News
243 news in 2021

20211228
Seminar ReportiTHEMS Math Seminar by Prof. Yosuke Morita on December 3, 2021
On December 3, Yosuke Morita from Kyoto university gave a talk titled “The Conley index of topological dynamical systems” at the iTHEMS math seminar. He reviewed the fundamental concepts of study of topological dynamical systems and introduced the notion of index neighborhood which is used to define his refined Conley index. His talk contained many instructive examples which enable us to understand his talk easily. Finally, his refined Conley index is defined as a functor into a category of (equivariant) condensed sets. This gives new conceptual understanding of Conley index in terms of condensed set introduced by Clausen and Scholze recently. His talk was very interesting and stimulated many questions and discussions. I believe it was a very worthwhile time for many participants. Reported by Masaki Taniguchi

20211228
Seminar ReportDMWG Seminar by Prof. Hidetoshi Otono on December 15, 2021
Among kinds of approaches for dark matter (DM), collider experiments are advantageous in their high precision. The FASER (ForwArd Search ExpeRiment at the LHC) is equipment to probe longlived particles created at the interaction point of the LHC at the distance of about 400m. Particles pass through the absorber between the FASER detector and the interaction point and have enough lifetime to reach the FASER detector should leave signatures there. Dark photon and axionlike particles are good candidates for such species, as well as DM. The equipment is set at the front of the LHC beam direction. The position is really good at reducing the background particles and making use of already existing but not used space. Multiple layers of scintillators, emulsion for neutrino detection, silicon trackers, the decay volume for new particles with dipole magnets, and calorimeter at the endpoint consists of the facility. In combination with the works of these pieces, new longlived particle signatures as raredecay signatures of neutral pion decay can be searched. It is already working well with LHC Run 3 and neutrino properties are now being probed. Furthermore, a new piece of the facility is decided to be installed to enhance the accessibility to axionlike particle signature in the channel of 2 photon decay. The installation does not disturb the current measurement and will be completed by the end of 2023. The FASER experiments should become a key facility to probe new particles at m~O(1) GeV scale. In addition, our understanding of the Standard Model sector is also significantly improved with its measurements. The collaboration is now intensively working. The idea for physics with FASER is highly welcomed. Stay tuned and work hard! Reported by Nagisa Hiroshima

20211227
Press ReleaseSimplifying Complex Chemical Reaction Networks  a reduction method using homological algebra
A team of researchers, Yuji Hirono (Visiting Scientist, iTHEMS), Takashi Okada (Senior Research Scientist, iTHEMS), Hiroyasu Miyazaki (Senior Research Scientist, iTHEMS) and Yoshimasa Hidaka (Visiting Scientist, iTHEMS), has developed a new method for simplifying complex chemical reaction networks using a mathematical technique called “homological algebra”. Using this method, complex networks can be simplified while preserving their important features and their properties can be studied more efficiently. The research is conducted by a team of physicists, a mathematician, and a biologist, and demonstrates the effectiveness of a crossdisciplinary approach. To read more, please see the related link.

20211223
Paper of the WeekWeek 4, December 2021
Title: Analytic Bootstrap in 2D Boundary Conformal Field Theory: Towards Braneworld Holography Author: Yuya Kusuki arXiv: http://arxiv.org/abs/2112.10984v1 Title: Polychronic Tunneling: New Tunneling Processes Experiencing Euclidean and Lorentzian Evolution Simultaneously Author: Naritaka Oshita, Yutaro Shoji, Masahide Yamaguchi arXiv: http://arxiv.org/abs/2112.10736v1 Title: Vacuum decay in the Lorentzian path integral Author: Takumi Hayashi, Kohei Kamada, Naritaka Oshita, Jun'ichi Yokoyama arXiv: http://arxiv.org/abs/2112.09284v1 Title: H.E.S.S. followup observations of Binary Black Hole Coalescence events during the second and third Gravitational Waves observing runs of Advanced LIGO and Advanced Virgo Author: H.E.S.S. Collaboration (Naomi Tsuji) Journal Reference: ApJ, 923, 109 (2021) doi: https://doi.org/10.3847/15384357/ac2e04 arXiv: http://arxiv.org/abs/2112.08307v1

20211222
Seminar ReportNEW WG Seminar by Dr. Tomoki Ozawa on December 20, 2021
Tomoki Ozawa (Tohoku/AIMR) gave a talk on "Quantum metric of topological and nontopological insulators in AMO and other systems." Quantum metric, or more generally quantum geometry, is attracting great interest recently in condensedmatter physics. Tomoki gave a pedagogical introduction to the concept of quantum metric as well as recent experimental progresses including the first detection of the quantum metric using a diamond NV center. Tomoki then explained his recent results on this topic, in particular, on relations among quantum metric, topology, and the Kähler geometry. More than 30 people have joined the seminar and enjoyed fruitful discussions. Reported by Hidetoshi Taya

20211222
Seminar ReportNEW WG Seminar by Dr. Yusuke Yamada on December 15, 2021
Yusuke Yamada (RESCEU/Tokyo) gave a talk on "Cosmological particle production as Stokes phenomena." Particle production from the vacuum takes place in the presence of timedependent backgrounds, and is of interest in various fields of physics. Yusuke reconsidered the particle production from a viewpoint of the Stokes phenomenon, a mathematical concept in theory of differential equations, and discussed its application to the early Universe. Yusuke pointed out that the Stokesphenomenon viewpoint gives a systematic and powerful framework to investigate the realtime dynamics of the particle production. About 20 people have joined the seminar, and enjoyed active discussions during and even after the seminar. Reported by Hidetoshi Taya

20211221
BookReading the World through the Window of Math
Authors: Hiroyasu Miyazaki, Akinori Tanaka, Ryosuke Iritani and Nagisa Hiroshima Editor: Tetsuo Hatsuda and Ryosuke Shibato Language: Japanese Release date: November 19, 2021 Exploring Prime Numbers, AI, Biology, and the Universe Young researchers who use math to tackle a variety of research themes explain their research and their career choices with fresh sensitivity.

20211217
Seminar ReportiTHEMS Biology Seminar by Prof. Hidetoshi Shimodaira on December 16, 2021
On December 16, Dr. Motomu Matsui (University of Tokyo) gave a lecture titled "Revisiting Standard Methods for Phylogenetic Tree Inference" at the iTHEMS Biology Seminar. He described the Graph Partitioning (GS) method, a new molecular phylogenetic analysis method based on graph theory and clustering, and explained its usefulness when used with real data. The GS method can reveal protein family relationships that cannot be clarified by conventional molecular phylogenetic analysis using maximum likelihood or distance methods. It was a very meaningful seminar for many participants. Thank you very much! Reported by Yuki Yazaki

20211217
Seminar ReportABBL/iTHEMS Astro Seminar by Prof. Jin Matsumoto on December 10, 2021
Prof. Jin Matsumoto (Assistant Professor, Keio Institute of Pure and Applied Sciences (KiPAS), Graduate School of Science and Technology, Keio University) gave a nice presentation on "Magnetic field dependence of neutrinodriven corecollapse supernova models". In the presentation, Prof. Matsumoto introduced his neutrinoradiationhydrodynamics supernova code (3DnSNe, Takiwaki et al. 2016) to include magnetohydrodynamics (MHD). Using this code, he performed threedimensional MHD simulations for the evolution of nonrotating stellar cores focusing on the difference in the magnetic field of the progenitors. He found that the neutrinodriven explosion occurs in both the weak and strong magnetic field models. It was concluded that the neutrino heating is the main driver for the explosion in his models, whereas the strong magnetic field slightly supports the explosion. Reported by Shigehiro Nagataki

20211216
Paper of the WeekWeek 3, December 2021
Title: Isovector density and isospin impurity in $^{40} \mathrm{Ca}$ Author: H. Sagawa, S. Yoshida, T. Naito, T. Uesaka, J. Zenihiro, J. Tanaka arXiv: http://arxiv.org/abs/2112.06169v1 Title: Toward a resolution of the NN controversy Author: Amy Nicholson, Evan Berkowitz, John Bulava, Chia Cheng Chang, M. A. Clark, Andrew D. Hanlon, Ben Horz, Dean Howarth, Christopher Korber, Wayne Tai Lee, Aaron S. Meyer, Henry MongeCamacho, Colin Morningstar, Enrico Rinaldi, Pavlos Vranasc, Andre WalkerLoud arXiv: http://arxiv.org/abs/2112.04569v1 Title: Dispersive qubit readout with machine learning Author: Enrico Rinaldi, Roberto Di Candia, Simone Felicetti, Fabrizio Minganti arXiv: http://arxiv.org/abs/2112.05332v1 Title: Neural quantum states for supersymmetric quantum gauge theories Author: Xizhi Han, Enrico Rinaldi arXiv: http://arxiv.org/abs/2112.05333v1 Title: Cooper quartet correlations in infinite symmetric nuclear matter Author: Yixin Guo, Hiroyuki Tajima, Haozhao Liang arXiv: http://arxiv.org/abs/2112.05349v1 Title: Global 4group symmetry and 't Hooft anomalies in topological axion electrodynamics Author: Yoshimasa Hidaka, Muneto Nitta, Ryo Yokokura arXiv: http://arxiv.org/abs/2108.12564v1 Title: Dynamical quantum phase transition in a nonHermitian Hubbard model Author: Tomoya Hayata, Yoshimasa Hidaka, Arata Yamamoto arXiv: http://arxiv.org/abs/2111.03893v2 Title: Lattice Lindblad simulation Author: Tomoya Hayata, Yoshimasa Hidaka, Arata Yamamoto arXiv: http://arxiv.org/abs/2111.04937v1 Title: Finite volume analysis on systematics of the derivative expansion in HAL QCD method Author: Takumi Doi, Yan Lyu, Hui Tong, Takuya Sugiura, Sinya Aoki, Tetsuo Hatsuda, Jie Meng, Takaya Miyamoto arXiv: http://arxiv.org/abs/2112.04997v1

20211216
Event ScheduleEvents for the 4th week of December 2021
Monday, December 20, 13:30– 15:00 NEW WG Seminar Friday, December 24, 12:30 Coffee Meeting

20211215
Press ReleaseUniversal chords played by black holes  Toward the verification of general relativity by black hole fluctuations
Naritaka Oshita (Special Postdoctoral Researcher, iTHEMS) has revealed the "universal combination" of vibration patterns of black holes that are most easily excited from theoretical calculations. This research result is expected to contribute to the measurement of the weight and rotation speed of black holes by observational data of spacetime ripples (gravitational waves) propagating immediately after the merger of a binary black hole, and to the precise test of Einstein’s general theory of relativity. To read more, please see the related link (in Japanese).

20211213
Research NewsRIKEN Research: Exotic sixquark particle predicted by supercomputers
Dr. Takuya Sugiura (Postdoctoral Researcher, iTHEMS) was featured in the Research News on the RIKEN website. The predicted existence of an exotic particle made up of six elementary particles known as quarks by RIKEN researchers could deepen our understanding of how quarks combine to form the nuclei of atoms. To read more, please see the related links.

20211210
Seminar ReportiTHEMS Math Seminar by Dr. Ryosuke Iritani on December 8, 2021
On December 8, Dr. Ryosuke Iritani (iTHEMS) gave a talk in Math Seminar. He talked about expectation value of certain random variables. He and his collaborators obtained a result on its explicit formula together with an algorithm of its fast calculation. This was the last Math Seminar talk of the year 2021. After the seminar there was an online Christmas party. Reported by Michiya Mori

20211210
Seminar ReportiTHEMS Biology Seminar by Prof. Hidetoshi Shimodaira on December 9, 2021
In this week’s biology seminar, the invited speaker Prof. Hidetoshi Shimodaira introduced his recent work about selective inference. Selective inference is an important statistical problem described also by another word “the filedrawer effect”. For example, Journals are much more likely to publish studies with low P values, and the readers never hear about the great number of studies that showed no effect and were filed way. This makes it difficult to assess the strength of a reported P value. The challenge of correcting for the effects of selection is a complex one. Prof. Hidetoshi Shimodaira explained a method to improve the previously proposed approximately unbiased test by adjusting the selection bias. This method is applied to predict trees and edges in phylogeny. In the seminar, he started by an interesting introduction of Darwin's theory of evolution and the tree of life. Based on this theory, modern phylogenetic inference is developed by analyzing DNA sequences of species as system relationships like trees. He also showed us, different statistical tests can give different P values of trees and edges in the trees. Therefore, we should be careful doing the tests and aware of the bias types in the problem. We thank Prof. Hidetoshi Shimodaira for his great talk and precious time with us! Reported by Yingying Xu

20211209
Paper of the WeekWeek 2, December 2021
Title: Most charming dibaryon near unitarity Author: Yan Lyu, Hui Tong, Takuya Sugiura, Sinya Aoki, Takumi Doi, Tetsuo Hatsuda, Jie Meng, Takaya Miyamoto arXiv: http://arxiv.org/abs/2112.01682v1 Title: Information Scrambling Versus Quantum Revival Through the Lens of Operator Entanglement Author: Kanato Goto, Ali Mollabashi, Masahiro Nozaki, Kotaro Tamaoka, Mao Tian Tan arXiv: http://arxiv.org/abs/2112.00802v1

20211209
Event ScheduleEvents for the 3rd week of December 2021
Wednesday, December 15, 13:30– 15:00 NEW WG Seminar Wednesday, December 15, 17:00– 18:00 DMWG Seminar Friday, December 17, 12:30 Coffee Meeting

20211207
Seminar ReportiTHEMS Biology Seminar by Dr. Yuka Suzuki on November 18, 2021
On November 18, Yuka Suzuki from Okinawa Institute of Science and Technology (OIST) gave a talk titled "Spatial structure in ecology: the effects of dispersal network structure on biodiversity pattern and stability in metacommunities" at the iTHEMS Biology Seminar. She introduced the basic concepts of spatial structure in ecology and explained how computational tools and network theoretical concepts are used to investigate spatial structures in ecology using her own study. Her talk was easy to understand and also very interesting and stimulated many questions and discussions. I believe it was a very worthwhile time for many participants. Thanks Yuka! Reported by Jeffrey Fawcett

20211207
Seminar ReportiTHEMS Math Seminar by Prof. Koichi Taira on November 26, 2021
In November 26, there was a seminar by professor Kouichi Taira. He explained the relations between selfadjointness and the completeness of the classical dynamics. He especially explained a conjecture that selfadjointness and completeness of classical dynamics are equivalent. He then gave some examples on this conjectures. Reported by Keita Mikami

20211207
Seminar ReportiTHEMS Math Seminar by Dr. Shinichiro Seki on November 19, 2021
On November 19, we invited Professor Shinichiro Seki from Aoyama Gakuin University to give a talk in the Math Seminar. He explained about the graph removal lemma, which is one of the key ingredients of the proof of his recent joint work with Kai, Mimura, Munemasa and Yoshino on a generalization of the celebrated GreenTao theorem. In the first half of the talk, he gave a survey of Szemerédi's regularity lemma and the graph removal lemma, and explained how to extend the removal lemma to the case of (weighted) hypergraphs. In the second half of the talk, he presented Fox's result on a quantitative version of the graph removal, and discussed the prospects for future research. After the seminar, we had an online drinking party, and enjoyed a lot of discussion with the speaker. Reported by Hiroyasu Miyazaki

20211207
Seminar ReportNEW WG Seminar by Prof. Ryosuke Oketani on November 25, 2021
Ryosuke Oketani from Kyushu University gave a talk on "Imaging Theory of Optical Microscopy: Basic to Super Resolution." Optical microscopy is a powerful tool to observe microscopic objects such as living microorganisms. Recently, several superresolution techniques have been developed, which enabled us to overcome the limit in spatial resolution caused by the wave nature of light. Ryosuke explained the basics and recent theoretical developments of optical microscopy and the superresolution techniques. We also had fruitful discussions on the theory of optical microscopy from an interdiciplinary point of view. Reported by Hidetoshi Taya

20211202
Paper of the WeekWeek 1, December 2021
Title: Flavor number dependence of QCD at finite density by the complex Langevin method Author: Yusuke Namekawa, Yuhma Asano, Yuta Ito, Takashi Kaneko, Hideo Matsufuru, Jun Nishimura, Asato Tsuchiya, Shoichiro Tsutsui, Takeru Yokota arXiv: http://arxiv.org/abs/2112.00150v1 Title: Emergence of the rho resonance from the HAL QCD potential Author: Yutaro Akahoshi, Sinya Aoki, Takumi Doi arXiv: http://arxiv.org/abs/2111.15138v1 Title: Color superconductivity in a small box: a complex Langevin study Author: Shoichiro Tsutsui, Yuhma Asano, Yuta Ito, Hideo Matsufuru, Yusuke Namekawa, Jun Nishimura, Asato Tsuchiya, Takeru Yokota arXiv: http://arxiv.org/abs/2111.15095v1 Title: Perturbative predictions for color superconductivity on the lattice Author: Takeru Yokota, Yuhma Asano, Yuta Ito, Hideo Matsufuru, Yusuke Namekawa, Jun Nishimura, Asato Tsuchiya, Shoichiro Tsutsui arXiv: http://arxiv.org/abs/2111.14578v1 Title: QHC21 equation of state of neutron star matter  in light of 2021 NICER data Author: Toru Kojo, Gordon Baym, Tetsuo Hatsuda arXiv: http://arxiv.org/abs/2111.11919v1 Title: Flux tube profiles in twocolor QCD at low temperature and high density Author: Katsuya Ishiguro, Kei Iida, Etsuko Itou arXiv: http://arxiv.org/abs/2111.13067v1

20211202
Event ScheduleEvents for the 2nd week of December 2021
Wednesday, December 8, 16:00– 18:00 iTHEMS Math Seminar Thursday, December 9, 10:00– 11:00 iTHEMS Biology Seminar Friday, December 10, 12:30 Coffee Meeting

20211201
Seminar ReportABBL/iTHEMS Astro Seminar by Dr. Hirotaka Yoshino on November 12, 2021
Dr. Yoshino gave us a talk on his recent work on axions around rotating black holes. He showed results of his numerical simulations of socalled “superradiant instability” in which an axion field around a rotating black hole extracts the energy of the black hole. These results suggest that every astrophysical black hole is expected to wear a cloud of the axion. Reported by Akira Mizuta (ABBL, RIKEN)

20211130
Seminar ReportQuantum Matter SG seminar by Prof. Harshman Nathan on November 17, 2021
From American University, Prof. Nathan Harshman gave a seminar talk about topological exchange statistics in one spatial dimension on Nov. 17th, 2021. To introduce exchange statistics as done in the literature, he started with statistics for bosons and fermions and extended fractional and nonabelian exchange statistics. Then, the speaker raised questions about particle exchange in 1D and the collisions of the particles. Can a collision and an exchange at all be distinguished in one dimension? Is it reasonable to include points of coincidence in the configuration space? The way to resolve these problems is to introduce orbifolds. After pedagogically explaining the concepts of the orbifolds, he began to use the orbifold topological approach to study exchange statistics for any dimension. This approach offers great chances for novel abelian and nonabelian anyons in effectively 1D cold atom and condensed matter systems. Reported by Thore Posske (University of Hamburg, Germany) and ChingKai Chiu

20211130
Seminar ReportiTHEMS Biology Seminar by Prof. Catherine Beauchemin on October 14, 2021
Defective interfering virus particles (DIPs) are viruses that are defective in a very specific way that allows them to outcompete standard, nondefective virus. It is difficult to count DIPs because they can look too similar to standard virus. So instead, people are counting them based on their effect on suppressing the standard virus population. In this talk, C. Beauchemin explained the basic biology of virus replication, what are DIPs, and how they compete with standard virus. She presented her group's mathematical model (ordinary differential equation) that describes coinfection competition with DIPs and standard virus. She also showed applications of the mathematical model to show how experiments to count DIPs can give incorrect results, and proposed some solutions.

20211130
Seminar ReportInformation Theory SG Seminar by Dr. Enrico Rinaldi on November 29, 2021
In the first part, he introduced the concept of simulationbased inference (SBI), which is inference methods driven by machine learning, and show some examples. In the later part, he showed some preliminary results of SBI on a biological neural circuit. We had a great discussion during Enrico’s talk. Thanks again for the fantastic talk, Enrico! We look forward to working with you. Reported by Akinori Tanaka

20211129
Person of the WeekSelfintroduction: Tomoki Nosaka
My name is Tomoki Nosaka. I have joined RIKEN iTHEMS as a research parttime worker in November 2021. My research field is the theoretical physics. I have been trying to reveal new aspects of Mtheory, which is supposed to be the theory of everything though still being mysterious, by means of the supersymmetric gauge theories, matrix models and their integrability. Recently I am also interested in the quantum information theory and the various notions of chaos in quantum manybody systems which are found to be closely related to the black hole physics. I am looking forward to interacting with people in iTHEMS working with various research interests and finding a new direction of research out of it.

20211125
Paper of the WeekWeek 4, November 2021
Title: Factorizing Wormholes in a Partially DisorderAveraged SYK Model Author: Kanato Goto, Kenta Suzuki, Tomonori Ugajin arXiv: http://arxiv.org/abs/2111.11705v1

20211125
Event ScheduleEvents for the 1st week of December 2021
Monday, November 29, 13:30– 15:00 Information Theory SG Seminar Friday, December 3, 12:30 Coffee Meeting

20211124
Seminar ReportiTHEMS Math Seminar by Prof. Song Sun on October 22, 2021
In this seminar, Professor Song Sun started with explaining the most basic concepts like, Riemannian metric, curvature in differential geometry. He then introduced one of the most important equations differential geometry, the socalled Einstein equation. After defining the holonomy group of a Riemannian manifold, he explained Berger's classification of holonomy groups of Riemannian manifolds which are not locally symmetric. He then pointed out the importance of studying Riemannian manifolds with special/exceptional holonomy groups, e.g. CalabiYau manifolds, hyperkahler manifolds, G2 and Spin(7) manifolds. He concentrated on hyperkahler 4manifolds and explained their geometry and topology in more details. In the end, he introduced his recent research result on studying GromovHausdorff limit of hyperkahler 4manifolds. Reported by Yalong Cao

20211124
Seminar ReportiTHEMS Math Seminar by Prof. Siqi He on October 15, 2021
In this seminar, Professor Siqi He started with mean curvatures and minimal submanifolds in differential geometry. Then he introduced the notion of calibrated geometry of HarveyLawson. As important examples of calibrated submanifolds, special Lagrangian submanifolds in CalabiYau manifolds are introduced. Then he explained a branch cover problem raised by Simon Donaldson and sketched a proof of it. Reported by Yalong Cao

20211124
Seminar ReportiTHEMS Math Seminar by Prof. Chen Jiang on October 8, 2021
In this seminar, Professor Chen Jiang started with several basic notions like geometric genus and canonical volume in birtaional geometry and introduced the question of geography problem. On algebraic surfaces, the boundary of geography problem is given by MiyaokaYau inequality and Noether inequality. Then he explained generalizations of the story on 3folds, including his joint work with M. Chen and J.K.Chen. Finally he gave an outline for the proof of his main theorem. Reported by Yalong Cao

20211124
Seminar ReportiTHEMS Math Seminar by Prof. Yukinobu Toda on October 1, 2021
In this seminar, Professor Yukinobu Toda started with the example of counting rational curves on hypersurfaces in complex projective spaces to illustrate ideas in enumerative geometry. Then he introduced several advanced topics including DonaldsonThomas theory and mirror symmetry. Finally he explained his recent work on wallcrossing formulae for categorified DT invariants on resolved conifold. Reported by Yalong Cao

20211118
Event ScheduleEvents for the 4th week of November 2021
Monday, November 22, 13:30– 15:00 Brownian Motion Monday, November 25, 13:30– 15:00 NEW WG Seminar Friday, November 26, 12:30 Coffee Meeting

20211118
Paper of the WeekWeek 3, November 2021
Title: Evaluation of origin of the driving force for loop formation in a chromatin fiber Author: Hiroshi Yokota, Masashi Tachikawa arXiv: http://arxiv.org/abs/2111.08881v1 Title: Impacts of Jets and Winds From Primordial Black Holes Author: Volodymyr Takhistov, Philip Lu, Kohta Murase, Yoshiyuki Inoue, Graciela B. Gelmini arXiv: http://arxiv.org/abs/2111.08699v1 Title: Generalized harmonic analysis reveals a frequency modulated timer regulates mammalian hibernation Author: Shingo Gibo, Yoshifumi Yamaguchi, Gen Kurosawa doi: https://doi.org/10.1101/2021.11.12.468369 Title: Nucleon Axial Form Factor from Domain Wall on HISQ Author: Aaron S. Meyer, Evan Berkowitz, Chris Bouchard, Chia Cheng Chang, M. A. Clark, Ben Hörz, Dean Howarth, Christopher Körber, Henry MongeCamacho, Amy Nicholson, Enrico Rinaldi, Pavlos Vranas, André WalkerLoud arXiv: http://arxiv.org/abs/2111.06333v1 Title: Emergence of Hilbert Space Fragmentation in Ising Models with a Weak Transverse Field Author: Atsuki Yoshinaga, Hideaki Hakoshima, Takashi Imoto, Yuichiro Matsuzaki, Ryusuke Hamazaki arXiv: http://arxiv.org/abs/2111.05586v1

20211118
Seminar ReportNEW WG Seminar by Prof. Naoto Nagaosa on November 15, 2021
Naoto Nagaosa (Tokyo/RIKEN) gave a talk on "Geometry in optical responses of quantum materials." Geometry and topology provide new insight into optical responses of solids and are of interdisciplinary interest in physics. After an excellent review on this topic made over the past decade, Naoto mainly discussed (i) shift current in noncentrosymmetric quantum materials driven by Berry phases, and (ii) Riemannian geometry in nonlinear optical responses. About 50 physicists from various fields have joined the seminar and enjoyed fruitful discussions during and after the seminar. Reported by Hidetoshi Taya

20211117
Seminar ReportiTHEMS Biology Seminar by Dr. Takaharu Mori on November 4, 2021
On Nov 4th 2021, Dr. Takaharu Mori from Molecular Science Lab (Sugita Lab), RIKEN gave an online talk, entitled, "Protein structure modeling from cryoelectron microscopy data". He talked about the theoretical method to determine threedimensional structures of biomolecules at nearatomic resolution, using a molecular dynamics (MD) simulation and also microscopy data. In addition, he showed their combined approach of coarsegrained model and allatom model. According to him, Bayesian inference and machine learning are useful for the determination of biomolecule's 3D structure which can be the seeds of future collaborations between us. During the seminar, there were many discussions with iTHEMS members especially about the theoretical method to use recent microscopy data. We enjoyed his talk very much. Thanks, Morisan! Reported by Gen Kurosawa

20211117
Seminar ReportiTHEMS Biology Seminar by Dr. Jae Kyoung Kim on November 11, 2021
On Nov 11th 2021, Prof. Jae Kyoung Kim from KAIST, South Korea gave an online talk at iTHEMS. The title of the talk is “Toward mathematical medicine: development of a new drug and digital medicine for sleep disorders”. In the seminar, Dr. Kim talked about mathematical model (e.g. IBM) of our daily rhythms when environment within cells is crowded by lipids, and its implication for obesity. In addition, he showed their successful collaboration with Pfizer and Samsung medical center. The talk thrilled us very much. There were many intensive discussions with iTHEMS members and also experimental biologists from outside. Thanks, Jae! Reported by Gen Kurosawa

20211116
Hot TopicFarewell message from Dr. Jason Chang
Our colleague Jason Chang moves on to a new carrier at LinkedIn as of November 14th. We all will miss him and wish him the best of luck in his latest endeavor. Here is a message from Jason: It was truly a pleasure to be part of iTHEMS. I have matured so much during this time through all the opportunities that have been made available to me because of how much iTHEMS has supported me in the decisions that I made. I certainly will miss everyone as well. I will move on to a data science position at LinkedIn. If anyone from iTHEMS is curious or has interest in transitioning to some industry position especially around the Bay Area, feel free to reach out to me. I will be more than happy to help with the process and introduce the person to the right recruiters as well. I believe I can convince LinkedIn to let me continue research in quantum algorithms for around 1 day / week as well. So perhaps in the end, I am not going away as far as one might think. The world is quite small after all. My direct manager at LinkedIn was Aida’s postdoc when I was her graduate student. One never knows which doors life decides to open. Kind Regards, Jason

20211115
Seminar ReportiTHEMS Math Seminar by Prof. Todor Milanov on November 12, 2021
Professor Todor Milanov gave a talk on his recent research on Ktheoretic GW theory. He first recalled the definition of GromovWitten invariants and its Ktheoretic generalization. Then he mentioned how to use genus 0 GW invariants to define quantum product on the usual cohomology group of a symplectic manifold. Such formulation has deep connection to integrable systems. He then introduced his research results, including a proof of the fact that small Jfunction in quantum cohomology of a Fano manifold can be obtained as a limit q >1 of the small Jfunction in quantum Ktheory. Reported by Yalong Cao

20211115
Seminar ReportiTHEMS Math Seminar by Prof. Naichung Conan Leung on November 5, 2021
Professor Conan Leung gave an introductory talk to mirror symmetry. He first started with the discussion on the sum of inner angles of a triangle to illustrate the difference between our familiar Euclidean spaces and spaces with nontrivial curvature. He then introduced the notion of complex numbers and how it is related to solving polynomial equations in algebra. Recalling that gravity theory and quantum theory having very different nature of behaviour, he introduced super string theory as a potential unification of these two theories and its great impact to the study of modern mathematics, e.g. enumerative geometry, geometry of special holonomy. Finally he introduced mirror symmetry and how to understand it from the perspective of Fourier transform following a proposal of Strominger, Yau and Zaslow. Reported by Yalong Cao

20211111
Paper of the WeekWeek 2, November 2021
Title: Lefschetz fibrations on the Milnor fibers of cusp and simple elliptic singularities Author: Naohiko Kasuya, Hiroki Kodama, Yoshihiko Mitsumatsu, Astuhide Mori arXiv: http://arxiv.org/abs/2111.00749v1 Title: Planckian Physics Comes Into Play At Planckian Distance From Horizon Author: PeiMing Ho, Hikaru Kawai, Yuki Yokokura arXiv: http://arxiv.org/abs/2111.01967v1

20211111
Event ScheduleEvents for the 3rd week of November 2021
Monday, November 15, 13:30– 15:00 NEW WG Seminar Friday, November 19, 12:30 Coffee Meeting Friday, November 19, 15:00 18:00 MACS Colloquium

20211111
Seminar ReportInformation Theory SG Seminar by Dr. Michiya Mori on November 4, 2021
On November 4, Dr. Michiya Mori gave a talk entitled “Boolean algebras and operator algebras” at the Information Theory SG Seminar. He explained some of the basic concepts of Boolean algebra. Then he talked about some interesting issues and his contributions in the field. It was a very informative and stimulating talk. Reported by Yukimi Goto

20211111
Seminar ReportAstroAI WG/Information Theory SG Joint Seminar by Dr. Takehiko Saito on November 8, 2021
The seminar was held online plus 4 people onsite. Dr.Saito gave a talk about “hunting hypernuclei by machine learning in nuclear emulsions”. Recent experimental studies with heavy ion beams have revealed that the nature of the hypertriton is unclear, especially on its biding energy and lifetime. The group led by Dr. Saito conducted measurements of them using nuclear emulsion, which requires a huge human load on visual image analyses. Therefore, they have developed machine learning models to detect events associated with production and decay of hypertriton in nuclear emulsions data, and successfully have discovered hypertriton events. Reported by Naomi Tsuji

20211110
Seminar ReportiTHEMS Theoretical Physics Seminar by Prof. Katsuki Aoki on November 2, 2021
On November 2, 2021, at a seminar as part of the iTHEMSphys seminar series, Dr. Katsuki Aoki (YITP, Kyoto University) delivered a talk on the topic of consistency conditions on the Standard Model of particle physics imposed from the requirements of a more fundamental ultraviolet (UV) theory. Underlying assumptions on UV completion can impose constraints on its lowenergy effective field theories (EFTs). The swampland program aims to clarify consistent and inconsistent EFTs with quantum gravity and aims to understand quantum gravity from lowenergy physics and vice versa. One of the most wellestablished constraints is called positivity bounds, provided that general assumptions such as Poincare invariance and unitarity are satisfied at all scales. Dr. Aoki first explained how these consistency conditions arise especially in the presence of gravity. He then showed that the positivity bound is violated if the Standard Model coupled to General Relativity is extrapolated up to 10^16 GeV, requiring new physics there or below. The precise value of the cutoff is determined by hadronic physic while it is insensitive from nongravitational physics beyond the Standard Model. This is a signal from established physics for the necessity of quantum gravity below 10^16 GeV. Reported by Ryo Namba

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Paper of the WeekWeek 1, November 2021
Title: Planckian Physics Comes Into Play At Planckian Distance From Horizon Author: PeiMing Ho, Hikaru Kawai, Yuki Yokokura arXiv: http://arxiv.org/abs/2111.01967v1

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Hot TopicCan social issues be solved by mathematical science? attempts and challenges
On Oct.26, the symposium "Can social issues be solved by mathematical science? attempts and challenges" was held under the leadership of Takashi Sakajo (Kyoto Univ.) and Shingo Iwami (Nagoya Univ.) who are also iTHEMS colleagues. The symposium was held in a hybrid matter with more than 220 participants. After the presentations on various approaches to bridge the academia and industry, there were lively discussions on how to cross the valley between the mathematical science and social needs.

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Event ScheduleEvents for the 2nd week of November 2021
Monday, November 8, 14:00– 15:00 ABBLiTHEMS Joint Seminar Thursday, November 11, 12:30– 13:30 iTHEMS Biology Seminar Friday, November 12, 12:30 Coffee Meeting
243 news in 2021