Yu Watanabe, YITP Kyoto University
量子f-divergenceの一般化とそこから誘導される情報幾何的性質
Seminar room, Kenkyu honkan 3F
正値性およびCPTP単調性を満たす量子f-divergenceには、様々なバリエーションがあることが知られている。我々は2つの作用素単調関数をパラメタとしてもつ一般化された量子f-divergenceのクラスを定義し、それらが正値性やCPTP単調性を持つことを示した。また、いくつかの既存の量子f-divergenceがこのクラスに含まれていることを示した。ひとたび量子状態空間に対してdivergenceが定義されると、その微分からその空間の計量や接続を得ることができる。一般化された量子f-divergenceからどのような計量や接続が得られるかを示した。
Kenji Toma, Frontier Research Institute for Interdisciplinary Sciences, Tohoku University
[Cosmophysics group seminar] Relativistic Jets Driven by Black Holes
Meeting room 1, Kenkyu honkan 1Fslides (kek.jp only)
Relativistic Jets are collimated plasma outflows with speeds close to the light speed from the vicinities of black holes, and observed in association with some active galaxies and gamma-ray bursts. They could be the emitters of high-energy cosmic-rays, high-energy neutrinos, and gravitational waves. In spite of the significant progress in recent years, there are still many unresolved key issues concerning the energy injection, mass injection, acceleration, collimation, and energy dissipation/emission mechanisms of jets. This talk reviews the current theoretical framework for solving those issues and then focuses on the energy injection mechanism, in particular the Blandford-Znajek process, i.e., steady electromagnetic energy injection by rotating black holes themselves. Physical differences among this process, pulsar winds, and mechanical Penrose process are discussed.
Valentin V. Khoze, Durham U., IPPP
Higgsplosion
Seminar room, Kenkyu honkan 3F
I will introduce and review the Higgsplosion phenomenon proposed in my recent work with Michael Spannowsky https://arxiv.org/pdf/1704.03447.pdf Higgsplosion occurs at some critical energy in the 10^2-10^3 TeV range and leads to an exponentially growing decay rate of highly energetic particles into multiple Higgs bosons. We argue that this a well-controlled non-perturbative phenomenon in the Higgs-sector which involves the final state Higgs multiplicities n in the regime nλ ≫ 1 where λ is the Higgs self-coupling. If this mechanism is realised in nature, the cross-sections for producing ultra-high multiplicities of Higgs bosons are likely to become observable and even dominant in this energy range. At the same time, however, the apparent exponential growth of these cross-sections at even higher energies will be tamed and automatically cut-off by a related Higgspersion mechanism. As a result, and in contrast to previous studies, multi-Higgs production does not violate perturbative unitarity. We then argue that the effects of Higgsplosion alter quantum corrections from very heavy states to the Higgs boson mass. Above a certain energy, which is much smaller than their masses, these states would rapidly decay into multiple Higgs bosons. The loop integrals contributing to the Higgs mass will be cut off not by the masses of the heavy states, but by the characteristic loop momenta where their decay widths become comparable to their masses. Hence, the cut-off scale would be many orders of magnitude lower than the heavy mass scales themselves, thus suppressing their quantum corrections to the Higgs boson mass.
Yuji Satoh, University of Tsukuba
A world-sheet approach to non-geometric backgrounds in string theory
Meeting room 1, Kenkyu honkan 1F, slides (kek.jp only)
String dualities allow us the non-geometric string backgrounds whose transition functions involve duality transformations. We first discuss such non-geometric backgrounds obtained through T-duality, i.e. T-folds, from the world-sheet point of view. In particular, we construct their modular invariant partition functions systematically based on the momentum lattices. Second, as an application, we show that our non-geometrical setting, or its analogs, can simply realize non-supersymmetric backgrounds with vanishing cosmological constant at one loop, as well as non-supersymmetric D-branes with vanishing self-overlap, which give non-perturbatively small cosmological constant. If time is allowed, we would also like to comment on the world-sheet theories obtained from conformal interfaces.
Yuichi Uesaka, Osaka University
Charged lepton flavor violating process in a muonic atom, μ- e- → e- e-
Meeting room 1, Kenkyu honkan 1F
The charged lepton flavor violation (CLFV) is a good probe to search for new physics beyond the standard model. Though various CLFV processes have been investigated, any singns of new physics have not yet found. In 2010, the CLFV decay of the muonic atom, μ- e- → e- e-, was proposed as one of the promising processes. In this talk, I report on our improved analysis of this process by taking into account the distortion of the out-going electrons in the nuclear Coulomb potential and the relativistic treatment of the muon and the electrons. These effects are important and modify the previous understanding of the mass number dependence of transition rate. I also talk that the process has a capability to discriminate between contact and photonic CLFV interactions.
永谷幸則, 自然科学研究機構生理研
[第一回KEK連携コロキウム] 加速器で顕微イメージング：電子顕微鏡からミュオン顕微鏡へ
4号館1階セミナーホール 生理学研究所ではマイクロ波で電子を加速する線形加速器を電子顕微鏡に導入した透過型電子顕微鏡(500kV Linac-TEM)を開発しました。本講演では、電子顕微鏡のイメージングの基礎から始めて、線形加速器を電子顕微鏡に導入するのに必要であったビームの安定化に関する各種の技術やその成果を解説します。
生理学研究所ではマイクロ波で電子を加速する線形加速器を電子顕微鏡に導入した透過型電子顕微鏡(500kV Linac-TEM)を開発しました。本講演では、電子顕微鏡のイメージングの基礎から始めて、線形加速器を電子顕微鏡に導入するのに必要であったビームの安定化に関する各種の技術やその成果を解説します。
さらに、加速器の顕微イメージングへの応用として、電子の透過能をはるかに凌ぐミュオンを用いた「透過ミュオン顕微鏡」や、走査電子顕微鏡(SEM)よりも極めて検出感度の高い「走査ミュオン顕微鏡」の開発についても解説します。近年のJ-PARC/MLFにおける正ミュオン冷却の技術の進展と、生理研での加速器電子顕微鏡の成果の融合として、これまで粒子としてしか利用されてこなかったミュオンを「コヒーレントな波動」として用い、電子顕微鏡に匹敵する分解能で、これまでにない機能イメージングを実現します。
Tadashi Takayanagi, YITP/Kavli IPMU
AdS Space from Optimization of Euclidean Path-Integral in CFT
Meeting room 1, Kenkyu honkan 1F
We introduce a new optimization procedure for Euclidean path integrals which compute wave functionals in CFTs. We optimize the background metric in the space on which the path integration is performed. Equivalently this is interpreted as a position dependent UV cut-off. For two dimensional CFT vacua, we find the optimized metric is given by that of a hyperbolic space and we interpret this as a continuous limit of the conjectured relation between tensor networks and AdS/CFT. We confirm our procedure for excited states, the thermofield double state, the SYK model and discuss its extension to higher dimensional CFTs. We also show that when applied to reduced density matrices, it reproduces entanglement wedges and holographic entanglement entropy. We suggest that our optimization prescription is analogous to the estimation of computational complexity. This talk is mainly based on arXiv:1703.00456.
Yuji Sugimoto, Osaka University
Calabi-Yau geometry and electrons on 2d lattice
Meeting room 1, Kenkyu honkan 1F, slides (kek.jp only)
I will talk about the mysterious correspondence between the topological string and condensed matter physics. Recently, it was pointed out that the quantum eigenvalue problem for a particular Calabi–Yau manifold, known as local $\mathbb{F}_0$, is closely related to the Hofstadter problem for electrons on a two-dimensional square lattice. Then we generalize this result, and find that the local $\cB_3$ geometry, which is a three-point blow-up of local $\mathbb{P}^2$, is associated with electrons on a triangular lattice. This correspondence allows us to use known results in condensed matter physics to investigate the quantum geometry of the toric Calabi–Yau manifold.
Naoki Watamura, Nagoya University
The entanglement of locally excited states in Maxwell theory
Seminar room, Kenkyu honkan 3F We have studied the time evolution of Entanglement Entropy (EE) in 4 dimensional (space time) Maxwell theory. We perform a local excitation by acting with a local operator on the vacuum state. An inserted local gauge invariant operator changes the structure of entanglement, and so the EE. We take the half of the total space as the subspace, and evaluate the increase of (Renyi) EE from the one of the vacuum state by using the replica method. The increase of the (Renyi) EE converges to a value as t goes to infinity (late time limit). We showed that in this limit, the increase of Renyi EE can be interpreted in terms of quasi-particles, but descrived with a non-trivial algebra reflecting the specialty of gauge theory. We found a way of determining this algebra from the propagator, and confirmed that this works also in the case for free scalar field theory and 6d Maxwell Theory.
We have studied the time evolution of Entanglement Entropy (EE) in 4 dimensional (space time) Maxwell theory. We perform a local excitation by acting with a local operator on the vacuum state. An inserted local gauge invariant operator changes the structure of entanglement, and so the EE. We take the half of the total space as the subspace, and evaluate the increase of (Renyi) EE from the one of the vacuum state by using the replica method. The increase of the (Renyi) EE converges to a value as t goes to infinity (late time limit). We showed that in this limit, the increase of Renyi EE can be interpreted in terms of quasi-particles, but descrived with a non-trivial algebra reflecting the specialty of gauge theory. We found a way of determining this algebra from the propagator, and confirmed that this works also in the case for free scalar field theory and 6d Maxwell Theory.
References)
Masahiro Nozaki, Naoki Watamura “Quantum Entanglement of Locally Excited States in Maxwell Theory” arXiv:1606.07076 [hep-th].
Bryan Webber, University of Cambridge
Standard Model Parton Distributions at Very High Energies
Meeting room 1, Kenkyu honkan 1F
