吉村浩司, 岡山大学異分野基礎科学研究所
[金茶会] 超高精度「原子核時計」で探る基礎物理
4号館セミナーホール リモート会場：JRB 2階大会議室, 仁科記念棟210室 https://www-conf.kek.jp/kincha/
https://www-conf.kek.jp/kincha/
トリウムの同位体であるトリウム２２９は、原子核として極めて特異な約8 eVという非常に低いエネルギーの励起準位（アイソマー準位）を持ち、レーザー光による直接的な励起が可能な唯一の原子核として注目を集めている。原子核は外部場の影響をほとんど受けないため、極めて安定した量子状態を実現することが可能である。もしレーザーを用いた原子核の制御が可能となれば、従来の原子時計を凌駕する精度を持つ「原子核時計」の実現へと繋がり、その波及効果は基礎物理学の革新に留まらず、産業や社会に多大な恩恵をもたらすと期待されている。トリウム２２９の特異性は1970年代から科学者の注目を集め、研究が進められてきたが、その詳細な特性は長らく謎に包まれていた。しかし、２０１６年にドイツの研究グループがアイソマー準位からの電子放出遷移を初めて観測したことで、この分野の研究は飛躍的な進展を遂げて、２０２４年には大きなマイルストーンとして、レーザーによるトリウム２２９の励起がついに実現した。この成果を受け、今後、世界各国で原子核時計の開発競争が本格化すると予想される。本講演では、こうした最近の原子核時計研究の進展について概観し、基礎物理学への応用や、その発展がもたらす科学的・技術的な可能性について展望する。
Shota Komatsu, CERN
Einstein Gravity from a Matrix Integral
Online (Zoom)
We formulate and test holography between a supersymmetric mass deformation of the Ishibashi-Kawai-Kitazawa-Tsuchiya (IKKT) matrix model and type IIB supergravity backgrounds with exceptional F4 supersymmetry. This is arguably the simplest example of holography in which the dual description contains Einstein gravity. We conjecture a one-to-one correspondence between saddle points of matrix integral and supergravity backgrounds, and test it through the supersymmetric localization of the matrix integral.
Tejhas Kapoor, IJCLab Orsay
New physics searches via angular distributions of B -> D* l nu ( l = e, mu, tau) decays
Hybrid On-site: Kenkyu Honkan Seminar room 321, 322 Online: Zoom
Angular distributions are powerful probes to search for new physics signals and constrain the Standard Model parameters. The Belle collaboration has analyzed the B -> D* l nu (l = e, nu) distribution to constrain Vcb and B -> D* form factors. Using the newly released lattice QCD data along with the experimental data, we constrain new physics parameters and obtain correlations between new physics parameters and form factors to understand the hadronic uncertainties better. In the next step, to study B -> D* tau nu decay, we build a measurable angular distribution by considering the additional tau -> mu nu nu decay, and perform a sensitivity study with pseudo experimental data, indicating 5-6% sensitivity on right-handed and tensor currents.
Xiaoyang Wang, RIKEN- iTHEMS
Imaginary Hamiltonian variational ansatz for the Schwinger model and combinatorial optimization problems
Hybrid On-site: Kenkyu Honkan Seminar room 321, 322 Online: Zoom
Variational quantum algorithms hold promise for efficiently solving combinatorial optimization problems that are difficult to solve classically on near-term quantum devices. The commonly used quantum approximate optimization algorithm (QAOA) suffers from adiabatic bottlenecks, leading to deep quantum circuits or longer evolution time. In contrast, imaginary time evolution algorithm often requires a constant evolution time. In this work, we propose the imaginary Hamiltonian variational ansatz (iHVA) to the ground state preparation of the Schwinger model and solve the MaxCut problem. This variational ansatz is inspired by the quantum imaginary time evolution algorithm. We introduce a tree arrangement of the parametrized quantum gates, enabling the exact solution of the MaxCut problem for any tree graphs. For randomly generated regular graphs, we numerically demonstrate that the MaxCut problem can be exactly solved using iHVA with a constant number of rounds. In contrast, QAOA requires the number of rounds that increases with system size, and the classically near-optimal Goemans- Williamson algorithm often yields only approximate solutions. We validate our algorithm’s advantage over QAOA through hardware experiments on a graph with 67 nodes.
Shaoping Li, Osaka U
Resonant Forbidden Leptogenesis
Hybrid On-site: Kenkyu Honkan Seminar room 321, 322 Online: Zoom
Finite-temperature effects open more opportunities to explain the baryon asymmetry of the universe in minimal models beyond the standard model (SM). In this talk, I will introduce the forbidden CP asymmetry that is generated via soft-lepton resummation at finite temperatures and has a SM-predicted resonant enhancement. It features leptogenesis at the electroweak scale that is accessible at colliders, and dark matter cogenesis in the early universe.
Gary Shiu, UW Madison
The String Genome Project
Hybrid On-site: Kenkyu Honkan Seminar room 321, 322 Online: Zoom Considerations from both the Landscape and the Swampland suggest that 1) consistent quantum theories of gravity are rare in the space of all possible theories; 2) the number of consistent string vacua is enormous but finite. In light of these properties of quantum gravity, exhaustive searches for realistic vacua would not be feasible
Considerations from both the Landscape and the Swampland suggest that 1) consistent quantum theories of gravity are rare in the space of all possible theories; 2) the number of consistent string vacua is enormous but finite. In light of these properties of quantum gravity, exhaustive searches for realistic vacua would not be feasible
while random sampling would not be representative of the Landscape. In this talk, I will discuss how AI can be used to search for optimal solutions in string theory, to enumerate the exact number of solutions in regions of the Landscape and to discover structures therein, and to generate new Calabi-Yau compactifications.
Hidetoshi Omiya, Kyoto U
Impact of the self-interaction on the axion cloud and its gravitational wave signatures
Hybrid On-site: Kenkyu Honkan Seminar room 321, 322 Online: Zoom
The superradiant instability provides a promising avenue for detecting ultra-light axions through the formation of axion clouds around black holes. The way to observe the axion cloud includes observation of the spin of the black hole and the gravitational waves.To effectively observe these axions, it is crucial to have a precise understanding of the cloud’s evolution and its observable signatures. In this talk, I will discuss the impact of axion self-interaction on both the evolution of the cloud and its observational signatures. In particular, I will show that the self-interaction can produce signals in the different frequency bands.
Toru Kojo, KEK
[KEK-JAEA Joint Seminar] A quarkyonic matter model for dense QCD and hyperon problems
Hybrid On-site: Room 116, KEK Tokai campus Online: Zoom
Recent neutron star observations combined with the nuclear constraints suggest that QCD matter quickly stiffens at density close to nuclear matter density. We argue that the stiffening is triggered by a transition from nuclear to quark matter. The concept of quarkyonic matter captures relevant features necessary to understand the stiffening. We present an ideal model of quarkyonic matter and apply it to isospin symmetric and a matter of neutral baryons including the strangeness. We argue how the quark description mitigates the hyperon problems in neutron star constraints.
Justin Kaidi, Kyushu U
Non-Supersymmetric Heterotic Branes
Hybrid On-site: Kenkyu Honkan Seminar room 321, 322 Online: Zoom
The common statement that any consistent quantum gravity theory contains dynamical objects with all possible charges suggests that there are still a number of hitherto-unidentified branes in string theory. In this talk I will discuss four of these new branes, focusing on heterotic string theories. The focus of the discussion will be on the relationship between these branes and the lower-dimensional vacua obtained by closed string tachyon condensation in the ten-dimensional, non-supersymmetric heterotic string theories.
榎戸輝揚, 京都大学理学研究科/理化学研究所開拓研究本部
[金茶会] 宇宙放射線から切り拓く学際研究：高エネルギー大気物理学から月面物理学へ
4号館セミナーホール リモート会場：東海1号館115室、仁科記念棟106室 https://www-conf.kek.jp/kincha/
