安田正美, 産業技術総合研究所 計量標準総合センター
[金茶会] 秒の再定義に向けた状況と産総研での研究活動
https://www-conf.kek.jp/kincha/
1967年以降、現在に至るまで、国際単位系(SI)における時間の単位である秒は、セシウム原子のマイクロ波領域の遷移周波数で定義されている。
2000年頃に我が国で発明された光格子時計をはじめとする、近年の光周波数標準の性能向上により、秒の再定義の機運が高まっている。
2030年開催の国際度量衡総会にて再定義決議の採択を目指している。この秒の再定義の現状を紹介するとともに、産総研における関連研究を紹介する。
山崎雅人, 東京大学大学院理学系研究科
[金茶会] 超弦理論は我々の宇宙を記述するか?
https://www-conf.kek.jp/kincha/
「21世紀の物理学」とも称される超弦理論がこれまで人類の世界観の深化に貢献してきたことは間違いないが,我々の宇宙における素粒子標準模型やそれを超えた物理の理解により直接的に役立つのかどうかは自明ではない.
これは実験・観測の問題であると同時に,弦理論の理解そのものについての理論的な問題でもある.
本講演では,超弦理論が我々の宇宙について何を語りうるのか,そしてそのために何が必要とされているのかという大問題について,その一端を取り上げ議論したい.
Satoshi Shirai, KIPMU
Metastable Cosmic Strings and Gravitational Waves
Gravitational wave signals hinted at by recent pulsar timing array (PTA) observations have brought renewed interest to the scenario of metastable cosmic strings. These signals can be naturally explained by cosmic strings with lifetimes on the order of seconds. Such metastable strings are made possible by the presence of monopoles, and the PTA data suggest that the monopole mass scale is remarkably close to the energy scale of the cosmic strings. Previous analyses of gravitational wave signals from metastable strings have generally assumed a large hierarchy between these two scales. However, the observed closeness raises concerns about the validity of such assumptions—particularly regarding string formation, string decay, and the efficiency of gravitational wave emission. In this talk, I will discuss how the near-degeneracy of the monopole and string scales impacts these processes. The discussion will be based on concrete symmetry-breaking patterns that give rise to such scale configurations.
Atsushi Nishizawa, Hiroshima U
Hunting axion dark matter signatures in terrestrial magnetic fields
Axions are one of the candidates for the unknown dark matter. Ultralight axions form a huge number of clouds in galactic halos. When such an axion cloud passes through the Earth, it interacts electromagnetically with the geomagnetic field and generates a monochromatic electromagnetic wave whose frequency corresponding to the axion mass. Recently we modeled the axion-induced electromagnetic wave signals by solving Maxwell’s equations under the appropriate boundary conditions of the ionosphere for geomagnetic fields and showed that Earth’s natural environment can serve as a powerful probe for ultralight axion dark matter with masses ranging from 10^{-15} eV — 10^{-13} eV. Based on the derived theoretical model, we searched for axion-induced magnetic field signals within the observational data of global geomagnetic field variations (Eskdalemuir Observatory, 2012–2022). In this talk, I report on the idea of the search, the data analysis mehtod, the results of the search having several tens of axion signal candidates.
Franz Ciceri, Ecole Normale Superieure
Holography for the IKKT matrix model
A particularly interesting corner of holographic dualities is the correspondence between type II strings on near-horizon Dp branes geometries and d = p+1 dimensional super Yang-Mills theories with sixteen supercharges. For the extremal case p=-1, this suggests a holographic duality for the IKKT matrix model. Despite intriguing and highly non-trivial results in the IKKT model, this duality has so far remained largely unexplored. In this talk, I will consider the lowest supermultiplet of gauge invariant operators of the model and identify its states with the lowest Kaluza Klein fluctuations of (Euclidean) IIB supergravity on the D(-1) instanton background. I will explain how to construct its holographic bulk realisation as a one-dimensional maximal supergravity with 32 supercharges and local SO(10) invariance, capturing the full non-linear dynamics. By analysing the bulk Killing spinor equations, I will present a general class of half-supersymmetric solutions that typically break SO(10), and discuss their uplifts to IIB supergravity. I will end with some remarks on open questions and future directions.
Ayumi Kasagi, Rikkyo University
[KEK-JAEA Joint Seminar] Applications of Machine Learning and Deep Learning to Experimental Data Analysis
The spectacular advances of deep learning in recent years have led to breakthroughs across a wide range of data analysis tasks. At the same time, the techniques used to boost model performance have become increasingly intricate, with ever larger parameter counts and training datasets. What, then, are the practical steps needed to harness these methods for fundamental science especially in the analysis of physics experiments? In this talk we first survey how machine learning and deep learning are being employed in international experimental collaborations. We then present, step by step, the workflow we have developed to tailor deep-learning models for the microscopic image analysis of nuclear emulsion detectors. Finally, we discuss several modern deep-learning ideas and how they might further benefit experimental data analysis.
Adil Jueid, IBS
CosmiXs: Cosmic messenger spectra for indirect dark matter searches
The spectra of stable particles such as photons, positrons, antiprotons and neutrinos are one of the main ingredients to calculate the
fluxes of cosmic rays and radiation searched for in indirect detection experiments. The modeling of the whole process is however very complicated since after dark matter annihilation or decay, a number of phenomena occur including resonance decays, parton showering, hadronization and hadron decays. Therefore the modeling itself cannot be performed from first principles. I will discuss some progress in this direction and present CosmiXs which uses VINCIA to properly model electroweak corrections, and handles the polarization information. I will then move to the modeling of antideuterons and discuss briefly the associated theoretical uncertainties (The dataset can be found in this repo: https://github.com/ajueid/CosmiXs)
Talk is based on:
https://arxiv.org/abs/2411.04815
https://arxiv.org/abs/2312.01153
https://arxiv.org/abs/2303.11363
https://arxiv.org/abs/2202.11546
Koichi Miyamoto, Osaka University
Quantum computing for cosmology: An application in stochastic inflation as an example
Quantum computing technology has been developing rapidly in recent years, and it is expected to speed up some kinds of computation that are highly time-consuming in classical computing, e.g., operations on extremely large matrices. Practical applications in various fields are being explored, and cosmology is one of them. In this talk, after an introduction to quantum computing, I explain its application in stochastic inflation, a formalism for analyzing the inflationary perturbation based on the probability theory. In this formalism, the perturbation is related to the Fokker-Planck equation, and its probability distribution is characterized by the eigenvalues of the differential operator. However, calculating them can be challenging, especially in multi-field cases, since it corresponds to finding eigenvalues of an exponentially large matrix. I explain a quantum algorithm to calculate the differential operator eigenvalues efficiently and share results from numerical demonstrations that suggest its applicability to the stochastic inflation problem.
横山将志, 東京大学 大学院理学系研究科
[金茶会] で、Hyper-K、どうなんすか?
https://www-conf.kek.jp/kincha/
ハイパーカミオカンデ計画は、超大型水チェレンコフ検出器「ハイパーカミオカンデ」と、J-PARCからの大強度・高品質なニュートリノビーム、さらに高性能の前置・中間検出器を組み合わせることで、素粒子・宇宙の研究を推進するプロジェクトである。東京大学とKEKをホスト機関とし、現在、国際共同研究グループによる建設・準備が佳境を迎えている。
本講演では、計画の概要と進捗状況、期待される科学的成果と国際的な優位性、将来の展望について紹介し、世話人から与えられたタイトルの問いに答えられるよう努力する。
Gary Shiu, UW Madison
Formulating the Weak Gravity Conjecture in AdS Space