コーヒーミーティング過去ログ
2022-01-14
Cosmic origin of r-process elements?
西村 信哉 (理化学研究所 開拓研究本部 (CPR) 長瀧天体ビッグバン研究室)
The astronomical site of r-process nucleosynthesis has been a long-standing mystery in nuclear astrophysics studies. However, in recent years, there has been significant progress. We confirmed the r-process-driven transient "kilonova" associated with binary-neutron-star mergers. In this talk, I will discuss the possibility of the r-process in magneto-rotational supernovae, which are in the extreme class of core-collapse supernovae. Although this scenario is physically challenging and hypothetical, observational evidence appears to grow. Since this scenario is related to supernovae with many observational examples, we expect future direct/indirect observation. I will also discuss the theoretical perspective of observational properties.
2021-12-24
Quantum chaos, Entanglement and Black holes
野坂 朋生 (理化学研究所 数理創造プログラム (iTHEMS) 研究パートタイマー Ⅰ)
Quantum chaos is a notion to characterize the mechanism of how the time evolution of a quantum many body system, which should be in principle reversible, end up with the thermal equilibrium where the information of the initial condition is lost. This resembles the black hole information problem, which suggests that one can address various fundamental questions related to black holes through the study of quantum chaos. In this talk I will overview the notions of quantum chaos and black hole geometry, and then introduce an interesting phenomenon called revival where these notions are tightly entangled with each other.
2021-12-17
Dimensional regularization
マティアス・ベアヴァイン (理化学研究所 数理創造プログラム (iTHEMS) 特別研究員)
Dimensional regularization is one of the most important tools for analytic calculations in quantum field theory. I will explain, how the concept of integration over (integer) n variables can be extended to a continuous number D, the dimension, and how this can be used to make sense of the divergent parts of quantum corrections.
2021-12-10
Dispersal and organization of glioma cells
ジルベルト・ナカムラ (理化学研究所 数理創造プログラム (iTHEMS) 特別研究員)
Cell migration plays a pivotal role in modeling the invasiveness of gliomas (a type of brain cancer) while the formation of new tumors often relies on cell-cell adhesive forces. I will talk about motility-induced phase separation as an alternative explanation to tackle both cell migration and tumor formation.
2021-12-03
Machine leaning approaches for weather prediction
大塚 成徳 (理化学研究所 数理創造プログラム (iTHEMS) 研究員 / 理化学研究所 計算科学研究センター (R-CCS) データ同化研究チーム 研究員)
Recently, many groups are applying deep learning techniques for weather prediction problems. In this talk, I would like to introduce our research activities at R-CCS. We have been developing an algorithm to integrate data-driven approaches and process-driven approaches for precipitation nowcasting.
2021-11-26
Evolution of core-collapse supernovae to their supernova remnants
小野 勝臣 (理化学研究所 数理創造プログラム (iTHEMS) 研究員 / 理化学研究所 開拓研究本部 (CPR) 長瀧天体ビッグバン研究室 研究員)
Observations of nearby supernova remnants (SNRs) could potentially provide the clues to elucidate the dynamical evolution of core-collapse supernovae (CCSNe), chemical evolution of elements in the ejecta, explosion mechanisms, properties of neutron stars and progenitor stars. In this talk, our recent three-dimensional hydrodynamical models for the evolution of CCSNe to their SNR are introduced. Additionally, an attempt to model the molecule formation in the ejecta is also mentioned.
2021-11-19
A Tale of Two Spaces
多田 司 (理化学研究所 数理創造プログラム (iTHEMS) コーディネーター / 理化学研究所 仁科加速器科学研究センター (RNC) 量子ハドロン物理学研究室 副主任研究員)
2021-11-05
Gravitational wave asteroseismology on protoneutron stars
祖谷 元 (理化学研究所 数理創造プログラム (iTHEMS) 研究員 / 理化学研究所 開拓研究本部 (CPR) 長瀧天体ビッグバン研究室 研究員)
Focusing on the supernova gravitational waves, we are considering to extract the EOS inofrmation for dense matter with asteroseismology.
2021-10-29
Nuclear physics from lattice QCD
土井 琢身 (理化学研究所 数理創造プログラム (iTHEMS) 専任研究員 / 理化学研究所 仁科加速器科学研究センター (RNC) 量子ハドロン物理学研究室 専任研究員)
The interactions between nucleons (and in general, hadrons) govern the structure of matter, such as nuclei and neutron stars. I will talk about first-principles calculations to determine the interactions from the fundamental theory of quarks and gluons, QCD.
2021-10-22
Physics of Relativistic Radiation Mediated Shocks
伊藤 裕貴 (理化学研究所 数理創造プログラム (iTHEMS) 研究員 / 理化学研究所 開拓研究本部 (CPR) 長瀧天体ビッグバン研究室 研究員)
2021-10-15
Annoucement of Super Smash Problems (SSP) workshop
宮﨑 弘安 (理化学研究所 数理創造プログラム (iTHEMS) 上級研究員)
I will make an annoucement of the forthcoming Super Smash Problems workshop on Novermber 24-26.
2021-10-08
Cooper triples in atomic fermi gas: Implication for dense quark matter
筒井 翔一朗 (理化学研究所 仁科加速器科学研究センター (RNC) 量子ハドロン物理学研究室 基礎科学特別研究員)
I propose a microscopic mechanism to reproduce the peak structure of the speed of sound of within a cold atomic model. This would be useful to understand equations of state of neutron star.
2021-09-24
GRB afterglows and you
ドン・ウォレン (理化学研究所 数理創造プログラム (iTHEMS) 研究員 / 理化学研究所 開拓研究本部 (CPR) 長瀧天体ビッグバン研究室 研究員)
2021-09-17
Localization in the directions of Schrödinger equations
三上 渓太 (理化学研究所 数理創造プログラム (iTHEMS) 研究員)
For a particular class of Schrödinger equations, the solutions to the equation localize in the directions as time goes infinity. In this small talk, we review some known results on this subject.
2021-09-10
An invitation to algebraic quantum field theory
及川 瑞稀 (理化学研究所 数理創造プログラム (iTHEMS) 大学院生リサーチ・アソシエイト / 理化学研究所 数理創造プログラム (iTHEMS) 研修生 / 東京大学 大学院数理科学研究科 博士課程)
I am a new member of RIKEN iTHEMS and working on mathematics of conformal field theory. In this talk, noninteger dimensions in tensor categories and their relationship to algebraic quantum field theory will be introduced.
2021-08-27
Toward quantum computation of quantum field theory
伊藤 悦子 (理化学研究所 数理創造プログラム (iTHEMS) 特別研究員 / 理化学研究所 仁科加速器科学研究センター (RNC) ストレンジネス核物理研究室 協力研究員)
Public2021-08-06
Message-passing algorithms for graphical models
許 インイン (理化学研究所 数理創造プログラム (iTHEMS) 基礎科学特別研究員)
Inference problems like marginalization and maximization are NP-hard to solve exactly and approximately in a graphical model. The complexity can be reduced dramatically when the underlying factor graph has some special structure. One extreme case is that of tree factor graphs, in which marginals can be computed in a number of operations which grows linearly with number of notes. This can be done by a ‘dynamic programming’ procedure often called as message passing or belief propagation algorithms. The update rules have been discovered independently in several different contexts: statistical physics (‘Bethe-Peierls approximation’), coding theory (the ‘sum-product’ algorithm), and artificial intelligence (‘belief propagation’, BP). The time evolution of the message’s distributions is known under the name of ‘density evolution’, and the fixed-point analysis of them is done by the replica-symmetric cavity method.
2021-07-30
Conformal Bootstrap in AdS/CFT
楠亀 裕哉 (理化学研究所 数理創造プログラム (iTHEMS) 基礎科学特別研究員 / Burke Fellow, Burke Institute, California Institute of Technology, USA)
A consistency condition for a given theory is a very vague concept, but in conformal field theories it can be formulated explicitly, known as the "conformal bootstrap equation". The main applications of the conformal bootstrap in recent years can be roughly classified into two categories: "deriving universality (of energy spectrum, etc.)" and "excluding impossible theories". Here I will introduce an application of the conformal bootstrap in the context of understanding quantum gravity.
2021-07-16
Ringing Black Holes
大下 翔誉 (理化学研究所 数理創造プログラム (iTHEMS) 基礎科学特別研究員)
I will provide a brief review of the quasinormal modes of black holes. The study of black hole perturbations is important to model the waveform of ringdown gravitational waves emitted from binary black hole mergers or coalescences of compact objects leading to the formation of black holes. In the latter part of my talk, I will discuss the "ease of excitation" of quasinormal modes. This is indeed important to test the no-hair theorem of balck holes.