News
130 news in 2023

20230927
Seminar ReportABBLiTHEMS Joint Astro Seminar by Arno Vanthieghem on September 8, 2023
Relativistic radiationmediated shocks (RRMS) dictate the early emission in numerous transient sources such as supernovae, low luminosity gammaray bursts, binary neutron star mergers, and tidal disruption events. These shock waves are mediated by Compton scattering and copious electronpositron pair creation. It has been pointed out that a high pair multiplicity inside the shock transition leads to a leptonbaryon velocity separation, prone to plasma instabilities. The interaction of the different species with this radiationmediated microturbulence can lead to coupling and heating that is unaccounted for by current singlefluid models. Arno presented a theoretical analysis of the hierarchy of plasma microinstabilities growing in an electronion plasma loaded with pairs and subject to a radiation force. His results are validated by particleincell simulations that probe the nonlinear regime of the instabilities and the leptonbaryon coupling in the microturbulent electromagnetic field. Based on this analysis, he derived a reduced transport equation for the particles that demonstrates anomalous coupling of the species and heating in a Joulelike process by the joined contributions of the decelerating turbulence, radiation force, and electrostatic field. Arno then discussed the effect of finite magnetization on the general dynamics and recent efforts toward a more selfconsistent description of the coupling. In general, his results suggest that radiationmediated microturbulence could have important consequences for the radiative signatures of RRMS. Reported by Shigehiro Nagataki

20230926
Seminar ReportiTHEMS Biology Seminar by Ryo Yamaguchi on June 8, 2023
During this session, Dr. Yamaguchi delivered a lecture on evolutionary ecology and its theoretical aspects. He is a researcher who has successfully discovered and quantified new biodiversity patterns through mathematical models in population genetics. In this presentation, he explained his recent research findings in a way that even beginners could easily understand. Various questions and discussions took place. Particularly noteworthy was the high compatibility of his expertise in insects and yeast with other biological fields, allowing for exchanges of ideas with various researchers. My own area of expertise lies in microbiology, specifically in bacteria. While his models primarily focus on eukaryotic organisms, direct application may be challenging, but applying his concepts is feasible. Applying these concepts is likely to yield new insights into the heterogeneity of populations in microbiology. In conclusion, this presentation provided a valuable platform for active discussions among researchers from diverse biological disciplines, making it a highly meaningful session. Reported by Daiki Kumakura

20230921
Paper of the WeekWeek 4, September 2023
Title: Dynamical chirality production in one dimension Author: Tomoya Hayata, Katsumasa Nakayama, Arata Yamamoto arXiv: http://arxiv.org/abs/2309.08820v1 Title: Chemical potential (in)dependence of hadron scatterings in the hadronic phase of QCDlike theories and its applications Author: Kotaro Murakami, Etsuko Itou, Kei Iida arXiv: http://arxiv.org/abs/2309.08143v1 Title: Zariski dense discontinuous surface groups for reductive symmetric spaces Author: Kazuki Kannaka, Takayuki Okuda, Koichi Tojo arXiv: http://arxiv.org/abs/2309.08331v1 Title: Limits to Fluctuation Dynamics Author: Ryusuke Hamazaki arXiv: http://arxiv.org/abs/2309.07301v1 Title: Genus$g$, $n$point, $b$boundary, $c$crosscap correlation functions of twodimensional conformal field theory: Definition and general properties Author: Xun Liu arXiv: http://arxiv.org/abs/2309.07528v1

20230918
Seminar ReportQuantum Matter Seminar by Ashley Cook on September 14, 2023
In a recent online seminar for RIKEN iTHEMS' QMSG series, Dr. Ashley Cook of the Max Planck Institute for Complex Systems delved into her interesting research on topological skyrmion phases in electronic systems. The talk was centered on noninteracting electronic topological phases that feature a skyrmion in their momentumspace spin polarization. After a succinct introduction that framed the talk within the broader context of topological classification in condensed matter physics, Dr. Cook pivoted to explore quantum skyrmion structures in momentum space. She specifically discussed these structures in the context of expected spin polarization in the ground state of centrosymmetric superconductors. Intriguingly, she demonstrated that the topological protection of the skyrmion number extends to the electronic structure through a generalized bulkboundary correspondence, after accounting for nonspin degrees of freedom. This results in the formation of unique edge states that bridge one types of the energy bands (conduction bands and valence bands). Moreover, Dr. Cook emphasized that the adiabatic pumping of these edge states signifies the flow of quantum skyrmions. She suggested that this insight necessitates a reevaluation of the theoretical framework for the quantum Hall effects, which was initially conceived around point charges nearly half a century ago. Her work, therefore, not only suggests a pathway to discover new forms of topological boundary states but also calls for a more nuanced classification of topological states in electronic matter, beyond the limitations of the "tenfold way." The talk sparked a lively discussion, underscoring its significance and the excitement it generated among the participants. We extend our gratitude to Dr. Ashley Cook for her illuminating and thoughtprovoking contribution. Reported by ChingKai Chiu (iTHEMS) and Thore Posske (University of Hamburg, Germany)

20230914
Paper of the WeekWeek 3, September 2023
Title: Dynamic relationship between XRP price and correlation tensor spectra of the transaction network Author: Abhijit Chakraborty, Tetsuo Hatsuda, Yuichi Ikeda arXiv: http://arxiv.org/abs/2309.05935v1 Title: Greybody Factors Imprinted on Black Hole Ringdowns: an alternative to superposed quasinormal modes Author: Naritaka Oshita arXiv: http://arxiv.org/abs/2309.05725v1 Title: Symmetryresolved Entanglement Entropy, Spectra & Boundary Conformal Field Theory Author: Yuya Kusuki, Sara Murciano, Hirosi Ooguri, Sridip Pal arXiv: http://arxiv.org/abs/2309.03287v1

20230907
Paper of the WeekWeek 2, September 2023
Title: Efficient Simulation of Low Temperature Physics in OneDimensional Gapless Systems Author: Yuya Kusuki, Kotaro Tamaoka, Zixia Wei, Yasushi Yoneta arXiv: http://arxiv.org/abs/2309.02519v1 Title: Involutions and the ChernSimons filtration in instanton Floer homology Author: Antonio Alfieri, Irving Dai, Abhishek Mallick, Masaki Taniguchi arXiv: http://arxiv.org/abs/2309.02309v1 Title: A Semiclassical Spacetime Region with Maximum Entropy Author: Yuki Yokokura arXiv: http://arxiv.org/abs/2309.00602v1

20230905
Seminar ReportLabTheory Standing Talk #2 by Yusaku Nishimiya on September 5, 2023
At this LabTheory Standing Talks, taken place at the third floor open space, Yusaku Nishimiya explained the effect of heavyion beam on yeast. Reported by Tsukasa Tada

20230827
Hot Topic3rd Summer School of Mathematical Biology
From the 23rd to the 25th of August 2023, the 3rd Summer School of Mathematical Biology took place at Sokendai University (Hayama, Kanagawa Prefecture). It was a lecture camp organized primarily by our iTHEMS colleagues, Daiki Kumakura and Keiichi Morita. The topics included virus evolution, immune response, coexistence theories in biology and rapid evolution, human migration and its processes, optimization strategies in marine organism reproduction, and modeling biological metabolism. At the summer school, Tetsuo Hatsuda (iTHEMS Director) also participated as an attendee. In the end, there was a fruitful event, including an introduction to iTHEMS. The summer school will be held again next year.

20230825
Seminar ReportExploring 2D Quantum Spacetime Based on Causal Dynamical Triangulations by Yuki Sato on August 21, 2023
The fourth set of intensive lectures organised by the iTHEMS Quantum Gravity Gatherings study group has now concluded. Approximately 15 participants joined this three day event in which we were given a comprehensive overview of the causal dynamical triangulations (CDT) approach to 2D quantum spacetime. Leading affairs was Dr Yuki Sato of the National Institute of Technology, Tokuyama College, who presented in a tightly organised and very pedagogical manner. Following some brief motivations for the CDT approach to quantum gravity and a summary of the numerical understanding of the theory in 4D, Satosan began with an overview of discrete geometry in Lorentzian spaces and used this to introduce Lorentzian Regge calculus. The fundamental idea here is to realise curvature as a conical defect at certain codimension 2 regions of piecewiseflat manifolds. We concluded the first day by using this to construct the Lorentzian EinsteinRegge action in arbitrary dimension before specialising to the 2D case. We began the second day by explicitly quantising this 2D action and then proceeded to take its continuum limit, allowing for the deduction of the quantum Hamiltonian of the theory. We then briefly covered the formalism of 2D projectable Hořava–Lifshitz (PHL) gravity and demonstrated the equivalence of this theory to 2D CDT by showing that PHL gravity is described by the same Hamiltonian as in the CDT case. On the third day we learnt about a generalisation of the 2D CDT model allowing for topology change to occur, employing ideas from string field theory in the process; we studied a dual matrix model representation of the theory and derived an effective quantum Hamiltonian including the contribution of such wormhole configurations. Finally we saw how topology change in 2D generalised CDT could be realised in terms of stochastic timedependent fluctuations of the cosmological constant in line with the socalled Coleman mechanism. In addition to the scientific activities above we had a number of short talks on the first and second days of the event by participants as well as a banquet on the first day where we were joined by several iTHEMS members. The intimate nature of the event lead to the active participation of attendees and overall a very lively and productive learning environment. Reported by Christy Koji Kelly

20230824
Paper of the WeekWeek 4, August 2023
Title: Universality in quasinormal modes of neutron stars with quarkhadron crossover Author: Hajime Sotani, Toru Kojo arXiv: http://arxiv.org/abs/2308.11494v1 Title: KramersKrönig approach to the electric permittivity of the vacuum in a strong constant electric field Author: Hidetoshi Taya, Charlie Ironside arXiv: http://arxiv.org/abs/2308.11248v1 Title: de Sitter space is sometimes not empty Author: Vijay Balasubramanian, Yasunori Nomura, Tomonori Ugajin arXiv: http://arxiv.org/abs/2308.09748v1 Title: Plant GARDEN: a portal website for crosssearching between different types of genomic and genetic resources in a wide variety of plant species Author: Hisako Ichihara, Manabu Yamada, Mitsuyo Kohara, Hideki Hirakawa, Andrea Ghelfi, Takuro Tamura, Akihiro Nakaya, Yasukazu Nakamura, Sachiko Shirasawa, Samatchaya Yamashita, Yosuke Toda, Daijiro Harada, Tsunakazu Fujishiro, Akiko Komaki, Jeffrey A. Fawcett, Eiji Sugihara, Satoshi Tabata, Sachiko N. Isobe Journal Reference: BMC Plant Biology 23, 391 (2023) doi: https://doi.org/10.1186/s12870023043928 Title: Genome sequencing reveals the genetic architecture of heterostyly and domestication history of common buckwheat Author: Jeffrey A. Fawcett, Ryoma Takeshima, Shinji Kikuchi, Euki Yazaki, Tomoyuki KatsubeTanaka, Yumei Dong, Meifang Li, Harriet V. Hunt, Martin K. Jones, Diane L. Lister, Takanori Ohsako, Eri OgisoTanaka, Kenichiro Fujii, Takashi Hara, Katsuhiro Matsui, Nobuyuki Mizuno, Kazusa Nishimura, Tetsuya Nakazaki, Hiroki Saito, Naoko Takeuchi, Mariko Ueno, Daiki Matsumoto, Miyu Norizuki, Kenta Shirasawa, Chengyun Li, Hideki Hirakawa, Tatsuya Ota, Yasuo Yasui Journal Reference: Nature Plants volume 9, pages 1236–1251 (2023) doi: https://doi.org/10.1038/s41477023014741

20230823
Press ReleaseDeciphering the Buckwheat Genome  HighPrecision Genome Sequence Illuminates the Past and Future of Buckwheat 
As the world population is expected to reach 9.7 billion by 2050, the dependence on the three major cereals  rice, wheat, and corn  is becoming a concern. In response, interest in "orphan crops" is increasing, which have high value as food but whose research has lagged, leaving their potential untapped. Determining the genomes of orphan crops using nextgeneration sequencing technology is expected to promote their efficient breeding and contribute to the achievement of SDGs such as eradicating hunger and improving nutrition. An international collaborative research group (including Jeffrey Fawcett, iTHEMS) deciphered the genome sequence of buckwheat, an orphan crop cultivated in Eurasia that is used for making soba noodles in Japan, at the chromosomal level with high precision, revealing the evolution of the buckwheat genome and the origin of cultivated buckwheat. Moreover, they modified the predicted genes using methods that do not rely on genome editing technology. As a result, they successfully developed a glutinous buckwheat and a new selfpollinating buckwheat that did not previously exist. The breeding methods used in this study are expected to contribute to the improvement of a wide variety of orphan crops in which genome editing technology cannot be used. For more information, please see the Kyoto University press release article at the related links.

20230817
Paper of the WeekWeek 3, August 2023
Title: Deconfinement transition in the revolving bag model Author: Kazuya Mameda, Keiya Takizawa arXiv: http://arxiv.org/abs/2308.07310v1 Title: Universality of Effective Central Charge in Interface CFTs Author: Andreas Karch, Yuya Kusuki, Hirosi Ooguri, HaoYu Sun, Mianqi Wang arXiv: http://arxiv.org/abs/2308.05436v1

20230817
AwardYixin Guo received two awards for his presentation
Yixin Guo (iTHEMS JRA/Univ. Tokyo) received two awards for his presentation on Aug. 10 at the A3F Summer School 2023. 1. Outstanding presentation award at Young Scientists Session at the A3F Summer School 2023, with the title "Cooper quartet correlations in infinite symmetric nuclear matter". 2. Asian Nuclear Physics Association & AAPPSDNP Award for Young Scientist (1st place) for his outstanding presentation "Cooper quartet correlations in infinite symmetric nuclear matter". Congratulations, Yixin!

20230816
Seminar Report3rd QGG Intensive Lectures: Spinfoam path integrals for Quantum Gravity by Etera Livine on July 26, 2023
The 3rd Intensive Lecture by iTHEMS’ Quantum Gravity Gatherings concluded with resounding success. Around 30 enthusiasts, including students, junior and senior researchers from various disciplines, convened at the RIKEN Wako Campus to learn and discuss spinfoam quantum gravity. Prof. Etera Livine from ENS Lyon, our distinguished lecturer this time, delivered a fantastic 3day lecture about the spinfoam approach to quantum gravity (QG). He began with a wonderful introduction explaining why physicists have long sought the theory of quantum gravity: the ultimate theory that unifies physics at both macroscopic and subatomic scales. Prof. Livine highlighted various existing candidates for quantum gravity theory and forged connections among these diverse approaches. Regarding the main topic, he started with the basics of loop quantum gravity and clearly explained the origin of the fundamental discreteness of spacetime. In the latter half of his lecture, he detailed how to construct the spinfoam path integral for QG in 3D before moving on to the 4D case. He concluded his lecture by discussing the limitations of this approach and outlining future directions. Throughout his lecture, he consistently elaborated on the mathematical similarities between these QG approaches and other areas of physics, such as condensed matter physics. This allowed the audience to grasp the current advancements in the field, recognizing how their areas of expertise, seemingly distant from quantum gravity, could intricately interlace with it. This event presented a great opportunity for fostering interdisciplinary research, as it brought together people with various interests, including physicists working on highenergy physics, gravity, cosmology, and condensed matter systems, as well as pure mathematicians. Everyone exhibited keen enthusiasm for quantum gravity, creating an atmosphere of unity and togetherness that permeated the room. Many interesting questions were posed during the lecture, and participants enthusiastically engaged in discussions during coffee breaks. Some of them also shared their stories and work during the short talk sessions, and everyone enjoyed the banquet on the second day. Overall, this event provided a relaxed and active platform for learning, offering an exceptional opportunity to strengthen connections and friendships among participants, particularly those in the early stages of their research careers. Reported by Puttarak Jaiakson

20230811
Seminar ReportHigher Algebra in Geometry by Hiro Lee Tanaka on July 31, 2023
8 days of introductory lectures on Higher Algebra (infinity categories) were given by Dr. Hiro Lee Tanaka (Texas State University). Recent developments on infinitycategory theory and their applications have received attraction from various areas of mathematics, including geometric topology, symplectic geometry, and algebraic geometry. The lectures were targeted to students and researchers interested in applications of infinitycategorical tools. The first day was devoted to nonspecialists, where Dr. Tanaka introduced the concept of associativity and homotopies, and explained how they naturally lead us to the ideas of infinitycategories. From the second day, Dr. Tanaka introduced the basic concepts of infinitycagetories together with familiar examples. In the second week, some of the works of Dr. Tanaka were given as applications of the ideas of inifitycategories. His aim was to show us that these concepts are not mere abstractions, but are accessible and usefully applicable to concrete questions of geometry. The participants also shared their own works and interests after the lectures, and lively discussions took place. Reported by Taketo Sano

20230810
AwardNagisa Hiroshima received "Toyama Daiichi Bank Scholarship Foundation Award"
Nagisa Hiroshima (Toyama Univ. and iTHEMS Visiting Scientist) received "Toyama Daiichi Bank Scholarship Foundation Award (Incentive Award)". The citation for the award is "Theoretical research on dark matter using astrophysical approach". The award ceremony was held on July 7, 2023 at Toyama Daiichi Bank Head Office. The certificate and catalog of research grants were handed over to Nagisa by the Vice Governor of Toyama Prefecture. Congratulations, Nagisa!

20230810
Paper of the WeekWeek 2, August 2023
Title: Mediuminduced bosonic clusters in a BoseFermi mixture: Towards simulating cluster formations in neutronrich matter Author: Yixin Guo, Hiroyuki Tajima arXiv: http://arxiv.org/abs/2308.04738v1 Title: Onedimensional spinless fermions with attractive two and threebody forces Author: Yixin Guo, Hiroyuki Tajima arXiv: http://arxiv.org/abs/2308.04737v1 Title: Activityinduced ferromagnetism in onedimensional quantum manybody systems Author: Kazuaki Takasan, Kyosuke Adachi, Kyogo Kawaguchi arXiv: http://arxiv.org/abs/2308.04382v1 Title: Universal entanglement signatures of interface conformal field theories Author: Qicheng Tang, Zixia Wei, Yin Tang, Xueda Wen, W. Zhu arXiv: http://arxiv.org/abs/2308.03646v1 Title: On the Scottish Book Problem 155 by Mazur and Sternbach Author: Michiya Mori arXiv: http://arxiv.org/abs/2308.03339v1 Title: On the shape of correlation matrices for projections and unitaries Author: Michiya Mori arXiv: http://arxiv.org/abs/2308.03345v1 Title: Is the Coleman de Luccia action minimum?: AdS/CFT approach Author: Naritaka Oshita, Yutaro Shoji, Masahide Yamaguchi arXiv: http://arxiv.org/abs/2308.02159v1

20230803
Paper of the WeekWeek 1, August 2023
Title: Calculating compositeparticle spectra in Hamiltonian formalism and demonstration in 2flavor QED$_{1+1\text{d}}$ Author: Etsuko Itou, Akira Matsumoto, Yuya Tanizaki arXiv: http://arxiv.org/abs/2307.16655v1 Title: Two dimensional lattice with an imaginary magnetic field Author: Tomoki Ozawa, Tomoya Hayata arXiv: http://arxiv.org/abs/2307.14635v1

20230802
Person of the WeekSelfintroduction: Yuta Sekino (2023)
I am Yuta Sekino. After finishing my Ph. D at Tokyo Institute of Technology in 2019, I worked in RIKEN as a JSPS Postdoctoral Fellow (201921) and Postdoctoral Researcher in ABBL (202123). During 20212023, I also belonged to iTHEMS as a concurrent member. In July 2023, I officially joined iTHEMS as a Postdoctoral Researcher associated with RIKEN Quantum. I am a theoretical condensedmatter physicist mainly working on ultracold atomic systems. My main research interest is superfluidity, superconductivity, and spin transport. Because these phenomena have been widely discussed not only in condensedmatter physics but also in nuclear physics and astrophysics, I would like to collaborate with iTHEMS researchers working in these fields. As a member of RIKEN Quantum, I also would like to apply quantum computational methods to nonequilibrium phenomena such as postquench dynamics in quantum spin systems. Because quantum computing would have the potential to tackle unsolved problems in every field of science, I would be happy to have interdisciplinary discussions in RIKEN Quantum. At iTHEMS, I hope to broaden my research horizon through discussions with researchers in various fields.

20230802
Person of the WeekSelfintroduction: Steffen Backes
Hello! My name is Steffen Backes, and I just joined RIKEN Quantum as a Senior Scientific Researcher. My research interest is focused on the physics and phenomena that can be found in strongly correlated electron systems, such as transition metal oxides, cuprate and ironbased superconductors, nickelate materials, or other lowdimensional lattice systems. In these systems the Coulomb repulsion between electrons gives rise to unexpected emergent phenomena such as magnetism, charge order, superconductivity, the metaltoinsulator transition, changes in their optical properties, and many more. My particular interest lies in going beyond an effective singleparticle description of the electronic system, using perturbative and nonperturbative methods. For this, I am employing the GW approximation, Dynamical meanfield theory and its extensions such as cluster methods, or combinations in the form of GW+DMFT. In iTHEMS I will investigating how current Quantum processors, or "Noisy Intermediate Scale Quantum" (NISQ) devices can be used to solve the problems we encounter when studying such correlated electron systems with stateoftheart numerical methods. Since these devices are inherently noisy, the development of faulttolerant algorithms is one of my major goals.

20230802
Person of the WeekSelfintroduction: Yaokun Lei
My name is YaoKun Lei, and I joined iTHEMS in August 2023. I am originally from a city in the south of China. After finishing my undergraduate studies, I pursued a Ph.D. at Peking University, where I focused on studying the significant role of dynamic solvent effects in chemical reactions in condensed phases using enhanced sampling methods. Upon completing my Ph.D., I became a visiting scholar at the ShenZhen Bay Laboratory. During this period, I developed efficient strategies for rare event sampling and reaction coordinate analysis without prior knowledge of the reaction mechanism, using Reinforcement Learning and likelihood maximization techniques. In July 2021, I joined Theoretic Molecular Science Laboratory at RIKEN. Over the past two years, my research has been centered around developing accurate, efficient, and transferable machine learning force fields for systems embedded in external potentials, with the aim of accelerating QM/MM simulations using multiscale equivariant graph convolution networks. Looking ahead, I am enthusiastic about leveraging quantum computing to accelerate largescale molecular dynamics simulations. Specifically, I plan to utilize highprecision quantum computational results to expedite the parameterization of machine learning force fields. Additionally, I aim to enhance sampling in highdimensional spaces through quantum computing. During my time at iTHEMS, I hope to have the opportunity to collaborate with researchers from different disciplines and embark on exciting new explorations.

20230727
Paper of the WeekWeek 5, July 2023
Title: Universal properties of repulsive selfpropelled particles and attractive driven particles Author: Hiroyoshi Nakano, Kyosuke Adachi arXiv: http://arxiv.org/abs/2306.17517v1

20230726
Seminar ReportQuantum Matter Seminar by Xinloong Han on July 24, 2023
On July 24th, 2023, quantum matter SG hosted a seminar entitled "Electronic instabilities emerging from higherorder van Hove singularities", and the guest speaker was Xinloong Han, a Postdoctoral Fellow at the Kavli Institute for Theoretical Sciences, University of Chinese Academy of Sciences, China. Xinloong Han started by introducing van Hove singularity (VHS). Building on the conventional understanding of VHS points, Han introduced the concept of higherorder VHSs, which have recently been explored in ABCstacked trilayer graphene and twisted bilayer graphene. He elucidated the differences between conventional VHSs and higherorder VHSs, paving the way for a discussion on the enhanced nematicity driven by large flavor number with higherorder VHSs on the square and Kagome lattices. Towards the conclusion of his talk, Han shed light on the possibility of robust topological superconductivity emerging on the square lattice due to the interplay of spinorbital coupling and higherorder VHSs. This revelation presented a captivating insight into the advancements in the study of topological superconductors. Reported by ChingKai Chiu

20230721
Hot TopicThe Discovery Evening was held on June 22 at Wako Campus
The second onsite Discovery Evening since the COVID19 pandemic was held on June 22 at Wako Campus. 35 people attended the event, which was organized by the Research Personnel Affairs Section, RIKEN. José Said GutiérrezOrtega (Special Postdoctoral Researcher, iTHEMS) was one of the two speakers in the event. He gave a presentation titled "Natural history of cycads: Deciphering the Rosetta Stone of plant evolution." He explained that cycads existed from the time of the dinosaurs, but they were able to live on despite the dinosaurs going extinct. For more details, please visit the RIKENETIC website through the related link below. To access RIKENETIC, you will need to use the intranet.

20230720
Paper of the WeekWeek 4, July 2023
Title: Numerical simulation of photospheric emission in long gammaray bursts: prompt correlations, spectral shapes, and polarizations Author: Hirotaka Ito, Jin Matsumoto, Shigehiro Nagataki, Donald C. Warren, Maxim V. Barkov, Daisuke Yonetoku arXiv: http://arxiv.org/abs/2307.10023v1 Title: Continuum limit for Laplace and Elliptic operators on lattices Author: Keita Mikami, Shu Nakamura, Yukihide Tadano arXiv: http://arxiv.org/abs/2307.08894v1 Title: 4D Weyl Anomaly and Diversity of the Interior Structure of Quantum Black Hole Author: PeiMing Ho, Hikaru Kawai, Henry Liao, Yuki Yokokura arXiv: http://arxiv.org/abs/2307.08569v1 Title: Quasinormal modes of black holes encircled by a gravitating thin disk Author: CheYu Chen, Petr Kotlařík arXiv: http://arxiv.org/abs/2307.07360v1 Title: Complete characterization of robust perfect adaptation in biochemical reaction networks Author: Yuji Hirono, Ankit Gupta, Mustafa Khammash arXiv: http://arxiv.org/abs/2307.07444v1 Title: Cosmic ray processes in galactic ecosystems Author: Ellis R. Owen, Kinwah Wu, Yoshiyuki Inoue, H. Y. Karen Yang, Alison M. W. Mitchell arXiv: http://arxiv.org/abs/2306.09924v2 Title: SVD Entanglement Entropy Author: Arthur J. Parzygnat, Tadashi Takayanagi, Yusuke Taki, Zixia Wei arXiv: http://arxiv.org/abs/2307.06531v1

20230720
Seminar ReportDMWG Seminar by Slivia Manconi on July 10, 2023
As a nature of dark matter that feels gravity, dark matter in our Universe forms halos, which are gravitationallybounded macroscopic structures. The halo structure is highly hierarchical and the halo of our Milky Way, for example, hosts many subhalos inside. However, smaller halos below a certain scale could not be visible because they cannot host galaxies. If we look at the sky in gammaray wavelength, there are lots numbers of bright sources. Most of them are socalled active galactic nuclei (AGN), which are related to the powerful jet activities of black holes. A certain portion of point sources are not categorized yet. They could be AGNs, while it is also possible that they are bright due to DM annihilation occurring in compact and small subhalos in our Galaxy. Neural networks, which are tools we have obtained in this era, powerfully help us to obtain insights into the properties of unknown gammaray sources. Properties of known sources such as spectrum and population serve as data for the supervision of the neural network. The trained network is used to look for outliers in the gammaray unknown sources which can be candidates for subhalos emitting gammarays by DM annihilations. In this way, a conservative upper limit on the annihilation crosssection of DM is derived. The scheme is highly flexible and has many possibilities for extensions. In the near future, a huge amount of data, which is far beyond human ability to analyze all, from experiments in multiple wavelengths and probes should appear. The future of DM study assisted with machine learning should be bright. Reported by Nagisa Hiroshima

20230713
Paper of the WeekWeek 3, July 2023
Title: On the distance from a matrix to nilpotents Author: Michiya Mori arXiv: http://arxiv.org/abs/2307.04463v1 Title: Neural Polytopes Author: Koji Hashimoto, Tomoya Naito, Hisashi Naito arXiv: http://arxiv.org/abs/2307.00721v2

20230707
Seminar ReportABBLiTHEMS Joint Astro Seminar by Takatoshi Ko on July 7, 2023
Iras 00500+6713 is a bright nebula in the infrared, and Xray observations show it consists of diffuse region and strong illuminated central region. In addition, optical spectral observations have recently revealed that fast wind with about 15,000 km/s is blowing from the massive white dwarf at the center. The properties of this nebula and white dwarf are very similar to those theoretically predicted by the binary white dwarf merger. In addition, its position on the celestial sphere and the extent make it a prime candidate for the remnant of SN 1181, a historical supernova. In this seminar, Mr. Takatoshi Ko proposed that such a multilayered structure is formed by the collision between the remnant of SN 1181 and the stellar wind blowing from the central white dwarf, and succeeded in constructing a model that is consistent with the multiwavelength observations. The results show that the progenitor of SN 1181 is a binary white dwarf with 1.31.9 solar mass and that their merger triggered an explosion that ejected mass with 0.20.6 solar mass to form the present object. The extent of the Xray source concentrated in the center reveals that these winds began blowing within the last 30 years, and Mr. Takatoshi Ko discussed this property as well. Reported by Shigehiro Nagataki

20230706
Paper of the WeekWeek 2, July 2023
Title: Stringnet formulation of Hamiltonian lattice YangMills theories and quantum manybody scars in a nonabelian gauge theory Author: Tomoya Hayata, Yoshimasa Hidaka arXiv: http://arxiv.org/abs/2305.05950v1 Title: HBT signature for clustered substructures probing primordial inhomogeneity in hot and dense QCD matter Author: Kenji Fukushima, Yoshimasa Hidaka, Katsuya Inoue, Kenta Shigaki, Yorito Yamaguchi arXiv: http://arxiv.org/abs/2306.17619v1

20230703
Person of the WeekSelfintroduction: Jan SchuetteEngel
Hi, I'm Jan SchütteEngel and I recently started as a RIKENBerkeley fellow. My research focusses on gravitational waves (GWs) from the early and late universe. In particular, I'm interested in cosmological and astrophysical GW sources and what we can learn from the emitted GW signals about new physics phenomena. We expect many GW signals which encode new physics phenomena over a broad frequency range. Therefore, I also investigate novel detection ideas for GWs in frequency regimes that are difficult to probe with laser interferometers. Finally, I am working on novel ideas for axion dark matter direct detection. This line of research is highly interdisciplinary and often uses techniques from condensed matter physics and quantum sensing.

20230629
Paper of the WeekWeek 5, June 2023
Title: The Centimeter to Submillimeter Broad Band Radio Spectrum of the Central Compact Component in A Nearby TypeII Seyfert Galaxy NGC 1068 Author: Tomonari Michiyama, Yoshiyuki Inoue, Akihiro Doi arXiv: http://arxiv.org/abs/2306.15950v1 Title: Fractional time differential equations as a singular limit of the KobayashiWarrenCarter system Author: Yoshikazu Giga, Ayato Kubo, Hirotoshi Kuroda, Jun Okamoto, Koya Sakakibara, Masaaki Uesaka arXiv: http://arxiv.org/abs/2306.15235v1 Title: Spin transport between polarized Fermi gases near the ferromagnetic phase transition Author: Tingyu Zhang, Daigo Oue, Hiroyuki Tajima, Mamoru Matsuo, Haozhao Liang arXiv: http://arxiv.org/abs/2306.13536v1

20230622
Paper of the WeekWeek 4, June 2023
Title: Breaking new ground for quantum and classical simulations of $\mathrm{SU(3)}$ YangMills theory Author: Tomoya Hayata, Yoshimasa Hidaka arXiv: http://arxiv.org/abs/2306.12324v1 Title: Revisiting the extraction of charge radii of $^{40}$Ca and $^{208}$Pb with muonic atom spectroscopy Author: Hui Hui Xie, Tomoya Naito, Jian Li, Haozhao Liang arXiv: http://arxiv.org/abs/2306.09026v1 Title: The Average Number of Goldbach Representations and ZeroFree Regions of the Riemann ZetaFunction Author: Keith Billington, Maddie Cheng, Jordan Schettler, Ade Irma Suriajaya arXiv: http://arxiv.org/abs/2306.09102v1 Title: Resonant orbits of rotating black holes beyond circularity: discontinuity along parameter shift Author: CheYu Chen, HsuWen Chiang, Avani Patel arXiv: http://arxiv.org/abs/2306.08356v1 Title: Exotic Dehn twists on 4manifolds Author: Hokuto Konno, Abhishek Mallick, Masaki Taniguchi arXiv: http://arxiv.org/abs/2306.08607v1 Title: Evidence for the utility of quantum computing before fault tolerance Author: Youngseok Kim, Andrew Eddins, Sajant Anand, Ken Xuan Wei, Ewout van den Berg, Sami Rosenblatt, Hasan Nayfeh, Yantao Wu, Michael Zaletel, Kristan Temme, Abhinav Kandala Journal Reference: Nature 618, 500–505 (2023) doi: https://doi.org/10.1038/s41586023060963

20230622
Press ReleaseControl Simulation Experiments of Extreme Events  New Theories for Extreme Weather Control
A collaborative research team led by Takemasa Miyoshi (Team Leader, Data Assimilation Research Team, RIKEN Center for Computational Science (RCCS) / Deputy Program Director, iTHEMS) has revealed the controllability to prevent the occurrence of extreme phenomena such as heavy rainfall and high temperatures through lowdimensional ideal experiments. This research achievement is expected to contribute to the development of theoretical research aimed at controlling intensifying typhoons and torrential rains, thereby mitigating the threat of extreme weather disasters. For more details, please visit the related link.

20230621
Hot TopiciTHEMS Science Outreach Workshop 2023 was held on June 1618, 2023
On June 1618, we had Meeting on Outreach of RIKEN iTHEMS 2023 @Sendai & Zoom. This year the meeting was held at TOKYO ELECTRON House of Creativity 3F, Lecture Theater, Katahira Campus, Tohoku University. It was organized by RIKEN iTHEMS and Mathematical Science Center for Cocreative Society of Tohoku University and coorganised by Tohoku Forum for Creativity, Organization for Research Promotion, Tohoku University and RIKEN CPR, Prediction Science Laboratory. There were 37 people participated at TOKYO ELECTRON House of Creativity and 13 more by zoom. There were 19 talks at the venue and 2 talks by zoom. 4 talks were by members of iTHEMS explaining recent development in various fields in sciences. 8 talks were from universities or institutes on different aspects of research, where 2 were by exmembers of iTHEMS. 8 talks were given by journalists and 1 by MEXT. There was also 1 poster by a journalist, a display of photos of fingers of mathematicians, a display of monthly academic magazine. The participants consist of 9+4 members from RIKEN, 14+2 from universities and institutes, and 14+7 journalists (at venue + by zoom). The venue was so nicely organized and ideal for the meeting of 30  40 participants, and the lounge next to the conference room was comfortably clouded which greatly contributed the success of the meeting. We organized social gathering on the two evenings and which were also successful. We thank very much for the help of Profs. Yoshiaki Maeda and Hiroshi Suito for the warm hospitality. By the success of this meeting, we hope the continuation of Journalist in residence program and this workshop next year. Reported by Takashi Tsuboi

20230620
Press ReleaseEvidence for the utility of quantum computing before fault tolerance
Quantum computing promises to offer substantial speedups over its classical counterpart for certain problems. However, the implementation of faulttolerant quantum circuits is out of reach for current processors. The recent paper by Yantao Wu (RIKEN iTHEMS) together with the IBM and UC Berkeley teams demonstrates the measurement of accurate expectation values on a noisy IBMQ 127qubit processor for circuit volumes at a scale beyond bruteforce classical computation. In the regime of strong entanglement for the temporal dynamics of the transversefield Ising model, the quantum computer provides correct results for which leading classical approximations such as the tensor network methods break down. This represents evidence for the utility of quantum computing in a prefaulttolerant era. At the same time, their results will motivate and help advance classical approximation methods as both approaches serve as valuable benchmarks of one another.

20230619
Seminar ReportiTHEMS Biology Seminar by Dr. Yu Okamura on May 25, 2023
We had the pleasure to have Dr. Yu Okamura (The University of Tokyo) as an invited speaker of our Biology seminar of May 25th, 2023. Dr. Okamura introduced us to the mechanism that allow herbivory of Pieris butterflies on Brassicaceae plants (plants of the group of the mustard). Brassicaceae, as well as most plants, will defend from herbivores by producing chemical compounds that can be lethal, but at the same time, insects will need to evolve strategies to elude the chemical defenses of the plants. This relationship leads to an interesting coevolutionary pathway that has not been widely explored from the genomic perspective. In his study system, Dr. Okamura has performed experiments to research how the toxic chemical compounds derived from glucosinolates of plants are eluted by their butterfly herbivores thanks to the expression of two specific genes that produce proteins that decompose the glocusinolates into nonlethal metabolites. One of the two genes (NSP gene) is known to be expressed in most Pieris butterflies that feed on Brassicaceae plants, but in his research, Dr. Okamura found that another gene (MA gene) is complementary of the effect of the NSP gene. Using genome editing techniques (CRISPR/Cas9), Dr. Okamura showed that the absence of NSP or MA genes can be lethal for herbivores. It is concluded that, in combination, NSP and MA genes are necessary for Pieris butterflies to maintain herbivory on a wide variety of plants in the Brassicacae family. Reported by José Said GutiérrezOrtega

20230615
Paper of the WeekWeek 3, June 2023
Title: Shear and interface modes in neutron stars with pasta structures Author: Hajime Sotani arXiv: http://arxiv.org/abs/2306.07531v1 Title: Light Scalar Meson and Decay Constant in SU(3) Gauge Theory with Eight Dynamical Flavors Author: Lattice Strong Dynamics Collaboration, R. C. Brower, E. Owen, C. Rebbi, C. Culver, D. Schaich, K. K. Cushman, G. T. Fleming, A. Gasbarro, A. Hasenfratz, E. T. Neil, J. Ingoldby, X. Y. Jin, J. C. Osborn, E. Rinaldi, P. Vranas, E. Weinberg, O. Witzel arXiv: http://arxiv.org/abs/2306.06095v1 Title: Effective model and pairing tendency in bilayer Nibased superconductor La$_3$Ni$_2$O$_7$ Author: Yuhao Gu, Congcong Le, Zhesen Yang, Xianxin Wu, Jiangping Hu arXiv: http://arxiv.org/abs/2306.07275v1 Title: An unconditional Montgomery Theorem for Pair Correlation of Zeros of the Riemann Zeta Function Author: Siegfred Alan C. Baluyot, Daniel Alan Goldston, Ade Irma Suriajaya, Caroline L. TurnageButterbaugh arXiv: http://arxiv.org/abs/2306.04799v1 Title: On a smoothed average of the number of Goldbach representations Author: Daniel A. Goldston, Ade Irma Suriajaya arXiv: http://arxiv.org/abs/2306.04807v1

20230614
Press ReleaseRicoh and RIKEN Develop Unique Algorithm to Visualize Changing Points of Technological Trends from Literature Data
Ricoh Co., Ltd. (President and CEO: Akira Oyama) and RIKEN iTHEMS (Aoyama Hideaki, Senior Visiting Scientist / Wataru Soma, Visiting Scientist) have jointly developed an algorithm to quantitatively measure and understand the points of change in new trends from existing technical literature data. For more details, please visit Ricoh group's website through the related link below.

20230613
Seminar ReportiTHEMS Math Seminar by Mr. Kan Kitamura on June 7, 2023
In iTHEMS Math Seminar on June 7, 2023, Kan Kitamura gave us a talk on his recent research on quantum groups. In the first half of the talk, he introduced the definition of C*algebras and compact quantum groups. In the latter half of the talk, he explained his theorem on the classification of the discrete quantum subgroups of the quantum double of qdeformed simple Lie groups. The talk was highly clear and stimulating. Reported by Mizuki Oikawa

20230612
Research NewsRIKEN NEWS: Unraveling the Puzzle of Complex Ecosystems with Mathematical Models
Ryosuke Iritani (Senior Research Scientist, iTHEMS) is interviewed on the RIKEN website. Nature is home to a multitude of ecosystems, each teeming with a rich variety of organisms. Within these intricate webs of life, diverse species interact and adapt, giving rise to complex and fascinating structures. However, comprehending the inner workings of these ecosystems poses a significant challenge, owing to their inherent complexity. At RIKEN, a team of dedicated researchers is harnessing the power of mathematical models to elucidate the intricacies of ecosystems and unlock their enigmatic nature. To shed light on this endeavor, we turn to Ryosuke Iritani, who graciously provides us with insights into their ongoing work. To read more, please visit the related link.

20230608
Paper of the WeekWeek 2, June 2023
Title: Nuclear mass predictions based on deep neural network and finiterange droplet model (2012) Author: To Chung Yiu, Haozhao Liang, Jenny Lee arXiv: http://arxiv.org/abs/2306.04171v1 Title: Finiterange effect in the twodimensional densityinduced BCSBEC crossover Author: Hikaru Sakakibara, Hiroyuki Tajima, Haozhao Liang arXiv: http://arxiv.org/abs/2306.02127v1 Title: Quasimaps to quivers with potentials Author: Yalong Cao, Gufang Zhao arXiv: http://arxiv.org/abs/2306.01302v1 Title: Topological quadraticnode semimetal in a photonic microring lattice Author: Zihe Gao, Haoqi Zhao, Tianwei Wu, Xilin Feng, Zhifeng Zhang, Xingdu Qiao, ChingKai Chiu, Liang Feng Journal Reference: Nature Communications 14, 3206 (2023) doi: https://doi.org/10.1038/s41467023388613 Title: The origin of MeV gammaray diffuse emission from the inner Galactic region Author: Naomi Tsuji, Yoshiyuki Inoue, Hiroki Yoneda, Reshmi Mukherjee, Hirokazu Odaka doi: https://doi.org/10.22323/1.417.0037 arXiv: http://arxiv.org/abs/2306.00290v1

20230606
Person of the WeekSelfintroduction: Derek Beattie Inman
Hello! My name is Derek Inman, and I am a scientist at iTHEMS whose research is focused on cosmology. Our Universe contains a substantial amount of dark matter the behavior of which we broadly know, but the composition of which we don’t. I try to understand how different ideas for what dark matter is (particles? black holes? something else?) change how the Universe looks and evolves at various times and length scales. I am particularly interested in cosmological structure formation, which rapidly becomes a nonlinear problem and so I tend to use numerical simulations run on supercomputers to understand the relevant physics.

20230601
Paper of the WeekWeek 1, June 2023
Title: Survival Probability of Unstable States in CoupledChannels  nonexponential decay of "thresholdcusp" Author: Wren A. Yamada, Osamu Morimatsu, Toru Sato, Koichi Yazaki arXiv: http://arxiv.org/abs/2305.11695v2 Title: Chiral fermion in the Hamiltonian lattice gauge theory Author: Tomoya Hayata, Katsumasa Nakayama, Arata Yamamoto arXiv: http://arxiv.org/abs/2305.18934v1 Title: QCDBased Charge Symmetry Breaking Interaction and OkamotoNolenSchiffer Anomaly Author: Hiroyuki Sagawa, Tomoya Naito, Xavier RocaMaza, Tetsuo Hatsuda arXiv: http://arxiv.org/abs/2305.17481v1

20230601
Seminar ReportQuantum uncertainty of fields and its effect on entanglement generation in quantum particles by Mr. Yuki Sugiyama on May 31, 2023
The unification of gravity and quantum mechanics is one of the important problems. To elucidate the theory of quantum gravity, it is becoming more and more important to get any hint of the quantum nature of gravity. In particular, the quantumgravityinducedentanglement of masses (QGEM) scenario, which is expected to observe the quantum nature of nonrelativistic gravity, has recently attracted great attention. In this talk, Sugiyamasan showed the effect of relativistic fields on entanglement generation based on quantum field theory. We also discussed the relationship between the entanglement generation and quantum uncertainty of the fields. Reported by Shigehiro Nagataki

20230531
Seminar ReportiTHEMS Theoretical Physics Seminar by Dr. Masaki Tezuka on May 30, 2023
On May 30, Dr. Masaki Tezuka gave a talk on Spectral correlations and scrambling dynamics in SachdevYeKitaev(SYK) type models. He explained his recent studies on quantum chaotic features, quantum scrambling, and connections to holography and quantum error corrections in the SYKtype models. Reported by Yuta Sekino

20230530
AwardDr. Tomoki Ozawa selected to receive an Asian Young Scientist Fellowship
Dr. Tomoki Ozawa (Visiting Scientist, iTHEMS / Associate Professor, Advanced Institute for Materials Research (AIMR), Tohoku University) has been selected to receive an Asian Young Scientist Fellowship 2023. This fellowship aims to encourage and support young Asian scientists in three fields: 1) Life Science, 2) Physical Science, and 3) Mathematics and Computer Science. Dr. Ozawa has been selected in his contribution to the topological states in photonics crystals with synthetic dimensions and his exploration in the direction of manybody physics in synthetic and tunable AMO platforms. For more information, please see the related links.

20230528
Seminar ReportExploring GPT’s Influence on Natural Science and Mathematics on May 17, 2023
The emergence of ChatGPT has shocked the world. Its influence on our society is inestimable, both for its possibility and its potential risk. Together with MLPhys (Foundation of “Machine Learning Physics”), we held a workshop “Exploring GPT’s Influence on Natural Science and Mathematics” on 17th May, to discuss the influence of GPT particularly on natural science and mathematics. An introductory lecture on GPT (generative pretrained transformer) and LLM (large language model) was given by Mr. Shota Imai (The University of Tokyo), and an introductory lecture on proof assistant system (automated theorem proving) was given by Dr. Yoshihiro Mizoguchi (Kyushu University). Around 30 people attended in place, and over 400 people attended the workshop online. Lively discussion took place among specialists of Mathematics, Physics and Computer science. Reported by Taketo Sano (iTHEMS, RIKEN)

20230526
Seminar ReportMathPhys Seminar by Dr. Masazumi Honda on February 16, 2023
On Febururary 16, Masazumi Honda gave a talk. He explained his recent results on the relationship between Riemann hypothesis and fourdimensional N=4 supersymmetric YangMills theory. Reported by Keita Mikami

20230525
Paper of the WeekWeek 4, May 2023
Title: A Stochastic Approach To Reconstruct Gamma Ray Burst Lightcurves Author: Maria G. Dainotti, Ritwik Sharma, Aditya Narendra, Delina Levine, Enrico Rinaldi, Agnieszka Pollo, Gopal Bhatta arXiv: http://arxiv.org/abs/2305.12126v2 Title: Chiral anomaly in a (1+1)dimensional Floquet system under highfrequency electric fields Author: Kenji Fukushima, Yoshimasa Hidaka, Takuya Shimazaki, Hidetoshi Taya arXiv: http://arxiv.org/abs/2305.11432v1

20230525
Seminar ReportiTHEMS Math Seminar by Dr. Kohei Hayashi on May 24, 2023
On May 24, there was a math seminar by Kohei Hayashi. In the first part of his talk, he start by explaining the idea of the hydrodynamic limit and the fluctuating hydro dynamic limit. He then explained Markov chain and how to obtain the diffusion equation. In the second part, he explained KPZ equation and its universality. Reported by Keita Mikami
130 news in 2023