How did the Universe Begin? -Inflation Theory & Road to the Proof-

May 21 (Tue) at 15:00 - 16:30, 2019

Katsuhiko Sato (Professor Emeritus, The University of Tokyo / Director, Research Center for Science Systems, Japan Society for the Promotion of Science)

Venue: Okochi Hall

Broadcast:R511, Computational Science Research Building / SUURI-COOL (Kyoto) / SUURI-COOL (Sendai)

Event Official Language: Japanese

Introduction to Singularity Theory in Algebraic Geometry

May 16 (Thu) at 16:00 - 18:10, 2019

Kenta Sato (Special Postdoctoral Researcher, iTHEMS)

Plan of the seminar: we separate each talk into two. In the first 60 minutes the speaker gives an introductory talk for non-mathematicians. After a short break, the second 60 minutes is spent for a bit more detailed talk for mathematicians (working in other areas). We welcome you joining both parts of the seminar or only the first/second half. In this talk, I will explain for all scientists how singularities are studied in algebraic geometry. In algebraic geometry, we study algebraic varieties, which are figures defined as the zero sets of polynomial equations. To study an algebraic variety, we often expect that the variety is smooth, that is, the variety locally resembles Euclidian spaces. However, even if we start from smooth varieties, we sometimes encounter non-smooth varieties. This is one of the reasons why we need to study singularities. Part I: In the first one hour, I will explain how singularities are studied. I will introduce two invariants of singularities by which we can compare singularities numerically. One invariant is defined in terms of resolution of singularities and the other is defined in terms of positive characteristic methods. I also explain a surprising relation of these invariants. Part II: In the second one hour, I will explain how singularity theory is used to study smooth projective varieties. I will introduce Minimal Model Program and explain the relation with singularity theory.

Venue: Seminar Room #160

Event Official Language: English

Introduction to Quantum Computation

May 13 (Mon) - 15 (Wed), 2019

Shunji Matsuura (Fundamental Researcher, Quantum Simulation Division, 1QBit, Canada)

The schedule of the lectures on "Quantum Computation" by Dr. Shunji Matsuura (1QBit) is as follows. May 13 (Mon) [Lecture 1] 10:00-11:30, [Lecture 2] 14:00-15:30 May 14 (Tues) [Lecture 3] 10:00-11:30, [Lecture 4] 14:00-15:30 May 15 (Wed) [Lecture 5] 10:00-11:30, [Lecture 6] 14:00-15:30

Venue: Nishina Hall

Event Official Language: English

Three quantizations of conformal field theory

May 1 (Wed) at 15:40 - 17:30, 2019

Tsukasa Tada (Coordinator, iTHEMS / Vice Chief Scientist, Quantum Hadron Physics Laboratory, RIKEN Nishina Center for Accelerator-Based Science (RNC))

Needless to say, conformal field theory is elemental in the study of string theory, statistical quantum systems, and various quantum field theories. Two-dimensional conformal field theory is usually quantized by the so-called radial quantization. However, this is not the only way. As a matter of fact, there are two other distinctive choices for the time foliation, or equivalently, the Hamiltonian. One of these choices yields the continuous Virasoro algebra, while the other choice leads to the Virasoro algebra on a torus. The former case corresponds to the recently found (and perhaps less known) phenomenon, sine-square deformation. The latter yields the well-known entanglement entropy. I will present a comprehensive treatment of these three quantizations and discuss its physical implications.

Venue: Old LeConte Hall 402, UC Berkeley

Event Official Language: English

Gauge Theory and Symmetries of 4-Dimensional Spaces

April 26 (Fri) at 16:00 - 18:10, 2019

Hokuto Konno (Special Postdoctoral Researcher, iTHEMS)

Plan of the seminar: we separate each talk into two. In the first 60 minutes the speaker gives an introductory talk for non-mathematicians. After a short break, the second 60 minutes is spent for a bit more detailed talk for mathematicians (working in other areas). We welcome you joining both parts of the seminar or only the first/second half. Although the term "gauge theory" is usually used in physical contexts, in the early 1980's, mathematicians found that gauge theory has many striking applications to purely mathematical problems. Most of typical applications are related to topology of 4-dimensional spaces. As a recent development in this direction, I used gauge theory to study "the shape of the space of all symmetris of a 4-dimensional space". In the first one hour, I will explain a notion of mathematical spaces, called manifolds, and try to describe the idea: how mathematicians make use of gauge theory to study the topology of a 4-dimensional manifold. In the second one hour, I will explain what the space of symmetries of a manifold means, and which type of theorems about the space of symmetries can be obtained using gauge theory.

Venue: Seminar Room #160

Event Official Language: English

Quantum computing: current status and prospects

April 25 (Thu) at 15:00 - 16:30, 2019

Keisuke Fujii (Professor, Graduate School of Engineering Science, Osaka University)

Supported by extensive experimental efforts for realization of quantum computing devices, quantum computers of a hundred qubits are now within reach in the near future. This level of a quantum computer is not enough for fully fledged fault-tolerant quantum computing, but is still expected to have computational advantage against classical computers. Such a noisy intermediate scale quantum computing (NISQ) device is thought to be a testbed for proof-of-principle experiments of quantum algorithms and verification of quantum physics in the limit of extremely high complexity. In this talk, I will provide a general introduction to quantum computing starting from how and for what quantum computers work. Then I will provide an overview of the current status and prospects of the field of quantum computing. As the final part, I will also talk about our own activities on quantum-classical hybrid algorithm, which is a kind of quantum algorithms specifically designed for the NISQ devices.

Venue: Suzuki Umetaro Hall

Broadcast:R511, Computational Science Research Building / SUURI-COOL (Kyoto) / SUURI-COOL (Sendai)

Event Official Language: English

Introduction to Galois Theory and Class Field Theory

April 18 (Thu) at 16:00 - 18:00, 2019

Hiroyasu Miyazaki (Special Postdoctoral Researcher, iTHEMS)

Plan of the seminar: we separate each talk into two. In the first 60 minutes the speaker gives an introductory talk for non-mathematicians. After a short break, the second 60 minutes is spent for a bit more detailed talk for mathematicians (working in other areas). We welcome you joining both parts of the seminar or only the first/second half. Part I: Galois theory is one of the most important theories in mathematics. Speaking in one phrase, it explains the correspondence between “extensions of numbers” and “subgroups of Galois group”. Basically, finding subgroups of a finite group is much easier than finding extensions of numbers. As a result, Galois theory has incredibly strong applications. For example, we can prove polynomial equations of degree greater than 4 are not always solvable by radicals, which is a celebrated result by Abel and Galois. In the first part of the talk, I will introduce Galois theory in an accessible way for all scientists. Part II: Class Field Theory (CFT) is a monumental work in number theory. Given Galois theory, which is explained in Part I, classifying “extension of numbers” is reduced to classifying “subgroups of Galois group”. So, the next thing to do would be to analyze the structure of Galois groups. CFT enables us to describe the Galois group of a number field K by using only the language of K, i.e., not by using its extensions. In the second part of the talk, I will explain CFT in an as accessible way as possible for all scientists (in particular, also for mathematicians). If time permits, I would like to explain a geometric interpretation of Galois theory, and higher dimensional CFT.

Venue: Seminar Room #160

Event Official Language: English

International Molecule-type Workshop "Frontiers in Lattice QCD and related topics"

April 15 (Mon) - 26 (Fri), 2019

International Molecule-type Workshop "Frontiers in Lattice QCD and related topics" will be held in Yukawa Institute for Theoretical Physics (YITP) on April 15 - 26, 2019 under the support of iTHEMS and YITP. Lattice quantum chromodynamics (QCD) is a systematic method to investigate strong interaction of hadrons with numerical simulations. In this workshop, frontiers of lattice QCD will be discussed under relaxed atmosphere in Kyoto. Organizers: Sinya Aoki (YITP), Yasumichi Aoki (RIKEN, CCS), Hidenori Fukaya (Osaka U.), Shoji Hashimoto (KEK), Tetsuo Hatsuda (RIKEN, iTHEMS), Takumi Doi (RIKEN, Nishina Center), Atsushi Watanabe (YITP)

Venue: Yukawa Institute for Theoretical Physics, Kyoto University

Event Official Language: English

The 8th MACS Colloquium

April 12 (Fri) at 15:00 - 17:30, 2019

Hayato Chiba (Professor, Advanced Institute for Materials Research (AIMR), Tohoku University)

15:00- Teatime 15:15- Talk by Prof. Hayato Chiba 16:45- MACS Student Conference FY2019 The 8th MACS colloquium is supported by iTHEMS. It will be broadcasted to Wako, but if you can join the colloquium physically in Kyoto, that would be better. iTHEMS provides good confectionary at Kyoto!

Venue: Lecture room #401, Graduate School of Science Building No 6, Kyoto University

Broadcast:#235, 2F, Main Research Building

Event Official Language: Japanese

ABBL, iTHEMS, r-EMU Joint Seminar: Impacts of New Carbon Fusion Cross Sections on Type Ia Supernovae

April 12 (Fri) at 15:00 - 16:00, 2019

Kanji Mori

Venue: Seminar Room #132

Event Official Language: English

Introduction to Public-Key Cryptography (10th)

April 9 (Tue) at 13:30 - 15:30, 2019

Eren Mehmet Kıral (Visiting Scientist, iTHEMS / Visiting Scientist (JSPS Research Fellow), Faculty of Science and Technology, Sophia University)

Venue: Seminar Room #160

Event Official Language: English

iTHEMS Seminar+discussion on "non-equilibrium physics of living matter"

April 8 (Mon) at 14:00 - 15:30, 2019

Kyogo Kawaguchi (The University of Tokyo / RIKEN Hakubi Team Leader, Nonequilibrium physics of living matter RIKEN Hakubi Research Team, RIKEN Center for Biosystems Dynamics Research (BDR))
Kyosuke Adachi (Research Scientist, Nonequilibrium Physics of Living Matter RIKEN Hakubi Research Team, RIKEN Center for Biosystems Dynamics Research (BDR))

14:00-14:50 (40 min. talk + 10 min discussion) "Physical" problems in multicellular dynamics and cell differentiation Kyogo Kawaguchi (RIKEN Hakubi Research Group) 14:50-15:30 (30 min. talk + 10 min. discussion) Phase transition in a chromatin model with epigenetic modification Kyosuke Adachi (Kawaguchi Lab.) 15:30- Informal discussions

Venue: Seminar Room #160

Event Official Language: English

Lifting low dimensional local systems

April 3 (Wed) at 15:45 - 16:45, 2019

De Clercq Charles (Université Paris 13, Sorbonne, France)

The content of this seminar is basically for mathematicians (sorry). If you are interested in how a professional math seminar works, please feel free to join! A long-standing conjecture predicts the existence of lifts for Galois representations with F_p coefficients to p-adic coefficients. The case 2-dimensional representations of the absolute Galois group of Q is closely related to Serre's modularity conjecture, proved by Khare and Witenberger. After some recollection on the state of the art about this problem, i will develop the machinery underneath the notion of smooth profinite groups. We will then show how this machinery allows to prove some lifting theorems for low dimensional Galois representations and local systems, getting out of the classical arithmetic world usually considered for this conjecture.

Venue: Seminar Room #160

Event Official Language: English

The Origin of the X-ray Clumpy Ejecta in Type Ia Supernova Remnants

April 3 (Wed) at 14:00 - 15:00, 2019

Toshiki Sato (Special Postdoctoral Researcher, High Energy Astrophysics Laboratory, RIKEN Cluster for Pioneering Research (CPR))

X-ray-emitting clumpy structures are generally observed in young Type Ia supernova remnants although the origin is still obscure. There are two candidates for explaining the formation of clumps; initial clumpiness in ejecta at the explosion (i.e., clumpy ejecta model) or hydrodynamic instabilities made from smooth ejecta profile (i.e., smooth ejecta model). This information should reflect the initial ejecta structure of SNe Ia, so it is important for understanding the Type Ia explosion itself. Our preliminary investigations into constraining the structure of SN Ia remnants using Fourier and wavelet-transform analyses did not turn out to be sufficiently powerful at discriminating the two hydro models and the observed Tycho image from each other. This led us to investigate an approach that would be more sensitive to patterns in the distribution of clumps and holes in the images, such as the "genus statistic.” In this study, for the first time, the genus statistics have been applied to a famous type Ia remnant, Tycho (SN 1572) to understand the formation of the clumps by comparing with hydrodynamical models (Sato et al. 2019, arXiv: 1903.00764). We found the genus curve from Tycho's supernova remnant strongly indicates a skewed non-Gaussian distribution of the ejecta clumps, which is similar to that of a hydrodynamical model for the clumpy ejecta model. In contrast, a hydrodynamical model for the smooth ejecta model has a genus curve that is similar to that of a random Gaussian distribution. Thus, our results support the initial clumpiness in the Type Ia ejecta is more reasonable for the origin of the clumps and demonstrate usefulness of the genus statistics for this field. In addition, we will also discuss the origin of “Fe-rich” ejecta clumps in Type Ia SNRs in this seminar.

Venue: #433, Main Research Building

Event Official Language: English

Tensor Berry connections and their topological invariants

April 2 (Tue) at 14:00 - 15:00, 2019

Giandomenico Palumbo (Researcher, Université Libre de Bruxelles, Belgium)

The Berry connection plays a central role in our description of the geometric phase and topological phenomena. In condensed matter, it describes the parallel transport of Bloch states and acts as an effective "electromagnetic" vector potential defined in momentum space. Inspired by developments in high-energy physics, where higher-form Kalb-Ramond gauge fields were introduced, I hereby explore the existence of "tensor Berry connections" in quantum matter. My approach consists in a general construction of effective gauge fields, which I ultimately relate to the components of Bloch states. I apply this formalism to various models of topological matter, and I investigate the topological invariants that result from generalized Berry connections. I introduce the 2D Zak phase of a tensor Berry connection, which I then relate to the more conventional first Chern number; I also reinterpret the winding number characterizing 3D topological insulators to a Dixmier-Douady invariant, which is associated with the curvature of a tensor connection. Besides, my approach identifies the Berry connection of tensor monopoles, which are found in 4D Weyl-type systems in ultracold atoms.

Venue: Seminar Room #160

Event Official Language: English

iTHEMS-AIMR Joint Workshop "Medicine meets Mathematics"

March 29 (Fri) at 10:00 - 17:00, 2019

Speakers: Takuya Ueda (Tohoku Univ. Hospital) Noriaki Ogawa (RIKEN iTHEMS) Takayuki Sakajo (Math. Dep., Kyoto Univ.) Yoshiki Sugitani (AIMR, Tohoku Univ.) Jun Seita (RIKEN MIH) Tetsuro Sekine (Nippon Medical School Hospital) Masato Taki (RIKEN iTHEMS) Kenji Takizawa (Faculty of Sci. and Eng., Waseda U.) Hosted by SUURI-COOL Sendai（iTHEMS-AIMR Mathematical Science Cooperative Lab.） Co-hosted by iTHEMS, AIMR Sponsored by CREST "New Challenges for Mathematical Modeling in Clinical Medicine" Organizers: Hiroshi Suito (AIMR), Tetsuo Hatsuda (iTHEMS)

Venue: 3rd floor Lecture Theater, Katahira Campus, Tohoku University

Event Official Language: Japanese

AI Smart Robot Network

March 22 (Fri) at 15:00 - 17:00, 2019

Yoshihiro Ohta (The University of Tokyo / Arithmer Inc.)

Arithmer Inc. is a startup company providing with business solutions in the field of AI / machine learning / robotics, which emerged from Mathematical Science Dep., Univ. of Tokyo. I will present our recent success stories and ambitious attempts in which applied mathematics is fully utilized, such as optical character recognition, automatic artificial tooth design, scoring driver's skill from movie, and image measurement of human body.

Venue: Large Meeting Room, 2F Welfare and Conference Building (Cafeteria)

Broadcast:R311, Computational Science Research Building

Event Official Language: Japanese

Value distribution of zeta and L-functions and related topics

March 22 (Fri) - 27 (Wed), 2019

March 22–26, 2019 Main Conference (invited talks, posters and a limited number of short contributed talks) Welcome Reception: March 22, 2019 (18:00~20:00) Conference Dinner: March 25, 2019 (18:30~21:00) March 27, 2019 (9:30~17:00) One-day Workshop (a series of short contributed talks by young researchers to facilitate active discussions) ORGANIZING COMMITTEE Ade Irma Suriajaya (RIKEN) Yoshinosuke Hirakawa (Keio University) Masataka Ono (Kyushu University) Shin-ichiro Seki (Tohoku University) Keiju Sono (Ehime University) Shingo Sugiyama (Nihon University) Yuta Suzuki (Nagoya University) ADVISORY COMMITTEE Tetsuo Hatsuda (RIKEN iTHEMS) Kenichi Bannai (Keio University, RIKEN AIP Center)

Venue: Okochi Hall / Large Meeting Room, 2F Welfare and Conference Building (Cafeteria)

Event Official Language: English

ZetaValue2019-iTHEMS Special Mathematics Colloquium

March 21 (Thu) at 14:00 - 17:30, 2019

Kohji Matsumoto (Professor, Nagoya University)
Jörn Steuding (University of Würzburg, Germany)

Prof. Kohji Matsumoto (Nagoya University) "An overview of the theory of multiple zeta-functions" Multiple zeta-functions are generalizations of the Riemann zeta-function, and its theory has been rapidly developed in these decades. It is connected with various fields of mathematics and mathematical physics. In this talk I will give an overview of some part of recent developments, mainly from the analytic viewpoint. Prof. Jörn Steuding (University of Würzburg, Germany) "On the Infinite in Number Theory" Beginning with two simple examples from elementary number theory (one of diophantine origin and one of arithmetical nature), we discuss the role of “infinity” in number theory. We touch upon topics like how to find good rational approximations to irrational quantities and the distribution of prime numbers. We conclude with a motivation of the big open question in this field, namely, the Riemann hypothesis (one of the six unsolved millennium problems) and the Langlands program.

Venue: Okochi Hall

Event Official Language: English

Machine Learning for Intelligent Multiscale Modeling of Platelet Dynamics

March 19 (Tue) at 15:00 - 17:00, 2019

Yuefan Deng (Professor, Applied Mathematics Department, Stony Brook University, USA)

Multiscale modeling in biomedical engineering is gaining momentum because of progress in supercomputing, applied mathematics, and quantitative biomedical engineering. For example, scientists in various disciplines have been advancing, slowly but steadily, the simulation of blood including its Olowing and the physiological properties of such components as red blood cells, white blood cells, and platelets. Platelet activation and aggregation stimulate blood clotting that results in heart attacks and strokes causing nearly 20 million deaths each year. To reduce such deaths, we must discover new drugs. To discover new drugs, we must understand the mechanism of platelet activation and aggregation. To model platelets’ dynamics involves setting the basic space and time discretization in huge ranges of 5-6 orders of magnitudes, resulting from the relevant fundamental interactions at atomic, to molecular, to cell, to Oluid scales. To achieve the desired accuracy at the minimal computational costs, we must select the correct physiological parameters in the force Oields such as the Morse potential and Hooke’s law as well as the spatial and temporal discretization, by machine learning. We demonstrate our preliminary results of speeding up a multiscale two-platelet aggregation simulation, while maintaining sufOicient accuracy, by nearly one order of magnitude, compared with traditional algorithm that uses the smallest of all temporal and spatial scales in order to capture the Oinest details of the dynamics. We present our analyses of the accuracies and efOiciencies of the representative modeling. We will also outline the general methodologies of multiscale modeling of cells at atomic resolutions.

Venue: 224-226, Main Research Building

Event Official Language: English