165 events in 2023

Seminar
Topological Kondo superconductors
March 2 (Thu) at 17:00  18:15, 2023
YungYeh Chang (Postdoctoral Researcher, National Center for Theoretical Sciences & National Chiao Tung University, Taiwan)
Spintriplet pwave superconductors are promising candidates for topological superconductors. They have been proposed in various heterostructures where a material with strong spinorbit interaction is coupled to a conventional swave superconductor by proximity effect. However, topological superconductors existing in nature and driven purely by strong electron correlations are yet to be studied. Here we propose a realization of such a system in a class of Kondo lattice materials in the absence of proximity effect. Therein, the oddparity Kondo hybridization mediates ferromagnetic spinspin coupling and leads to spintriplet resonantvalencebond (tRVB) pairing between local moments. Spintriplet p±p’ wave topological superconductivity is reached when Kondo effect coexists with tRVB [1]. We identify the topological nature by the nontrivial topological invariant and the Majorana zero modes at edges. Our results on the superconducting transition temperature, Kondo coherent scale, and onset temperature of Kondo hybridization not only qualitatively but also quantitatively agree with the observations for UTe2, a Ubased ferromagnetic heavyelectron superconductor. *This work is supported by the National Science and Technology Council, Taiwan. Field: condensed matter physics Keywords: strongly correlated systems, topological superconductor, Kondo effect, resonant valence bond, heavyfermion compounds
Venue: via Webex
Event Official Language: English

Seminar
How to sit Maxwell and Higgs on the boundary of AdS
February 28 (Tue) at 13:30  15:00, 2023
Matteo Baggioli (Associate Professor, School of Physics and Astronomy, Shanghai Jiao Tong University, China)
Within the holographic correspondence, boundary conditions play a fundamental role in determining the nature of the dual field theory. In this talk, I will show how to exploit mixed boundary conditions to obtain dynamical electromagnetism in the boundary theory. This is necessary to apply AdSCFT to many realworld applications, e.g., magnetohydrodynamics, plasma physics, superconductors, etc. where dynamical gauge fields and Coulomb interactions are fundamental. As a proof of concept, I will show two emblematic cases. First, I will prove that the results from the 4dimensional EinsteinMaxwell bulk theory with these deformed boundary conditions are in perfect agreement with relativistic magnetohydrodynamics in 2+1 dimensions. Second, I will discuss the collective excitations of a bonafide holographic superconductor and prove the existence of the AndersonHiggs mechanism therein.
Venue: Room 6209, Korakuen Campus, Chuo University (Main Venue) / via Zoom
Event Official Language: English

Interdisciplinary Science Conference in Okinawa (ISCO 2023)
February 27 (Mon)  March 3 (Fri), 2023
The scientific method of studying the natural world has persisted over the centuries. The key to its longevity and progression lies in sharing and building upon accumulated knowledge. Physics, which explores the origin of the universe and matter; biology, which studies living organisms, and their functions and evolution; and medicine, which explores health based on the structure and function of living organisms: all have made enormous advancements that impact all aspects of our lives. As the scientific study progresses, however, additional challenges have arisen which are increasingly difficult to solve. Many of the challenges that humanity faces are in achieving sustainable development. These include environmental changes due to climate change, food crises caused by the gap between population growth and food production, and pandemics caused by the spreading of resistant bacteria and viruses. To rise to these new challenges, it is important to reassess the issues from a broader perspective: to combine the knowledge and methods of different scientific fields and to look for new approaches that can bridge the boundaries and work across multiple fields The purpose of ISCO 2023 is to bring together leading researchers in their respective fields, explore methods for solving issues through the fusion of different fields, and form a new network of researchers. The workshop will bring together speakers from Japan and abroad in the fields of space science, particle and nuclear physics, quantum computing, life sciences, and medicine to discuss the challenges they face and the latest advancements in their respective fields. We call for presentations from fields related to those subjects mentioned above and on the sustainable development of humankind. In addition, we plan to hold a poster session to facilitate a wide range of discussions. We hope that the knowledge gained at this workshop will lead to the creation of new research fields that will not only advance basic science but will also help solve the various new challenges that humanity faces.
Venue: OIST Auditorium / via Zoom
Event Official Language: English

Seminar
Algebra of symmetry in BFlike models in 3d and 4d
February 22 (Wed) at 14:00  15:30, 2023
Christophe Goeller (Humboldt Fellow, LudwigMaximiliansUniversität München, Germany)
In this talk, I will discuss the construction of the boundary symmetry algebra for BFlike theories in 3D and 4D. In the 3D case, the theory corresponds to (an extension of) 3D gravity allowing for a source of curvature and torsion. I will show how the study of the current algebra and its associated Sugawara construction allows for two notions of quadratic charges (the usual diffeomorphism and its "dual") independently of boundary conditions. I will discuss their resulting algebra and its relation with the usual construction of the asymptotic boundary algebra. In the 4D case, a similar yet fundamentally different construction is possible, similarly resulting in multiple quadratic charges. I will discuss their constructions and their possible relations to 4D gravity.
Venue: Hybrid Format (Common Room 246248 and Zoom)
Event Official Language: English

The ElectronIon Collider: the Ultimate Electron Microscope
February 20 (Mon) at 15:00  16:30, 2023
Gordon Baym (Professor Emeritus, University of Illinois, USA)
How does the nucleon get its mass? Certainly not from the Higgs  the rest masses of the quarks it contains add up to only one percent of the nucleon mass. Rather the remaining 99% comes from the zeropoint energy of the quarks, antiquarks and gluons localized in the nucleon. How do nuclei differ from being a simple collection of nucleons? How are the gluons, for example, distributed in nuclei? Do they stick out, or are they clumped towards the center of the nucleon? Gluons, like dark matter unseen but playing the crucial role in gluing matter together, are strongly interacting. Do such gluons form new emergent quantum states in nuclei, as in condensed matter physics? And how is the spin of the proton  the key to NMR imaging  put together from the spin and orbital motion of the quarks and gluons in the proton?
Venue: Okochi Hall (Main Venue) / via Zoom
Event Official Language: English

Connecting the hierarchies: from cosmos to life
February 20 (Mon) at 10:00  16:45, 2023
Yuki Yokokura (Senior Research Scientist, iTHEMS)
Etsuko Itou (Senior Research Scientist, iTHEMS)
Catherine Beauchemin (Deputy Program Director, iTHEMS)As each research field in modern science has matured and become more sophisticated and deepened, it has also created the problem that it has become too fragmented from the perspective of the field as a whole. On the other hand, looking at individual research themes, research that connects different hierarchical structures, such as cosmogenesis and particle theory, neutron stars and nuclear theory, largescale structure of the universe and formation of galaxies, stars, and planets, turbulent phenomena over a wide range of scales, life and nonequilibrium phenomena, etc., is progressing, and efforts to understand physical phenomena from an integrated perspective is spreading. The term "hierarchy" can also be interpreted as a hierarchy of theories, different principles and perspectives. Therefore, in this TJR workshop, we invite relevant lecturers from external institutes to give talks focusing on how they are striving to link different hierarchies in their respective research fields, with the aim of broadening our research perspectives and inspiring future research. Of course, the purpose is also to inform and inspire the younger generation about crossdisciplinary research topics.
Venue: Nambu Hall, Toyonaka Campus, Osaka University / via Zoom

Seminar
Coherent sheaves, quivers, and quantum groups
February 17 (Fri) at 14:00  16:00, 2023
Gufang Zhao (Senior Lecturer, University of Melbourne, Australia)
This talk aims to illustrate symmetries in geometry. The first half surveys a few examples of parametrizing coherent sheaves on a variety and how quantum groups control the symmetry of parametrization space. The second half aims to illustrate some special cases when the variety is a local toric 3CalabiYau.
Venue: Hybrid Format (Common Room 246248 and Zoom)
Event Official Language: English

String theory, N=4 SYM and Riemann hypothesis
February 16 (Thu) at 14:00  16:10, 2023
Masazumi Honda (Assistant Professor, Yukawa Institute for Theoretical Physics, Kyoto University)
We discuss new relations among string theory, fourdimensional N=4 supersymmetric YangMills theory (SYM) and the Riemann hypothesis. It is known that the Riemann hypothesis is equivalent to an inequality for the sum of divisors function σ(n). Based on previous results in literature, we focus on the fact that σ(n) appears in a problem of counting supersymmetric states in the N=4 SYM with SU(3) gauge group: the Schur limit of the superconformal index plays a role of a generating function of σ(n). Then assuming the Riemann hypothesis gives bounds on information on the 1/8BPS states in the N=4 SYM. The AdS/CFT correspondence further connects the Riemann hypothesis to the type IIB superstring theory on AdS5×S5. In particular, the Riemann hypothesis implies a miraculous cancellation among KaluzaKlein modes of the supergravity multiplet and D3branes wrapping supersymmetric cycles in the string theory. We also discuss possibilities to gain new insights on the Riemann hypothesis from the physics side. This talk is based on a collaboration with Takuya Yoda (arXiv:220317091).
Venue: Hybrid Format (Common Room 246248 and Zoom)
Event Official Language: English

Seminar
Quantum groups and cohomology theories
February 15 (Wed) at 14:00  16:00, 2023
Yaping Yang (Senior Lecturer, University of Melbourne, Australia)
In the first half of my talk, I will review quantum groups at roots of unity and their representation theory. In the second half, I will explain a construction of new quantum groups using cohomology theories from topology. The construction uses the socalled cohomological Hall algebra associated to a quiver and an oriented cohomology theory. In examples, we obtain the Yangian, quantum loop algebra and elliptic quantum group, when the cohomology theories are the cohomology, Ktheory, and elliptic cohomology respectively.
Venue: Hybrid Format (Common Room 246248 and Zoom)
Event Official Language: English

Kyoto Univ. MACS Program x RIKEN iTHEMS Collaborative Research Forum
February 13 (Mon) at 13:00  18:00, 2023
RIKEN iTHEMS and the SACRA Interdisciplinary Research Division of the Graduate School of Science, Kyoto University signed a joint research agreement on the task "Creation of new fields and solution of various problems in science using mathematicalbased interdisciplinary methods", which started in 2018, and the two institutions have been strengthening collaboration over the past five years. During this period, various collaborative activities in both research and education have been carried out and results have been achieved, including the holding of research symposia, joint lectures across universities, the establishment of visiting lectures, and educational activities in the MACS Study Group. At this forum, we would like to present the results of these five years of joint research and to link them to the start of further collaboration in the future. In particular, many undergraduate and graduate students have participated in the "MACS Study Group 2022SG5 Pipeline Connecting RIKEN and MACS", and have been actively engaged in research activities with RIKEN researchers. The results of these SG5 activities will be presented by the students.
Venue: 4F, South Tower, School of Science Bldg. No.6, Kyoto University (Main Venue) / via Zoom
Event Official Language: Japanese

Seminar
Entanglement in nonHermitian quantum systems and nonunitary conformal field theories
February 9 (Thu) at 17:00  18:15, 2023
Chang PoYao (Assistant Professor, Department of Physics, National Tsing Hua University, Taiwan)
Time: 5pm ~ 6:15pm (JST); 9am ~ 10:15am (CET); 4pm ~ 5:15pm (Taiwan) Entanglement is a powerful tool to diagnose manybody quantum systems. One example is the critical system where the low energy property can be described by conformal field theories (CFTs), and the central charge which uniquely characterizes the CFT can be perfectly extracted from the entanglement entropy. However, the entanglement properties for nonunitary CFTs are not well understood. Moreover, the entanglement properties in manybody microscopic models which can be described by nonunitary CFTs have not been explored. In this talk, I would like to demonstrate several nonHermitian systems which can be described by nonunitary CFTs, and show their entanglement properties can be correctly obtained by the proposed generic entanglement entropy. Field: Condensed Matter Physics Keywords: nonHermitian systems, conformal field theory, manybody systems, entanglement entropy
Venue: via Webex
Event Official Language: English

Seminar
Elasticities of population growth and their significance to evolutionary biology
February 9 (Thu) at 16:00  17:00, 2023
Stefano Giaimo (Postdoc, Department for Evolutionary Theory, Max Planck Institute for Evolutionary Biology, Germany)
The elasticity of population growth to a demographic parameter quantifies the proportional sensitivity of population growth to such parameter. In this talk, I will illustrate some cases where elasticities of population growth to demographic parameters acquire a special importance to evolutionary biology. In particular, I will discuss the relevance of these elasticities in studying the evolution of aging, their role in the computation of the generation time and their relationship to some tradeoffs organisms may face as they optimise their fitness.
Venue: via Zoom
Event Official Language: English

Seminar
Boltzmann or Bogoliubov? A Case of Gravitational Particle Production
February 9 (Thu) at 13:30  15:00, 2023
Kunio Kaneta (Lecturer, Graduate School of Science, Tokyo Woman's Christian University)
Despite its weakness, gravity is the primordial source of particle production in the early Universe. All the particles, including dark matter, can inevitably be created after the end of inflation through gravity. To study this production channel, two different approaches have commonly been considered, one of which is based on the Boltzmann equation, and the other is based on the Bogoliubov transformation. The former approach has widely been used in phenomenological studies of dark matter, while the latter has been developed to describe particle production in curved spacetime. I will discuss when these two approaches are equivalent and when they are not by considering the pure gravitational production of a scalar particle.
Venue: Hybrid Format (Common Room 246248 and Zoom)
Event Official Language: English

Seminar
Fuzzy DM simulation (TBA)
February 9 (Thu) at 11:00  12:00, 2023
Jowett Chan (Postdoc, Physics Division, National Center for Theoretical Sciences, Taiwan)
Venue: via Zoom
Event Official Language: English

Seminar
Thermodynamic inequalities: motivation, foundations, and applications
February 7 (Tue) at 13:30  15:00, 2023
Andreas Dechant (Lecturer, Graduate School of Science, Kyoto University)
In this talk, I will introduce the topic of thermodynamic inequalities. One motivation for studying inequalities is that they can provide universal constraints on what can and cannot happen in physical systems. From a more practical point of view, they can be used to estimate physical observables even in situations where no equality is available. I will highlight a few recent examples of thermodynamic inequalities in the form of uncertainty relations and speed limits. In the main part of the talk, I will explain a general technique for deriving new inequalities, by starting from informationtheoretic bounds and considering “virtual perturbations” of a physical system. I will show how this method can be used to derive and generalize the socalled “thermodynamic uncertainty relation”. An interesting application of such uncertainty relations is to estimate the dissipation in biological systems such as molecular motors. The second main topic is how to relate inequalities to equalities. When using inequalities to estimate physical quantities, it is crucial to understand the conditions under which the inequality can be tight. One way to achieve this is to “promote” the inequality into an equality via a variational principle. On the one hand, this provides conditions for obtaining a tight bound. On the other hand, variational expressions can also serve as a starting point to derive new inequalities.
Venue: via Zoom
Event Official Language: English

Seminar
Universal Biology in Adaptation and Evolution: Dimensional Reduction and FluctuationResponse Relationship
February 2 (Thu) at 16:00  17:00, 2023
Kunihiko Kaneko (Professor, Niels Bohr Institute, University of Copenhagen, Denmark)
A macroscopic theory for adaptive changes of cells is presented, based on consistency between cellular growth and molecular replication, as well as robustness of fitted phenotypes against perturbations. Adaptive changes in highdimensional phenotypes are shown to be restricted within a lowdimensional slow manifold, from which a macroscopic law for cellular states is derived, as is confirmed by adaptation experiments of bacteria under stress. The theory is extended to phenotypic evolution, leading to proportionality between phenotypic responses against genetic evolution and by environmental adaptation, which also explains the evolutionary fluctuationresponse relationship previously uncovered. Relevance of statisticalphysics and dynamicalsystems approach is discussed.
Venue: via Zoom
Event Official Language: English

Scaling Optimal Transport for High dimensional Learning
January 24 (Tue) at 17:00  18:30, 2023
Gabriel Peyré (Research Director, CNRS/École Normale Supérieure, France)
iTHEMSAIP Joint Colloquium Optimal transport (OT) has recently gained a lot of interest in machine learning. It is a natural tool to compare in a geometrically faithful way probability distributions. It finds applications in both supervised learning (using geometric loss functions) and unsupervised learning (to perform generative model fitting). OT is however plagued by the curse of dimensionality, since it might require a number of samples which grows exponentially with the dimension. In this talk, I will explain how to leverage entropic regularization methods to define computationally efficient loss functions, approximating OT with a better sample complexity. More information and references can be found on the website of our book "Computational Optimal Transport" (see related link below).
Venue: via Zoom
Event Official Language: English

Lecture
Introduction to the Quantum Theory of Gravity via Asymptotic Safety
January 24 (Tue)  26 (Thu), 2023
Ohta Nobuyoshi (Visiting Professor, Department of Physics, National Central University, Taiwan)
We give an introduction to the formulation towards the quantum theory of gravity using the functional (or exact) renormalization group, the socalled asymptotic safety. First we briefly explain the necessity of quantization of gravity and why the Einstein gravity is not sufficient for this purpose. Second, we introduce the functional renormalization group equation and explain what is the asymptotic safety program to achieve the quantum theory of gravity. This includes the notion of relevant, irrelevant and marginal operators, and it is important that there are finite number of relevant operators to make any prediction of quantum effects. This gives a nonperturbatively renormalizable theory of gravity. We then discuss various examples how the program may be applied to various theories, and summarize the current status of this approach. (Tentative schedule) [Day 1: Jan. 24, 2023] Free discussion: 9:30  10:30 Lecture 1: 10:30  12:00 Lunch: 12:00  13:30 Lecture 2: 13:30  15:00 Break: 15:00  15:30 Lecture 3: 15:30  17:00 [Day 2: Jan. 25, 2023] Free discussion: 9:30  10:30 Lecture 4: 10:30  12:00 Lunch: 12:00  13:30 Lecture 5: 13:30  15:00 Break: 15:00  15:30 Lecture 6: 15:30  17:00 [Day 3: Jan. 26, 2023] Q&A + discussion: 9:30  15:00
Venue: #535537, 5F, Main Research Building
Event Official Language: English

Seminar
Physicsinformed deep learning approach for modeling crustal deformation
January 23 (Mon) at 10:30  11:30, 2023
Naonori Ueda (Deputy Director, RIKEN Center for Advanced Intelligence Project (AIP))
The movement and deformation of the Earth’s crust and upper mantle provide critical insights into the evolution of earthquake processes and future earthquake potentials. Crustal deformation can be modeled by dislocation models that represent earthquake faults in the crust as defects in a continuum medium. In this study, we propose a physicsinformed deep learning approach to model crustal deformation due to earthquakes. Neural networks can represent continuous displacement fields in arbitrary geometrical structures and mechanical properties of rocks by incorporating governing equations and boundary conditions into a loss function. The polar coordinate system is introduced to accurately model the displacement discontinuity on a fault as a boundary condition. We illustrate the validity and usefulness of this approach through example problems with strikeslip faults. This approach has a potential advantage over conventional approaches in that it could be straightforwardly extended to high dimensional, anelastic, nonlinear, and inverse problems.
Venue: via Zoom
Event Official Language: English
165 events in 2023
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