Past Events
2021
RIMS x OIST Jointlyfunded Workshop:
"Interactions of New Trends in Algebraic Geometry and Singularities"
 Date: October 11 15, 2021
 Remote: Zoom
 Organizers:
 Shihoko Ishii (Univ. of Tokyo)
 Hiraku Kawanoue (Chubu Univ.)
 Tohru Ohmoto (Hokkaido Univ.)
 Shinobu Hikami (OIST)
 Description :
Algebraic Geometry has 400 years history after René Descartes introduced coordinates to geometry. Recently this area is remarkably developing under cooperation with Number Theory, Commutative Algebra, Combinatorics, Representation Theory and so on.
In Algebraic Geometry, Japan is in one of the central position. Three Fields Medalists from Japan; Kunihiko Kodaira, Heisuke Hironaka and Shigefumi Mori contributed the big development of Algebraic Geometry. Nowadays a new generation; like Takehiko Yasuda, Yoshinori Gongyo and Masahiko Yoshinaga made remarkable progress in Algebraic Geometry. Because of this broad and quick progress, it became difficult for an algebraic geometer to cover all ideas. On the other hand, it is very important and useful for an algebraic geometer to know many ideas in topics different from ones own.
The aim of the workshop is to bring together experts of various fields of algebraic geometry who would like to learn different fields from their own and let them have a chance to learn other fields. We try to make the atmosphere very friendly and easy to ask any questions. To this end, it is very nice for all participants stay in a one accommodation and spend time together whole a week.
The topics we take in the workshop are (1) Minimal Model Problem, (2) Hyperplane arrangement and (3) Stacks.
Three main speakers  Yoshinori Gongyo (University of Tokyo), Masahiko Yoshinaga (Hokkaido University) and Takehiko Yasuda (Tohoku University)  will give five courses each. These are all quite new fields and developed very quickly. In the workshop the participants will learn these topics and try to find ways to make use of them for their own researches.
 Titles & Abstracts
 Schedule (each lecture50 min. discussion 5 min.)
 Lecturers:
MMP
 Yoshinori Gongyo (Expository, Univ. Tokyo)
 AnneSophie Kaloghiros (Brunel Univ.)
 Chen Jiang (Fudan Univ.)
Stack
 Takehiko Yasuda (Expository, Osaka Univ.)
 Yusuke Nakamura (Univ. of. Tokyo)
 Victoria Hoskins (Freie Univ. Berlin)
Arrangement
 Masahiko Yoshinaga (Expository, Hokkaido Univ.))
 Takuro Abe (Kyushu Univ.)
 Elisa Palezzato (Hokkaido Univ.)
 List of participants
 Kohsuke Shibata (Nihon Univ.)
 Shoji Yokura (Kagoshima Univ.)
 Keiichi Watanabe (Nihon Univ.)
 Takahiro Yamamoto (Tokyo Gakugei Univ.)
 Mahito Tanno (Osaka Univ.)
 Herwig Hauser (Univ. Wien)
 Video

This workshop will be held on zoom. Registration for the general public is also accepted. Please register using this webform. Registration will be completed after approval by the organizers.
(Application closed. Oct 4, 2021)
 Contact: miwako.tokuda@oist.jp, workshop@oist.jp
*This workshop is supported by RIMS, OIST, and JSPS KAKENHI
● Code of Conduct for OIST Workshops and Minisymposia
https://groups.oist.jp/cws/codeconduct
2020 OIST Workshop “Quantum Math, Singularities and Applications”
 Dates: 2/82/12, 2021
 Remote: Zoom
 Application was closed
 Organizers:
 Shihoko Ishii (Tsinghua University/Univ. Tokyo)
 Yasuyuki Kawahigashi (The University of Tokyo)
 Shinobu Hikami ( OIST)
 Contact: workshop@oist.jp
 Tentative list of invited talkers
 Shihoko Ishii (Tsinghua Univ. /Univ. Tokyo, Organizer)
 Lawrence Ein (University of Illinois at Chicago)
 Keiichi Watanabe (Nihon University)
 Yasuyuki Kawahigashi (The University of Tokyo, Organizer)
 Vladimir Dotsenko (Univ. Strasbourg)
 Benoit Collins (Kyoto University)
 Shunsuke Takagi (The University of Tokyo)
 Kohsuke Shibata (Nihon University)
 Takehiko Yasuda (Osaka University)
 Zhenghan Wang (Microsoft Station Q)
 Kyoji Saito (Kyoto Univ. RIMS)
 Shinobu Hikami (OIST, Organizer)
 Masahiko Yoshinaga (Hokkaido University)
 Terry Gannon(University of Alberta)
 Motoko Kato (Ehime University)
 Makiko Mase (Mannheim University)
 Mayuko Yamashita (Kyoto Univ. RIMS)
 Conference description:
This conference of quantum mathematics and singularity includes subjects in new developments of the singularity theories and the conformal field theory. The followings are key words: two and three dimensional normal singularities, arc space and jet scheme, moduli space and operad, noncommutative geometry, conformal bootstrap and super conformal field theory. The topological materials of condensed matter physics need rigorous mathematical classifications, which will be one of applications.
 Program: PDF
 Titles and Abstracts: PDF
 Zoom recording FILE
 20210208 10:0012:00 (JST) Prof. S. Ishii, Prof. S. Takagi
 20210208 18:0020:00 (JST) Dr. K. Shibata, Prof. M. Kato
 20210209 10:0012:00 (JST) Prof. L. Ein, Prof. K. Watanabe
 20210209 18:0020:00 (JST) Prof. M. Mase, Prof. V. Dotsenko
 20210210 10:0012:00 (JST) Prof. T. Gannon, Prof. Y. Kawahigashi
 20210210 18:0020:00 (JST) Prof. M. Yamashita, Prof. B. Collins
 20210211 10:0012:00 (JST) Prof. Z. Wang, Prof. M. Yoshinaga
 20210211 18:0019:00 (JST) Prof. K. Saito
 20210212 10:0012:00 (JST) Prof. T. Yasuda, Prof. S. Hiakmi
2020
Silver workshop 2020 : Flat Structure and Singularities
 Date：6^{th} March 2020
 Venue： OIST Lab3B700 and B711
 Invited speakers：
 Kyoji Saito（IPMU）
 Kostantin Aleshkin (Columbia Univ.)
 Mitsuo Kato (Ryukyu Univ.)
 Yoshihisa Saito (Rikkyo Univ.)
 Shinichi Tajima （Niigata Univ.）
 Motoko Kato (Ehime Univ.)
 Shinobu Hikami (OIST)
Seminar:
 Date: Thursday, February 6th
 Time: 14:0015:00
 Venue: C016Lab1, OIST campus
 Speaker: Fujihiko Sugino, Institute for Basic Science, South Korea
Title: Study of highly entangled quantum spin chains
Abstract:
Quantum entanglement is one of the most surprising features of quantum mechanics.
Ground states of quantum manybody systems with local interactions typically obey
an ``area law'' meaning the entanglement entropy proportional to the boundary length.
It is exceptional when the system is gapless, and the area law had been believed
to be violated by at most a logarithm for over two decades.
Recent discovery of Motzkin and Fredkin spin chain models is striking, since these
models provide significant violation of the entanglement beyond the belief,
growing as a square root of the volume in spite of local interactions.
Although importance of intensive study of the models is undoubted to reveal novel
features of quantum entanglement, it is still far from their complete understanding.
In this talk, I will explain how such violation of the area law arises mainly in the Motzkin model.
In computation of the Renyi entropy, we observe a novel phase transition never seen in any other
spin chain model studied so far.
2019
Workshop “SuperRiemann surfaces and related topics”
 This is a joint project between OIST and University of Tokyo.
 Date: 2019.12.24
 Venue: University of Tokyo,Graduate school of mathematical sciences
(December 2,3: Room 123, December 4: Room 128).  Organizers: Nariya Kawazumi (Univ. of Tokyo), Takuya Sakasai(University of Tokyo),
Shinobu Hikami(OIST)  Schedule
December 2 (Mon)
10:30  11:30 Yusuke Kuno (Tsuda University)
On spin structures associated with a trivalent fatgraph spine
13:00  15:00 Anton Zeitlin (Louisiana State University)
Introduction to the theory of super Riemann surfaces.
December 3 (Tue)
10:30  11:30 Casey Blacker (East China Normal University)
Polysymplectic Reduction and the Moduli Space of Flat Connections
13:00  15:00 Anton Zeitlin (Louisiana State University)
N = 1 and N = 2 superTeichmueller theory
15:30  16:30 Shinobu Hikami(OIST)
Ramond punctures and pspin curves in a random matrix theory
17:00  18:30 Tuesday Seminar on Topology
Anton Zeitlin (Louisiana State University)
Homotopy Gerstenhaber algebras, Courant algebroids, and Field Equa tions
December 4 (Wed)
10:30  11:30 Motoko Kato (EhimeUniversity)
Thompson’s groups and their actions on nonpositively curved spaces
13:00  15:00 Anton Zeitlin (Louisiana State University)
SuperTeichmueller theory: some recent results
Workshop: Singularities and related topics
 Date: July 30August 2, 2019
 Venue: The University of Tokyo (Komaba),Room 002.
 Organizers:
 Shihoko Ishii (The university of Tokyo/Tsinghua University)
 Keiichi Watanabe (Nihon University)
 Masataka Tomari (Nihon University)
 Shinobu Hikami (OIST)
 Invited Speakers:
 Anne Moreau(Lille)
 Claus Hertling(Mannheim)
 Shihoko Ishii(The University of Tokyo/Tsinghua University)
 Masataka Tomari(Nihon University)
 Keiichi Watanabe(Nihon University)
 Makiko Mase (Mannheim)
 Kazuhiko Kurano (Meiji University)
(others)
 Description; Brieskorn type quasi homogeneous singularities are related to the theory of the moduli space of spin curves, as discussed by Natanzon and Pratoussevitch. In this workshop, we discuss related topics of the singularities, jet schemes and arc spaces, mirror symmetry and conformal field theory.
 Program
 Slides
 Correspondence: shiho.saito@oist.jp
OIST Symposium: Quantum and Gravity
 Date: July 2327, 2019
 Venue: OIST, Seaside house
 Organizers:
 Reiko Toriumi(OIST) and Shinobu Hikami(OIST)
 Description:
Quantizing gravity has been one of the most difficult problems in physics. There have been many approaches to quantizing gravity, which have given us mathematically and physically interesting ideas, such as the unification of forces, the emergence of spacetime, the problem of time, information paradox, spacetime foam, noncommutativity of spacetime, extra dimensions like CalabiYau manifold, duality, holography, etc. Geometry, which initially found a link to gravity by Einstein has been playing a major role in the studies of quantum gravity such as matrix models, tensor models, lattice methods like causal dynamical triangulations and Regge calculus, etc. Quantum field theory (QFT), which gave us a tremendous success in describing the Standard Model including the weak, the strong and the electromagnetic forces, is also a central solid modern tool in describing physical systems with many degrees of freedom. QFT lets us explore critical phenomena and the scale dependence of the physics through the renormalization group. In this symposium, we focus on such pillars of modern physics which are tied together in the research of quantum gravity. We aim at creating an open versatile atmosphere in order to advance further in the better understanding of each approaches in order to understand the grand problems of quantum description of gravitation.  Website
 Correspondence: quantumandgravity@oist.jp, workshop@oist.jp
RIKENOIST mini Workshop 2019: Mathematical Condensed Matter Physics
 Date: July 56, 2019
 Venue: B250, Center Building, OIST
 Organizers:
 Masahiro Nozaki (RIKEN) Chair person
 Masaru Hongo (Keio Univ./RIKEN)
 Kanato Goto (RIKEN)
 Hidehiko Shimada (OIST)
 Lecturers
 Takuya Furusawa (TIT/RIKEN)
 Yuta Sekino (RIKEN)
 Shinobu Hikami (OIST)
 Participants:
 Keisuke Fujii (TIT)
 Kanato Goto (RIKEN)
 Masaru Hongo (Keio Univ./RIKEN)
 Arkaprava Mukherjee (OIST)
 Masahiro Nozaki (RIKEN)
 Hidehiko Shimada (OIST)
 Ken Shiozaki (RIKEN)
 Masato Taki (RIKEN/Rikkyo Univ.)
 Shoichiro Tsutsui (RIKEN)
 Wenliang Li (OIST)
 Program
 Workshop Website
RIMS x OIST Workshop: “On the problem of resolution of singularities and its vicinity”
 Date: June 10  June 14, 2019
 Venue: Seaside house (OIST)
 Organizers:
 K. Matsuki (Purdue Univ.)
 H.Kawanoue (Chubu Univ.)
 S. Ishii (Univ. of Tokyo/Tsinghua Univ.)
 T.Yasuda (Tohoku Univ.)
 S.Hikami (OIST)
 Description:
The goal of this workshop is to study the recent developments on one of the most longstanding and fundamental problems in Algebraic Geometry, the problem of resolution of singularities in positive characteristic, and communicate the results in its surrounding areas, with a view toward its ultimate solution. The workshop will give us a unique opportunity for the world leaders on the problem and the active experts on the subject to gather at one place and carry out intensive discussions in a seminarstyle environment. We also aim at disseminating the basic techniques and methods among the younger researchers and students through the lectures given in the morning.  Participants list:PDF file
 Program
 Group Photo
 Correspondence: shiho.saito@oist.jp
*This workshop is supported by RIMS, OIST, and JSPS KAKENHI (Grant Number18K18710)
Workshop: Johnson homomorphisms and related topics 2019
 Date: May 13 – 17, 2019
 Venue: The University of Tokyo, Lecture Hall of the Mathematical Science Building
 Organizers:
 Shinobu Hikami
 Nariya Kawazumi
 Gwenael Massuyeau
 Hiroaki Nakamura
 Takuya Sakasai
 Christine Vespa
 Correspondence: Takuya Sakasai, sakasai (at) ms.utokyo.ac.jp
 Description: Website
Seminar:
 Date: Tue, Mar 5 2019
 Time: 10:3011:30
 Venue: C016, Lab1
 Speaker: Prof. Chushun Tian (Institute of Theoretical Physics, Chinese Academy of Sciences)
Title: "Topology from chaos: quantum Hall physics, Haldane conjecture and beyond"
Abstract: Chaotic and topological phenomena have totally opposite characteristics: the former/latter are extremely sensitive to/robust against the change in system's details (e.g., the parameters of the Hamiltonian, the initial conditions, etc.). Thus they are commonly considered not to be compatible. In this talk, I will show how, by introducing a spin degree of freedom to the canonical model of chaotic dynamics, the socalled quantum kicked rotor (QKR), which is simply a particle moving on a ring and subjected to pulsed external force, rich dynamical behaviors of topological origin arise. These include, notably, the realization of quantum Hall physics and Haldane conjecture, which occur originally to totally different systems, namely, manyelectron systems and quantum antiferromagnetic chains, respectively. I will show how a supersymmetry structure arises from the timedriving nature of QKR, and serves as a seed for a wealth of topological phenomena in this chaotic system as simple as being singleparticle.
Workshop “Quantum Math”
 Organizers: Y. Kawahigashi (Univ. Tokyo) and S. Hikami (OIST)
 Description:
Collaboration between mathematics and physics becomes more important and essential for recent development in quantum mathematical physics. We discuss new issues such as entropy of black hole, integrable system, conformal field theory and bootstrap in higher dimensions, algorithm in resolution of singularities, super moduli space, noncommutative geometry and operator algebra, and their application to quantum information and quantum computation.  Date: Mar 23, 2019
 Time: 13:0018:00 (Mar 2), 9:3013:00 (Mar3)
 Venue: B700, Lab3, OIST Campus
 Confirmed Speakers:
 S. Hikami (OIST) Abstract
 Y. Kawahigashi (Univ. Tokyo) Abstract
 K. Nabeshima (Tokushima Univ.) Abstract
 Y. Nakayama (Rikkyo Univ.) Abstract
 T. Sakasai (Univ. Tokyo) Abstract
 T. Shibuta (Kyushu Sangyo Univ.) Abstract
 H. Shimada (OIST) Abstract
 S. Yamaguchi (Osaka Univ.) Abstract
 M.Yamazaki (Univ.Tokyo, KavliIPMU) Abstract
 Program
 Photo
 Accommodation: Hotel Moon Beach
 Transportation
 Correspondence: shiho.saito@oist.jp
*This workshop is supported by KAKENHI KIBAN(C)16K05491
Silver Workshop: Complex Geometry and NonCoummutative Geometry
 Organizers: Noriko Yui (Queen's University), Kyoji Saito (IPMU) and Shinobu Hikami (OIST)
 Date: Feb 28Mar1, 2019
 Time: Feb 28 10:30 am  6:00 pm, Mar 1 10:30 am  4:50 pm
 Venue: C210, Center Building, OIST Campus
 Talkers:
 George Elliott (Toronto Univ) Abstract
 Shinobu Hikami (OIST) Abstract
 Toshiyuki Mano (Ryukyu Univ.) Abstract
 Yasuyuki Kawahigashi (Univ. Tokyo) Abstract
 Kyoji Saito (IPMU) Abstract
 Noriko Yui (Queen's Univ.) Abstract
 Konstantin Aleshkin (Landau Institute) Abstract
 Motoko Kato (Univ. Tokyo) Abstract
 Shigeru Iitaka (Gakushuin University) Abstract
 Mutsuo Oka (Tokyo Univ. of Science) Abstract
 Program
 Accommodation: Hotel Moon Beach
 Transportation
 Contact: shiho.saito@oist.jp
Seminar: Towards a theory of classification: general setting
 Speaker: George Elliott (University of Toronto)
 Date: Feb.27, 2019, 14:0016:00
 Venue: C210, OIST Center building
An abstract classifying invariant—a functor!—for a certain kind of given category is constructed by passing to equivalence classes of morphisms, which themselves form a category. Thus, the objects are the same, but the classifying category—so named because isomorphism of objects downstairs implies isomorphism upstairs—is typically much simpler than the given one, as many morphisms are identified by the classification functor, and many automorphisms killed. (Note that one cannot just replace objects by isomorphism classes, as one doesn’t get a category this way.) The classifying category is a priori an abstract one, but, perhaps surprisingly, in interesting cases, its Yoneda concretization becomes spectacularly simple.
Workshop on "Hyperbolic Geomerty of the Moduli Space and Related Topics."
 Dates: January 2426, 2019
 Venue : Jan 2425:Room #123, Jan 26: Room #056
Graduate School of Mathematical Sciences, The Univ. of Tokyo
(Komaba Campus)  Description:
The moduli space of compact Riemann surfaces, the space of all biholomorphism classes of compact Riemann surfaces, is one of the most attractive subjects in mathematics. Nowadays it firmly combines
mathematical physics and integrable systems with lowdimensional topology including hyperbolic geometry of surfaces, which induces the WeilPetersson symplectic structure on the space. In particular, the topological recursion by Eynard and Orantin generalizing Mirzakhani's recursive formula for the WeilPetersson volume has some strong influence in various research areas.
In this workshop, we will intensively discuss some specific topics on the hyperbolic structure of the moduli space, and will have some talks on original researches.  Program
Special Lecture: Modularity of CalabiYau Manifolds
 Date: Friday, February 22, 2019
 Time: 10:00 am  4:00 pm
 Venue: Lecture room B715 (Lab3) , OIST.
 Speaker: Noriko Yui (Queen’s University)
 Abstract :
Let X be a CalabiYaumanifold of dimension d. In this talk, I would like to address the modularity questions around CalabiYau manifolds. We will confine ourselves to CalabiYau manifolds of small dimensions, e.g., d ≤ 3. There are two types of modularity:
(A) Arithmetic modularity/automorphy. This is concerned with CalabiYau varieties defined over Q (ornumberfields). The main questions are the modularity/automorphy of the cohomological Lseriesoftheladic Galois representations associated to these varieties in the framework of Langlands Philosophy.
(G) Geometric modularity. This is concerned with families of CalabiYau manifolds. The main questions are the modular/automorphic properties of various invariants associated to these varieties, e.g., mirror maps, GromovWitten invariants, DonaldsonThomas invariants, holomorphic anomaly equations, etc. arising in string theory. Quasimodular forms, Jacobi forms, Siegel modular forms, and more general modularlike forms show their appearances in this land scpae.
Seminar:
 Date: Wednesday, January 30, 2019
 Time: 11:00  12:00
 Venue: C016, Lab1
 Speaker: Prof. Anton Zabrodin (National Research University Higher School of Economics, Moscow)
Title: "Elliptic solutions to BKP equation and manybody systems"
Abstract: We derive equations of motion for poles of doubleperiodic (elliptic) solutions to the Bversion of the KP equation. The motivation is the wellknown story about elliptic solutions of the usual KP equation, where the dynamics of poles is given by the CalogeroMoser manybody system with elliptic potential. The basic tool is the auxiliary linear problem for the wave function.The result is a new manybody dynamical system with threebody interaction expressed through the Weierstrass elliptic function. This system does not admit Lax representation but, instead, it is equivalent to a sort of Manakov's triple equation with a spectral parameter. We also discuss integrals of motion which follow from the equation of the spectral curve and analyze analytic properties of the wave function on the spectral curve.
2018
OIST Mini Symposium "Holographic Tensors"
 Organizers: Reiko Toriumi (OIST) , Vincent Rivasseau (Univ. Paris Sud) and Shinobu Hikami (OIST)
 Date: Oct 31Nov 2, 2018
 Venue: OIST Conference Center & Seaside House
 URL: https://groups.oist.jp/cws/event/oistminisymposiumholographictensors
Silver Workshop : Complex geometry and related topics
 Organizers: Noriko Yui (Queen’s Univ.), Kyoji Saito (IPMU) and Shinobu Hikami(OIST)
 Date: July 27th (Friday), 2018
 Time: 10:30 am – 6:00 p.m. (6:00p.m. – 8:00pm, dinner for Prof. Sasakura)
 Venue: University of Tokyo, Math. Department, Room 123
 Tentative Program:
 10:3010:40 Opening Kyoji Saito (IPMU)
 10:4011:10 Shinobu Hikami (OIST), Brieskorn singularity and intersection theory (Abstract)
 11:1011:30 Coffee break
 11:3012:30 Keiichi Watanabe (Nihon Univ.), Homogeneous prime elements of 2 dimensional normal graded rings (Abstract)
 12:3013:40 Lunch
 13:4014:10 Shigeru Iitaka (Gakushuin), Super perfect numbers and super twin primes
 14:1014:15 Break
 14:1515:15 Shihoko Ishii (Tokyo Woman’s Christian Univ.) Singularities in positive characteristic (Abstract)
 15:1515:35 Coffee break
 15:3516:35 Noriko Yui (Queen’s Univ.), Supercongruences for rigid hypergeometric Calabi–Yau threefolds (Abstratct)
 16:3516:45 Break
 16:4517:15 Kyoji Saito (IPMU), Elliptic Artin group (Abstract)
 17:1517:25 Break
 17:2517:55 Mutsuo Oka (Tokyo University of Science), Remarks on the roots of generalized Lens equation
 18:0020:00 Dinner at Lever son Verre (inside Campus)
Symposium: Bootstrap Approach to Conformal Field Theories and Applications
Scale invariant theories, i.e. theories which look the same at all distance and energy scales, play an important role in physics. Through Wilson’s renormalization group, scale invariant theories arise naturally in phase transitions. They are also the bread and butter of current thinking about particle physics beyond the Standard Model. These theories usually possess an emergent symmetry, conformal invariance, and are hence referred to as `Conformal Field Theories’ (CFTs). The quest to classify and solve CFTs is a major goal of theoretical physics. Recently, this quest has received a strong boost with the development of the ‘conformal bootstrap’ technique. This workshop will bring together two groups of researchers: theorists working on the conformal bootstrap and on formal aspects of CFTs, and condensedmatter and statistical theoretical physicists working on the concrete examples of systems exhibiting phase transitions described by CFTs. The goal will be to inform about the most important theoretical and practical developments in the conformal bootstrap, and about the most urgent questions relevant for condensed matter and statistical physics which can be addressed using conformal bootstrap.
 Organizers: Slava Rychkov and Shinobu Hikami
 Date: March 1923, 2018
 Venue: Conference Center, OIST
 Invited Speakers:
 Luis Fernando Alday (Oxford)
 Nando Gliozzi (Torino)
 Rajesh Gopakumar (ICTSTIFR)
 Sean Hartnoll (Stanford)
 Shinobu Hikami (OIST)(organizer)
 Yu Nakayama (Rikkyo)
 Silviu Pufu (Princeton)
 Leonard Rastelli (SUNY)
 Slava Rychkov (ENS, CERN)(organizer)
 Aninda Sinha (IIS, Bangalore)
 Satoshi Yamaguchi (Osaka)
 Masahito Yamazaki (IPMU,Tokyo)
RIKENOsakaOIST Joint Workshop 2018
 Organizers: :Koji Hashimoto (Osaka), Yoshimasa Hidaka (RIKEN), Hirohiko Shimada (OIST), Sotaro Sugishita (Main) (Osaka)
 Date: March 1214, 2018
 Venue: B250 (Mar 12 & 13), C209 (Mar 14), OIST
Symposium:
The moduli space of compact Riemann surfaces, the space of all biholomorphism classes of compact Riemann surfaces, is one of the most attractive subjects in mathematics. Nowadays it firmly combines mathematical physics and integrable systems with lowdimensional topology including hyperbolic geometry of surfaces, which induces the WeilPetersson symplectic structure on the space. In particular, the topological recursion by Eynard and Orantin generalizing Mirzakhani's recursive formula for the WeilPetersson volume has some strong influence in various research areas.
In this workshop, we will read intensively some research papers on the symplectic structure of the moduli space and related topics, and will have some talks on original researches. This workshop is supported by a joint project between the OIST and the University of Tokyo.
This workshop is supported by a joint project between the OIST and the University of Tokyo.
 Date: January 26 (Friday)  28 (Sunday), 2018
 Venue: Room 123, Graduate School of Mathematical Sciences Bldg., University of Tokyo (Komaba Campus).
 Organizers: Y. Tadokoro (Kisarazu), T. Sakasai (Univ. Tokyo) and N. Kawazumi (Univ. Tokyo)
2017
MINI SYMPOSIUM: New development in Teichmuller space theory ; MCM2017
Theory of Teichmuller space has a long history for the moduli space of Riemann surface. Recently beyond classical Teichmuller space research, new extended concept and technique are developed and they are important for various areas of mathematical physics. Particularly higher Teichmuller space attracts interest, which concerns SL(n,R) geometry and its boundary. In this mini symposium, we concentrate on the new concept and technique and discuss from wide point of view of topology, physics and integrable systems. For examples, the cluster algebra and open intersection numbers are discussed closely. We intend to develop a theory for new structure of Teichmuller space in a new direction of mathematical physics.
 Date: November 28 – 30, 2017
 Venue: C210, Center Building, OIST
 Organizers: Nariya Kawazumi (Univ. of Tokyo), Takuya Sakasai (Univ. of Tokyo), Shinobu Hikami (OIST)
 Invited talkers:
 A. Alekseev, Geneve Univ.
 R. Inoue, Chiba Univ.
 R. Kashaev, Geneve Univ.
 T. Kitayama, Univ. of Tokyo
 A. Kuniba, Univ. of Tokyo
 A. Tsvietkova, OIST
 Program: PDF
 Photo: JPEG
Seminar:
 Date: Thursday, November 9, 2017
 Time: 13:30  14:30
 Venue: Room 056, Graduate School of Mathematical Sciences Bldg., University of Tokyo (Komaba Campus). Seminar via TV conference system in Room B611 (Lab2) , OIST.
 Speaker: Prof. Edouard Brezin (lpt ens, Paris)
Title: "Various applications of supersymmetry in statistical physics".
Abstract: Supersymmetry is a fundamental concept in particle physics (although it has not been seen experimentally so far). But it is although a powerful tool in a number of problems arising in quantum mechanics and statistical physics. It has been widely used in the theory of disordered systems (Efetov et al.), it led to dimensional reduction for branched polymers (ParisiSourlas), for the susy classical gas (Brydges and Imbrie), for Landau levels with impurities. If has also many powerful applications in the theory of random matrices. I will briefly review some of these topics.
Workshop: MSRI Summer Graduate School – Commutative Algebra and Related Topics
The purpose of the school will be to introduce graduate students to foundational results in commutative algebra, with particular emphasis of the diversity of the related topics with commutative algebra. Some of these topics are developing remarkably in this decade and through learning those subjects the graduate students will be stimulated toward future research. The lecturers will give topics courses and then the graduate students will meet in small groups and challenge problems and have discussion sessions related to each topic.
 Date: May 22—June 2, 2017
 Venue: OIST Seaside House (May 23 at Conference Center, OIST Campus)
 Organizers: Shihoko Ishii (TWCU), Kazuhiko Kurano (Meiji), Kenichi Yoshida (Nihon), Shinobu Hikami (OIST)
 Lecturers:
 David Eisenbud (MSRI / University of California)
 Claudia Polini (University of Notre Dame)
 Claudiu Raicu (University of Notre Dame)
 Shunsuke Takagi (University of Tokyo)
 Ryo Takahashi (Nagoya University)
 Program: PDF
 Photo: jpg
Symposium: Geometry of Quadratic Differentials and Related Topics
Quadratic differentials, meromorphic tensor fields on Riemann surfaces of some special type, have been studied classically in hyperbolic geometry and complex analysis. Recently it has been clarified that lowdimensional topology including hyperbolic geometry of surfaces is closely related to mathematical physics and integrable systems. This can be illustrated by the topological recursion by Eynard and Orantin generalizing computation of the WeilPetersson volume of the moduli space of Riemann surfaces, whose influence one can find in various research areas. Accordingly quadratic differentials are playing some important roles also in mathematical physics and integrable systems. In this workshop, we will read intensively some research papers on the geometry of quadratic differentials and related topics, and will have some talks on original researches. This workshop is supported by a joint project between the OIST and the University of Tokyo.
 Organizers: Y. Tadokoro (Kisarazu), T. Sakasai (Univ. Tokyo) and N. Kawasumi (Univ. Tokyo)
 Date: January 1113, 2017
 Venue: University of Tokyo, Komaba, Mathematical Science Building #002 Info (in Japanese)
2016
PreConference MCM2016 at Tokyo
 Date: October 2022, 2016
 Venue: University of Tokyo, Komaba, Mathematical Science Building
 Organizers: Nariya Kawazumi(Univ. Tokyo), Shinobu Hikami(OIST)
 Program & Abstracts
Workshop: Moduli space, conformal field theory and matrix models; MCM2016
 Date: October 2427, 2016
 Venue: C209, OIST
 Organizers: Nariya Kawazumi(Univ. Tokyo), Shinobu Hikami(OIST)
 Program & Abstracts
 Group Photo
TSUDA COLLEGE AND OIST JOINT WORKSHOP ONCALABI–YAU VARIETIES:ARITHMETIC, GEOMETRY AND PHYSICS
 Date: August 1–3, 2016
 Venue: August 1–2 at Tsuda College Room 7309, August 3 at Tokyo University Komaba Campus Room 117
 Organizers: Noriko Yui (Queen’s University) and Takayuki Oda (OIST)
 Program (PDF) & Abstracts (PDF)
"OISTiTHESCTSR 2016" International Workshop
 Date: Friday 8  Monday 11 July, 2016
 Venue: Fri 8th (B250), Sat 9th (C209), Mon 11th (B250)
 Organizers: RIKEN iTHES, OSAKA CTSR, and OIST (Theoretical Units)
Seminar:
 Date: Thursday, July 7, 2016
 Time: 15:00  16:00
 Venue: C209, Center Building, OIST
 Speaker: Prof. Jean ZinnJustin (CEA Saclay)
Title: 3D field theories with ChernSimons term for large N in the Weyl gauge
Abstract: ADS/CFT correspondance has led to a number of conjectures concerning, conformal invariant, U(N) symmetric 3D field theories with ChernSimons term for N large. An example is bosonfermion duality. This has prompted a number of calculations to shed extra light on the ADS/CFT correspondance.
We study here the example of gauge invariant fermion matter coupled to a ChernSimons term. In contrast with previous calculations, which employ the lightcone gauge, we use the more conventional temporal gauge. We calculate several gauge invariant correlation functions. We consider general massive matter and determine the conditions for conformal invariance. We compare massless results with previous calculations, providing a check of gauge independence.
We examine also the possibility of spontaneous breaking of scale invariance and show that this requires the addition of an auxiliary scalar field.
Our method is based on field integral and steepest descent. The saddle point equations involve nonlocal fields and take the form of a set of integral equations that we solve exactly.
Seminar:
 Date: Wednesday, March 30, 2016
 Time: 11:00  12:00
 Venue: C209, OIST
 Speaker: Prof. Katsuya Shimizu（Osaka University）
Title: 200K superconductivity in compressed hydrogen sulfide systems
Abstract: After finding superconductivity in 100 years ago, "roomtemperature"superconductor has been longfascinated target for physicists. Superconductivity above 200K was recently reported in the highly compressed hydrogen sulfide (H2S) by Drozdov et al1. The crystal structure of the superconducting sulfur hydride systems was studied by using the synchrotron xray diffraction at room temperature and the superconducting temperature. H2S and D2S were compressed to 150 GPa in DAC with same process with Drozdov et al1, and cooled down to 10 K in the cryostat in the xray diffractometer in SPring8. The resistivity was onitored at all cooling process. The critical temperature and zero resistivity were observed around 180 K, and the collected xray diffraction data showed good agreement with the theoretically predicted structures of R3m and Im3m2. No structural difference was observed between at 10 K and room temperature. The creation of the hightemperature superconductor was experimentally also confirmed by our Osaka group. H2S gas was cooled down to around 200 K and liquefied then compressed up to 150 GPa in a diamondanvil cell (DAC). The resistance decreased with increasing pressure and showed metallic behavior in cooling process. The superconducting transition was observed at 6070 K with zero resistance. At the second cooling after warmed up to room temperature, the resistance dropped to zero from 180 K.
This work was supported by JSPS KAKENHI Grant Number 26000006 and the European Research Council 2010Advanced Grant 267777.
References:
[1] A. Drozdov et al., Nature 525 73 (2015).
[2] D. Duan et al., Scientific Reports 4, 6968 (2014).
2015
Seminar:
 Date: Friday, December 25, 2015
 Time: 11:00  12:00
 Venue: C015, Lab1, OIST
 Speaker: Prof. Yasutomo J. Uemura （Columbia University）
Title: BEC to BCS crossover picture for highTc cuprate and unconventional superconductors, and pairing due to comparable spincharge energy scales: message from muons and neutrons
Abstract: Soon after the discovery of highTc superconductors in 1986, we started muon spin relaxation (MuSR) measurements of the magnetic field penetration depth, and demonstrated nearly linear correlations between Tc and the superfluid density n_{s}/m^{*}, which are manifest not only in cuprates but also in many other unconventional superconductors including Alkali doped C60, FeAs and some of the heavyfermion systems . The strong dependence of Tc on carrier density is not expected in the BCS condensation, but is a main characteristic of Bose Einstein Condensation. Another important scaling of Tc is seen with the energy of the magnetic resonance mode measured by neutron scattering, which can be viewed as a spin–charge soft mode related to competing antiferromagnetic state, analogous to rotons in superfluid He related to competing solid HCP phase. This rotonlike scaling is expected when condensed bosons are excited with phase fluctuations to another bosonic state, without pair breaking. This again is different from pairbreaking excitations across the energy gap in BCS condensation. We discuss these features and adopting BECBCS crossover picture for the cuprates, which I proposed in 1994 . Further analyses of the Tcsuperfluid density (charge energy) scaling and Tcspin wave energy (mediating boson energy) correlations lead to a possible pairing mechanism based on comparable spin and charge energy scales and dynamic synchronized charge motion in “trafficlight resonance”
References:
[1] Y.J. Uemura et al., Universal Correlations between Tc and ns/m∗ (Carrier Density over Effective Mass) in HighTc Cuprate Superconductors, Phys. Rev. Lett. 62 (1989) 23172320.
[2] Y.J. Uemura et al., Basic Similarities among Cuprate, Bismuthate, Organic, Chevrel Phase, and HeavyFermion Superconductors Shown by Penetration Depth Measurements, Phys. Rev. Lett. 66 (1991) 26652668.
[3] Y.J. Uemura, Superconductivity: Exotic Commonalities in Phase and Mode, Nature Materials 8 (2009) 253255.
[4] Y.J. Uemura, Energy Scales of Exotic Superconductors, an invited talk presented at the International Workshop on Polarons and Bipolarons in HighTc Superconductors and Related Materials,Cambridge, UK, April, 1994, in Polarons and Bipolarons in HighTc Superconductors and Related Materials, ed. by E. Salje, A.S. Alexandrov and Y. Liang, Cambridge University Press (1995), p.p.453460.
[5] Y.J. Uemura, Energyscale phenomenology and pairing via resonant spincharge motion in FeAs, CuO, heavyfermion and other exotic superconductors (Plenary Talk at SCES2008, Buzios, Brazil, Aug., 2008), Physica B404 (2009) 31953201.
Workshop on "Moduli spaces of abelian varieties and curves, and related analysis"
 Dates: December 1518, 2015
 Venue : Graduate School of Mathematical Sciences, The Univ. of Tokyo (@Komaba Campus)
 Program: PDF
RMT2015: Random matrix theory from fundamental mathematics to biological applications
 Date: Monday, November 2 Friday, November 6, 2015
 Venue: C209, OIST
 Schedule, Title and Abstract: PDF
 Slides
Seminar:
 Date: Friday, November 20, 2015
 Time: 11:0012:00
 Venue: C016, Lab1, OIST
 Speaker: Tsunehide Kuroki (Kagawa Kosen)
Title: Spontaneous supersymmetry breaking in matrix model and superstring theory
Abstract: We show that a supersymmetric matrix model is a promising candidate for the first example of nonperturbative definition of superstring theory. We prove that in this model, the supersymmetry is preserved in all orders in perturbation theory in the 1/N expansion, but that it gets broken nonperturbatively and spontaneously. We observe that this breaking is triggered by an instanton in the matrix model. We also present quite recent results of correlation functions in the matrix model in all orders of the 1/N expansion by using the random matrix theory. These results convince us that the matrix model is a string theory.
MCM2015 Autumn:
 Date: Thursday, October 29 and Friday, October 30, 2015
 Venue: Komaba, University of Tokyo, Math. Dep. Room 002.
 Schedule:
 October 29th (Thursday)
 10:0011:00 Hikami
 11:3012:30 Andersen
 14:3015:30 Sakasai
 16:0017:00 Hayata
 18:00 Dinner at Komaba
 October 30th (Friday)
 10:0011:00 Murakami
 11:3012:30 ZinnJustin
 14:3015:30 Kuno
 16:0017:00 Shimada
 October 29th (Thursday)
 Title and Abstract: PDF
Seminar:
 Date: Wednesday, May 27th, 2015
 Time: 13:0014:00
 Venue: C016, Lab1, OIST
Speaker: Dr. Serguei Brazovskii from CNRS & University ParisSud, Orsay, France
Title: Solitons in low dimensional electronic systems of synthetic conductors.
Abstract: A vast variety and whole families of “synthetic conductors” have been designed by motivation and for the purpose of obtaining desired electronic and optical properties. A firework of new physical effects of electronic correlations feeds fundamental experimental and theoretical researches. Diverse phase transitions are commonly observed towards various electronic phases: superconductivity, antiferromagnetism, ferroelectricity, charge order, charge and spin density waves, Mott and Peierls insulators, phases induced by high magnetic and electric fields and by optical pumping. Vulnerability of the broken symmetries gives rise to topological defects like electronic vortices, walls, stripes. The typical lowdimensional architecture of these compounds brings these objects to a microscopic scale giving rise to “solitons” which description will be the major content of this talk. The solitons are selflocalized configurations which shapes explore the ground state degeneracy. The mathematics of exact solutions for manybody models relates these trajectories to profiles of waves’ arrays and of superwaves in the ocean and to pulses in optical fibers. The solitons can be the lowest energy optical excitations or the carriers of charge or/and spins, taking these functions from conventional electrons. The “instantons” appear as processes of dynamic conversion of normal electrons into solitons. In a broad class of strongly correlated systems, beyond the lowdimensionality, the solitons can persist acquiring forms of more complicated topological excitations which give incarnations to long time searched “spinons” and "holons"
Host: Prof. Shinobu Hikami
Seminar:
 Date: Wednesday, June 3, 2015
 Time: 13:0014:00
 Venue: C016, Lab1, OIST
 Speaker: Dr. Natasha Kirova from CNRS & University ParisSud, Orsay, France
Title: Electronic ferroelectricity in carbonbased systems: from reality of organic conductors to promises of polymers
Abstract: All families of carbon based materials – graphite, graphene, nanotubes, fullerenes and a vast multitude of conjugated polymers and organic crystals – are promising electronically and optically active substances. Recently a new perspective has been added to their researches: an electronic ferroelectricity. Ferroelectrics are exploited as active gate materials, in capacitors, electroopticalacoustic modulators, in WiFi devices, in perspective RAM. Flexible lightweight carbon ferroelectrics are desired as ultrasound sensors in medical imaging. The superpolarisable state of “the ferroelectric Mott semiconductor” was discovered (GrenobleOrsayMoscow) in conducting organic stacks. Less conducting ferroelectrics complexes with neutralionic transitions (TokyoTsukuba) became the objects of studies by advanced femtosecond and teraHz optics (Tokyo). The principle novelty of organic ferroelectrics is that the polarization comes from electronic ordering rather than from ionic displacements. The microscopic design of all new materials is based on coexisting symmetry lowering effects: the dimerization of bonds and the dimerization of sites. With this forecast we could indicate the class of conducting polymers where the ferroelectricity should be present. The theory predicted an existence of solitons (which might have been already observed in Utah experiments on Kyoto materials) with noninteger variable charges, which are the walls separating domains with opposite electric polarisations. Their physics will serve to relate transient ferroelectric processes and the visible range optics. The same symmetry principle applies also to zigzag edges of graphene nanoribbons which can be tested for the ferroelectricity.
Host: Prof. Shinobu Hikami
RIKENOsakaOISTTaiwan mathphys workshop
 Date: March 24, 2015
 Venue: OIST Main Campus, B503, Lab.1
Seminar:
 Date: March 5, 2015 10:00 am11:00 am
 Venue: C016, Lab1, OIST
 Speaker: Dr. Tatsuo Azeyanagi (LPTENS, Paris)
Title: Anomalies, ChernSimons Terms and Black Hole Entropy
Abstract: Quantum anomalies enable us to access to some important information about quantum field theories in a robust way. Recently, the hydrodynamic limit of the systems with the anomalies has been actively investigated, together with its dual holographic description by gravitational theories with ChernSimons terms. In this presentation, I will start with a review on the effect of the anomalies in the hydrodynamic limit of conformal field theories. Then I would like to explain how the beautiful property of ChernSimons terms helps us to compute in detail various quantities relevant to the anomalies through the dual gravitational description. I will also discuss the implication of our analysis to microscopic counting of black hole entropy in higher dimensions.
Topotronics2015: The 1st International Workshop on the Topological Electronics,
 OIST B250, March 911, 2015
MCM2015: Moduli Space, Conformal Field Theory and Matrix Model,
 OIST C209, March 1618, 2015
 Program, Titles and Abstracts of the Talks (PDF)
 The slide files (PDF) are listed HERE. You need the password in order to open these files.
20122014
RMT2013 Fluctuations of Complex Systerms, OIST Seaside House & C209, Oct 27  Nov 1, 2013
JIBW 3rd JapanIsrael Binational Workshop on Quantum Phenomena, OIST Seaside House, March 1013, 2013
RMT2012 :OIST Spring Course on Random Matrix Theory for Complex Systems OIST Seaside House, April 1521, 2012