Kyushu IAS-iTHEMS conference: Non-perturbative methods in QFT

Contribution List

1. Angular fractals in thermal CFT

Nathan Benjamin (USC)

10/03/2025, 10:00

I will discuss universal properties of partition functions at high temperature and large angular fugacity in d>2 conformal field theories (CFTs). This provides spin-refined information -- namely the statistics of spins of local operators -- valid for all CFTs, that in some sense generalizes modular invariance of d=2 CFTs. As an example application, I will show that the effective free energy of...

2. Short talks

10/03/2025, 11:30

3. Taming Asymptotic Freedom with Anti-de-Sitter

Shota Komatsu (CERN)

10/03/2025, 14:00

Anti-de-Sitter space acts as an infra-red cut off for asymptotically free theories, allowing interpolation between a weakly-coupled small-sized regime and a strongly-coupled flat-space regime. We scrutinize the interpolation for theories in two dimensions from the perspective of boundary conformal theories. We show that the appearance of a singlet marginal operator destabilizes a gapless phase...

4. Short talks

10/03/2025, 15:30

5. Infinitely many new renormalization group flows between Virasoro minimal models from non-invertible symmetries

Yu Nakayama (YITP)

11/03/2025, 10:00

We discuss the role of non-invertible symmetries in RG flows between
Virasoro minimal models.
They give infinitely many new constraints by generalizing the notion
of anomaly matching to non-invertible symmetries, leading to the
predictions of infinitely many new RG flows.
Our general classification includes the old flows such as
Zamolldchikov's unitary flows, but also all the examples...

6. Pinning Defects, Fusion and Factorization

Yifan Wang (NYU)

11/03/2025, 11:30

I'll discuss recent results on the dynamics of defects in conformal field theory. In particular, I'll describe the phenomena of defect fusion and the factorization of spacetime under renormalization group flows on defects. I'll illustrate these phenomena with the so-called pinning field defects which have simple definitions in quantum field theory and also comment on the broader implications...

7. Holographic Entanglement, Pseudo Entropy and Wormholes

Tadashi Takayanagi (YITP)

11/03/2025, 14:00

The idea of holographic duality in string theory provides a simple
geometric computation of entanglement entropy. This generalizes the celebrated
Bekenstein-Hawking formula of black hole entropy and strongly suggests that a
gravitational spacetime consists of many qubits with quantum entanglement.
Recently, a new extension of entanglement entropy, called pseudo entropy,
which depends on...

8. Short talks

11/03/2025, 15:30

9. Topological symmetries and their gaugings in 2dCFT and 3dTFT

Ingo Runkel (Hamburg U.)

12/03/2025, 10:00

The study of topological defects in quantum field theory has seen a wealth of activity recently leading to many interesting insights, for example the explicit realisation of non-invertible topological defects in higher dimensional QFTs via the gauging of higher form symmetries, or the description of the higher algebraic structures inherent in these topological defects.

In this talk, I would...

10. Short talks

12/03/2025, 11:30

11. No-go theorems for higher-spin charges in AdS_2

Marco Meineri (U. Turin)

12/03/2025, 14:00

Higher-spin conserved currents and charges feature prominently in integrable 2d QFTs in flat space. Motivated by the question of integrable field theories in Anti de-Sitter space, we consider the consequences of higher-spin currents for QFTs in AdS2, and find that their effect is much more constraining than in flat space. Specifically, it is impossible to preserve:(a) any higher-spin charges...

12. Short talks

12/03/2025, 15:30

13. From Weyl Anomaly to Defect Supersymmetric R\'enyi Entropy and Casimir Energy

Yang Zhou (Fudan U.)

13/03/2025, 10:00

We present a closed-form expression for the contribution of surface defects to the supersymmetric Rényi entropy in six-dimensional (2,0) theories. Our results show that this defect contribution is a linear function of 1/n and is directly proportional to 2b-d_2, where b and d_2 are the surface defect Weyl anomaly coefficients. We also derive a closed-form expression for the defect contribution...

14. Short talks

13/03/2025, 11:30

15. Localized RG flows on composite defects and C-theorem

Dongsheng Ge (Osaka U.)

13/03/2025, 14:00

We consider a composite defect system where a lower-dimensional defect (sub-defect) is embedded to a higher-dimensional one, and examine renormalization group (RG) flows localized on the defect. A composite defect is constructed in the (3 − ϵ)-dimensional free O(N) vector model with line and surface interactions by triggering localized RG flows to non-trivial IR fixed points. Focusing on the...

16. Non-Invertible Symmetry and Entanglement Entropy

Yichul Choi (IAS)

14/03/2025, 10:00

Given a quantum field theory with a global symmetry, it is important to understand how the various observables organize into representations of the symmetry. In this talk, we focus on 2d conformal field theories with non-invertible global symmetries described by fusion categories. We will discuss how the boundary local operators connecting two potentially different conformal boundary...

17. Short talks

14/03/2025, 11:30

18. Non-Supersymmetric Heterotic Branes

Justin Kaidi (Kyushu U.)

14/03/2025, 14:00

The common statement that any consistent quantum gravity theory contains dynamical objects with all possible charges suggests that there are still a number of hitherto-unidentified branes in string theory. In this talk I will discuss four of these new branes, focusing on heterotic string theories. The talk will cover aspects such as exact worldsheet descriptions of the branes, their relation...