井元信之, 大阪大学
QND測定・状態の空間発展・量子情報処理
Seminar room, Kenkyu honkan 3F
国立大学法人に移籍する前のNTT基礎研究所のときから表題のような研究ができたのは、光ファイバー通信のイノベーションに繋がるからであった。一方、これらの研究を通じて高エネルギー研究所や天文台の方々との会話もあった。研究のスコープも通信のみならず純学問から量子ゲームまで広がって来た。会話を途切れさせないためにあるいはもっと深めるためにも、プロジェクト研究の報告でなく、素朴な疑問から始めて最後はまだ途中の感がある余韻を残して説明を試みたい。
Sergei V. Ketov, Tokyo Metropolitan University and Kavli IPMU
New supergravity framework and its applications to the early Universe cosmology
Meeting room 1, Kenkyu honkan 1F, slides (kek.jp only)
in the first part of my talk I give a very simple introduction to the Dark Side of the Universe (cosmological inflation, dark energy and dark matter), and then briefly review its possible gravitational origin. In the second part of my talk I introduce the supergravity description of the Dark Universe and describe the new tools in the supergravity model building.
Keisuke Harigaya, Institute for Advanced Study
Higgs parity, strong CP problem and unification
Seminar room, Kenkyu honkan 3F
The quartic coupling of the Standard Model Higgs nearly vanishes at a high energy scale. We show that this is explained by the parity symmetry and its spontaneous break down by the condensation of the parity partner of the Higgs. The parity can solve the strong CP problem. The theory is embedded into SO(10) unification and the precise gauge coupling unification is achieved.
山下雅樹, ICRR
地下から探る宇宙暗黒物質実験
先端計測実験棟の多目的室
暗黒物質は銀河団の運動からF. Zwickyにより80年前からその存在を示唆されてきた。その後、銀河の回転速度、宇宙背景放射などの観測により、その存在は確実視されている。一方、素粒子模型からも期待される暗黒物質であるが、未だにその正体は不明である。宇宙の物質の約80%を担っている暗黒物質は我々の身の周りにも飛来し、1Lに数個程度存在していると考えられ、直接探索ではこの粒子の検出を目指している。本講演では地下実験室における液体キセノンを中心とした暗黒物質直接探索実験を紹介する。
Di-Lun Yang, Yukawa Institute of Theoretical Physics, Kyoto University
Chiral kinetic theory and quantum transport of chiral fluids
Seminar room, Kenkyu honkan 3F, slides (kek.jp only) Recently, the anomalous transport of Weyl fermions such as the renowned chiral magnetic effect stemming from the chiral anomaly has been widely studied in relativistic heavy ion collisions, Weyl semimetals, or even in astrophysics. Although such anomalous transport is in general non-dissipative and independent of couplings in thermal equilibrium, the non-equilibrium (or near-equilibrium) transport of Weyl fermions could be affected by other quantum effects and interactions. The chiral kinetic theory (CKT), which delineates quasi-particle transport with the chiral anomaly, is a useful tool to investigate quantum transport in and out of equilibrium for Weyl-fermion systems at weak coupling. In this talk, I will review the recent development of CKT based on quantum field theories, which manifests Lorentz covariance and consistently incorporates collisions. We then apply the CKT to study second-order quantum transport of chiral fluids near local equilibrium. By using a relaxation-time approximation, novel anomalous Hall currents pertinent to interactions and triggered by electric fields and temperature/chemical-potential gradients are discovered. Moreover, the chiral magnetic/vortical effects receive viscous corrections. In addition, one finds that the CKT yields a non-vanishing antisymmetric component of the canonical energy-momentum tensor in chiral fluids with vorticity, which reveals the spin-orbit interaction responsible for angular-momentum transfer in the presence of an axial chemical potential.
Recently, the anomalous transport of Weyl fermions such as the renowned chiral magnetic effect stemming from the chiral anomaly has been widely studied in relativistic heavy ion collisions, Weyl semimetals, or even in astrophysics. Although such anomalous transport is in general non-dissipative and independent of couplings in thermal equilibrium, the non-equilibrium (or near-equilibrium) transport of Weyl fermions could be affected by other quantum effects and interactions. The chiral kinetic theory (CKT), which delineates quasi-particle transport with the chiral anomaly, is a useful tool to investigate quantum transport in and out of equilibrium for Weyl-fermion systems at weak coupling. In this talk, I will review the recent development of CKT based on quantum field theories, which manifests Lorentz covariance and consistently incorporates collisions. We then apply the CKT to study second-order quantum transport of chiral fluids near local equilibrium. By using a relaxation-time approximation, novel anomalous Hall currents pertinent to interactions and triggered by electric fields and temperature/chemical-potential gradients are discovered. Moreover, the chiral magnetic/vortical effects receive viscous corrections. In addition, one finds that the CKT yields a non-vanishing antisymmetric component of the canonical energy-momentum tensor in chiral fluids with vorticity, which reveals the spin-orbit interaction responsible for angular-momentum transfer in the presence of an axial chemical potential.
References :
Di-Lun Yang, arXiv:1807.02395
Yoshimasa Hidaka, Di-Lun Yang, Phys.Rev. D98 (2018) no.1, 016012, arXiv:1801.08253
Yoshimasa Hidaka, Shi Pu, Di-Lun Yang , Phys. Rev. D 97 (2018) no.1, 016004, arXiv:1710.00278
Yoshimasa Hidaka, Shi Pu, Di-Lun Yang , Phys.Rev. D95 (2017) no.9, 091901, (Rapid Communication), arXiv:1612.04630
永長直人, 理研・東大
[第八回KEK連携コロキウム] Chirality in dynamics
つくばキャンパス4号館1階セミナーホール/東海キャンパス東海1号館115号室 (TV会議中継) When the system lacks both parity and mirror symmetries, it is called “chiral” and can be classified into right-handed and left-handed. Chirality is one of the most fundamental issues in many branches of science [1]. In biology, the chirality of DNA is the same for all the living creatures on earth. In chemistry, to synthesize the molecules of one chirality selectively is an important issue. In physics, the parity violation is a striking feature of weak interaction. Here we focus on the chirality appearing in dynamics. It appears trivial that the flows of particles are different between right and left directions when the system is chiral. However, this is not the case as seen from the simplest problem of a single particle scattering problem by one-dimensional asymmetric potential. Namely, the unitary nature of the quantum mechanical time evolution put the constraint on the S-matrix, and the transmission/reflection probabilities are the same for right and left incident waves. Dissipation breaks the unitary nature of the time evolution, and hence the friction, which brings the classical nature of the dynamics, plays an important role for the directional (nonreciprocal) responses of the system. The time-reversal symmetry of the microscopic Hamiltonian also plays an essential role in the nonreciprocal responses of the system. In this talk, I will discuss that the most fundamental principles in physics manifest themselves in the nonreciprocal responses of chiral systems, i.e., the symmetries, dissipation, quantum-classical crossover/transition, quantal Berry phase and topology, and many-body correlation effects. The concrete examples to discuss include magnetochiral anisotropy of semiconductors [2], Weyl semimetals [3], and superconductors [4], nonlinear spin current generation in Rashba-Dresselhaus systems, and shift currents under photo-excitations [5]. The collaborators of these works are T. Morimoto, K.W. Kim, R. Wakatsuki, K. Hamamoto, M. Ezawa, H. Ishizuka, S. Hoshino, S. Koshikawa, S. Shimizu, Y. Kaneko Y. Saito, T. Ideue, Y. Iwasa, and Y. Tokura.
When the system lacks both parity and mirror symmetries, it is called “chiral” and can be classified into right-handed and left-handed. Chirality is one of the most fundamental issues in many branches of science [1]. In biology, the chirality of DNA is the same for all the living creatures on earth. In chemistry, to synthesize the molecules of one chirality selectively is an important issue. In physics, the parity violation is a striking feature of weak interaction. Here we focus on the chirality appearing in dynamics. It appears trivial that the flows of particles are different between right and left directions when the system is chiral. However, this is not the case as seen from the simplest problem of a single particle scattering problem by one-dimensional asymmetric potential. Namely, the unitary nature of the quantum mechanical time evolution put the constraint on the S-matrix, and the transmission/reflection probabilities are the same for right and left incident waves. Dissipation breaks the unitary nature of the time evolution, and hence the friction, which brings the classical nature of the dynamics, plays an important role for the directional (nonreciprocal) responses of the system. The time-reversal symmetry of the microscopic Hamiltonian also plays an essential role in the nonreciprocal responses of the system. In this talk, I will discuss that the most fundamental principles in physics manifest themselves in the nonreciprocal responses of chiral systems, i.e., the symmetries, dissipation, quantum-classical crossover/transition, quantal Berry phase and topology, and many-body correlation effects. The concrete examples to discuss include magnetochiral anisotropy of semiconductors [2], Weyl semimetals [3], and superconductors [4], nonlinear spin current generation in Rashba-Dresselhaus systems, and shift currents under photo-excitations [5]. The collaborators of these works are T. Morimoto, K.W. Kim, R. Wakatsuki, K. Hamamoto, M. Ezawa, H. Ishizuka, S. Hoshino, S. Koshikawa, S. Shimizu, Y. Kaneko Y. Saito, T. Ideue, Y. Iwasa, and Y. Tokura.
References
[1] M. Gardner, The Ambidextrous Universe. Left, Right and the Fall of Parity, Basic Books Inc. (1964)
[2] T. Ideue et al., Nature Physics 13, 578-583 (2017).
[3] T. Morimoto and N. Nagaosa, Phys. Rev. Lett. 117, 146603 (2016).
[4] R. Wakatsuki et al., Science Advances 3, e1602390 (2017)
[5] T. Morimoto and N. Nagaosa, Science Advances 2, e1501524 (2016).
Tomoaki Ishiyama, Chiba University
Supercomputer simulations of dark matter structure formation in the Universe
Meeting room 1, Kenkyu honkan 1F, slides (kek.jp only)
We report the results of ultralarge cosmological N-body simulations of small and large scale structure formation in the Universe. In particular, I focus on the formation and evolution of dark matter halos and subhalos near the free streaming scale, and their impact on the indirect dark matter detection experiments. We also present the implementation of our massively parallel simulation code for modern huge supercomputers.
本間謙輔, 広島大学
Search for weakly-coupling pseudo Nambu-Goldstone bosons by mixing multi-wavelength coherent lights
Room 345, 4 go-kan
素粒子実験が発見してきた素粒子群は、重力を基準にした場合、例外なく「極めて強く結合する重い粒子群」の交換によって顕在化できるものに限られてきた。しかし、宇宙の暗黒成分をほとんど説明できない観測事実に直面すると、これまでの実験手法では到達不可能な「極めて弱く結合する軽い粒子群」に敢えて着眼することに新たな意義を見出せる。加えて、自発的対称性の破れには質量零のボゾンが伴うことは、連続かつグローバル対称性である限り理論的に予見されており、この点を新粒子探索の主導原理に据えるならば、零に近い質量を持つボゾン群を一般的に探索することは理論的にも強固な根拠を持つ。本講演では、データの乏しいsub-eV-keV域の質領域に対し、光と弱結合する未知ボゾン場を介した誘導共鳴散乱を、多色のコヒーレント光衝突により探索する実験について、その現状と展望を述べる。
Sai Wang, KEK
Probing primordial black hole dark matter with aLIGO using stochastic background of gravitational waves
Meeting room 1, Kenkyu honkan 1F
Advanced LIGO’s discovery of gravitational-wave events is stimulating extensive studies on the origin of binary black holes. Assuming that the gravitational-wave events can be explained by binary primordial black hole mergers, we utilize the upper limits on the stochastic gravitational-wave background given by Advanced LIGO as a new observational window to independently constrain the abundance of primordial black holes in dark matter. We show that Advanced LIGO’s first observation run gives the best constraint on the primordial black hole abundance in the mass range from ~1 to ~100 solar mass, pushing the previous microlensing and dwarf galaxy dynamics constraints tighter by 1 order of magnitude. Moreover, we discuss the possibility to detect the stochastic gravitational-wave background from primordial black holes, in particular from subsolar mass primordial black holes, by Advanced LIGO in the near future.
Sanjaye Ramgoolam, Queen Mary, University of London
Branes, Dominoes and Words.
Meeting room 1, Kenkyu honkan 1F, slides (kek.jp only)
