Koji Ichikawa, IPMU
Non-Sphericity/foreground effect on the dark matter halo estimation of dwarf spheroidal galaxies
Meeting room 3, Kenkyu honkan 1F
One of the most promising ways to detect dark matter is to look for its annihilation or decay products among cosmic-rays. Especially, it is found that quite strong constraints can be imposed by the gamma-ray measurements of dwarf spheroidal galaxies. However, recent studies reveal that these constraints are largely affected by the uncertainty of the dark matter halo density. In this talk, we will discuss the robustness of the dark matter halo estimation especially focusing on the effect of the non-sphericity and contamination of foreground stars.
Yohei Saito, Institute of Industrial Science, University of Tokyo
Discreteness-Induced Transition in Multi-body Reaction Systems
Meeting room 3, Kenkyu honkan 1F Qualitative change in dynamical behaviors due to finite system size attracts much attention in various interdisciplinary fields such as systems biology (stochastic chemical reactions), ecology (population dynamics), game theory, and social networks (agent dynamics). Actually, increase in multiplicative noise intensity due to smaller system size can induce qualitative transition of stationary distribution, which has been known as noise-induced transition since 1970s [1]. Although finite system size not only increases noise intensity but also emphasizes state space discreteness, the role of such discreteness of state space has been rarely studied [2]. Thus, we identify such discreteness-induced transition in a simple 1-and 3 body reaction system[3]. This model enables us to derive a sufficient condition under which the discreteness-induced transition arises. Furthermore, we find that the critical size of discreteness-induced transition can become quadratically large, if multi-body reactions are allowed.
Qualitative change in dynamical behaviors due to finite system size attracts much attention in various interdisciplinary fields such as systems biology (stochastic chemical reactions), ecology (population dynamics), game theory, and social networks (agent dynamics). Actually, increase in multiplicative noise intensity due to smaller system size can induce qualitative transition of stationary distribution, which has been known as noise-induced transition since 1970s [1]. Although finite system size not only increases noise intensity but also emphasizes state space discreteness, the role of such discreteness of state space has been rarely studied [2]. Thus, we identify such discreteness-induced transition in a simple 1-and 3 body reaction system[3]. This model enables us to derive a sufficient condition under which the discreteness-induced transition arises. Furthermore, we find that the critical size of discreteness-induced transition can become quadratically large, if multi-body reactions are allowed.
References:
[1] W. Horsthemke and R. Lefever, Noise-Induced Transitions in Physics, Chemistry, and Biology (Springer, 2006); J. Ohkubo, N. Shnerb, and D. A. Kessler, J. Phys. Soc. Jpn. 77 (2008); T. J. Kobayashi, Phys. Rev. Lett. 106, 228101 (2011).
[2] Y. Togashi and K. Kaneko, Phys. Rev. Lett. 86, 2459 (2001).
[3] Y. Saito, Y. Sughiyama, K. Kaneko and T. J. Kobayashi, arXiv:1605.06273.
Shoichiro Tsutsui, Kyoto University
Improvement in complex Langevin dynamics from a view point of Lefschetz thimble
Meeting room 1, Kenkyu honkan 1F We develop a way of improving complex Langevin dynamics motivated by the Lefschetz-thimble decomposition of integrals. In this talk, we consider the cosine model which has a global sign problem due to its multi-thimble structure. We show that the toy model can be modified so that the new model consists of a single Lefschetz thimble and the configurations sampled by the improved complex Langevin process are distributed around on the thimble.
We develop a way of improving complex Langevin dynamics motivated by the Lefschetz-thimble decomposition of integrals. In this talk, we consider the cosine model which has a global sign problem due to its multi-thimble structure. We show that the toy model can be modified so that the new model consists of a single Lefschetz thimble and the configurations sampled by the improved complex Langevin process are distributed around on the thimble.
Reference: S. T. and T. M. Doi, (arXiv:1508.04231) To be published in PRD.
Thorsten Feldmann, U Siegen
Combining Pati-Salam Grand Unification with Gauged Flavour Symmetries
Meeting room 1, Kenkyu honkan 1F
Starting with a general introduction to the flavour puzzle in the Standard Model (SM) and the flavour problem in generic new physics scenarios, I present a specific SM extension which is based on grand unification with Pati-Salam symmetry. The setup is supplemented with the idea of spontaneous flavour symmetry breaking which is mediated through flavon fields with renormalizable couplings to new heavy fermions. While new gauge bosons in this approach can be sufficiently heavy to be irrelevant at low energies, the fermionic partners of the SM fermions, in particular those for the third generation, can be relatively light and provide new sources of flavour violation. The size of the effects turns out to be constrained by the observed values of the SM Yukawa matrices, but in a way that is different from the standard minimal-flavour violation hypothesis. We determine characteristic deviations from the SM that could eventually be observed in future precision measurements in the quark and lepton sector.
Hiroyuki Shimizu, Kavli IPMU, University of Tokyo
Recent developments in 6d N=(1,0) SCFTs
Meeting room 1, Kenkyu honkan 1F, slides (kek.jp only) Recently, there is a huge amount of progress in the study of 6d N=(1,0) theories. We now have a better understanding of the landscape of such theories and have a general formula for their anomaly polynomials. For a large class of 6d (1,0) theories, we have 2d gauge theory descriptions of the worldsheet 2d (0,4) SCFTs on the BPS strings. The compactifications of 6d (1,0) theories are also being studied by many authors. In this talk, I’d like to explain such recent developments in 6d (1,0) theories, based on my works with collaborators.
Recently, there is a huge amount of progress in the study of 6d N=(1,0) theories. We now have a better understanding of the landscape of such theories and have a general formula for their anomaly polynomials. For a large class of 6d (1,0) theories, we have 2d gauge theory descriptions of the worldsheet 2d (0,4) SCFTs on the BPS strings. The compactifications of 6d (1,0) theories are also being studied by many authors. In this talk, I’d like to explain such recent developments in 6d (1,0) theories, based on my works with collaborators.
In the first part of the talk, I will review the basic ingredients of 6d (1,0) theories, such as moduli spaces of vacua, anomalies of global symmetries, and BPS strings on the tensor branch. I will also describe the string theory realizations of important examples of 6d (1,0) theories.
In the second part of the talk, I will explain the compactification of 6d (1,0) theories on a 2-torus as a first step toward considering more general backgrounds. I’d like to focus on the similarities and differences between 6d (1,0) theories and the 6d (2,0) theory under the compactification.
References: arXiv:1408.5572, 1503.06217 and 1508.00915 with K.Ohmori, Y.Tachikawa and K.Yonekura. arXiv:1608.05894 with Y.Tachikawa.
Kazunobu Maruyoshi, Seikei University
Infrared supersymmetry enhancement in 4d QFT
Meeting room 1, Kenkyu honkan 1F, slides (kek.jp only)
We study certain deformations of four-dimensional N=2 superconformal field theories (SCFTs) with non-abelian flavor symmetry which preserve an N=1 supersymmetry. The deformation is described by adding an N=1 chiral multiplet transforming in the adjoint representation of the flavor symmetry with a superpotential coupling, and giving a nilpotent vacuum expectation value to the chiral multiplet which breaks the flavor symmetry. This triggers a renormalization group flow to an infrared SCFT. Remarkably, we find that classes of theories flow to enhanced N=2 superconformal fixed points in the infrared under the deformation. For instance, the deformations of N=2 supersymmetric SU(N) QCD with 2N flavors and Sp(N) QCD with 2N+2 flavors flows to the (A_1, A_{2N-1}) and (A_1, A_{2N}) Argyres-Douglas theories respectively. From these “Lagrangian descriptions,” we compute the full superconformal indices of the (A_1,A_n) theories and find perfect agreements with the previous results in some limits. Other examples of the infrared supersymmetry enhancement include generalized Argyres-Douglas theories and rank-one SCFTs with non-abelian flavor symmetries. This talk is based on the collaborations with Jaewon Song and on the papers arXiv:1606.05632 and 1607.04281.
Takayuki Myo, Osaka Institute of Technology
Recent development of complex scaling method for many-body unbound states in light nuclei
Meeting room 1, Kenkyu honkan 1F Complex scaling method is one of the approaches to study the resonances in many-body quantum system and widely used in atomic and molecular physics, nuclear physics and hadron physics. For nuclear physics, in proton-rich and neutron-rich nuclei, most of the states are observed as unbound states owing to the weak binding nature of valence protons/neutrons. Complex scaling method becomes a powerful tool to investigate the properties of unbound states in those nuclei. We present the recent development of complex scaling method for the description of the many-body resonances and continuum states in light unstable nuclei.
Complex scaling method is one of the approaches to study the resonances in many-body quantum system and widely used in atomic and molecular physics, nuclear physics and hadron physics. For nuclear physics, in proton-rich and neutron-rich nuclei, most of the states are observed as unbound states owing to the weak binding nature of valence protons/neutrons. Complex scaling method becomes a powerful tool to investigate the properties of unbound states in those nuclei. We present the recent development of complex scaling method for the description of the many-body resonances and continuum states in light unstable nuclei.
The seminar consists of two parts as
1) Fundamental properties of the complex scaling method and its application to the many-body resonances decaying into the system of three-body and more, which are often seen in light unstable nuclei.
2) Application of the complex scaling method to the reaction phenomena with light unstable nuclei. In particular, we present the complex-scaled Green’s function method to obtain the cross sections. Green’s function is essential to evaluate the cross sections not only of resonances, but also of non-resonant continuum part individually. This decomposition of the cross section is useful to clarify the reaction mechanism in the connection with the role of resonances.
Morimichi Kawasaki, Institute of Basic Science, Korea
シンプレクティック・トポロジーと不確定性関係について
Seminar room, Kenkyu honkan 3F シンプレクティック幾何学は解析力学に起源をもつ非常に古い幾何学であるが、1985年のグロモフの有名な仕事以降、急速な発展を遂げていて、それを一部ではシンプレクティック・トポロジーと呼ぶ。 シンプレクティック・トポロジーと不確定性関係にはいくつかの関係が知られており、これについて概要を説明する。
シンプレクティック幾何学は解析力学に起源をもつ非常に古い幾何学であるが、1985年のグロモフの有名な仕事以降、急速な発展を遂げていて、それを一部ではシンプレクティック・トポロジーと呼ぶ。 シンプレクティック・トポロジーと不確定性関係にはいくつかの関係が知られており、これについて概要を説明する。
参考文献：Polterovich-Rosen, Function theory on symplectic manifolds (https://sites.google.com/site/polterov/miscellaneoustexts/function-theory-on-symplectic-manifolds)
Pascal Naidon, RIKEN
From the Yukawa to the Efimov attraction
Meeting room 3, Kenkyu honkan 1F
The Yukawa attraction (screened 1/r interaction) is known to arise between two particles exchanging bosons, such as nucleons exchanging mesons. On the other hand, at the three-body level, the Efimov attraction (1/r^2 three-body interaction) can emerge from resonant two-body interactions, leading to the existence of the famous Efimov three-body bound states. In this talk, I will first review the Efimov attraction from its theoretical discovery in 1970 to its most recent experimental confirmations. I will then show how the mediated interaction between two particles immersed in a Bose-Einstein condensate can go from the Yukawa attraction to the Efimov attraction.
Holger Motz, ICSEP, Waseda University
[Cosmophysics Seminar] Methods and Prospects for Science Analysis of CALET Data
Seminar room, Kenkyu honkan 3F, slides (kek.jp only) The ISS based CALET (Calorimetric Electron Telescope) detector is directly measuring the energy spectrum of electron+positron cosmic rays up to 20 TeV with an expected energy resolution of 2%. With an estimated proton rejection capability of 1 : 10^5 and an aperture of approximately 1200 cm^2 sr, it will provide good statistics even well above one TeV. This precise spectrum is going to be analysed for signatures from nearby astrophysical sources such as pulsars and supernova remnants (SNR), as well as from Dark Matter annihilation and decay.
