberg.pdf

15:30 Research Talk 12 - Non-Invertible Symmetry, Duality, and Anomalies

Speaker: Clay Cordova (University of Chicago)

Strings23.pdf

Wednesday, 26 July

08:30 → 09:30 Discussion Session

08:30 Discussion Session 2 - Strings, QFT, and Mathematics

Speakers: Miranda Cheng (University of Amsterdam), Sakura Schafer-Nameki (University of Oxford)

Schafer-Nameki-Strings2023.pdf

09:30 → 10:15 Coffee+Breakfast Available 8:30-11 Monday-Friday

Breakfast Available 8:30-11 Monday-Friday

10:15 → 11:00 Challenge Talks

10:15 Challenge Talk 3 - Symmetry/Topological-Order correspondence -- from string theory to condensed matter physics

Speaker: Xiao-Gang Wen (Massachusetts Institute of Technology)

23PI.pdf

11:00 → 12:00 Research Talks

11:00 Research Talk 13 - Six- and eleven-dimensional theories via superspace torsion and Poisson brackets

I will review some recent developments that attempt to put modern mathematical tools and structural insights to effective use in physics. The focus will be on two such tools. The first is a perspective on superspace geometry that leads to powerful structural analogies between twisted theories (which encode the dynamics of particular BPS subsectors) and their untwisted parents. The second deals with generalizations of typical field theories akin to the generalization from symplectic to Poisson phase spaces. As an application, one obtains an object with N=(2,0) superconformal symmetry in six dimensions. Working at the holomorphic level on flat space, this object becomes the current algebra of the exceptional simple superalgebra E(3|6), which localizes to the W_2 algebra and dimensionally reduces to sl(2) super Yang-Mills theory. This is a mixture of joint work with numerous collaborators, in particular Hahner, Raghavendran, and Williams.

Speaker: Ingmar Saberi (University of Heidelberg)

STRINGS-25min.pdf

11:30 Research Talk 14 - Irreversibility, QNEC, and defects

In this talk we will analyze renormalization group flows on d-dimensional planar defects, embedded in a D-dimensional conformal field theory. This general setup includes the case of quantum field theory with no defects ($D=d$), as well as defects of different dimensionality that are of interest in high energy and condensed matter physics. Using methods from quantum information theory, we will establish the irreversibility of renormalization group flows for defect dimensions $d \le 4$, and for all $D$. The main ingredients in the proof are strong subadditivity of the entanglement entropy, the Markov property of the conformal vacuum, and the quantum null energy condition.

Speaker: Gonzalo Torroba (Centro Atomico Bariloche)

torroba-talk-strings.pdf

12:00 → 13:30 Lunch

Buffet stations will be set up in the 1st FL and 2nd FL Bistro areas, with additional seating in the Atrium.

13:30 → 14:30 Research Talks

13:30 Research Talk 15 - dS_2 supergravity

I will discuss the interplay between 2d de Sitter and supersymmetry in two concrete supergravity models coupled to superconformal field theories. Upon fixing a supersymmetric analogue of the Weyl gauge these theories can be viewed as supersymmetric extensions of timelike Liouville theory with N=1 and N=2 supersymmetry respectively. Supersymmetric timelike Liouville is well behaved in the UV and combines supersymmetry with a positive cosmological constant and a de Sitter saddle. The theory is amenable to a variety of techniques including systematic loop expansions and localization methods.

Speaker: Beatrix Mühlmann (McGill University)

Strings2023.pdf

14:00 Research Talk 16 - The Hilbert space and holography of information in de Sitter quantum gravity

We obtain all solutions of the Wheeler-DeWitt equation with positive cosmological constant for a closed universe in the large-volume limit. We define a natural norm on the solution space and thereby obtain a description of the Hilbert space of quantum gravity in an asymptotically de Sitter spacetime. This provides the finite G_N generalization of the Hilbert space constructed by Higuchi using group averaging. All the states in this Hilbert space share the symmetries of the Euclidean vacuum. We use this property to generalize the principle of holography of information to de Sitter space: data about cosmological correlators (defined as appropriately gauge-fixed observables) in an arbitrary small region suffices to specify them everywhere.

Speaker: Suvrat Raju (International Centre for Theoretical Sciences)

strings_2023.pdf

14:30 → 15:00 Coffee Break

15:00 → 16:00 Research Talks

15:00 Research Talk 17 - Off Shell Strings and Black Hole Entropy

In order to derive the classical string action from the worldsheet, it is necessary to take string theory off shell. This can be done by a prescription of Tseytlin, who proposed taking the worldsheet sphere QFT partition function and differentiating it with the log of the UV cutoff. I will explain why this strange prescription always gives the correct answers, for both the S-matrix and equations of motion, to all orders in perturbation theory. I will also compare the Susskind-Uglum off-shell method of calculating black hole entropy, to the more popular (but also more dubious) orbifold method. Based on work with Amr Ahmadain (arXiv:2211.08607 and arXiv:2211.16448).

Speaker: Aron Wall (University of Cambridge)

off_strings3.pdf

15:30 Research Talk 18 - Bespoke Dual Resonance

String amplitudes famously accomplish several extraordinary and interrelated mathematical feats, including an infinite spin tower, tame UV behavior, and dual resonance: the ability of the amplitude to be represented as a sum over a single scattering channel. But how unique are these properties to string amplitudes? In this talk, I will demonstrate that it is possible to construct infinite new classes of tree-level, dual resonant amplitudes with customizable, non-Regge mass spectra. Crucial ingredients are Galois theory and a particular dlog transformation of the Veneziano amplitude. The formalism generalizes naturally to n-point scattering and allows for a worldsheet-like integral representation. In the case of a Regge spectrum, I will investigate whether the structure of the Veneziano amplitude can be bootstrapped from first principles. Even there, we will find that there is extra freedom in the dynamics, allowing for a new class of dual resonant hypergeometric amplitudes with a linear spectrum.

Speaker: Grant Remmen (Kavli Institute for Theoretical Physics)

Remmen_Strings.pdf

16:00 → 17:00 Poster Session

18:00 → 20:00 Banquet

Thursday, 27 July

08:30 → 09:30 Discussion Session

08:30 Discussion Session 3 - It from Qubit

Speakers: Juan Maldacena (Institute for Advanced Study), Geoff Penington (UC Berkeley)

09:30 → 10:15 Coffee+Breakfast Available 8:30-11 Monday-Friday

10:15 → 11:00 Challenge Talks

10:15 Challenge Talk 4 - Learning in a quantum world

After reflecting on the fruitful connections between quantum information and quantum gravity, I'll discuss recent results about using classical and quantum machine learning to predict the properties of quantum systems.

Speaker: John Preskill (Caltech)

Strings 2023 Preskill.pdf

11:00 → 12:00 Research Talks

11:00 Research Talk 19 - Regge sum rules and stringy amplitudes

Speaker: Alexander Zhiboedov (CERN)

11:30 Research Talk 20 - Algebraic ER=EPR

Speaker: Netta Engelhardt (Massachusetts Institute of Technology)

12:00 → 13:00 Lunch

Buffet stations will be set up in the 1st FL and 2nd FL Bistro areas, with additional seating in the Atrium.

13:00 → 14:30 Town Hall

13:00 Town Hall

Strings Planning Committee Proposal (60 minutes) and Revised Postdoc Accord Proposal (30 minutes)

Speakers: Rajesh Gopakumar (ICTS), Cynthia Keeler (ASU)

StringsPostdocAccordSlides.pdf

18:00 → 19:00 Speaker Dinner

19:00 → 20:00 Outreach Talk

19:00 Public Talk - The meaning of spacetime: Black holes, wormholes and quantum entanglement

According to Einstein's theory of gravity, spacetime is curved and dynamical. The theory had two surprising predictions, black holes and the expansion of the universe. In both cases there are regions of spacetime that are outside the reach of the classical theory, the so called ``singularities''. In order to treat them, we need a quantum mechanical description of spacetime. We will describe some ideas that arose from the study of quantum aspects of black holes. They involve an interesting connection between the basic quantum mechanical description and the geometry of spacetime. We will describe how wormholes are related to quantum entanglement.

Speaker: Juan Maldacena (IAS)

PublicTalkStrings2023.pdf

Friday, 28 July

08:30 → 09:30 Discussion Session

08:30 Discussion Session 4 - Life on the Lattice

Speakers: Nathan Seiberg (IAS), Anton Kapustin (Caltech)

Life on the lattice Seiberg.pdf

Strings_2023_Kapustin.pdf

09:30 → 10:30 Poster Session

10:30 → 11:00 Coffee Break

11:00 → 12:00 Gong Show

-recording-

Biswas_Gong Show_ Shovon Biswas.pdf

Correia_Non pert an treshold_v4.pdf

Crawley_Erin Crawley Gong Show Strings 2023 -- pdf final.pdf

Danielson_FINAL_Strings_GongShow_07-28-2023.pdf

Heuveline_Strings_talk_Heuveline.pdf

Offertaler_Strings Gong Show Talk PDF.pdf

Torres_UpdatedStrings23GongShowEthanTorres.pdf

Waddleton_Strings23_GongShow.pdf

Zhang_MengyangZhang_GongShow.pdf

Zigdon_Statistical Analysis of NS5-F1 States V5.pdf

12:00 → 13:30 Lunch

Buffet stations will be set up in the 1st FL and 2nd FL Bistro areas, with additional seating in the Atrium.

13:30 → 14:30 Research Talks

13:30 Research Talk 21 - A Background Independent Algebra for Quantum Gravity?

To define an algebra of observables in quantum gravity in a way that is universal and does not depend on a background spacetime, one can consider the observables along the worldline of an observer, rather than the observables in a region of spacetime.

Speaker: Edward Witten (Institute for Advanced Study)

BackgroundHandout.pdf

14:00 Research Talk 22 - Infrared Aspects of QFT and Quantum Gravity: Scattering and Coherence

A long-standing problem in QFT and quantum gravity is the construction of an “IR-finite” S-matrix. Infrared divergences in scattering theory are intimately tied to the “memory effect” and the existence of an infinite number of “large gauge charges”. A suitable “IR finite” S-matrix requires the inclusion of states with memory (which do not lie in the standard Fock space). For QED such a construction was achieved by Faddeev and Kulish by appropriately “dressing” charged particles with memory. However, we show that this construction fails in the case of massless QED, Yang-Mills theories, linearized quantum gravity with massless/massive sources, and in full quantum gravity. In the case of quantum gravity, we prove that the only "Faddeev-Kulish" state is the vacuum state. We also show that non-Faddeev Kulish representations are also unsatisfactory. Thus, in general, it appears there is no preferred Hilbert space for scattering in QFT and quantum gravity. Nevertheless we show how scattering can be formulated in a manner that manifestly IR-finite without any “ad-hoc” restrictions or dressing on the states. Finally, we investigate the consequences of the superselection due to the “large gauge charges” and illustrate that, in QED, nearly all scattering states are completely decohered in the bulk.

Speaker: Gautam Satishchandran (Princeton University)

Strings_2023.pdf

14:30 → 15:00 Coffee Break

15:00 → 16:00 Research Talks

15:00 Research Talk 23 - A holographic dual for Krylov complexity

There are several suggestions for an appropriate entry for quantum complexity in the holographic duality dictionary. The question is which notion of complexity and what is the precise duality. In this talk I endeavor to answer exactly this question for one, well studied, system. Krylov complexity has the signatures of quantum complexity at all time scales; it can be defined for operators or states. I will describe some of its features and show that in the setup of 2-dimensional JT gravity, Krylov complexity computed on the boundary has a well defined, precise geometrical meaning in the bulk.

Speaker: Ruth Shir (Luxembourg University)

15:30 Research Talk 24 - A fake explanation of sub-maximal chaos

Speaker: Henry Lin (Stanford University)

Strings-talk-BACKUP.pdf

16:00 → 16:30 Remarks

16:00 Closing Remarks

Speaker: Hirosi Ooguri (Caltech)

mentoring-strings.pdf

Strings 2023 Closing Combined.pdf

Strings Abu Dhabi.pdf

Saturday, 29 July

11:00 → 13:00 Women in Strings Brunch