古林敬顕, 秋田大学
[金茶会] 脱炭素社会に向けたエネルギー需給の現状と将来
東海キャンパスAQBRC2階会議室 リモート会場 ：3号館セミナーホール https://www-conf.kek.jp/kincha/
https://www-conf.kek.jp/kincha/
2050年のカーボンニュートラル社会実現のためには、原子力や再生可能エネルギーの導入促進による化石燃料削減、エネルギー効率の向上による最終エネルギー消費量の削減、森林などによる温室効果ガスの吸収量の増加が重要となる。本講演では、日本のエネルギー需給の現状および再生可能エネルギーやエネルギー需要の偏在性を踏まえて、脱炭素化に向けて導入が求められる技術、インフラ、政策などについて、エネルギーシステムの知見に基づいて説明する。
Björn Garbrecht, Technical University of Munich
CP conservation in the strong interactions
Online (Zoom) There is no empirical evidence for CP conservation in the strong interactions. As there generally is a renormalizable, parity-odd coupling between the field strength and its dual, this requires an explanation from theory.
There is no empirical evidence for CP conservation in the strong interactions. As there generally is a renormalizable, parity-odd coupling between the field strength and its dual, this requires an explanation from theory.
I will therefore first review what interactions are present when constructing an effective theory for hadrons from QCD. But I will also point out, that from such considerations alone, it cannot be decided whether the effective interactions (that, e.g., give mass to eta-prime) are misaligned (CP violation) or aligned (no CP violation) with the quark mass phase.
To see whether or not there is a material effect of the parity-odd operator in QCD requires therefore an understanding of how field configurations from different topological sectors contribute to the path integral or, in canonical quantization, whether topology implies different ground states that are in general not parity eigenstates. To that end, I will review the pertinent homeomorphisms between the SU(2) subgroups of the strong interactions and the boundaries of spacetime or spatial hypersurfaces.
As for the Euclidean path integral approach, I will note that pure gauge configurations on the boundary only follow when the latter is placed at infinity. Picard-Lefschetz theory then implies that steepest-descent integration contours cover all field configurations within a topological sector that one can find in the infinite spacetime volume. Consequently, the limit of infinite spacetime volume must be taken before summing over sectors, and it turns out that parity violation then vanishes. Commuting these limits, as tacitly done in standard approaches, corresponds to a singular deformation of the original Cauchy contour, falsely suggesting parity-violating results.
Regarding canonical quantization, I will note that the usually considered theta-vacua are not properly normalizable, which is at odds with the probability interpretation from the axioms of quantum mechanics. The root of this problem is the summation over gauge-redundant configurations in the orthonormality relations among theta-vacua. Imposing that (in temporal gauge) the wave functionals and Hilbert-space operators are well-defined when the inner product covers each physical field configuration one time and one time only, I recover that the consistent states satisfy Gauß’ law and are moreover eigenstates of parity.
References:
2001.07152 [hep-th]
2403.00747 [hep-th]
2404.16026 [hep-ph]
So Matsuura, Keio University
Phases and Duality in Fundamental Kazakov-Migdal Model on the Graph
Hybrid On-site: Kenkyu Honkan Seminar room 321, 322 Online: Zoom
In this talk, we will explore the fundamental Kazakov-Migdal (FKM) model on a generic graph, where the partition function is represented by the Ihara zeta function weighted by unitary matrices. The effective action of the FKM model is described by a summation of all Wilson loops on the graph, which can be regarded as an extension of the usual Wilson action in lattice gauge theory. We show that the FKM model on regular graphs exhibits an exact strong/weak coupling duality, reflecting the functional equation of the Ihara zeta function. Although this duality is not precise for irregular graphs, we show that the effective action in the large coupling region can also be represented by a summation of Wilson loops, similar to that in the small coupling region. We also discuss the stability of the model and show that the FKM model becomes unstable in the critical strip of the Ihara zeta function. Interestingly, the FKM model universally exhibits the so-called Gross-Witten-Wadia (GWW) phase transitions. By comparing the FKM model with the GWW model, we estimate the phase structure of the FKM model in both small and large coupling regions, which is validated through numerical simulations. For the benefit of graduate students, we will begin the seminar with an introductory explanation of lattice gauge theory and graph theory, providing a foundation for understanding the subsequent discussion.
梶洋隆, トヨタ自動車株式会社未来創生センター
[金茶会] 未来につながる研究：トヨタ自動車未来創生センターの取組み
４号館セミナーホール リモート会場：東海キャンパスAQBRC2階会議室 https://www-conf.kek.jp/kincha/
https://www-conf.kek.jp/kincha/
未来創生センターは、モビリティ・カンパニーへの変革を目指すトヨタ自動車の先端研究の分野を担う研究センターです。本講演では、未来創生センターの概要とロボティクス、ライフサイエンス、社会インフラ、数理・データサイエンスの四つの分野の研究開発事例、および講演者がこれまで取り組んできたAI研究についてご紹介します。
Soumitra Nandi, IIT Guwahati
Interpretations of the data on b-> c(u) l nu decays: SM and beyond
Hybrid On-site: Kenkyu Honkan Seminar room 321, 322 Online: Zoom
I will discuss the role of inclusive and exclusive b-> c(u) l nu decays in the extractions of $|V_{cb}|$ and $|V_{ub}|$. Also, I will focus on the possible role of the available data on these decays in constraining the parameters associated the new interactions beyond the SM.
Sotaro Sugishita, YITP
Subregion Complementarity in AdS/CFT
Hybrid On-site: Kenkyu Honkan Seminar room 321, 322 Online: Zoom
We examine the bulk reconstruction in the AdS/CFT correspondence. It is believed that CFT operators in a CFT subregion can construct arbitrary bulk local operators in the bulk subregion associated with the CFT subregion. This correspondence is called the entanglement wedge reconstruction or the subregion duality. We argue that the duality fails to hold by presenting problems existing even in a simple setup (the causal wedge reconstruction). Nevertheless, we propose the subregion complementarity, illustrating that different CFT operators can describe a bulk subregion. While we expect that this complementarity is valid outside the horizon in general eternal black holes, it is inapplicable for single-sided black holes where a semi-classical description at the stretched horizon is absent.
Takahiko Terada, Nagoya U
Dissipative Genesis of the Inflationary Universe
Hybrid On-site: Kenkyu Honkan Seminar room 321, 322 Online: Zoom
We study an inflation model with a flat scalar potential supported by observations and find that slow-roll inflation can emerge after a quasi-cyclic phase of the Universe, where it undergoes repeated expansions and contractions for a finite time period. The initial conditions and the positive spatial curvature required for such nontrivial dynamics align with the quantum creation of the Universe. The key ingredients that trigger inflation are dissipative interactions of the inflaton, which are necessary to reheat the Universe after inflation and thus give us an observational handle on pre-inflationary physics. Our discovery implies that inflation occurs more robustly after the creation.
Yuta Michimura, RESCEU
Laser interferometric searches for ultralight dark matter
Hybrid On-site: Kenkyu Honkan Seminar room 321, 322 Online: Zoom
Despite overwhelming observational evidence for the existence of dark matter, its identity and properties remain a mystery. Bosonic ultralight fields with masses below 1 eV are gaining a lot of attention, as they are well motivated by cosmology. Laser interferometers are sensitive to oscillations from such fields that change the interference fringe. Recently, we have proposed to search for axion dark matter by measuring the birefringence effect using a bow-tie optical ring cavity [PRL 121, 161301 (2018)] and gravitational wave detectors [PRL 123, 111301 (2019)]. We have also proposed to search for vector dark matter by searching for non-standard force acting on mirrors [PRD 102, 102001 (2020)]. In this talk, I will present some of the first results from a table-top experiment, Dark matter Axion search with riNg Cavity Experiment (DANCE) [PRD 108, 072005 (2023)], and the status of axion and vector dark matter searches using gravitational wave detectors.
Toshifumi Futamase, Tohoku University
An interpretation of Hubble tension and S8 tension by the observed Inhomogeneous matter density
Hybrid On-site: Kenkyu Honkan Seminar room 321, 322 Online: Zoom
Hubble parameter describes the expansion rate of the universe and is one of the most important parameter to characterize our universe. Thus, the measurement has been a major topic in the observational cosmology. Recently there has been a significant discrepancy in the measured value depending on the method of the observation. This is called as the Hubble tension. If the discrepancy is real, it will cause a revolutionary change in the standard cosmology. Not only Hubble parameter but also recent galaxy survey reported a similar discrepancy in the structure formation parameter S8 from CMB measurement. On the other hand, there is observational evidence by the observation of K-band luminosity density that our galaxy is in a low-density region of the order of three hundred Mega parsec. We consider the effects of this inhomogeneous matter distribution on the Hubble parameter and S8 parameter. For this purpose, Einstein equation is averaged over an arbitrary finite region to construct local Friedman universe which is characterized by local cosmological parameters, and thus we can derive the relation between local and horizon scale cosmological parameters. According to this relation we can explain the observed discrepancies of Hubble parameter and S8 without introducing any new physics.
Ryan Hill, The university of Edinburgh
Variance-Reduction Techniques for Disconnected Isospin-Breaking QED Corrections
Hybrid On-site: Kenkyu Honkan Seminar room 321, 322 Online: Zoom
Sub-percent calculations of an increasing number of physical observables are within the reach of modern Lattice QCD. In order to achieve such precision, we must include the (typically) O(1%) corrections from isospin-breaking contributions in our calculations. These corrections include disconnected diagrams, which can be prohibitively expensive to resolve using standard techniques. In this talk, I will discuss ongoing efforts to calculate several disconnected topologies relevant at O(alpha) to e.g. Kl2 decays, on RBC-UKQCD physical-point domain-wall ensembles, following on from exploratory calculations [1]. We make use of the ‘split-even’ estimator [1, 2], which can improve statistical errors by an order of magnitude or more, and explore the use of a distance-splitting technique [1] to take advantage of the dominant short-distance behaviour of some topologies. These techniques are applicable beyond disconnected diagrams, and might improve statistical errors in many contractions involving noisy loop estimators. I will explore the potential to make great improvements on the statistical error of our previous result for rare K+->Pi+l+l- decays [3] using these techniques.
[1] Harris, T., Gülpers, V., Portelli, A., Richings, J. Efficiently unquenching QCD+QED at O(alpha) PoS LATTICE2022 (2023). https://arxiv.org/abs/1903.10447
[2] Giusti, L., Harris, T., Nada, A. et al. Frequency-splitting estimators of single-propagator traces. Eur. Phys. J. C 79, 586 (2019). https://doi.org/10.1140/epjc/s10052-019-7049-0
[3] Boyle, P. A., Erben, F., Flynn, J. M., Gülpers, V., Hill, R. C., Hodgson, R., Jüttner, A., Ó hÓgáin, F., Portelli, A., Sachrajda, C. T. Simulating rare kaon decays K+->Pi+l+l- using domain wall lattice QCD with physical light quark masses. Phys. Rev. D 107 (2023) L011503. https://link.aps.org/doi/10.1103/PhysRevD.107.L011503
