セミナー
615 イベント

セミナー
ShortLived Hawking Radiation Under Stringy Effects
2024年4月11日(木) 13:30  15:00
WeiHsiang Shao (Ph.D. Student, Department of Physics, National Taiwan University, Taiwan)
A UV theory is required in order to describe the origin of latetime Hawking radiation. In this talk, I will explore Hawking radiation in a nonlocal model of the radiation field inspired by Witten's open string field theory. An attempt at extracting the correlators of this theory will be discussed, which leads to a spacetime uncertainty relation. As a result, the characteristics of transPlanckian field modes differ significantly from that in the standard lowenergy effective theory, and I will argue that this ultimately results in the termination of Hawking radiation around the scrambling time of the black hole.
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

セミナー
A socioecological and genomic approach to mixedspecies formation of African forest guenons
2024年4月4日(木) 16:00  17:00
北山 遼 (北海道大学 大学院環境科学院 博士課程)
While many animal groups consist of a single species, some species have been observed forming mixedspecies groups (MSGs). It is thought that by forming groups with different species, animals may reduce predation risk, improve foraging efficiency, and even gain social and reproductive benefits. Redtailed monkeys and blue monkeys, African forest guenons (Tribe Cercopithecini), are known to form MSGs in several regions in Africa, despite the large niche overlap. The underlying mechanisms driving the formation of MSGs in redtailed monkeys and blue monkeys are still unclear. One reason is that previous studies have been limited to behavioral ecological approaches. By combining field observations with genomic analyses in the laboratory, we seek to shed light on the role of genetic factors in mediating interspecies interactions within MSGs. In this talk, I will introduce our studies on genomic introgression and gut microbiome sharing within the mixedspecies population of redtailed monkeys and blue monkeys in the Kalinzu Forest Reserve, Uganda.
会場: via Zoom
イベント公式言語: 英語

Quantum simulation of QCD matter: from hadronic scattering to gauge field qubit encoding
2024年4月3日(水) 10:00  11:00
Tianyin Li (Ph.D. Student, Institute of Quantum Matter, South China Normal University, China)
Recently, quantum computing (QC) has become a new method for solving nonperturbative problems in highenergy physics. Compared to traditional Monte Carlo simulations, the QC method does not encounter the sign problem, making it an effective approach for solving dynamical and finite density problems. The first part of this talk focuses on the quantum simulation of the hadronic scattering process, including the initial state parton distribution functions, intermediate state partonic scattering amplitudes, and final state hadronization. The second part of this talk concentrates on the qubit encoding of Hamiltonian formalism in lattice gauge field theory with a Coulomb gauge. As a preliminary attempt, the qubit encoding of (3+1)dimensional Coulomb gauge QED will be discussed.
会場: via Zoom
イベント公式言語: 英語

セミナー
Coarsegraining black holes out of equilibrium with boundary observables on time slice
2024年4月1日(月) 16:00  17:30
竹田 大地 (京都大学 素粒子論研究室 博士課程)
In black hole thermodynamics, defining coarsegrained entropy for dynamical black holes has long been a challenge, and various proposals, such as generalized entropy, have been explored. Guided by the AdS/CFT, we introduce a new definition of coarsegrained entropy for a dynamical black hole in Lorentzian Einstein gravity. On each time slice, this entropy is defined as the horizon area of an auxiliary Euclidean black hole that shares the same mass, (angular) momenta, and asymptotic normalizable matter modes with the original Lorentzian solution. The entropy is shown to satisfy a generalized first law within Einstein theory and, through holography, the second law as well. This second law corresponds to the positivity of the relative entropy in the CFT. Furthermore, by applying this thermodynamics to several Vaidya models in AdS and flat spacetime, we discover a connection between the second law and the null energy condition.
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

A Selective Survey of Ideas, Tools and Results in Constructive QFT II
2024年4月1日(月) 13:00  14:30
クリスティ・コウジ・ケリー (数理創造プログラム 基礎科学特別研究員)
In this talk we continue to discuss the constructive programme in rigorous QFT. Our aim is discuss a few points on difficulties in relation to the definition of Euclidean path integrals and the general strategy of constructive field theory from a constructive perspective. This will motivate a discussion of the fundamental results in probability theory which are the main tools for the construction of Euclidean path integral measures. We might also discuss some points in relation to free fields, including in particular difficulties in the characterisation of massless fields.
会場: via Zoom / セミナー室 (359号室)
イベント公式言語: 英語

セミナー
Fast Rotating Neutron Stars: Spectra, Stability and Universal Relations
2024年3月27日(水) 11:00  12:30
クリスチャン・クルーガー (Postdoctoral Researcher, University of Tuebingen, Germany)
In this talk, we study rapidly rotating relativistic stars which are present in various astrophysical systems. First, we study their oscillations and instabilities by taking into account the contribution of a dynamic spacetime. The study is based on the linearised version of Einstein’s equations and via this approach the oscillation frequencies as well as the critical values for the onset of a secular instability are determined. We show asteroseismological relations for the fundamental eigenfrequency which are crucial for tackling the inverse problem. Further, we provide universal relations that allow to estimate the moment of inertia (and other bulk quantities) from the knowledge of the triple mass, radius and moment of inertia of an associated nonrotating star. The proposed universal relations facilitate computationally cheap EOS inference codes that permit the inclusion of observations of rotating neutron stars. As a demonstration, we deploy them into a recent Bayesian framework for equation of state parameter estimation that is now valid for arbitrary, uniform rotation. The results are important for all stages of a neutron star’s life but particularly interesting in pre and postmerger cases. This seminar is held by GWEOS WG in iTHEMS.
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

セミナー
Arrhythmic activity rhythms in ants
2024年3月26日(火) 16:00  17:00
藤岡 春菜 (岡山大学 環境生命自然科学学域 助教)
Most organisms exhibit a periodic activity of about 24 h. This circadian rhythm is considered to be an adaptation to the fluctuations of the environment. In social insects such as honeybees and ants, individual behavior, including activityrest rhythms, is influenced by interactions within the colony. However, it is challenging to monitor individual activityrest rhythms in an ant colony due to their large group size and small body size. To address this, we developed an imagebased tracking system using 2D barcodes a monomorphic ant and measured the locomotor activities of all colony members under laboratory conditions. Activityrest rhythms appeared only in isolated ants, not under colony conditions. This suggests that a mixture of social interactions, not light and temperature, induces the loss of activityrest rhythms. These findings contribute to our understanding of the diverse patterns of circadian activity rhythms in social insects.
会場: via Zoom
イベント公式言語: 英語

セミナー
Multimessenger probes of superheavy dark matter decay and annihilation
2024年3月26日(火) 10:18  11:00
Saikat Das (京都大学 基礎物理学研究所 ポスドク研究員)
We revisit constraints on decaying very heavy dark matter (VHDM) using the latest ultrahighenergy cosmicray (UHECR; E >1e18 eV) data and ultrahighenergy (UHE) gammaray flux upper limits, measured by the Pierre Auger Observatory. We present updated limits on the VHDM lifetime for masses up to ∼ 1e15 GeV, considering decay into quarks, leptons, and massive bosons. In particular, we consider not only the UHECR spectrum but their composition data that favors heavier nuclei. Such a combined analysis improves the limits at <1e12 GeV because VHDM decay does not produce UHECR nuclei. We also show that the constraints from the UHE gammaray upper limits are ∼ 10 times more stringent than that obtained from cosmic rays, for all of the Standard Model final states we consider. The latter improves our limits to VHDM lifetime by a factor of two for dark matter mass >1e12 GeV. We also provide constraints using neutrino flux from dark matter decay, including the neutrinoinduced cascades. We consider the interaction of UHE neutrinos with the cosmic neutrino background, leading to the attenuation of the extragalactic flux reaching Earth, which improves our analysis to obtain tighter constraints.
会場: via Zoom
イベント公式言語: 英語

セミナー
The evolution of unusual inheritance and chromosome behaviour in flies and other critters
2024年3月14日(木) 16:00  17:00
Laura Ross (Senior Lecturer, Institute of Evolutionary Biology, University of Edinburgh, UK)
Under Mendelian inheritance, individuals receive one set of chromosomes from each of their parents, and transmit one set of these chromosomes at random to their offspring. Yet, in thousands of animals Mendel's laws are broken and the transmission of maternal and paternal alleles becomes unequal. Why such nonMendelian reproductive systems have evolved repeatedly across the tree of life remains unclear. My lab studies a variety of arthropod species to understand why, when and how the transmission of genes from one generation to the next deviate from Mendel’s laws. We mainly focus on species with Paternal Genome Elimination: Males transmit only those chromosomes they inherited from their mother to their offspring, while paternal chromosomes are excluded from sperm through meiotic drive. I will present recent work aimed at understanding the evolution of this unusual reproductive strategy in a clade of flies. These flies arguably have one of the most bizarre and complex chromosome systems of any insect and we use this complexity to study a range of topics including the evolution of sex chromosomes, germlinerestricted chromosomes and sexual conflict.
会場: セミナー室 (359号室) / via Zoom
イベント公式言語: 英語

セミナー
Brane field theory with higherform symmetry
2024年3月12日(火) 14:00  15:30
川名 清晴 (Research Fellow, Korea Institute for Advanced Study (KIAS), Republic of Korea)
We propose field theory for branes with higherform symmetry as a generalization of ordinary Landau theory. The field \psi[C_p^{}] becomes a functional of pdimensional closed brane Cp embedded in a spacetime. As a natural generalization of ordinary field theory, we call this theory brane field theory. In order to construct an action that is invariant under higherform transformation, we first generalize the concept of “derivative” for higherdimensional objects. Then, we discuss various fundamental properties of the brane field based on the higherform invariant action. It is shown that the classical solution exhibits the area law in the unbroken phase of U(1) pform symmetry, while it indicates a constant behavior in the broken phase for the large volume limit of Cp. In the latter case, the lowenergy effective theory is described by the pform Maxwell theory. If time permits, we also discuss branefield theories with a discrete higherform symmetry and show that the lowenergy effective theory becomes a BFtype topological field theory, resulting in topological order.
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

Macroscopic neutrinoless double beta decay: long range quantum coherence
2024年3月6日(水) 15:30  17:30
ゴードン・ベイム (Professor Emeritus, University of Illinois, USA)
This talk will introduce the concept of ``macroscopic neutrinoless double beta decay" (MDBD) for Majorana neutrinos. In this process an antineutrino produced by a nucleus undergoing beta decay, $X\to Y + e^ + \bar \nu_e$, is absorbed as a neutrino by another identical $X$ nucleus via the inverse beta decay reaction, $\nu_e + X \to e^+Y$. The distinct signature of MDBD is that the total kinetic energy of the two electrons equals twice the endpoint energy of single beta decay. The amplitude for MDBD, a coherent sum over the contribution of different mass states of the intermediate neutrinos, reflects quantum coherence over macroscopic distances, and is a new macroscopic quantum effect. We discuss the similarities and differences between the MDBD and conventional neutrinoless double beta decay, as well as give estimates of the rates of MDBD and backgrounds.
会場: 研究本館 3階 359号室とZoomのハイブリッド開催 (メイン会場) / via Zoom
イベント公式言語: 英語

セミナー
Do plants have bones? Silica phytoliths and their role and fate in the development of terrestrial plants and human civilizations
2024年3月1日(金) 14:00  15:15
Mikhail Blinnikov (Professor, St. Cloud State University, USA)
Silicon is the second most common element in the Earth’s crust. Some families of higher plants evolved mechanisms for soluble silica to be carried by xylem from groundwater and deposited as plant opal in or around plant cells as phytoliths thought to play a role in the structural support and defense against herbivores. While known since the early 19th century, phytoliths remain an intriguing class of microfossils whose formation and role in plants and their preservation in soils and sediments are a subject for a lot of active research. I outline some emerging themes in phytolith analysis including phytoliths’ role in global biogeochemical cycles, plantherbivore interactions, and their tracing of evolution of cultural plants, especially cereals such as rice (Oryza), wild rice (Zizania), maize (Zea), wheat (Triticum) and millet (Panicum), all relevant to global archaeology. Some emerging research on phytoliths connects their changes in shapes to plant taxonomy of some families such as grasses and opens up avenues for further investigation of their active construction in the cells of some taxa by yet undiscovered genetically mediated mechanisms. New image analysis techniques and some advanced microscopy methods will allow us to further the field of phytolith study using deep machine learning algorithms and true 3D analysis of their shapes, something where contribution from other branches of science are most welcome.
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

セミナー
Stochastic tunneling in de Sitter spacetime
2024年2月28日(水) 16:00  17:30
宮地 大河 (神戸大学 大学院理学研究科 物理学専攻 宇宙論研究室 博士課程)
The formulation of tunneling in real time formalism is discussed. In the case of de Sitter spacetime, there is a method called the stochastic approach, which is known to reproduce the tunneling predicted by Hawking and Moss in the imaginary time formalism. In the case of accelerated expansion of space, the shortwavelength modes are stretched and transformed into longwavelength modes. In the stochastic approach, such UVIR transition is incorporated as quantum noise, and the dynamics of the longwavelength modes are described by stochastic differential equations. In this talk, we construct a SchwingerKeldysh path integral that reproduces this stochastic differential equation and reformulate the tunneling probability. We also reproduce the HawkingMoss tunneling probabilities by using the saddle point approximation.
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

セミナー
Basic experimental considerations for analyzing gene expression
2024年2月28日(水) 13:00  14:00
藤 博貴 (理化学研究所 開拓研究本部 (CPR) 岩崎RNAシステム生化学研究室 学振特別研究員PD)
Methods such as RNAsequencing and ribosome profiling are indispensable tools for the comprehensive elucidation of the mechanisms underlying gene expression. A fundamental aspect that requires meticulous attention in the execution of these experiment is the extraction of intact RNA and Ribosomes. The integrity and purity of the extracted RNA is critical to ensure the accuracy and reliability of the sequencing data. In this seminar, I will introduce the basic but key points of the extraction process.
会場: 研究本館 3階 共有スペース
イベント公式言語: 英語

Using a trapped ion quantum computer for hamiltonian simulations
2024年2月28日(水) 10:30  12:00
リナルディ エンリコ (クオンティニュアム株式会社 Quantum Machine Learning and Algorithms Senior Research Scientist)
Trapped ion quantum computers, like the Hseries quantum hardware by Quantinuum, robustly encode quantum information in long lived and precise qubits. However, utilizing the hardware efficiently requires a fullstack workflow from software libraries to hardware compilers. In this talk we introduce the relevant elements of this stack in the context of solving the quantum dynamics of a spin system on Hseries hardware: we start from the definition of the Hamiltonian operator in the qubit Hilbert space using the opensource pytket python library and we define the quantum circuits in measurements to run, on a simulator first and on hardware later.
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

セミナー
Plant hackers: galling insects extend their phenotypes on the trees by novel plant organogenesis
2024年2月27日(火) 16:00  17:00
Xin Tong (理化学研究所 環境資源科学研究センター (CSRS) 細胞機能研究チーム 基礎科学特別研究員)
When it comes to plantinsect interactions, insects are generally seen as pests like caterpillars eating vegetables or fruits. However, one group of insects, the galling insects can induce de novo organogenesis on the host plants which are often woody plants. Each galling insect species ‘designs’ its own gall as the extended phenotype which are socalled speciesspecific gall formation. Different from leaves and roots, galls represent unique plant organs swiftly formed in response to parasitic organisms, observed across diverse plant species. Yet, the precise mechanisms by which normal plant development is interrupted and redirected to form galls by galling organisms remain elusive. During the talk, I will share some discoveries and views related to aphid gall formation on the elm tree, which is the super host plant for more than 30 galling species, and further discussion about why an insect gall is not simple cell mass but wellorganized structure, and how we could systematically understand insect gall formation.
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

An Investment Banker’s Journey to the World of Physicists Seeking the Truth in Economics and Finance
2024年2月26日(月) 15:30  17:00
Irena Vodenska (Professor, Boston University, USA)
I encountered many exciting opportunities to learn, grow intellectually, and teach during my educational, professional, and scientific journey. Life brings chances, and it is up to us to take or leave them. I took my chances, one of the fascinating ones being to embark on a scientific interdisciplinary research collaboration with physicists. My background is in economics and finance, and doing research with physicists has been fascinating from many different points of view, especially in light of being free from any ONE discipline, free to explore research possibilities to answer finance and economic questions based on a boundless horizon of possible solutions. I worked as an investment banker after my first graduate degree before returning to academia to continue chartering new pathways to research. During my work as a hedge fund manager and a NASDAQ market maker, I had an opportunity to witness firsthand, on the trading floor, the US market collapse sparked by the demise of the Long Term Capital Management in 1998 and later the European market plunge during the tragic events of the terrorist attack on New York City on September 11, 2001, when I lived and worked on Manhattan. Most world problems today are complex to solve with one discipline, as multidisciplinary THINKING is needed to cover various aspects of scientific inquiry. Experience is essential, translating realworld knowledge into academia even more so. I was fortunate to be in a position to build the bridge between investment banking and academia. Learning about the pioneer of Econophysics, Boston University Professor H. Eugene Stanley, was like discovering a gold mine for me. After an exciting investment banking experience in the 1990s and early 2000s, I left my investment banking job in New York City to join Professor Stanley’s research laboratory, a time I will cherish and remember as formative, enlightening, and transformative for the rest of my life. One may ask why physicists work with economists on financial economics problems. The answer is simple: physicists are naturally curious, inquisitive, and open to new ideas. Moreover, physicists and economists share the same language, the language of mathematics. The value of the achievement in econophysics research is the results and the empirical outcome based on data obtained with solid models grounded in natural and social science theory. It is not trivial to produce interdisciplinary research, but recognizing its necessity is already prominently featured in many universities’ strategic plans, including Boston University. Let me lay out several studies and results to give you a glimpse into the research I will discuss today. We analyze economic time series and panel data to understand their relationships and investigate whether some economic data could be informative of the behavior of others. We use a novel approach comprised of Complex Hilbert Principal Component Analysis (CHPCA), Rotational Random Shuffling (RRS), and HelmholtzHodge (HH) potential to unearth statistically significant comovements and identify noteworthy economic and geopolitical events that might influence such comovement dynamics. I will present results from four cases studied collaboratively with my international research collaborators over the last decade since 2013.
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

A Selective Survey of Ideas, Tools and Results in Constructive Field Theory
2024年2月26日(月) 13:00  14:30
クリスティ・コウジ・ケリー (数理創造プログラム 基礎科学特別研究員)
In this talk we discuss some aspects of constructive field theory with an emphasis on analytical and probabilistic methods and results. In particular after an overview of some points in the history of constructive QFT we plan to discuss some early achievements in axiomatic QFT, some features of the theory of distributions and the basic structure of the Wightman reconstruction theorem. We also introduce the OsterwalderSchrader axioms and overview the strategy for the construction of nontrivial measures describing pathintegrals for interacting QFTs. Depending on time constraints we might also discuss probabilistic tools (weak convergence of measures, the BochnerMinlos theorem etc), Gaussian measures, UV regularity of simple QFTs and the construction of (infinite volume) Euclidean P(phi)_2 measures. The plan is to discuss some of these topics in some detail after the end of the official seminar.
会場: via Zoom / セミナー室 (359号室)
イベント公式言語: 英語

セミナー
Cellularlevel leftright asymmetry, cell chirality, induces the chiral collective rotation of multicellular colony
2024年2月15日(木) 16:00  17:00
石橋 朋樹 (理化学研究所 生命機能科学研究センター (BDR) フィジカルバイオロジー研究チーム 基礎科学特別研究員)
西澤 凌平 (大阪大学 大学院生命機能研究科 博士課程)The leftright (LR) asymmetric morphology of organs is essential for the development and maintenance of their functions in various species. In recent years, it has become clear that the LR asymmetry of organs originates from cell chirality, the LR asymmetric nature at the cellular level [1]. However, it is unclear how the cell chirality generates the LR asymmetry at the multicellular level. Here we show a mechanism of LR asymmetry formation at the multicellular level based on cell chirality. We previously found that Caco2 cells, a typical cultured epithelial cell line derived from human colon cancer, exhibit stereotypical and directional cell chirality; when Caco2 cells are cultured as single cells, their nuclei and cytoplasm rotate in the clockwise direction at a rate of 50°/h [2]. Interestingly, when Caco2 forms multicellular colonies, the colonies also undergo a collective clockwise rotation at 10º/h. We revealed that the actomyosin cytoskeleton is essential for the formation of the collective rotation [2]. We also found that Caco2 cells formed lamellipodia and focal adhesions LR asymmetrically during the collective colony rotation, which may be responsible for the chiral collective motion. Interestingly, the disruption of microtubules reversed the direction of collective rotation. The LR asymmetric formation of lamellipodia and focal adhesions was also reversed by inhibition of microtubule polymerization. We will discuss the possible mechanism and the mathematical model where cell chirality induces multicellular chiral rotation depending on microtubules.
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

セミナー
Chemical reaction network theory and the problem of reaction rate
2024年2月8日(木) 16:00  17:00
須田 智晴 (理化学研究所 環境資源科学研究センター (CSRS) 生体機能触媒研究チーム 特別研究員)
A chemical system can be described at different levels. When we focus on the population of chemical species, it is convenient to consider the system as consisting of a number of chemical reactions, which assumes the structure of a (hyper)graph together with the species. The chemical reaction network theory studies chemical systems described in such a way. It aims to elucidate the dynamics of overall chemical composition in terms of the associated graph structure. Notably, it applies not only to chemical systems but also to more general systems as long as the mathematical structure is compatible. In the first part of this talk, we will review the basic concepts and results of the theory, which mainly concern the existence and stability of the equilibrium. From the viewpoint of chemical kinetics, it is interesting to consider the rate of the overall reaction, which may be obtained by the total balance of chemical species. The second part of the talk will be devoted to this topic. Formulation of the problem and some results will be presented. In particular, chemical reaction networks with firstorder reactions will be considered in detail.
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
615 イベント
イベント
カテゴリ
シリーズ
 iTHEMSコロキウム
 MACSコロキウム
 iTHEMSセミナー
 iTHEMS数学セミナー
 Dark Matter WGセミナー
 iTHEMS生物学セミナー
 理論物理学セミナー
 情報理論SGセミナー
 Quantum Matterセミナー
 ABBLiTHEMSジョイントアストロセミナー
 MathPhysセミナー
 Quantum Gravity Gatherings
 RIKEN Quantumセミナー
 Quantum Computation SGセミナー
 NEW WGセミナー
 LabTheory Standing Talks
 場の量子論セミナー
 STAMPセミナー
 QuCoInセミナー
 Number Theory Seminar
 BerkeleyiTHEMSセミナー
 iTHEMS仁科センター中間子科学研究室ジョイントセミナー
 産学連携数理レクチャー
 RIKEN Quantumレクチャー
 作用素環論
 iTHEMS集中講義Evolution of Cooperation
 公開鍵暗号概論
 結び目理論
 iTHES理論科学コロキウム
 SUURICOOLセミナー
 iTHESセミナー