Yutaka Matsuo, Tokyo University
Dimensional oxidization on coset space
Online (Zoom), indico page, slides (kek.jp only) In the matrix model approaches of string/M theories, one starts from a generic symmetry gl(infty) to reproduce the space-time manifold.
In the matrix model approaches of string/M theories, one starts from a generic symmetry gl(infty) to reproduce the space-time manifold.
In this talk, we propose the generalization in which the space-time manifold emerges from a gauge symmetry algebra which is not necessarily gl(infty).
We focus on the second nontrivial example after the toroidal compactification, the coset space G/H, and propose a specific infinite- dimensional symmetry which realizes the geometry.
It consists of the gauge-algebra valued functions on the coset and Lorentzian generator pairs associated with the isometry.
We show that the 0-dimensional gauge theory with the mass and Chern- Simons terms gives the gauge theory on the coset with scalar fields associated with H.
宮下精二, 日本物理学会, 東大物性研
[KEK連携コロキウム] 磁石への微視的モデルからのアプローチ −有限温度での保磁力解析−
Online (Zoom)
磁石、つまり永久磁石は身近な物質であり、モーターや記録媒体などの多くの機器で重要な役割を果たしている。その機構解明、高性能化に向けて盛んに研究が進められている。特にその温度依存性の解明は重要課題になっている。しかし、そこには現在の物理学の方法では取り扱いが困難な多くの興味深い問題を含まれている。この問題への我々の試みを紹介する。ここでは、現在最強の磁石であるNd2Fe14Bを取り上げる。磁石の重要な性質である有限温度での保磁力は、通常の熱力学諸量とはちがい、理論的な定式化がない。この問題は準安定状態の緩和の問題であり、その崩壊はいわゆるスピノーダル過程とみなされるが、短距離力相互作用系では核生成過程のため、真の意味での特異性を持たない。そのため、見かけ上のスピノーダル過程を定式化しなくてはならないという困難な問題がある。この問題に対し、有限温度LLG方程式の方法や、Wang-Landau法を用いたモンテカルロ法によって、ナノサイズ粒子での保磁力の温度依存性を定量的に評価した。さらに、双極子相互作用のため多磁区構造が現れる大きなグレインでの保磁力機構についても解析した。最後に、磁石は、グレインの集合体であり、その集団としての保磁力機構の解析の試みについても触れたい。
Yuto MInami, RCNP, Osaka University
Search for parity-violating physics in the polarisation of the cosmic microwave background, so called “Cosmic Birefringence”
Online (Zoom) https://kds.kek.jp/event/36423/
Polarised light of the cosmic microwave background, the remnant light of the Big Bang, is sensitive to parity-violating physics, cosmic birefringence. In this presentation we report on a new measurement of cosmic birefringence from polarisation data of the European Space Agency (ESA)’s Planck satellite. The statistical significance of the measured signal is 2.4 sigma. If confirmed with higher statistical significance in future, it would have important implications for the elusive nature of dark matter and dark energy.
Makiko Nio, RIKEN
[EX] On determination of the fine-structure constant: Electron g-2 and Atomic interferometers
Online (Zoom) https://kds.kek.jp/event/36346/ Any precision tests of the elementary particles are carried out on the assumption that the fine-structure constant alpha is sufficiently known.
Any precision tests of the elementary particles are carried out on the assumption that the fine-structure constant alpha is sufficiently known.
Currently, there are two methods that provide equally accurate values of the alpha. One is the electron g-2 measurement together with its theoretical prediction from the QED theory. The other is the quotient of the Planck constant and the atomic mass (h/M) determined by using an atomic interferometer. I will report recent progress in both determination of the alpha including our own work on the five-loop QED calculation of the electron g-2.
Sinya Aoki, YITP
Conserved charges in gravity and entropy
Online (Zoom), indico page, slides (kek.jp only)
We propose a manifestly covariant definition of a conserved charge in gravity. We first define a charge density from the energy momentum tensor with a Killing vector, if exists in the system, and calculate the energy (and angular momentum) of the black hole by a volume integral. Our definition of energy leads to a correction of the known mass formula of a compact star, which includes the gravitational interaction energy and is shown to be 68% of the leading term in some case. Secondly we propose a new method to define a conserved charge in the absence of Killing vectors, and argue that the conserved charge can be regarded as entropy, by showing the 1st law of thermodynamic for a special case. We apply this new definition to the expanding universe, gravitational plane waves and the black hole. We discuss future directions of our research.
Yu Nakayama, Rikkyo University
[QCD theory Seminar] Anomalous hydrodynamics with dyonic charge
Online (Zoom)
We study anomalous hydrodynamics with a dyonic charge. We show that the local second law of thermodynamics constrains the structure of the anomaly in addition to the structure of the hydrodynamic constitutive equations. In particular, we show that not only the usual E ・ B term but also E^2 ? B^2 term should be present in the anomaly with a specific coefficient for the local entropy production to be positive definite.
Yasunori Lee, University of Tokyo
Revisiting Wess-Zumino-Witten terms
Online (Zoom), indico page, slides (kek.jp only)
We revisit various topological issues concerning 4d Wess-Zumino-Witten terms for SU and SO QCD, from the modern bordism point of view. We explain why the definition of the 4d WZW terms requires the spin structure, and also discuss how the mixed anomaly involving the 1-form symmetry of SO QCD is reproduced in the low-energy sigma model.
長谷川眞理子, 総合研究大学院大学
[KEK連携コロキウム] 少子化はなぜ起こるか 人間行動進化学からのアプローチ
Online (Zoom) external homepage
external homepage
自然人類学は、ヒトという生物の進化を研究する学問である。一方、文化人類学、社会人類学は、ヒトが持っているさまざまな文化や社会のあり方を研究する。両方とも、人間についての研究なのだが、アプローチも考え方もまったく異なる。それに対して、人間行動進化学（または進化心理学）は、ヒトという生物の行動や心理の進化を、文化も含めて分析しようとしている。この分野はまだ新しく、誤解されているところも多いので、本講演ではまず、人間行動進化学とは何か、その考え方の枠組みを述べたい。そして、少子化はなぜ起こるのかという具体的な問題について、人間行動進化学での分析による、私の試論を紹介したい。
Kazuya Mameda, RIKEN
Chiral transport under gravitational field
Online (Zoom), slides (kek.jp only)
The kinetic theory is a fundamental tool to describe transport phenomena, such as that induced by quantum anomaly. In this talk, we explain how the Boltzmann transport theory is modified by quantum corrections. Also we show the field-theoretical derivation of the kinetic theory of chiral fermions in general curved spacetime. Then, we briefly discuss possible applications of the resulting framework to high-energy and condensed matter physics.
Hua Xing Zhu, Zhejiang University
[QCD theory Seminar]Double-slit interference in jet substructure and light-ray OPE
Online (Zoom)
