The 32nd QCD Club

December 26 (Thu) at 15:00 - 17:00, 2019

Event Official Language: Japanese

RIKEN-Kyushu workshop on particle, nuclear and astrophysics

December 23 (Mon) - 24 (Tue), 2019

Organizers Emiko Hiyama (Kyushu U./RIKEN) Hiroshi Suzuki (Kyushu U.) Tetsuo Hatsuda (RIKEN)

Venue: Faculty of Science, Ito Campus, Kyushu University

Event Official Language: Japanese

2019 RIKEN Symposium: Understand to Predict the properties of Things and Matters through Computational Calculations ~ Data Science, Natural Intelligence and Category Theory~

December 23 (Mon) at 9:50 - 18:10, 2019

This workshop is supported by RIKEN iTHEMS (RIKEN Interdisciplinary Theoretical and Mathematical Sciences Program).

Venue: Okochi Hall

Event Official Language: Japanese

Constraining superheavy dark matter with the multi-messenger observations of accompanying radiation

December 20 (Fri) at 14:00 - 15:00, 2019

Yana Zhezher (Institute for Cosmic Ray Research (ICRR), The University of Tokyo)

One of the main alternatives for the weakly interacting massive particles (WIMP) dark matter scenario are the super-heavy X particles with masses larger than the weak scale by orders of magnitude. We assume the experimentally more plausible scenario of decaying superheavy dark matter (SHDM), which leads to the production secondary particles: electrons, positrons, gamma rays and neutrinos. The hypothetical X-particle has two main parameters: it’s mass MX and lifetime ?, which can be indirectly constrained by comparisons of predicted flux of secondary particles with the astrophysical observations. We present the limits on the SHDM parameters derived with the multi-messenger data from the Fermi-LAT, IceCube and other experiments.

Venue: Seminar Room #132

Event Official Language: English

Scalable Majorana vortex modes in iron-based superconductors

December 18 (Wed) at 13:30 - 15:00, 2019

Ching-Kai Chiu (Senior Research Associate, Kavli Institute for Theoretical Sciences, University of Chinese Academy of Sciences, China)

The iron-based superconductor FeTexSe1−x is one of the material candidates hosting Majorana vortex modes residing in the vortex cores. It has been observed by recent scanning tunneling spectroscopy measurement that the fraction of vortex cores possessing zero-bias peaks decreases with increasing magnetic field on the surface of FeTexSe1−x. The hybridization of two Majorana vortex modes cannot simply explain this phenomenon. We construct a three-dimensional tight-binding model simulating the physics of over a hundred Majorana vortex modes in FeTexSe1−x. Our simulation shows that the Majorana hybridization and disordered vortex distribution can explain the decreasing fraction of the zero-bias peaks observed in the experiment; the statistics of the energy peaks off zero energy in our Majorana simulation are in agreement with the experiment.

Venue: #435-437, Main Research Building

Event Official Language: English

Multiple Zeta Values: Interrelation of Series and Integrals

December 17 (Tue) at 16:00 - 18:10, 2019

Syuji Yamamoto (Associate Professor, Keio University)

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. Abstract: This is an introduction to multiple zeta values (MZVs). Although the study of MZVs is related to various areas of mathematics, we will concentrate on the algebraic structures of MZVs themselves. The key point is that MZVs have two kinds of representations: nested series and iterated integrals. We present how these two representations yield rich algebraic relations among MZVs.

Venue: Seminar Room #160

Event Official Language: English

Weak lensing cosmology by Subaru HSC survey

December 12 (Thu) at 10:30 - 12:00, 2019

Chiaki Hikage (Project Associate Professor, Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU), The University of Tokyo)

Place: IPMU seminar room C

Venue: Kavli IPMU Building

Event Official Language: English

Seminar talk on GRB190114C

December 11 (Wed) at 13:45 - 15:30, 2019

Susumu Inoue (Research Scientist, iTHEMS)

Detection of very high energy gamma-rays (~TeV) from GRB190114C by MAGIC telescope is reported in the latest nature issue. Dr. Susumu Inoue (iThems) who is one of MAGIC team members will give a seminar talk on this exciting event.

Venue: Seminar Room #132

Event Official Language: English

Young Researcher Association for Biological Rhythms 2019

December 7 (Sat) - 8 (Sun), 2019

Lecturers: Hiroshi Ito (Kyushu University) Shigehiro Ohdo (Kyushu University) Hiroyuki Kubota (Kyushu University) Gen Kurosawa (RIKEN) Shin G. Goto (Osaka City University) Fustin Jean-Michel (Kyoto University) Organizers: Minako Isoda (Kyoto University) Kyohei Uemoto (Kyoto University / Nara Institute of Science and Technology) Shingo Gibo (RIKEN) Motohide Seki (Kyushu University) Yusuke Nakane (Nagoya University) Arisa Hirano (University of Tsukuba) This workshop is supported by RIKEN iTHEMS (RIKEN Interdisciplinary Theoretical and Mathematical Sciences Program).

Venue: School of Agriculture, Ito Campus, Kyushu Univiesiry

Event Official Language: Japanese

Noncommutative crepant resolutions and some higher dimensional flops

December 4 (Wed) at 16:00 - 18:10, 2019

Wahei Hara (JSPS Research Fellow, School of Science and Engineering, Waseda University)

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. Abstract: We will talk about the theory noncommutative resolution of singularities. Noncommutative resolution is a noncommutative analog of usual (geometric) resolution of singularities, and allows us to generalise the idea of McKay correspondence to a large class of singularities. In the first part of the talk, we discuss the classical McKay correspondence, the definition of noncommutative crepant resolution, and some known results in lower dimensions. In the second half, we will discuss some concrete examples of noncommutative crepant resolutions in higher dimensions.

Venue: Seminar Room #160

Event Official Language: English

Workshop on Virtual Reality［Session 2］

November 26 (Tue) at 10:00 - 18:00, 2019

Gilles Ferrand and Don Warren will run a workshop on using virtual reality (VR) for data visualization and research. Anyone from any RIKEN campus, and any field of study, is welcome. We want to build a cross-disciplinary group of people with a shared interest in VR, and to apply this tool to a broad range of data types and topics. Please check the workshop website for up-to-date information ! Workshop on Virtual Reality［Seeeion 1］was held on Oct.7, 2019.

Venue: Seminar Room #132

Event Official Language: English

A multiscale study of turbulent heating in hot accretion flows

November 18 (Mon) at 14:00 - 15:00, 2019

Yohei Kawazura (Assistant Professor, Tohoku University)

Recently, the Event Horizon Telescope (ETH) collaboration revealed the stunning picture of radiation from the vicinity of the black hole. For accurate interpretation of the observation, it is crucial to understand the nature of plasma in the accretion disk. The disks that EHT is observing are called radiatively inefficient accretion flows, in which the plasma is hot and dilute, and consequently collisionless. In collisionless plasma, ions and electrons can have different temperatures as they do not thermally relax through Coulomb interaction. The ion-to-electron temperature ratio is the key to interpreting the observation because we can measure only the electrons' energy via radiation. To study ion and electron heating, kinetic treatment, rather than hydrodynamic treatment, is necessary. However, kinetic plasma turbulence is an extremely challenging subject. Therefore, we utilized gyrokinetics that is widely used in magnetic confinement fusion research. Our new multiscale approach treats a "large scale" where turbulence is driven by magnetorotational instability via MHD, and a "small scale" where turbulence is dissipated via gyrokinetics. Using this approach, we formulated a prescription of ion-to-electron heating ratio. In my talk, I will also present basic knowledge that is necessary to study collisionless turbulent heating.

Venue: Seminar Room #132

Event Official Language: English

The 10th MACS Colloquium

November 15 (Fri) at 14:45 - 18:45, 2019

Nami Sakai (Chief Scientist, Star and Planet Formation Laboratory, RIKEN Cluster for Pioneering Research (CPR))
Kazuya Watanabe (Professor, Graduate School of Science, Kyoto University)

14:45- Teatime 15:00- Talk by Dr. Nami Sakai 16:15- Talk by Prof. Kazuya Watanabe 17:45- Discussion The 10th MACS colloquium 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 confectionery at Kyoto!

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

Event Official Language: Japanese

Variational methods in quantum annealing

November 15 (Fri) at 13:30 - 15:00, 2019

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

The rapid progress in the manufacturing of quantum computing hardware has opened up the possibility of exploring its application in solving computationally challenging problems. In this work, we present variational methods in quantum annealing for solving problems more efficiently than the standard adiabatic methods. Important limitations common to all near-term quantum devices include the absence of error correction and the short coherence time, which restrict the computational power of these systems. Therefore, shortening the time taken to perform an individual run of a quantum algorithm and making the annealing process noise resilient is essential for successfully obtaining accurate results. The efficiency of the methods is demonstrated in the ground-state energy estimation of simple molecular systems. Compared with the standard annealing method, the variational algorithms show significant improvements in the annealing time required to achieve a high accuracy.

Venue: #433, Main Research Building

Event Official Language: English

RIKEN Open Campus in Kobe

November 9 (Sat) at 10:00 - 16:30, 2019

Takumi Doi (Senior Research Scientist, iTHEMS / Senior Research Scientist, Quantum Hadron Physics Laboratory, RIKEN Nishina Center for Accelerator-Based Science (RNC))

RIKEN Open Campus in Kobe will be held on Nov.9, 2019. Dr. Emiko Hiyama (Kyushu Univ.) and Dr. Takumi Doi (Nishina Center / iTHEMS) will give lectures on computational nuclear and particle physics at Kobe IIB building where SUURI-COOL Kobe is located. Please inform the news to anybody who are interested in visiting RIKEN Kobe.

Venue: Integrated Innovation Building (IIB)

Event Official Language: Japanese

Some topics in projective geometry of algebraic varieties

November 8 (Fri) at 16:00 - 18:10, 2019

Atsushi Ito (Assistant Professor, Graduate School of Mathematics, Nagoya University)

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. Abstract: We talk about Gauss maps and projective dual varieties, which are classical objects in projective geometry of algebraic varieties. In particular, we explain Gauss maps in positive characteristic and projective dual varieties of toric varieties in characteristic 0.

Venue: Seminar Room #160

Event Official Language: English

Collaborative Meeting on Supernova Remnants between Japan and USA

November 7 (Thu) - 12 (Tue), 2019

The aim of the workshop is to bring together experts on supernova remnants and related topics for active discussions and to initiate possible collaborations among the participants. The workshop will be held at RIKEN Wako campus (first week, Nov. 7th and 8th) and Kyoto University (second week, Nov. 11th and 12th). This workshop is supported by iTHEMS (RIKEN Interdisciplinary Theoretical and Mathematical Sciences Program) and r-EMU (RIKEN Pioneering Project:Evolution of Matter in the Universe).

Venue: Okochi Hall / 224-226, Main Research Building / SUURI-COOL (Kyoto)

Event Official Language: English

Semiclassical defect measures and observability estimate for Schrödinger operators with homogeneous potentials of order zero

October 30 (Wed) at 8:40 - 10:00, 2019

Keita Mikami (Research Scientist, iTHEMS)

Seminar will be held from 15:40 to 17:00 on Oct.29(PDT, the U.S. Pacific Daylight Time) as a Harmonic Analysis and Differential Equations Seminar.

Venue: UC Berkeley

Event Official Language: English

Atiyah-Hirzebruch spectral sequence in the band theory

October 24 (Thu) at 16:00 - 18:10, 2019

Ken Shiozaki (Assistant Professor, Yukawa Institute for Theoretical Physics, Kyoto University)

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. Abstract: The topological nature of the band theory in crystalline systems can be well described by the topological K-theory over the Brillouin zone torus. In the first part of my talk, I will present the band-theory understanding of the grading of the K-group, and how the exactness axiom and the Mayer-Vietoris sequence are naturally understood. In the second part, I discuss how to compute the differentials of the Atiyah-Hirzebruch spectral sequence associated with a cell decomposition.

Venue: Seminar Room #160

Event Official Language: English

Mean dimension of dynamical systems and information theory

October 21 (Mon) - 23 (Wed), 2019

Masaki Tsukamoto (Professor, Kyushu University)

Oct.21 15:30-16:30, 16:40-17:40, Okochi Hall Oct.22 13:30-14:30, room #435-437, Main Research Building Oct.23 13:30-14:30, room #435-437, Main Research Building

Venue: Okochi Hall / #435-437, Main Research Building

Event Official Language: Japanese