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175 news in 2022

20220215
Seminar ReportiTHEMS Biology Seminar by Dr. Gilberto Nakamura on February 10, 2022
Stochastic processes describe systems in which one or more variables fluctuate randomly. In the first part of the talk, I reviewed basic concepts in stochastic processes and how to express them in terms of localized spin operators and the probability vector (PV). This framework is convenient to compute statistics away from meanfield approximations because it can borrow methods traditionally used in manybody problems in Physics. The second part of the talk addressed the equation for the squared norm of the PV and its correspondence with the Rényi entropy. The general idea and challenges of employing estimates of the Rényi entropy were discussed shortly after. As a practical biological application, I explained the dynamical equations for averages and fluctuations in a simple stochastic epidemic model, highlighting the effects of noise and correlations in heterogeneous finite systems.

20220214
Seminar ReportiTHEMS Biology Seminar by Dr. Takashi Okada on December 23, 2021
The Hidden Markov Models (HMM) have been used in a variety of fields for different purposes. I reviewed HMM and basic algorithms such as the forward algorithm. Then, I explained how this statistical framework can be applied to biological problems.

20220214
Research NewsRIKEN Research: Modeling highharmonic generation without resorting to perturbation theory
An advanced mathematical model that can describe highenergy interactions between light and matter has been developed by two RIKEN researchers and a collaborator [1]. The approach could be extended to offer new insights in other areas of physics. Highharmonic generation is a powerful technique that converts laser light from one wavelength, or color, to another. Put simply, it converts a lowenergy, longwavelength photon into multiple higher energy, shorter wavelength photons. Highharmonic generation has several applications. For example, it offers a way to create tabletop sources of extreme ultraviolet or xray light using lasers, rather than expensive synchrotron facilities. Highharmonic generation can also produce ultrashort light pulses, as short as one attosecond ($10^{18}$ second) or maybe even one zeptosecond ($10^{21}$ second), which are useful for imaging extremely rapid processes such as those that occur in atoms. But highharmonic generation is inherently difficult to model mathematically, and thus understand fully. Now, Hidetoshi Taya and Masaru Hongo from the RIKEN Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS) Program, together with their colleague Tatsuhiko Ikeda from the University of Tokyo, have developed an analytical approach to highharmonic generation in the socalled nonperturbative regime for the first time. To read more, please visit the related link.

20220209
Hot Topic"RIKEN AIPSurijoshi Joint Seminar" was held on January 29, 2022
On 29th January, a joint seminar of RIKEN AIP and SuriJoshi took place and Ryosuke Iritani served as one of the guest speakers (including the iTHEMS affiliates Drs. Motoko Kato and Ade Irma Suriajaya). Unfortunately, the overwhelming COVID19 situation in Tokyo did not allow for an inperson seminar as had been originally planned, which was indeed a bit disappointing for me. Nevertheless, thanks to the huge effort of AIP staff as well as SuriJoshi organizers, we had a very successful talk session as well as Q&A session. I found the high diversity among the speakers considerably enriched our discussion. In this pandemic era, I can easily imagine many students struggling how to find dreams or what they want to be, which would have been already difficult even under normal circumstances. We emphasized that learning what you are interested in is a precious experience, which is the best motivating factor to work as a scientist. I hope the audience enjoyed our discussion, but as usual, I bet it was me who enjoyed best asif one of the audience. I cannot thank too much to SuriJoshi organizers and AIP staff for inviting me, to the speakers whom I was not able to meet in person this time but look forward to meeting in the near future, to the mathematically enthusiastic, professional announcer Naoko Shinozaki for her moderation of the sessions, and of course to the promising students who are deeply interested in learning and studying, for attending the seminar and asking excellent questions! Reported by Ryosuke Iritani

20220209
Paper of the WeekWeek 2, February 2022
Title: The double detonation of a double degenerate system, from Type Ia supernova explosion to its supernova remnant Author: Gilles Ferrand, Ataru Tanikawa, Donald C. Warren, Shigehiro Nagataki, Samar SafiHarb, Anne Decourchelle arXiv: http://arxiv.org/abs/2202.04268v1 Title: Detecting PreformedPair Current through Nonequilibrium Noise in the BCSBEC Crossover Author: Hiroyuki Tajima, Daigo Oue, Mamoru Matsuo, Takeo Kato arXiv: http://arxiv.org/abs/2202.03873v1 Title: Delocalized spectra of Landau operators on helical surfaces Author: Yosuke Kubota, Matthias Ludewig, Guo Chuan Thiang arXiv: http://arxiv.org/abs/2201.05416v1 Title: Bounds in Nonequilibrium Quantum Dynamics Author: Zongping Gong, Ryusuke Hamazaki arXiv: http://arxiv.org/abs/2202.02011v1 Title: Universal constraint on nonlinear population dynamics Author: Kyosuke Adachi, Ryosuke Iritani, Ryusuke Hamazaki arXiv: http://arxiv.org/abs/2202.02028v1 Title: Impact of Dissipation on Universal Fluctuation Dynamics in Open Quantum Systems Author: Kazuya Fujimoto, Ryusuke Hamazaki, Yuki Kawaguchi arXiv: http://arxiv.org/abs/2202.02176v1

20220209
Event ScheduleEvents for the 3rd week of February 2022
Monday, February 14, 13:00– 17:30 Workshop: Towards the Use of Data Assimilation for COVID19 Investigations Monday, February 14, 15:00– 17:30 Workshop: MACS Colloquium Tuesday, February 15, 13:30– 15:00 NEW WG Seminar Friday, February 18, 12:30 13:30 Coffee Meeting Friday, February 18, 14:00 15:00 ABBL/iTHEMS Astro Seminar Friday, February 18, 16:30 18:00 Seminar: iTHEMS  RCCS(FTRT) Joint Online Seminar: Second order chiral phase transition in three flavor quantum chromodynamics?

20220208
Hot TopicSSH Seminar "When highschool mathematics is useful in biology" was held on February 4, 2022
On February 4th, 2022, Ryosuke Iritani gave an online lecture on mathematical biology, entitled “高校で学ぶ数学が生物研究で活きるとき”（“when highschool mathematics is useful in biology”） for a Super Science Highschool program at Takatsuki Junior and Senior High School. I started off with how a scientific career develops and what it is like to work as a scientist. I then delved into a scientific world, and demonstrated high school mathematics is a powerful tool to research in biology, drawing examples from the Fibonacci series in genetics, Price equation using recursive equations, game theory with matrix algebra, and kin selection theory for ants' society. I closed the talk with an encouragement for the motivated, budding scientists, that learning and studying are both extremely fun. I thank Kandasensei for inviting me to such a fantastic opportunity, as well as SuriJoshi for giving me the opportunity to write an article that made this lecture possible by drawing Kandasensei's attention! Reported by Ryosuke Iritani

20220203
Paper of the WeekWeek 1, February 2022
Title: Spin relaxation rate for heavy quarks in weakly coupled QCD plasma Author: Masaru Hongo, XuGuang Huang, Matthias Kaminski, Mikhail Stephanov, HoUng Yee arXiv: http://arxiv.org/abs/2201.12390v1 Title: Filtered instanton Floer homology and the homology cobordism group Author: Yuta Nozaki, Kouki Sato, Masaki Taniguchi arXiv: http://arxiv.org/abs/1905.04001v4 Title: Seifert hypersurfaces of 2knots and ChernSimons functional Author: Masaki Taniguchi arXiv: http://arxiv.org/abs/1910.02234v3 Title: Stable pairs and GopakumarVafa type invariants on holomorphic symplectic 4folds Author: Yalong Cao, Georg Oberdieck, Yukinobu Toda arXiv: http://arxiv.org/abs/2201.11540v1

20220202
Seminar ReportDMWG Seminar by Dr. Kenji Kadota on January 31, 2022
Weakly Interacting Massive Particles (WIMPs) have long been a leading candidate of dark matter(DM). However, no signatures are found in any kinds of experiments. Investigation of the alternatives is now rapidly growing. Primordial black holes (PBHs), which are formed in the early Universe and source the gravitational potential for baryonic components to evolve, are being widely discussed and searched now. Recent progress of the gravitational, as well as electromagnetic, observations of the Universe already excludes a large portion of the parameter space of PBH as DM. So if it contributes to DM, it is natural to also consider contributions from other components such as WIMPs. In such a situation, PBHs are dressed with WIMP halos. Then WIMP annihilation proceeds in the vicinity of the central PBH and a cored structure is expected depending on the annihilation rate. This dependence of the core structure on the annihilation rate leads to a tricky behavior in the constraints for PBHWIMP mixed scenarios. Also, when PBHs are abundantly formed, we cannot neglect their clustering effects on the constraints obtained in the observable Universe because the dressed PBH with WIMP indicates the clustering of WIMP halos in host galaxies. In this case, the boost factor, which appears naturally in the scenario of pure WIMP DM models, needs to be evaluated in such a way that regarding the clustering of PBHs. Those interesting phenomena are only a part of examples that we can expect in the PBHWIMP mixed scenario for DM. Varieties of possibilities are waiting for our investigations. Discussions are blooming now! Reported by Nagisa Hiroshima

20220202
BookEvolutionary Ecology of Parasites
Authors: Robert Poulin Translation: Hirotaka Katahira, Ryota Kawanishi and Ryosuke Iritani Language: Japanese Translated from "Evolutionary Ecology of Parasites: Second Edition" ( Princeton University Press, 2007) by Robert Poulin

20220128
Seminar ReportQuantum Matter SG seminar by Prof. Rafael I. Nepomechie on January 26, 2022
The Quantum Matter Study Group invited Prof. Rafael Nepomechie from the University of Miami to talk about the Bethe ansatz and realizing Bethe states in quantum computers. In the beginning, he used the Heisenberg chain to introduce the coordinate Bethe ansatz. In condensed matter physics, it is extremely difficult to solve manybody Hamiltonians. For this specific Heisenberg model, Bethe came up with a judicious method for finding the exact manybody wave function. The manybody problem is transformed to solving the Bethe equations. Unfortunately, it is also hard to solve these equations completely. Prof. Nepomechie presented an alternative approach to find the exact wave function and hence the solution to the Bethe equations through quantum computation. He found that, by using specific quantum operations, the exact wave function of the Heisenberg model can be presented in the quantum computer with a probability decaying as the factorial of the number magnons that make up the wave function. It is interesting to learn about this connection between the Bethe ansatz and quantum computing. Discussions were made how to increase the probability of the discussed scheme and how to extend it to find the complete set of Bethe roots for larger systems. Reported by Thore Posske (University of Hamburg, Germany) and ChingKai Chiu

20220128
Seminar ReportiTHEMS Biology Seminar by Prof. Kenta Ishimoto on January 27, 2022
We successfully had a great time thanks to Dr. Kenta Ishimoto's fantastic talk, in which he talked about the basic background of fluid dynamics, followed by two topics of his own research. Thank you again for the fantastic talk! Reported by Ryosuke Iritani

20220127
Paper of the WeekWeek 5, January 2022
Title: GopakumarVafa type invariants of holomorphic symplectic 4folds Author: Yalong Cao, Georg Oberdieck, Yukinobu Toda arXiv: http://arxiv.org/abs/2201.10878v1 Title: Universal Properties of Weakly Bound TwoNeutron Halo Nuclei Author: Masaru Hongo, Dam Thanh Son arXiv: http://arxiv.org/abs/2201.09912v1 Title: On the evolution of the Hubble constant with the SNe Ia Pantheon Sample and Baryon Acoustic Oscillations: a feasibility study for GRBcosmology in 2030 Author: Maria Giovanna Dainotti, Biagio De Simone, Tiziano Schiavone, Giovanni Montani, Enrico Rinaldi, Gaetano Lambiase, Malgorzata Bogdan, Sahil Ugale arXiv: http://arxiv.org/abs/2201.09848v2 Title: Foundations and Applications of Quantum Kinetic Theory Author: Yoshimasa Hidaka, Shi Pu, Qun Wang, DiLun Yang arXiv: http://arxiv.org/abs/2201.07644v1 Title: Global study of the scalar quasinormal modes of KerrAdS${}_5$ black holes: Stability, thermality, and horizon area quantization Author: Issei Koga, Naritaka Oshita, Kazushige Ueda arXiv: http://arxiv.org/abs/2201.07267v1

20220125
Seminar ReportNEW WG Seminar by Mr. Tomohiro Tanogami on January 20, 2022
Tomohiro Tanogami from Kyoto University gave a talk titled "A simple XY model for cascade transfer." Cascade transfer is a ubiquitous phenomenon that appears in various physical systems. During a cascade transfer an inviscid conserved quantity such as energy is transferred conservatively from large/small to small/large scales, which results in a universal scaling law in the spectrum (e.g., Kolmogorov energy spectrum). In the talk, Tomohiro proposed a simple XY model which shows inverse energy cascade with a nonKolmogorov energy spectrum and pointed out that the model may characterize a novel "universality class" of cascade transfer. Tomohiro also explained possible relations between his model and, e.g., spin and atmospheric turbulences. About 20 physicists have joined the seminar and enjoyed discussions from various viewpoints. Reported by Hidetoshi Taya

20220124
Press ReleaseOrigin of Diverse Response Patterns in Signal Transduction  Determining Response Properties by Integrating Experiment and Theory
The ERBB family of receptors, consisting of ERBB1, ERBB2, ERBB3, and ERBB4, is a group of receptors that receive external signaling molecules. When the ERBB receptors receive signaling molecules, they bind to one another and induce phosphorylation reactions, leading to macroscopic responses such as cell proliferation and differentiation. However, it is difficult to measure the details of the binding and phosphorylation reactions of the ERBBs, and it has not been known how the various responses to signals are produced. In this study, we conducted experimental measurements using cells with various compositions of ERBBs and multiple signaling molecules and constructed a mathematical model, which incorporates all possible reactions of ERBBs. By applying the mathematical model, we succeed in explaining and predicting the experimental results on phosphorylation responses. Furthermore, we identified the reactions that play an essential role in the diversity of the phosphorylation responses. Our findings may allow us to control cell responses such as proliferation and differentiation in the future. For more details, please see the press release article from Kyoto University at related links.

20220120
Event ScheduleEvents for the 5th week of January 2022
Thursday, January 27, 10:00– 11:00 iTHEMS Biology Seminar Friday, January 28, 12:30 Coffee Meeting Saturday, January 29, 15:30 16:40 RIKEN AIPSurijoshi Joint Seminar

20220120
Seminar ReportiTHEMS Biology Seminar by Dr. Hiroyasu Miyazaki on January 20, 2022
In the iTHEMS Biology Seminar on 20th January, Dr. Hiroyasu Miyazaki (RIKEN iTHEMS) gave a talk on the topological aspect of chemical reaction network. His talk is composed of two parts: motivation and result part and method part. In the first part, he mentioned the reduction of the chemical reaction network in E. Coli and its result which shows the same steady state as that before the reduction. In the second part, he explained how the network should be reduced. The topological information of the network can be described by using the matrix and the vector. He explained that the quotient network is defined to have a sequence of linear maps called “exact sequence”, which describes the relation among the original network, the subnetwork and the quotient network. We enjoyed his beautiful talk. From the audiences, the lively discussion arose during and after the talk. Thank you very much, Hiroyasu! Reported by Hiroshi Yokota

20220120
Paper of the WeekWeek 4, January 2022
Title: Currentinduced inverse symmetry breaking and asymmetric critical phenomena at currentdriven tricritical point Author: Masataka Matsumoto, Shin Nakamura arXiv: http://arxiv.org/abs/2201.06894v1 Title: Global study of the scalar quasinormal modes of KerrAdS${}_5$ black holes: Stability, thermality, and horizon area quantization Author: Issei Koga, Naritaka Oshita, Kazushige Ueda arXiv: http://arxiv.org/abs/2201.07267v1

20220118
Seminar ReportDMWG Seminar by Dr. Kanji Mori on January 17, 2022
In this era of multimessenger astronomy, axionlike particle (ALP) searches using astrophysical transients are now excitingly discussed. ALPs are an extended class of particles from QCD axion, which could solve the strong CP problem of the Standard Model, and dark matter (DM) candidates of various connections to the physics beyond the Standard Model. ALPs could interact with our sector through their coupling to the photon, electron, and/or nucleons. The coupling of ALP to the photon is previously investigated using observations of SN 1987A, the most famous supernova explosion. MeV gammaray signals are expected when considering the conversion of ALP outside the stellar envelope, hence no observations of the associated gammaray emission to the supernova lead to the constraint on the coupling strength, for example. Also, the existence of such coupling should modify the dynamics of supernovae. When a star explodes, the difference between the masses of the progenitor star and the resulting compact object sources the radiation, neutrino emission, and kinetic energy of the ejecta material. ALP could be an additional channel for the energy release while its absorption heats the supernova. The balance between heating and cooling controls the supernova dynamics and shock restoration, which directly relates to the electromagnetic observables. Dr. Mori has shown that the heating rate is very sensitive to the coupling strength and enhancement of the electromagnetic emission is expected in the presupernova stage. The signatures could also be visible in the neutrino sector after the explosion. The results are fantastic, and there are a lot of things to do. For example, the inclusion of the ALPnucleon coupling effects is an interesting direction to pursue. Updates in the understanding of stellar models are important as well. We should see the signature of ALP in the near future in this field! Reported by Nagisa Hiroshima

20220117
Seminar ReportiTHEMS Biology Seminar by Dr. Wataru Nishima on January 13, 2022
Dr. Wataru Nishima (New Mexico Consortium, USA) gave a very interesting presentation about his published paper on the spike protein of the SARSCoV2, the virus which causes COVID19 [1]. He described the conformational change which the SARSCoV2 spike protein undergoes when it fuses with the host cell to initiate infection. His work offers and interesting alternative view of the process wherein parts of the spike protein ends up inside the host cell. This differs from the usual view where the spike protein would be left on the outside of the cell after virus fusion with the host. This alternative hypothesis could have important implication for better understanding disease severity, e.g. based on the possible toxic effect of spike protein components shed as part of the fusion process. Dr. Nishima's expertise is primarily in Molecular Dynamics and Bioinformatics and he is very interested to establish new collaborations with iTHEMS members. Reported by Catherine Beauchemin

20220117
Hot TopicReading the World through the Window of Math Focusing on the Sensitivity of Young Researchers
A column article about "Reading the World through the Window of Math" appeared on Imagineer Co., Ltd. Ten Minutes TV. The article is based on the coauthored book "Reading the World through the Window of Math: Exploring Prime Numbers, AI, Biology, and the Universe" (edited by Tetsuo Hatsuda and Ryosuke Shibato, Iwanami Shoten), which was written by young researchers from iTHEMS. Please see the related link for details.

20220114
Research NewsRIKEN NEWS: Uncovering the laws of evolution hidden in genomic information
Senior Research Scientist Jeffrey Fawcett is interviewed on the RIKEN website. Life on Earth has been around for about 4 billion years. Over the years, organisms have evolved into a wide variety of species. This is also the history of how the genomes have evolved. Jeffrey Fawcett (Senior Research Scientist, iTHEMS) is trying to unravel the mystery of how the differences between species arose by taking a mathematical science approach. To read more, please see the related link.

20220113
Paper of the WeekWeek 3, January 2022
Title: Biexcitonlike quartet condensates in an electronhole liquid Author: Yixin Guo, Hiroyuki Tajima, Haozhao Liang arXiv: http://arxiv.org/abs/2201.03031v1 Title: Optimized TwoBaryon Operators in Lattice QCD Author: Yan Lyu, Hui Tong, Takuya Sugiura, Sinya Aoki, Takumi Doi, Tetsuo Hatsuda, Jie Meng, Takaya Miyamoto arXiv: http://arxiv.org/abs/2201.02782v1 Title: A MeerKAT, eMERLIN, H.E.S.S. and Swift search for persistent and transient emission associated with three localised FRBs Author: James O. Chibueze, et al.; H.E.S.S. Collaboration (Naomi Tsuji) arXiv: http://arxiv.org/abs/2201.00069v1 Title: Analyticity of the energy in an Ising spin glass with correlated disorder Author: Hidetoshi Nishimori Journal Reference: J. Phys. A 55, 045001 (2022) doi: https://doi.org/10.1088/17518121/ac44ef arXiv: http://arxiv.org/abs/2110.01196v2 Title: The hyperon spectrum from lattice QCD Author: Nolan Miller, Grant Bradley, M. A. Clark, Ben Hörz, Dean Howarth, Malcolm Lazarow, Henry MongeCamacho, Amy Nicholson, Enrico Rinaldi, Pavlos Vranas, André WalkerLoud arXiv: http://arxiv.org/abs/2201.01343v1 Title: A path integral derivation of the equations of anomalous Hall effect Author: Kazuo Fujikawa, Koichiro Umetsu arXiv: http://arxiv.org/abs/2201.01104v1 Title: Gravitational wave asteroseismology on cooling neutron stars Author: Hajime Sotani, Akira Dohi arXiv: http://arxiv.org/abs/2201.00648v1 Title: NonEquilibrating a Black Hole with Inhomogeneous Quantum Quench Author: Kanato Goto, Masahiro Nozaki, Kotaro Tamaoka, Mao Tian Tan, Shinsei Ryu arXiv: http://arxiv.org/abs/2112.14388v1 Title: Chaos by Magic Author: Kanato Goto, Tomoki Nosaka, Masahiro Nozaki arXiv: http://arxiv.org/abs/2112.14593v1 Title: Cooling of Isolated Neutron Stars with Pion Condensation: Possible Fast Cooling in a LowSymmetryEnergy Model Author: Akira Dohi, Helei Liu, Tsuneo Noda, Masaaki Hashimoto arXiv: http://arxiv.org/abs/2112.13302v1 Title: Dynamical stability and filamentary instability in holographic conductors Author: Shuta Ishigaki, Shunichiro Kinoshita, Masataka Matsumoto arXiv: http://arxiv.org/abs/2112.11677v2

20220113
Event ScheduleEvents for the 4th week of January 2022
Monday, January 17, 11:00– 12:00 DMWG Seminar Thursday, January 20, 10:00– 11:00 iTHEMS Biology Seminar Thursday, January 20, 13:30– 15:00 NEW WG Seminar Friday, January 21, 12:30 Coffee Meeting

20220112
Seminar ReportiTHEMS Biology Seminar by Prof. Tetsuya Yamamoto on January 6, 2022
On January 6th, Prof. Tetsuya Yamamoto gave us a comprehensive talk about the physical aspects of nuclear bodies. He first introduced the liquidliquid phase separation and other selfassembly mechanisms in softmatter physics, such as micelle formation, with motivations from the experimental side. In the main part, he told us about three recent topics regarding how RNAs' dynamics and sequence properties lead to different types of assembly of nuclear bodies. The mathematical formulation, schematic figures, and comparisons with experiments were clear to understand. We are very grateful to Prof. Yamamoto for the exciting seminar. Reported by Kyosuke Adachi
175 news in 2022