Progress of Theoretical Bootstrap

Oct 27, 2025, 8:30 AM → Nov 28, 2025, 6:00 PM Asia/Tokyo

Panasonic Auditorium, Yukawa Hall (YITP)

YU NAKAYAMA (Yukawa Institute of Theoretical Physics)

Long-term and Nishinomiya-Yukawa Memorial Workshop "Progress of Theoretical Bootstrap" will be held at Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto, Japan, from October 27th to November 28th, 2025. The first week of the workshop is devoted to the Extreme Universe International Conference.

Please be cautious of scams from individuals pretending to be travel agency employees (e.g. Global Travel Team). They may try to steal your credit card number. No travel agency will contact you directly for this workshop. If a suspicious agency or person contacts you, please confirm with us. Please ignore any emails claiming to be related to 'Progress of Theoretical Bootstrap' unless they are sent from the domain yukawa.kyoto-u.ac.jp or by a member of the Local Organizing Committee."

Organizers:

(Local) Yu Nakayama, Tadashi Takayanagi, Katsuki Aoki, Toshifumi Noumi, Yuya Kusuki, Masazumi Honda, Yasuaki Hikida, Cristofoli Andrea

(Extreme Universe)  Akihiro Ishibashi, Kouichi Okunishi, Tomoyuki Morimae

(International) Slava Rychkov, Alexander Zhiboedov, Guilherme Pimentel

Schedule:

1st week (10/27~11/1): Extreme Universe Collaboration week: "Extreme Universe International Conference"

2nd week (11/4~7): Discussions week on Conformal Bootstrap, "Kyushu-IAS workshop #005"

3rd week (11/10~14): Core week on Conformal Bootstrap: 
"Nishinomiya-Yukawa Symposium: Progress of Conformal Bootstrap"

4th week (11/17~21): Core week on S-matrix/Cosmological Bootstrap: "iTHEMS-YITP Workshop: Progress of S-matrix/Cosmological Bootstrap"

5th week (11/25~28): Discussions week on S-matrix/Cosmological Bootstrap

Please note that 11/3 and 11/24 are national holidays in Japan. We do not have any talks on the days.

Registration: 

The deadline for early registration, including the VISA application, is June 30th. The general deadline is August 20th. 

We have closed the early registration, including VISA application, 1st week poster presentation, and accommodation support.

Due to the limited availability of seating, desk space, and facilities, we may limit the number of participants. We apologize in advance if this happens

Payments: 2,000 JPY for refreshments 

An online Payment link will be sent to the registered participants.

For those who registered by August 20th, we have already sent the payment link.

Submission for the presentations

We have some slots for contribution talks and posters on the 1st, 2nd, and 5th week. The deadline for the poster session will be around August 31st. The selection process for the contribution talks (from the poster applicants) will be around the beginning of July. The contribution talks will be selected from early applicants for the poster presentations. 

Bootstrap4-5.pdf

Monday, October 27

1 Registration

2 Opening

10:45 AM Coffee

1:00 PM lunch

3:30 PM coffee

6:00 PM Banquet

Tuesday, October 28

9:00 AM Coffee break

11:00 AM Lunch

2:00 PM Coffee break

Wednesday, October 29

11:30 AM Lunch

2:00 PM Coffee break

Thursday, October 30

9:30 AM Coffee break

11:30 AM Lunch

2:30 PM Coffee break

Friday, October 31

11:30 AM Lunch

2:00 PM Coffee break

Monday, November 3

National Holiday

We do not have any events

Tuesday, November 4

3 Opening

4 Slava Rychkov "The renaissance of axiomatic methods in quantum field theory"

The textbook approach to quantum field theory is to start from
the Lagrangian and then either do perturbation theory or, if the theory
is strongly coupled, resort to lattice Monte Carlo simulations. Recently
there has been renewed interest in developing and applying “bootstrap
methods”, which have different spirit. They use nonperturbatively valid
“axioms” to obtain concrete numerical results about experimentally
relevant strongly coupled QFTs. After a pedagogical background
introduction, I will describe these bootstrap methods and some of their
applications in the study of critical phenomena and scattering processes.

2025-Kyoto-colloquium.pdf

12:00 PM Lunch

5 Alessandro Piazza "Bootstrap bounds on Yang-Mills in AdS"

Yang-Mills theory in AdS_4 with Dirichlet boundary conditions is expected to undergo a deconfinement-confinement transition as the AdS radius varies, as the global symmetry of the boundary CFT cannot hold in flat space. We apply the conformal bootstrap to four-point functions of non-abelian conserved currents in 3d to place bounds on proposed mechanisms for the transition. We rule out the scenario in which the boundary current decouples by bounding the current central charge. We also obtain bounds on the dimension of the lightest scalar operators, which disfavour a bulk-Higgs mechanism and instead support a transition triggered by a scalar singlet becoming marginal.

yitp-251104.pdf

3:00 PM Coffee break

6 Free discussion

Wednesday, November 5

7 Andreas Stergiou "Redundancy Channels in the Conformal Bootstrap"

12:00 PM Lunch

8 Marten Reehorst " Bootstrapping the Simplest Deconfined Quantum Critical Point"

We study the $N=3$ case of the $NCCP^{N-1}$ model, which is a field theory of $N$ complex scalars in 3d coupled to an Abelian gauge field with $SU(N)\times U(1)$ global symmetry. Recent evidence suggests the $N=2$ theory is not critical, which makes the $N=3$ theory the simplest possibility of deconfined quantum criticality. We apply the conformal bootstrap to correlators of charge $q=0,1,2$ scalar operators under the $U(1)$ symmetry, which gives us access also to $q=3,4$ operators. After imposing that only the lowest $q=0,1,2$ scalar operators are relevant, we find that the bootstrap bounds are saturated by the large $N$ prediction for $q=1,2,3,4$ scalar monopole operator scaling dimensions, which were shown earlier to be accurate even for small $N$, as well as a lattice prediction for the $q=0$ non-monopole scalar operator. We also predict the scaling dimensions of the lowest spinning monopole operators, which we match to the large charge prediction for spinning operators. This suggests that the critical $NCCP^{2}$ model is described by this bootstrap bound.

9 Yuan Xin "Yang-Lee Criticality in Various Dimension" (online)

Yang-Lee criticality is the simplest non-Hermitian conformal field theory. The model was first reported as a phase transition of Ising model in imaginary longitudinal magnetic field more than half a centry ago. Since then, many qualitative and quantitative properties of YL criticality have been studied, remarkably, including the fact that the model can be described in Landau-Ginzburg scheme with a scalar $i\phi^3$ theory in $D<6$ and the fact that the 2D version is an exactly solvable minimal model. In higher dimensions, the model lacks the same level of understanding as the Ising criticality due to its non-Hermitian nature. We report a new study of 3D YL criticality as a phase transition of Fuzzy Sphere model, which facilitates a direct survey of many quantities such as the spectrum and OPE coefficient to high precision. These quantitative results show a beautiful agreement with conformal symmetry and previous estimates from $(6-\epsilon)$ expansion, high temperature expansion and conformal bootstrap. We also discuss possible approaches in dimensions higher than 3.

yuan-yitp.pdf

3:00 PM Coffee break

10 Poster Session

Stanislav Filatov "Geometry of Two-Qubit Entanglement on Two Bloch Spheres"
Yuma Furuta "On the quadratic equations for detecting duality symmetries of compact boson CFTs"
Samuel Laliberte "Quantum mechanics bootstrap and supersymmetry"
Yuefeng Liu "Bootstrap about new crosscap states and non-invertible symmetry"
Souparna Nath "Complexity Growth, Krylov-Wigner function and Gravity"
Toshiki Onagi "Do Conformal Bootstraps Dream of Duality?"
Dongsheng Ge
Ahmed Abdalla "Foundational Inconsistencies in the No-Boundary Proposal"
Ross Dempsey "Integral constraints for the superconformal bootstrap"
Indranil Dey "A universal inequality on the unitary 2D CFT partition function"
Mohammad Reza Khansari "Bubbles in AdS"
Kamran Salehi Vaziri "Non-perturbative cosmological bootstrap: A construction of de Sitter late-time boundary"
kangning liu "Supersymmetric complex Liouville string"

Thursday, November 6

11 Petr Kravchuk "Non-linearly realized symmetries, anomalies, and defect four-point functions"

12:00 PM Lunch

12 Francesco Bertucci "Bootstrapping Euclidean lattices"

bertucci_bootstrap_japan.pdf

13 Jiaxin Qiao "QFT as a set of ordinary differential equations"

I will discuss quantum field theories (QFTs) on hyperbolic surface (i.e. Euclidean AdS2) with a conformal boundary condition. Correlation functions of local operators in such QFTs can be fully characterized by the QFT data: (1) scaling dimensions of boundary operators, (2) boundary operator product expansion (OPE) coefficients, and (3) boundary operator expansion (BOE) coefficients for bulk operators.

We derive a universal set of first-order ordinary differential equations (ODEs) that encode the variation of the QFT data under an infinitesimal change of a bulk relevant coupling. In principle, these ODEs can be used to follow a renormalization group (RG) flow starting from a solvable QFT into a strongly coupled phase and toward the flat-space limit. If time permits, I will also discuss the mechanism of level repulsion, which arises as a natural consequence of the ODEs.

YITP_slides.pdf

3:00 PM Coffee break

14 Free discussion

Friday, November 7

12:00 PM Lunch

15 Sinya Aoki "Derivation of the GKP-Witten relation by symmetry without Lagrangian"

16 Wataru Harada "New Crosscap States with Non-Invertible Symmetry in RCFT"

17 Shim'on Sukholuski "Conformal Dispersion Relation for Mixed Correlators"

3:30 PM Coffee break

Monday, November 10

10:30 AM Coffee break

18 David Poland "This is the Moment"

12:00 PM Lunch

19 Volker Schomerus "Conformal data from thermal correlators"

3:00 PM Coffee break

20 Sridip Pal "Universality of spectrum at large spin in non-rational 2D CFT"

Abstract: In a unitary 2D modular invariant CFT, the high-energy density of states is universal and follows the famous Cardy formula, the precise version of which requires an averaging over an order-one window. In non-rational 2D CFTs, an extended version of the Cardy formula exists for the density of states with finite twist and large spin. In this talk, we will answer in which sense this extended formula gives a coarse-grained approximation of finite twist, large spin density of states. In particular, using elementary complex analysis methods, we prove that 1) the averaging over spin is NOT required and 2) if appropriately smeared over a window of twist, the extended Cardy formula is valid up to O(J^{-N}) for any N>0. This is much stronger/universal than the usual Cardy formula at large energy. Furthermore, by making the size of twist-window shrinking to 0 as J \to\ infty, we prove that the spectrum is dense in the large spin limit i.e, the spacing of operators with large spin and twist lying in a bound subinterval of ((c-1)/12,\infty) goes to 0 at least as fast as J^{-1/4} as J\to\infty. This is based on work with Jiaxin Qiao, Balt C van Rees, arXiv: 2505.02897

Reception

Tuesday, November 11

21 Dalimil Mazac " L-functions and the conformal bootstrap"

Recently, a close parallel emerged between conformal field theory in general dimension and the theory of automorphic forms. I will review this connection and explain how it can be leveraged to make rigorous progress on central open problems of number theory, using methods borrowed from the conformal bootstrap. In particular, I will use the crossing equation to prove new subconvex bounds on L-functions. Based on work with Adve, Bonifacio, Kravchuk, Pal, Radcliffe, and Rogelberg: https://arxiv.org/abs/2508.20576.

kyoto-2025.pdf

10:30 AM Coffee break

22 Shiraz Minwalla "Semi-universality of CFT$_d$ entropy at large J"

12:00 PM Lunch

23 Yuto Moriwaki "2d Conformal bootstrap equation and axiomatic QFT"

Axiomatic quantum field theory is a mathematically rigorous formulation of quantum field theory proposed in the 1950s.

Notable frameworks include the Wightman axioms for quantum fields on Minkowski spacetime and the Osterwalder-Schrader axioms, formulated via Schwinger functions on Euclidean spacetime.

In this talk, based on joint work with M. S. Adamo and Y. Tanimoto, we will discuss how, in two dimensions, one can construct an axiomatic QFT from the bootstrap equations under the assumption that the theory enjoys a sufficiently large chiral symmetry.

3:00 PM Coffee break

Wednesday, November 12

24 Vasileios Niarchos "Deep Finite Temperature Bootstrap"

Kyoto_2025_Niarchos.pdf

10:30 AM Coffee break

25 Parijat Dey "Towards bootstrapping de Sitter correlators"

Towards bootstrapping de Sitter correlators

dS_CFT_YITP.pdf

12:00 PM Lunch

26 Nathan Benjamin "Scalar partition functions in 2d CFTs"

nathan-talk-20251112.pdf

3:00 PM Coffee break

Thursday, November 13

27 Denis Karateev "Bounds on Conserved Currents in 4d CFTs"

I will discuss recent progress in constraining four-dimensional conformal field theories with Abelian conserved currents using the conformal bootstrap. After setting up the bootstrap problem for the four-point function of U(1) currents, I will present numerical bounds on operator dimensions and on physical quantities such as the ratio between the ’t Hooft anomaly and the current central charge. Finally, I will describe recent developments in the automatic construction of spinning conformal blocks in 4d, which enable systematic bootstrap analyses involving non-Abelian conserved currents and stress tensors.

10:30 AM Coffee break

28 Valentina Prilepina "Illuminating CFTs with the Higher-Point Bootstrap: A Powerful Approach"

In this talk, I will present a practical realization of the higher-point conformal
bootstrap, focusing on the five-point comb channel implementation thereof. I
will consider 5-point scalar correlators in d-dimensional conformal field theories
(CFTs). I will begin by laying out a robust algorithm for the efficient numeri-
cal evaluation of conformal blocks for exchanged primary operators of arbitrary spin. I will then describe an explicit implementation of the 5-point bootstrap.
With this, I will proceed to study 5-point correlators in the 3d critical Ising model. I will examine correlators involving \sigma, and \epsilon, truncating the oper-ator product expansion (OPE) to include contributions due to operators with
conformal dimension below a certain cutoff. In each case, I will approximate
the remaining contributions by their counterparts in a suitable disconnected five-point correlator. Finally, I will discuss the results obtained through the five-point
bootstrap for a number of OPE coefficients involving two or more spinning oper-
ators. While these coefficients are nontrivial to access by means of the four-point
bootstrap, they are within ready reach of the higher-point bootstrap, where we
are able to compute a number of OPE coefficients with greater accuracy than
previous methods. I will compare some newly-determined OPE coefficients to
corresponding results from the four-point bootstrap and the fuzzy sphere regu-
larization technique. At the end, I will give a preview of the six-point snowflake
channel implementation of this method. This analysis will ultimately establish
the higher-point bootstrap as a powerful tool for studying CFTs.

Higher-PointBootstrap_VPrilepina.pdf

12:00 PM Lunch

29 Fabiana De Cesare "Disturbing news about the 2+epsilon expansion"

The O(N) Non-Linear Sigma Model (NLSM) in d=2+epsilon has long been conjectured to describe the same conformal field theory as the Wilson-Fisher O(N) fixed point obtained from the (phi^2)^2 model in
d=4-epsilon. In this talk, we put this conjecture into question, building on the recent observation [Jones,2024] that the NLSM CFT possesses a protected operator with dimension N-1, which is instead absent in the WF O(N) CFT. We propose several scenarios that may explain this discrepancy.

3:00 PM Coffee break

Friday, November 14

30 Zechuan Zheng " The Analytic Functional in the Numerical Conformal Bootstrap"

10:30 AM Coffee break

31 Wenliang Li "Accurate boundary bootstrap for the 3d O(N) normal universality class"

Accurate boundary bootstrap for the 3d O(N) normal universality class

Li_Kyoto-Bootstrap.pdf

12:00 PM Lunch

32 Shai Chester "Bootstrapping critical 3d gauge theories"

We consider the simplest class of 3d gauge theories, which is N complex scalar fields coupled to an Abelian gauge field. For large N this theory is known to flow to a CFT with SU(N)xU(1) symmetry, but for finite N there is controversy in the literature. The N=2 case is particularly famous, as its believed to describe the Neel-VBS phase transition, which might be experimentally realizable. Previous lattice studies suggested the SU(2)xU(1) symmetry is enhanced to SO(5), but the assumption of no relevant SO(5) singlet was ruled out by the bootstrap. We perform a bootstrap study assuming SO(5) symmetry, and find a point on the boundary of the allowed region that matches large N predictions, and was recently confirmed by a newer lattice study. We also perform a bootstrap study of the N=3 theory, and find a point on the boundary of the allowed region that matches large N, large charge, and lattice predictions.

Kyoto (1).pdf

3:00 PM Coffee break

Monday, November 17

33 Guilherme L. Pimentel "Overview of Cosmological Correlators"

10:30 AM coffee

34 Yu-tin Huang "When gravity meets narrow resonances"

12:00 PM lunch

35 David Stefanyszyn

3:00 PM coffee

36 Xi Tong "Unitary renormalisation and the quantum breaking of cosmological reality"

Abstract: Cosmological correlators and the associated wavefunction coefficients serve as a smoking gun towards the physics of inflation at high energy scales. In minimal setups of single-field inflation, wavefunction coefficients are purely real at tree-level due to unitarity, locality and scale invariance, leading to the so-called no-go theorems on parity violation. Such parity-violating correlators are therefore null tests of fundamental principles. Yet interestingly, there exists a twist of plot when quantum loops are involved. We show that such cosmological reality must be spontaneously broken by the renormalisation of UV divergences in de Sitter loops. More specifically, unitarity and analyticity dictate a universal imaginary part from the logarithmic running of the real part of the wavefunction coefficients. We then discuss the implications related to this universality.

Xi Tong - Unitary renormalisation and the breaking of cosmological reality.pdf

Tuesday, November 18

37 Alexander Zhiboedov "Scattering on the Coulomb Branch of N=4 SYM"

10:30 AM Coffee

38 Hayden Lee "A Hidden Pattern in Cosmological Correlators" (online)

Kyoto.pdf

12:00 PM Lunch

39 Shota Komatsu "No Shift, Sherlock"

No Shift Komatsu.pdf

3:00 PM Coffee

40 Lucia Gomez Cordova "S-matrix Bootstrap and non-invertible symmetries"

NonInvSmatB_Kyoto25.pdf

Wednesday, November 19

41 Charlotte Sleight "Holograms in the Sky from EAdS"

10:30 AM Coffee

42 Massimo Taronna

12:00 PM Lunch

43 Vladimir Rosenhaus "Renormalization Group in far-from-equilibrium states"

3:00 PM Coffee

44 Martin Kruczenski "The Gauge Theory Bootstrap: Predicting pion dynamics from QCD"

Abstract: The Gauge Theory Bootstrap computes the strongly coupled pion dynamics by considering the most general scattering matrix, form factors and spectral densities and matching them with perturbative QCD at high energy and with weakly coupled pions at low energy. In this talk (based on https://arxiv.org/abs/2505.19332 with Yifei He, ENS, Paris), we show that further constraints on the spectral densities significantly reduce the possible solutions to a small set of qualitatively similar ones. Quantitatively, the precise solution is controlled by the asymptotic value of the form factors and SVZ sum rules. We also introduce an iterative procedure that, starting from a generic feasible point, converges to a unique solution parameterized by the UV input. For the converged solution we compute masses and widths of resonances that appear, scattering lengths and effective ranges of partial waves, low energy coefficients in the effective action. Additionally, we use these results to discuss the thermodynamics of a pion gas including pair correlations of pions with same and opposite charge.

Kruczenski_Kyoto_2025.pdf

Thursday, November 20

45 Balt van Rees "The flat-space limit of gapped QFTs in AdS"

10:30 AM Coffee

46 Lorenzo Di Pietro "QCD in AdS"

Kyoto 2025.pdf

12:00 PM Lunch

47 Zhong-Zhi Xianyu "Massive Inflationary Correlators and Family Trees"

3:00 PM Coffee

Banquet

Friday, November 21

48 Joan Elias Miro "Thermal partition function from the S-matrix reloaded"

talkYITP.pdf

10:30 AM Coffee

49 Anna Tokareva "Gravity is weak: consistency constraints on gravitational EFTs"

12:00 PM Lunch

50 Shuntaro Aoki "From Multi-Exchange Signals to Model Building in Cosmological Correlators"

progress of bootstrap_aoki.pdf

3:00 PM Coffee

51 Dong-Gang Wang "Infrared Divergences in de Sitter: wavefunction, density matrix and stochastic inflation"

IR-YITP.pdf

Monday, November 24

National Holiday

We do not have any events

Tuesday, November 25

52 Ning Su "Bootstrapping the pion scattering problem"

12:15 PM Lunch

53 Arnab Priya Saha "Bootstrapping string amplitudes"

Bootstrap25_APS.pdf

54 Felipe Figueroa Vilar "Progress on Regge theory for Dual Model amplitudes"

3:00 PM Coffee

Wednesday, November 26

55 Andrea Cristofoli "The Common On-Shell Language of Black Hole Mergers and Radiation"

Abstract: The two-body problem in general relativity can be described — in the post-Minkowskian expansion — purely in terms of on-shell amplitudes and their classical limit, without ever invoking a Lagrangian or equations of motion. However, beyond this perturbative regime, it is not known whether more complex aspects of binary dynamics — such as the merger phase or the influence of event horizons — can be captured on-shell. In this talk, I will argue that both the merger and the presence of an event horizon can indeed be described on-shell within a common framework based on mass-changing three-point amplitudes. The merger can be viewed as a fusion process once such amplitudes are introduced. Conversely, the presence of an event horizon can be described either as a decay process (Hawking radiation) or as a fusion process (classical wave absorption), following the same logic. This leads to a unified on-shell viewpoint in which black-hole mergers, gravitational-wave absorption, and Hawking radiation — seemingly distinct nonperturbative phenomena — reveal a surprising simplicity and common structure when formulated through on-shell methods. As an application, I will show how to derive conservation laws and compute memory waveforms associated with black-hole mergers, as well as how to describe the effects of Hawking radiation on the two-body problem using only gauge-invariant data and on-shell mass-changing amplitudes.

12:00 PM Lunch

56 Arundhati Goldar "Bulk Reconstruction in De Sitter Spacetime"

YITP_Talk.pdf

57 Harry Goodhew "Geometry of the Kinematic Flow"

58 Aditya Hebbar "S-matrix bounds from the conformal bootstrap"

Kyoto 2025.pdf

3:30 PM Coffee

59 Poster Session

Chen-Hsuan Hsu, "Electron-electron and electron-phonon scattering-driven topological phase transitions in helical liquids"
Damien Leflot,
Facundo Rost ,"The Cosmological Grassmannian"
Guangzhuo Peng, "Running EFT-hedron with null constraints at loop level"
Kamran Salehi Vaziri. "Non-perturbative cosmological bootstrap: A construction of de Sitter late-time boundary"
Mang Hei Gordon Lee, "Positivity for scalar propagators in dS"
Mehmet Asim Gumus, "A geometric view on Crossing Symmetric Dispersion Relations"
Nathan Meurrens, "Constraints on Long-Range Forces in De Sitter Space"
Simon Metayer, "Recent advances on primal S-matrix bootstrap"
Stanislav Filatov, "Geometry of Two-Qubit Entanglement on Two Bloch Spheres."
Sumer Jaitly "Exact superposition positivity bounds"
Tomoya Inada "Perturbative unitarity bounds on field-space curvature in de Sitter spacetime"
Yongjun Xu "Scalar weak gravity bound from full unitarity"
Yu Wenqi "On the IR dependence, conformal anomaly and renormalization of de Sitter correlators"

Thursday, November 27

60 Piotr Tourkine "The S-matrix bootstrap: UV completion, multi-particle screening, and space of the space theories"

12:00 PM Lunch

61 Carlos Duaso Pueyo "Boostless cosmological collider bootstrap of tensor bispectra"

BCCBTB Kyoto.pdf

62 Yu Wenqi "On the IR dependence, conformal anomaly and renormalization of de Sitter correlators"

3:00 PM Coffee

Friday, November 28

63 Xi Yin "Revisiting matrix string theory"

12:00 PM Lunch

64 Discussions

3:00 PM Coffee