Takeru Yokota, Department of Physics, Kyoto University
Functional renormalization group-aided density-functional theory - application to one-dimensional nuclear matter and two-dimensional electron gas -
Meeting room 1, Kenkyu honkan 1F, slides (kek.jp only)
The functional renormalization group-aided density-functional analysis (FRG-DFT) starts to be applied to realistic models of quantum many-body systems. Recently we have developed a new FRG-DFT formalism, which is suitable for analyzing systems with an infinite number of particles with fixed densities. In this talk, I will present our formalism and our two applications: The first one is the calculation of the equation of state (EOS) and the density-density spectral function of an infinite nuclear matter (NM) in (1+1) dimensions composed of spinless nucleons. The resultant EOS of the NM coincides with that obtained by the Monte-Carlo method within a few percents for the available range of density. We also reproduce a notable feature of the density spectral function of the non-linear Tomonaga-Luttinger liquid: The spectral function has singularities at the edge of its support at the lower-energy side. Subsequently, I will show our FRG-DFT analysis of the two-dimensional homogeneous electron gas, which is the first application of FRG-DFT to two-dimensional systems. We find that the result of FRG-DFT reproduces the exact correlation energy at the high-density limit and is consistent with the Monte-Carlo results for the high- and mid-density cases. Our study demonstrates that the FRG-DFT can be a promising method to analyze quantum many-body systems.
Yu-tin Huang, Department of Physics, National Taiwan University
Build the wall and drain the swamp: positive constraints on EFT from the UV
Meeting room 1, Kenkyu honkan 1F, slides (kek.jp only)
In this talk I will introduce new constraints on couplings of operators in effective field theory derived from Unitarity and Lorentz invariance in the UV. These constraints come in the form of positive geometries in the space of couplings. The origin of this positivity originates from the remarkable positive properties of Gegenbauer polynomials, which are the basis polynomials dictated by Lorentz invariance. Unitarity then dictates that the discontinuity of the S-matrix has a positive expansion on these polynomials. This double positivity give rises to the mathematical object that we named the “EFThedron”, for which all consistent QFT must reside in. Adding that the underlying theory has a worldsheet description, allows us to begin to carve out the string landscape in an on-shell fashion.
Yasunori Lee, Kavli IPMU
A study of time-reversal symmetry of Abelian anyons
Meeting room 3, Kenkyu honkan 1F, slides (kek.jp only)
(2+1)d TQFTs have been studied from various points of view. Recently, the actions of discrete symmetries on them are attracting attention in the context of topological phases of matter. In this talk, I will first review the basic concepts and formalism, and then present the analysis of time-reversal symmetries on Abelian anyon systems mainly focusing on their anomaly.
Takeshi Morita, Shizuoka University
Quantum quench of one-dimensional Fermi gas and thermalization to generalized Gibbs ensembles
Seminar room, Kenkyu honkan 3F, slides (kek.jp only)
Understanding thermalization and entropy production is one of the outstanding problem in theoretical physics. However, in integrable systems, we can explicitly solve the time evolution and observe thermalization to so called generalized Gibbs ensembles. In this talk, we demonstrate it in one-dimensional free Fermi gas, which are trapped in external potentials or a circle, through quantum quenches. We analytically compute local observables such as particle density and show that they always exhibit power law relaxation at late times. We find a simple rule which determines the power law exponent. Our findings are, in principle, observable in experiments in an one dimensional free Fermi gas or Tonk’s gas (Bose gas with infinite repulsion).
Keiichi Maeda, Kyoto University
Constraining progenitors and explosion mechanisms of supernovae through their nucleosynthesis characteristics
Meeting room 3, Kenkyu honkan 1F, slides (kek.jp only)
Supernovae (SNe) are the explosive death of stars, either triggered by gravitational collapse of massive stars (CCSNe; core-collapse SNe) or thermonuclear runway of a white dwarf (SNe Ia). Identifying the natures of their progenitors and explosion mechanisms is one of the central issues in stellar astrophysics and observational transient science. In this talk, I will first introduce basic concepts of the SN explosion nucleosynthesis. Then, a review is given on how different progenitors and explosion mechanisms would manifest themselves in observational properties of SNe. Finally, I will quickly go through some examples of recent progresses in individual topics, where the observational data are used to constraint the natures of the progenitors and explosions through the nucleosynthesis arguments; (1) the white dwarf masses and modes of thermonuclear runaway in SNe Ia, (2) the masses of progenitor stars for different classes of CCSNe, and (3) the standard neutrino-driven explosion models and beyond as confronted by the observations of CCSNe and peculiar outliers (such as those associated with Gamma-Ray Bursts).
Tim Maudlin, New York University
What is Wavefunction Realism?
Seminar room, Kenkyu honkan 3F
In the foundations of physics literature, the question is sometimes raised about whether one should—or even can—be a realist about the wavefunction. This query offers two targets for analysis and explication: “realist” and “wavefunction”. The first term is used in many different ways, as is the second, and to get down to a non-trivial and sensible question one has to specify exactly what one has in mind. I will argue that given the only sensible and non-trivial way to make a clear question here, the indeed one ought to be a “realist” about the “wavefunction”. There never should have been much controversy here, and the recent theorem by Pusey, Barrett and Rudolph settles the issue.
Anupam Mazumdar, University of Groningen
Scale free theory of infinite derivative gravity in the ultraviolet
Seminar room, Kenkyu honkan 3F
I will discuss how infinite derivative theory of gravity can be made ghost free and scale free in the ultraviolet to resolve blackhole and cosmological singularities in 4 spacetime dimensions. I will also discuss the consequences for infinite derivative gravity in 3 spacetime dimensions in AdS.
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
