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Exciting Possibilities of Multi-Messenger Windows on Cosmic Accelerators

2025年9月9日(火) 13:30 - 15:00

安田 航一朗 (Ph.D. Student, Department of Physics and Astronomy, University of California, Los Angeles, USA)

Active Galactic Nuclei (AGN) jets are among the most extreme particle accelerators in the universe and are thought to play a key role in the origin of ultra-high-energy cosmic rays. Yet, the physical processes inside these jets, particularly those involving heavy nuclei, remain poorly understood. In this talk, I will explore how nuclear and atomic processes in AGN jets can leave distinctive multi-messenger signatures, from neutrino production via nuclear decays to characteristic gamma-ray features from nuclear excitations. These phenomena offer a new window into the microscopic physics of nuclei under astrophysical extreme conditions, while also serving as macroscopic probes of jet composition and acceleration mechanisms. I will also discuss how upcoming observations, including neutrino flavor studies and MeV gamma-ray missions, could provide critical tests of these ideas and shed light on the role of nuclear physics in shaping cosmic accelerators.

会場: セミナー室 (359号室) 3階 359号室とZoomのハイブリッド開催

イベント公式言語: 英語

Geometry of 2d topological field theories and integrable hierarchies

2025年9月4日(木) 15:00 - 17:00

テツ・オウ (理化学研究所 数理創造研究センター (iTHEMS) 数理基礎部門 研究員)

In this talk, I will explain a mathematical formulation of 2d topological field theories making use of integrable hierarchies, which is a framework initiated by B. Dubrovin and developed by many other mathematicians. The talk is divided into two parts. The first 45 minutes is a gentle introduction on how the mathematical structure called Frobenius manifolds naturally appears from topological field theories. The remaining part of the talk is devoted to explaining relationships between Frobenius manifolds and integrable hierarchies via the example of the KdV hierarchy.

会場: セミナー室 (359号室) 3階 359号室 (メイン会場) / via Zoom

イベント公式言語: 英語

Synthesizing the evolutionary invasion analysis for high-dimensional population dynamics

2025年9月4日(木) 13:00 - 14:00

入谷 亮介 (理化学研究所 数理創造研究センター (iTHEMS) 数理基礎部門 上級研究員)

I will present a linear-algebraic (spectral) method for analyzing nonnegative matrices to study the dynamics of natural selection. This is a joint project with Troy Day (Queen's University, Canada). Within adaptive dynamics theory, evolutionary invasion analysis provides a powerful framework for studying adaptive evolution. It allows us to evaluate (i) whether a new type of individuals (mutants) can successfully invade and replace the resident type, and (ii) whether recurrent substitutions converge to an equilibrium that resists further invasion (an evolutionary Nash equilibrium). A central task is to quantify the reproductive success of mutants, which corresponds to computing the spectral radius (largest eigenvalue) of a nonnegative matrix. However, the high dimensionality of population dynamics often makes the analytical treatment of eigenvalues intractable. To address this problem, we have developed a methodology that applies to any high-dimensional adaptive dynamics system. I will first introduce the principles of adaptive dynamics and the associated eigenvalue problem. I will then present our new method, which translates the high-dimensional eigenvalue problem into another, lower-dimensional eigenvalue problem of arbitrary size, using (i) Perron–Frobenius theory and (ii) graph-theoretic arguments.

会場: セミナー室 (359号室) 3階 359号室とZoomのハイブリッド開催

イベント公式言語: 英語

Dust formation in the universe: reconstructing of theoretical models

2025年8月29日(金) 14:00 - 15:15

田中 今日子 (東京女子大学 現代教養学部 情報数理科学科 特任准教授)

The formation process of cosmic dust is the starting point of solid matter and is important for understanding the evolution of cosmic material and planet formation processes. The nucleation process at the initial stage of the phase transition is a key to how cosmic dust is formed and evolves. Recent studies of the nucleation have shown possibilities that are very different from the theoretical models that have been considered so far. We have investigated the nucleation process using molecular dynamics simulations, which allow us to observe the nucleation process at the molecular level and obtain new information. We also present our attempt to develop and reconstruct a new theoretical model to elucidate a comprehensive picture of cosmic dust formation in collaboration with experiments.

会場: セミナー室 (359号室) 3階 359号室とZoomのハイブリッド開催

イベント公式言語: 英語

Shadow formation in gravitational collapse: redshift and blueshift by spacetime dynamics

2025年8月28日(木) 16:00 - 17:30

古賀 泰敬 (大阪工業大学 情報科学部 情報知能学科 助教)

A black hole illuminated by a background light source is observed as a black hole shadow. For a black hole formed by the gravitational collapse of a transmissive object, redshift of light due to the spacetime dynamics is expected to play a crucial role in the shadow formation. In this talk, we investigate the redshift of light caused by the spacetime dynamics. First, we consider a spherical shell model. We see that the collapse of a shell typically leads to the redshift of light, while blueshift can be also observed in some cases. This result suggests that a shadow image is generally formed in the late stage of the gravitational collapse of a transmissive object. Second, we consider a general, dynamical, spherically symmetric spacetime and propose a new covariant formula for the redshift of light. This formula relates the dynamical redshift to the energy-momentum tensor of the background spacetime and provides its intuitive interpretation with Newtonian analogy.

会場: via Zoom / セミナー室 (359号室) 3階 359号室とZoomのハイブリッド開催

イベント公式言語: 英語

The link between ecology and evolution in the speciation process

2025年8月28日(木) 13:00 - 14:00

ホセ サイード・グティエレス オルテガ (理化学研究所 数理創造研究センター (iTHEMS) 数理基礎部門 研究員)

Both ecological and evolutionary processes shape biodiversity, but these are usually studied separately. Ecologists focus on current dynamics, while evolutionary biologists examine long-term changes. The intersection between the two perspectives lies in understanding speciation: the process of how new species arise. Understanding speciation can clarify how ecological processes build up into the global patterns we see in evolution, and in turn, how evolutionary trends promote ecological processes. Using observational data compiled from macroecological and phylogenetic methods on multiple plant and animal groups, I suggest that the ecological patterns left by the factors promoting speciation in a community correspond to the speciation/extinction dynamics within that community. This ecological-phylogenetic correspondence represents a connection between the ongoing and the long-term dynamics, an idea that may unify the disciplines of ecology and evolution. I expect this talk can promote discussion on the topics of eco-evolutionary dynamics, so that I can get some feedback from you, and that we can create chances for collaboration.

会場: セミナー室 (359号室) (メイン会場) / via Zoom

イベント公式言語: 英語

磁気回転効果による中性子星の自転と中性子スピンの間の角運動量変換

2025年8月28日(木) 10:00 - 12:00

舟木 博志 (慶応義塾大学 理工学部 特任助教)

[NOTE] 本インフォーマルセミナーは長瀧天体ビッグバン研究室により主に企画されており、日本語で行われます。また、GWX-EOS Working Group および iTHEMS-ABBL Joint Astro Study Groupとのジョイントイベントです。 概要: 本講演では、中性子星のクラストとコアの間で角運動量が交換される新たなメカニズムを、磁気回転効果を介して提案する。拡張された流体力学を用いることで、中性子星の自転に相当するマクロな角運動量と、中性子の軌道およびスピンから生じるミクロな角運動量の相互作用を取り込む。クラストにおけるマクロスケールな回転がコア内のミクロスケール角運動量に影響を与え、中性子スピン偏極を引き起こすことを明らかにし、(反)グリッチの代替シナリオを提案する。本研究は、中性子星物理学でこれまで見逃されていたマルチスケール角運動量相互変換を浮き彫りにし、磁気回転天文学の新たな道が拓かれると期待される。

会場: セミナー室 (359号室) 3階 359号室とZoomのハイブリッド開催

イベント公式言語: 日本語

Analysis of inflationary models in higher-dimensional uniform inflation

2025年8月27日(水) 16:00 - 18:00

廣瀬 拓哉 (九州産業大学 教育研究施設 基礎教育サポートセンター 特任助教)

In this talk, we consider higher-dimensional uniform inflation, in which the extra dimensions expand at the same rate as three-dimensional non- compact space during inflation. We compute the cosmological perturbation in $D+4$ dimensions and derive the spectral index $n_s$ and the tensor- scalar ratio $r$. We analyze five inflationary models: chaotic inflation, natural inflation, quartic hilltop inflation, inflation with spontaneously broken SUSY, and $R^2$ inflation. By combining the results from these models with the Planck 2018 constraints, we discuss that it is not desirable for the extra-dimensional space to expand at the same rate as the three-dimensional non-compact space, except for the case of one extra dimension. This talk is based on arXiv:2501.13581[hep-ph].

会場: セミナー室 (359号室)

イベント公式言語: 英語

Observational constraint of non-scalar phantom dark energies

2025年8月26日(火) 16:00 - 17:30

Hsu-Wen Chiang (Postdoc, Department of Physics, Southern University of Science and Technology, China)

Recent observation of DESI strongly disfavors cosmological constant. Given the lack of constraint regarding the fundamental field that constitutes a dynamical dark energy, people traditionally resort on a hypothetical scalar field. We instead consider minimally coupled non-spinless field as alternative, specifically the extended Proca-Nuevo theory (spin-1) and 3-form field (spin-3). Both theories at the background level permit pure phantom (w < -1) and phantom crossing (w < -1 to w > -1) scenarios. Furthermore, with reasonable choice of EFT parameters we can decouple the scalar perturbation of the dark energy from the matter sector. However, the Lorentz constraint within the higher-spin field inevitably modifies the response of the scalar potential to the matter perturbation. This leads to an enhancement of the matter power spectrum most obvious in BAO fullshape analysis. We then perform MCMC analysis and show that the Hubble tension is alleviated, and the non-spin-0 models are preferred marginally over a cosmological constant.

会場: セミナー室 (359号室) 3階 359号室とZoomのハイブリッド開催

イベント公式言語: 英語

Tamely Ramified Geometric Langlands Correspondence

2025年8月22日(金) 15:00 - 19:00

Yuki Matsubara (Ph.D. Student, Centre for Quantum Mathematics, University of Southern Denmark, Denmark)

The geometric Langlands correspondence (GLC) is a geometric analogue of the Langlands conjecture in number theory, relating algebraic geometry, representation theory, and many other areas. Since A. Kapustin and E. Witten pointed out the relation between GLC and mirror symmetry, there have been various studies on GLC from a physics perspective as well as a mathematical perspective. First talk: An introduction to Langlands conjecture for everyone This is an entirely accessible overview of the Langlands conjecture. Starting from famous topics, such as the Pythagorean theorem and Fermat’s Last Theorem, I will introduce the statement and motivations behind the Langlands conjecture. No prior background will be assumed, and technical details will often be sketched rather than fully developed, so that anyone with a general mathematical curiosity can follow along. Second talk: On a certain tamely ramified geometric Langlands correspondence In this talk, I will present my research. Arinkin’s 2001 result established the geometric Langlands correspondence for the case G = SL2 on the complex projective line P1 with four fixed regular singularities. When one attempts to extend this to five or more singularities, it turns out to be more natural to decompose the correspondence into a Radon transform-type correspondence and a “GLC‑like” correspondence. I will report on the calculations of cohomology that support the proof of this GLC‑like correspondence in the P1 with five fixed regular singularities case.

会場: via Zoom / セミナー室 (359号室) 3階 359号室

イベント公式言語: 英語

Detecting ghost ancestors in the human lineage

2025年8月21日(木) 13:00 - 14:00

シュパイデル 玲雄 (理化学研究所 数理創造研究センター (iTHEMS) 数理基礎部門 数理遺伝学理研ECL研究ユニット 理研ECL研究ユニットリーダー)

イベント公式言語: 英語

Dynamic Scaling Analysis for Enzymatic Degradation and Network Growth of DNA Liquid Droplets

2025年8月14日(木) 13:00 - 14:00

舘野 道雄 (JSPS Overseas Research Fellow, Material Research Laboratory, University of California Santa Barbara, USA)

In this talk, I will introduce two novel pattern formation dynamics exhibited by phase-separated liquid droplets composed of DNA nanoparticles: 1) By enzymatically inactivating the phase-separation ability of the nanoparticles, we observed the process by which droplets gradually disappeared. Notably, the droplet-size distribution density remained unchanged, while only the total number of droplets decreased over time. 2) We also observed the formation of a novel two-dimensional wire-like network pattern, in which two types of droplets are arranged in a one-dimensional, alternating manner. We confirmed that the characteristic size of the network follows power-law growth over nearly two decades, with a universal growth exponent that is independent of droplet viscosity and inter-droplet wetting affinity. We analyze these results within the framework of the dynamic scaling hypothesis and discuss the physical mechanisms underlying these behaviors.

イベント公式言語: 英語

Crossroads of Virology and Mathematical Sciences

2025年8月8日(金) 9:30 - 17:30

竹田 誠 (東京大学 大学院医学系研究科 教授)
山次 康幸 (東京大学 農学生命科学研究科 教授)
氣駕 恒太郎 (国立健康危機管理研究機構 室長)
藤田 大士 (京都大学 高等研究院 (KUIAS) 准教授)
小磯 深幸 (九州大学 名誉教授)
黒田 大祐 (日本大学 文理学部 生命科学科 准教授)
カトゥリン・ボシゥメン (理化学研究所 数理創造研究センター (iTHEMS) 副センター長)
谷川 眞一 (東京大学 大学院情報理工学系研究科 准教授)
橋口 隆生 (京都大学 医生物学研究所 教授)
福原 秀雄 (北海道大学 人獣共通感染症国際共同研究所 准教授)
小嶋 将平 (理化学研究所 生命医科学研究センター (IMS) ゲノム免疫生物学理研白眉研究チーム 基礎科学特別研究員)
宮下 脩平 (東北大学 大学院農学研究科 助教)
富安 亮子 (九州大学 マス・フォア・インダストリ研究所 教授)
鈴木 雄太 (国立研究開発法人科学技術振興機構 (JST) 専任研究者)
Adnan Sljoka (理化学研究所 革新知能統合研究センター (AIP))

午前セッション①（ウイルス） 10:00–10:20 麻疹ウイルス工学 竹田 誠（東大 医学系研究科） 10:20–10:40 ポテックスウイルスに対する植物免疫機構 山次 康幸（東大 農学生命科学研究科） 10:40–11:00 ファージの巧妙な感染戦略と細菌の防御応答 氣駕 恒太郎（感染研） 休憩（11:00–11:15） 午前セッション②（分子・数理） 11:15–11:35 多面体型の分子自己集合体を自在に設計する 藤田大士（京大 高等研究院） 11:35–11:55 Anisotropic energy and (curved) polyhedron 小磯 深幸（九大） 11:55–12:15 自然界に倣う二成分タンパク質集合体のデザイン：細胞骨格様構造からウイルス様構造へ 鈴木 雄太（JSTさきがけ） 昼休憩（12:15–13:20） 午後セッション①（計算・数理） 13:20–13:40 Computer-aided antibody design 黒田 大祐（日本大学 生命科学科） 13:40–14:00 Revealing Protein Allostery and Functional Dynamics via Rigidity Theory and NMR Adnan Sljoka（理研 革新知能統合研究センター） 14:00–14:20 Using mathematical models to identify experimental pitfalls when probing virus replication in vitro Catherine Beauchemin（理研 iTHEMS） 14:20–14:40 Combinatorics behind statics and flexibility of graphs 谷川 眞一（東大 情報理工） 休憩（14:40–14:55） 午後セッション②（構造） 14:55–15:15 Glycoprotein structures in human pathogenic RNA viruses 橋口 隆生（京大 医生物） 15:15–15:35 北海道大学におけるクライオ電子顕微鏡設備の紹介 福原 秀雄（北大 人獣共通感染症研） 休憩（15:35–15:50） 午後セッション③（ウイルス・数理） 15:50–16:10 ウイルス感染時の宿主応答のヒト集団遺伝学 小嶋 将平（慶應大 Bio2Q） 16:10–16:30 陸上植物の自殺型抗ウイルス集団抵抗性 宮下 脩平（東北大 農学研究科） 16:30–16:50 Mathematical and crystallographic perspectives in virology 富安 亮子（九大 IMI） 組織委員: Catherine Beauchemin（理研 iTHEMS） 竹田 誠（東大 医学系研究科） 富安 亮子（九大 IMI）

会場: 研究本館 3階 359号室 (メイン会場) / via Zoom

iTHEMS Cosmology Forum #4 - Evolving Cosmos: new physical insights from new spectroscopic data

2025年8月4日(月) - 5日(火)

Seshadri Nadathur (Associate Professor, University of Portsmouth, UK)
Andrei Cuceu (NASA Einstein Fellow, Lawrence Berkeley National Laboratory (LBNL), USA)
Gerrit Farren (Postdoc, Lawrence Berkeley National Laboratory (LBNL), USA)
Antonio De Felice (京都大学 基礎物理学研究所 准教授)
Linda Blot (東京大学 カブリ数物連携宇宙研究機構 (Kavli IPMU) 特任助教)
殷 文 (東京都立大学 大学院理学研究科 物理学専攻 准教授)

iTHEMS Cosmology Forum Workshop is a series of short workshops, each focusing on an emerging topics in cosmology. The target audience is cosmologists, high-energy physicists and astronomers interested in learning about the subject, not just those who have already worked on the topic. The goal of the workshop is to provide working knowledge of the topic and leave dedicated time for discussions to encourage mutual interactions among participants. The fourth workshop is dedicated to new physics discoveries enabled by new spectroscopic data. Nearly three decades after the discovery of accelerated expansion, there is at last compelling data pointing away from the simple cosmological constant. The results of new data hint at evolving dark energy, but the statistical significance and physical interpretation are both far from clear. Furthermore, another anticipated new physics measurement of the neutrino mass has also proven difficult. With this workshop, we aim to interrogate both the statistical evidence for new physics as well as the theoretical implications if these new results are confirmed. This forum will consist of two days. The workshop will be in English. The workshops are organised by the iTHEMS Cosmology Forum working group, which is the successor of the Dark Matter Working Group at RIKEN iTHEMS. Important dates: July 18 - Registration deadline August 4th, 5th - Workshop Days Invited Speakers: Sesh Nadathur (University of Portsmouth) Andrei Cuceu (LBNL) Gerrit Farren (LBNL) Antonio De Felice (YITP) Linda Blot (IPMU) Wen Yin (TMU)

会場: 研究本館 4階 435-437号室

イベント公式言語: 英語

Chemical and isotopic analyses of samples returned by the Hayabusa2 mission from the asteroid Ryugu

2025年8月1日(金) 14:00 - 15:30

横山 哲也 (東京科学大学 理学院 地球惑星科学系 教授)

The recent success of asteroid sample return missions has led to significant advances in Solar System science. JAXA's Hayabusa2 successfully retrieved and returned to Earth a total of 5.4 grams of samples from the C-type asteroid Ryugu. Sample return missions are critical to the scientific community, as they provide pristine, terrestrially unaltered extraterrestrial material. The analytical data obtained in laboratories for samples collected by space missions will facilitate the understanding of the formation and evolution of the Solar System. I was appointed deputy leader of the Initial Analysis Chemistry team of Hayabusa2 project, and was heavily involved in analyzing the chemical and isotopic compositions of Ryugu materials. A series of analyses of these samples indicated that the mineral, chemical, and isotopic compositions of Ryugu bear a strong resemblance to those of the Ivuna-type (CI) carbonaceous chondrites. CI chondrites have been recognized as a unique group of meteorites with a chemical composition similar to that of the solar photosphere except for highly volatile elements and Li. In the seminar, I will present the meaning and significance of the compositional similarity between Ryugu and CI chondrites. I will also present our recent activities in a new project called the Ryugu Reference Project, which was initiated to maximize the potential value of the returned samples.

会場: 理化学研究所和光キャンパス 本部棟2階大会議室 (メイン会場) / via Zoom

イベント公式言語: 英語

Targeting SARS-CoV-2 RNA: Insights for RNA-Directed Drug Discovery

2025年7月31日(木) 13:00 - 14:30

マリア・イヴォニナ (九州大学 エネルギー研究教育機構 学術研究員)

Traditional pharmacology fights virus infections by targeting proteins including enzymes, receptors, and structural proteins to break up the viral machinery. Nucleic acid-targeting therapies, on the other hand, can act directly on the genetic code of viruses, blocking their replication or translation in host cells. Coronaviruses and HIV are examples of RNA viruses that use a process called -1 programmed ribosomal frameshifting (-1 PRF) to produce their viral proteins. In this process, the translating ribosome is forced to shift into the alternative reading frame, replicating mRNA in the wrong order. Using small-molecule compounds to block this mechanism could be a promising way to neutralize such viruses. It is difficult to experimentally study the interactions between RNA and a drug candidate to understand where the drug binds and how it changes the shape of the viral RNA. I will discuss how Molecular Dynamics simulations are used to explore the conformational dynamics of mRNA structural elements and to investigate what happens when an antiviral agent binds to it. Additionally, I will show how the quantum-chemical orbital interaction analysis we developed, called Through-Space/Through-Bond Energy Decomposition Analysis (TS/TB-EDA), reveals which RNA nucleotides, at the atomic level, are critical for binding. This molecular modelling approach reveals strategies for targeting structured RNA elements — a crucial step toward expanding the arsenal of RNA-targeting therapeutics for future pandemics.

会場: 研究本館 3階 359号室とZoomのハイブリッド開催

イベント公式言語: 英語

iTHEMS NOW & NEXT 2025

2025年7月24日(木) - 25日(金)

We will hold this fiscal year’s annual in-house gathering, “iTHEMS NOW & NEXT,” as follows. This event is a rare opportunity for all iTHEMS members, including visiting researchers, to gain a comprehensive overview of iTHEMS’s current activities and future directions. Program July 24th 9:30-9:45 Opening by Director Iso 9:45-10:10 Keynote lecture Sonia Mahmoudi 10:10-10:35 Keynote lecture Masazumi Honda 10:35 20-min break 10:55 Fundamental Quantum Science Program (FQSP) introduction Working Group introduction 5-min each 11:30 Lunch break 13:30 Teams introduction part 1 RIKEN-Berkeley Center RIKENｰBerkeley Center (Shigehiro Nagataki) Mathematical Application Research Team (Motoko Kotani / Tsukasa Tada) 13:50 11 SG Presentation 5 min each 14:45 break 15:00 Flash talks & Poster session 18:00 Reception July 25th 9:30 Keynote lecture Yuto Yamamoto 9:55 Keynote lecture Kyosuke Adachi 10:20 break 10:40　Teams introduction part 2 Prediction Science Research Team (Takemasa Miyoshi) Medical Science Deep Learning Team (Jun Seita) Medical Science Data-driven Mathematics Team (Eiryo Kawakami) Quantum Mathematical Science Team (Tetsuo Hatsuda) Mathematical Social Science Team (Yohsuke Murase) 11:30 Lunch 13:30 Flash Talk & Poster presentation 16:30 Concluding remark

会場: 理化学研究所和光キャンパス 本部棟2階大会議室 (メイン会場) / via Zoom

イベント公式言語: 英語

Bridging applied math and quantum many-body physics and beyond via tensor methods

2025年7月23日(水) 16:00 - 17:00

品岡 寛 (埼玉大学)

In modern physics, high-dimensional functions and operators naturally arise in a wide range of contexts, including turbulence simulations, parameter-dependent partial differential equations (PDEs), and quantum field theory. Efficient representations and computations with such high-dimensional objects pose major challenges across disciplines. Dimensionality reduction techniques such as the Quantics Tensor Train (QTT) [1] and Tensor Cross Interpolation (TCI) [2] were originally developed in applied mathematics. In our work, we have extended these methods to quantum many-body problems, demonstrating their effectiveness in handling complex high-dimensional structures in theoretical physics [3–10]. Given their generality, QTT and TCI are expected to find applications beyond quantum theory itself, in fields such as statistical field theory, model reduction, and control of complex systems, where similar high-dimensional structures emerge. This presentation will first review the computational bottlenecks that arise in quantum many-body simulations and other high-dimensional problems. Then, we will introduce QTT and TCI from a broader, method-oriented perspective, aiming to bridge applied mathematics and quantum theoretical physics.

会場: セミナー室 (359号室) 3階 359号室とZoomのハイブリッド開催

イベント公式言語: 英語

A free probability approach to quantum chaos in random matrix ensembles

2025年7月22日(火) 16:00 - 17:00

プラティック・ナンディ (理化学研究所 数理創造研究センター (iTHEMS) 数理基礎部門 特別研究員)

In free probability theory, quantum chaos is marked by “free independence” between observables at early and late times, causing certain statistical measures (cumulants) to vanish. Motivated by this, we study the statistics of a time-evolved operator in the Rosenzweig-Porter (RP) random matrix ensembles. Analyzing operator statistics for different spin operators across these regimes reveals close alignment with free probability predictions in the ergodic phase, contrasted by persistent deviations in the fractal and localized phases even at late times. Using the distance measures and statistical methods, we define and characterize the onset of the free time in the ergodic phase. The talk is based on arXiv: 2506.04520.

会場: セミナー室 (359号室) 3階 359号室とZoomのハイブリッド開催

イベント公式言語: 英語

Peaks sphericity of non-Gaussian random fields

2025年7月22日(火) 10:30 - 12:00

上保 みちる (お茶の水女子大学 理学部 博士課程／日本学術振興会 特別研究員 DC)

We formulate the statistics of peaks of non-Gaussian random fields and implement it to study the sphericity of peaks. For non-Gaussianity of the local type, we present a general formalism valid regardless of how large the deviation from Gaussian statistics is. For general types of non-Gaussianity, we provide a framework that applies to any system with a given power spectrum and the corresponding bispectrum in the regime in which contributions from higher-order correlators can be neglected. We present an explicit expression for the most probable values of the sphericity parameters, including the effect of non-Gaussianity on the profile. We show that the effects of small perturbative non-Gaussianity on the sphericity parameters are negligible, as they are even smaller than the subleading Gaussian corrections. In contrast, we find that large non-Gaussianity can significantly distort the peak configurations, making them much less spherical.

会場: セミナー室 (359号室) 3階 359号室とZoomのハイブリッド開催

イベント公式言語: 英語