Mauricio Romo, Kavli IPMU
Two-dimensional supersymmetric field theories with boundaries
Meeting room1, Kenkyu honkan 1F I will discuss recent progress on a particular class of 2d supersymmetric field theories on the disk: N=(2,2) Witten’s gauged linear sigma models. These theories are closely related to string compactifications on Calabi-Yau 3-folds, and so, the results have not only physical but also interesting mathematical consequences.
I will discuss recent progress on a particular class of 2d supersymmetric field theories on the disk: N=(2,2) Witten’s gauged linear sigma models. These theories are closely related to string compactifications on Calabi-Yau 3-folds, and so, the results have not only physical but also interesting mathematical consequences.
I will discuss recent progress on a particular class of 2d supersymmetric field theories on the disk: N=(2,2) Witten’s gauged linear sigma models. These theories are closely related to string compactifications on Calabi-Yau 3-folds, and so, the results have not only physical but also interesting mathematical consequences.
Kunihito Ioka, KEK
[Cosmophysics seminar] The Origin of Cosmic-Ray Hardenings
Meeting room 2, Honkan building We will discuss the implications and possible origin of cosmic-ray hardenings recently observed by the AMS-02 experiment.
We will discuss the implications and possible origin of cosmic-ray hardenings recently observed by the AMS-02 experiment.
References:
AMS-02 Collaboration, “AMS Days at CERN” and Latest Results, 15, April, 2015.
Ohira & Ioka, ApJ 729 (2011) L13
Ohira, Kawanaka & Ioka, in preparation
Yuya Tanizaki, RIKEN
Lefschetz thimble積分法とその物理的応用
Seminar Room, Kenkyu Honkan 3F Picard-Lefschetz理論の量子系への応用が最近見いだされ、特に符号問題に対する新しいアプローチとしても注目を集めている。符号問題は大まかに言えば振動積分の評価の難しさに起因しており、とくにモンテカルロ法のimportance samplingが破綻してしまう、という内容が lattice field theory の文脈で有名であるが、平均場近似にもこの病的な振る舞いが引き継がれてしまうことが知られている。
Picard-Lefschetz理論の量子系への応用が最近見いだされ、特に符号問題に対する新しいアプローチとしても注目を集めている。符号問題は大まかに言えば振動積分の評価の難しさに起因しており、とくにモンテカルロ法のimportance samplingが破綻してしまう、という内容が lattice field theory の文脈で有名であるが、平均場近似にもこの病的な振る舞いが引き継がれてしまうことが知られている。
本セミナーでは、Picard-Lefschetz理論の基礎的な内容を説明し、これがなぜ符号問題に有用だと考えられているのかについて述べる。その後このアイディアを応用して、簡単な行列模型の相転移現象を調べることで、Lee-Yangの定理とこの手法の関係について説明する。また、最近この手法を用いれば平均場近似に引き継がれた符号問題が回避されることを発見したため、その進展についても発表したい。
Koji Ichikawa, IPMU
Current and Future dark matter constraints from dwarf spheroidal galaxies
Meeting room 1, Kenkyu honkan 1F
One of the most promising way to detect dark matter is to look for its annihilation or decay products among cosmic-rays (indirect detection). Recently, more and more interesting results are reported from measurements of cosmic-rays such as gamma-rays, neutrinos, positrons, antiprotons, etc. In this talk, I will especially focus on gamma-ray search from dwarf spheroidal galaxies (dSphs). Though the dSphs is one of the best target for the indirect detection, there remains large uncertainty on the estimation of dark matter profile around the dSphs. I will show how the constraints fluctuate under conservative estimation of the profile and discuss the future prospect of the constraints.
Yasuaki Hikida, Rikyo U.
N=3 higher spin holography and Higgs phenomenon
Meeting Room 1, Kenkyu-Honkan 1F
Superstring theory includes a lot of massive higher spin excitations, and there would appear a higher spi gauge symmetry at the tensionless limit. Moreover, it has been expected that these states could be described by a broken phase of higher spin gauge theory. Recently, it becomes possible to discuss the realizations of the idea with the help of Vasiliev theory and AdS/CFT correspondence. In this talk, I will explain recent developments on the concrete relation between higher spin gauge theory and superstring theory by making use of AdS/CFT correspondence. In particular, I will focus on the AdS_3 case. Moreover, I will show that higher spin fields become massive due to the braking of higher spin symmetry using a simple example.
Sadakazu Haino, Institute of Physics, Academia Sinica
[Cosmophysics Seminar] The new results from Alpha Magnetic Spectrometer (AMS)
Meeting Room 1, Kenkyu Honkan 1F
The AMS collaboration presented the latest results in its quest to understand the origin of cosmic rays and dark matter. These intriguing results were shared and discussed during the “AMS days” in April/2015. Some detailed discussions on the new results will be made in this seminar.
Biswarup Mukhopadhyaya, Harish-Chandra Research Institute, Allahabad, India
The credibility of SUSY phenomenology: some silver linings
Meeting room 3, Kenkyu Honkan 1F
With mass limits on supersymmetric particles going up, the role of supersymmetry (SUSY) as the prime option for physics beyond the standard model may appear somewhat debatable to some quarters. In this backdrop, we start by briefly touching upon the desirability as well viability of SUSY in the current context. Then we summarise a few recent works, particularly those by our group, where there is a slight departure from the commonest approaches to SUSY phenomenology, be it in logic, motivation or collider signals.
Yukinari Sumino, Tohoku University
Understanding Heavy QuarkAntiQuark System by Perturbative QCD
Meeting room 1, Kenkyu honkan 1F
Due to the discovery of renormalon cancellation, it became possible to describe the nature of a heavy quarkantiquark system (such as bottomonium) based on perturbative QCD, both qualitatively and quantitatively. Accordingly, interpretaions of the heavy quark mass and interquark force have been modified considerably. I overview what has been understood and some of theoretical progress since then. The UV part of the interquark potential can be computed in perturbative QCD. We show that a “Coulomb+linear” potential is obtained as the prediction.
Ryusuke Jinno, The University of Tokyo
Gravitational effects on inflaton decay
Meeting room 1, Kenkyu honkan 1F The inflaton inevitably couples to all non-conformally coupled matters to gravity, through an oscillation in the Hubble parameter or the cosmic scale factor. This oscillation leads to particle production during the inflaton oscillation regime. In this talk, I first apply the analysis of scalar particle production to the case of minimally-coupled inflaton to gravity, and then extend the analysis to non-minimally coupled case, in which the Hubble parameter oscillates more violently. I also show the analysis of the graviton production by the inflaton in both minimal & non-minimal case.
The inflaton inevitably couples to all non-conformally coupled matters to gravity, through an oscillation in the Hubble parameter or the cosmic scale factor. This oscillation leads to particle production during the inflaton oscillation regime. In this talk, I first apply the analysis of scalar particle production to the case of minimally-coupled inflaton to gravity, and then extend the analysis to non-minimally coupled case, in which the Hubble parameter oscillates more violently. I also show the analysis of the graviton production by the inflaton in both minimal & non-minimal case.
Reference :
1. Gravitational Effects on Inflaton Decay, Yohei Ema, Ryusuke Jinno, Kyohei Mukaida, Kazunori Nakayama arXiv:1502:02475
2. Yohei Ema, Ryusuke Jinno, Kyohei Mukaida, Kazunori Nakayama, to appear
Vojtech Krejcirik, RIKEN
[cancelled] Few new insights into $\bar{K}N$ interaction
Seminar room, Kenkyu honkan 3F
