KEK Theory Workshop 2022

Session

Invited talk

7 Dec 2022, 09:00

Online (Zoom)

Conveners

Invited talk: Yuya Tanizaki (YITP) "Symmetries in QFT and applications"

• Ryo Yokokura (KEK)

Invited talk: Satoshi Yamaguchi (Osaka U.) "Non-invertible symmetries on the lattice"

• Ryo Yokokura (KEK)

Invited talk: Kantaro Ohmori (U. of Tokyo) "Neutrino Masses from Generalized Symmetry Breaking"

• Yoshimasa Hidaka (KEK)

Invited talk: Alon Faraggi (U. of Liverpool) "Toward realistic de Sitter heterotic-string models with stable moduli"

• Yuta Hamada (KEK)

Invited talk: Masafumi Fukuma (Kyoto U.) "Sign problem and the Worldvolume Hybrid Monte Carlo method"

• Yuya Tanizaki (YITP)

Invited talk: Daisuke Kadoh (Doshisha U.) "Tensor renormalization group in field theory"

• Yuya Tanizaki (YITP)

Invited talk: Jun Nishimura (KEK) "Solving the sign problem in the IKKT model and the real-time quantum evolution by the generalized Lefschetz thimble method"

• Yuya Tanizaki (YITP)

Invited talk: Hervé Partouche (Ecole Polytech.) "Stability of open-string models with broken supersymmetry"

• Sota Nakajima (KEK)

Invited talk: Robert M. Wald (U. of Chicago) "Quantum Superpositions of Massive Bodies and Gravitationally Mediated Entanglement"

• Kengo Shimada (YITP)

Invited talk: Masahiro Hotta (Tohoku U.) "Expanding Edges of Quantum Hall Systems in a Cosmology Language - Hawking Radiation from de Sitter Horizon in Edge Modes"

• Kengo Shimada (YITP)

Invited talk: Yuji Sugawara (Ritsumeikan U.) "Constructions of Non-SUSY String Vacua with Vanishing Cosmological Constant"

• Sota Nakajima (KEK)

Invited talk: Suvrat Raju (ICTS) "Holography of information and the black-hole information paradox"

• Satoshi Iso (KEK)

36. Symmetries in QFT and applications

Prof. Yuya Tanizaki (YITP, Kyoto University)

07/12/2022, 09:00

Quantum field theory is a framework that can describe universal behavior in the low-energy region for quantum many-body systems, but solving it is often very difficult as it often becomes strongly coupled systems. One of possible approaches to such problems is to constrain the dynamics from general viewpoints instead of solving the dynamics directly. Symmetry in field theories has played a...

37. Non-invertible symmetries on the lattice

Prof. Satoshi Yamaguchi (Osaka University)

07/12/2022, 10:20

Recently, the concept of symmetry has been generalized, and what was not traditionally called symmetry is now being used similarly as symmetry. In this talk, we discuss a class of such generalized symmetries, called non-invertible symmetries, from the viewpoint of the lattice field theories. In particular, we construct topological defects in four-dimensional Z${}_2$ lattice gauge theory,...

38. Neutrino Masses from Generalized Symmetry Breaking

Prof. Kantaro Ohmori (University of Tokyo)

07/12/2022, 13:00

It is now understood that the concept of symmetry in quantum field theory should be vastly generalized from the ones come from a group action on fields. The generalization includes the higher-form symmetry, which acts on extended operators, and non-invertible symmetry, which does not have an inverse operation. In particular, a classical symmetry with an ABJ-anomaly with an abelian gauge group...

45. Toward realistic de Sitter heterotic-string models with stable moduli

Prof. Alon Faraggi (University of Liverpool)

07/12/2022, 16:30

The Standard Model of particle physics accounts for all experimental observations to date, and may provide viable parameterisation up to the Planck scale. In this eventuality, further insight into the fundamental origin of the Standard Model parameters can only be gleaned by synthesising it with gravity. String theory provides a framework for the construction of phenomenological models that...

39. Sign problem and the Worldvolume Hybrid Monte Carlo method

Prof. Masafumi Fukuma (Kyoto University)

08/12/2022, 09:00

The numerical sign problem is one of the major obstacles to first-principles calculations in a variety of important systems. Typical examples include finite-density QCD, some condensed matter systems such as strongly correlated electron systems and frustrated spin systems, and real-time dynamics of quantum fields. Until very recently, individual methods were developed for each target system,...

40. Tensor renormalization group in field theory

Prof. Daisuke Kadoh (Doshisha University)

08/12/2022, 10:20

Recently, a novel approach using tensor renormalization group (TRG) has made great progress in the numerical computation of lattice field theory. In the TRG, partition functions and correlation functions are represented as tensor networks. Their values can be evaluated by coarse-graining the network without using probabilities like Monte Carlo methods. Therefore, the TRG can easily be applied...

41. Solving the sign problem in the IKKT model and the real-time quantum evolution by the generalized Lefschetz thimble method

Prof. Jun Nishimura (KEK)

08/12/2022, 11:20

I report on recent developments in the generalized thimble method based on the Hybrid Monte Carlo algorithm using backpropagation. In particular, I discuss interesting results for the IKKT matrix model and the real-time evolution in quantum mechanics.

46. Stability of open-string models with broken supersymmetry

Prof. Hervé Partouche (Ecole Polytechnique)

08/12/2022, 17:00

We consider type IIB orientifold models in four-dimensional Minkowski spacetime, with N=2 supersymmetry spontaneously broken to 0. For an arbitrary choice of D9- and D5-brane configuration, we analyze the generation of masses at one-loop for all open- and closed-string sector moduli fields. In order to find non-tachyonic models at one-loop, a key ingredient is to consider brane configurations...

42. Quantum Superpositions of Massive Bodies and Gravitationally Mediated Entanglement

Prof. Robert Wald (University of Chicago)

09/12/2022, 09:00

In order to avoid contradictions with complementarity and causality in a gedankenexperiment involving a quantum superposition of a massive body, it was previously shown (in arXiv:1807.07015) that it is necessary for there to be both quantized gravitational radiation and local vacuum fluctuations
of the spacetime metric. We review this gedankenexperiment and the previously given “back of the...

43. Expanding Edges of Quantum Hall Systems in a Cosmology Language - Hawking Radiation from de Sitter Horizon in Edge Modes

Prof. Masahiro Hotta (Tohoku University)

09/12/2022, 10:20

Expanding edge experiments are promising to open new physics windows of quantum Hall systems. In a static edge, the edge excitation, which is described by free fields decoupled with the bulk dynamics, is gapless, and the dynamics preserve conformal symmetry. When the edge expands, such properties need not be preserved. We formulate a quantum field theory in 1+1 dimensional curved spacetimes to...

47. Constructions of Non-SUSY String Vacua with Vanishing Cosmological Constant

Prof. Yuji Sugawara (Ritsumeikan University)

09/12/2022, 13:00

In this talk, I discuss how one can systematically construct non-supersymmetric string vacua with vanishing cosmological constant at one loop, founded mainly on a series of my works. After making a review of related studies, I present the constructions of the string vacua possessing such a property based on the asymmetric orbifolds in various CFT set-ups. We further discuss the physical...

44. Holography of information and the black-hole information paradox

Prof. Suvrat Raju (ICTS)

09/12/2022, 16:00

We review recent progress in our understanding of how information is localized in a theory of quantum gravity. In such theories, we argue that, subject to weak assumptions, information in any bounded region is also available in its complement. This is very different from the manner in which quantum information is localized in nongravitational quantum field theories. This implies that the...