Tatsu Takeuchi 竹内 建, Virginia Tech
Matter Effect from Non-Standard Interactions of the Neutrino
Meeting Room 1, Kenkyu Honkan 1F
Neutrino oscillation in matter is sensitive to interactions between the neutrinos and the matter particles, including the Standard Model W-exchange interaction and any Non-Standard Interactions (NSI’s) that the neutrinos may have. In this talk, I will show how the Jacobi method can be utilized to find analytical expressions for the effective mixing angles and effective CP violating phase of the neutrinos in matter, which lead to extremely simple and compact expressions for the oscillation probabilities. All matter effects can be absorbed into the “running” of the effective parameters. It will be shown that the SM interactions cause theta12 and theta13 to run, while NSI’s involving the mu and tau neutrinos cause theta23 and delta to run. By looking at the “running” of the effective parameters, it is possible to find the best conditions under which the NSI effects will be manifest.
Kunio Kaneta, Institute for Cosmic Ray Research, U Tokyo
Spontaneous thermal leptogenesis
Meeting room1, Kenkyu honkan 1F Although cosmological and astrophysical observations have found the baryon asymmetry of the universe, the standard model of particle physics hardly explain its origin, and thus new physics beyond the standard model is required. Leptogenesis is one of convincing models for baryogenesis, in which tiny neutrino masses can be explained by the presence of right-handed Majorana neutrinos via seesaw mechanism. There, Majorana masses of the right-handed neutrinos would be originated from spontaneous symmetry breaking of $U(1)_{B-L}$, which can lead to a Nambu-Goldstone boson called Majoron. We discuss a possiblitity that leptogenesis takes place in the primordial thermal bath due to the background Majoron field in motion.
Although cosmological and astrophysical observations have found the baryon asymmetry of the universe, the standard model of particle physics hardly explain its origin, and thus new physics beyond the standard model is required. Leptogenesis is one of convincing models for baryogenesis, in which tiny neutrino masses can be explained by the presence of right-handed Majorana neutrinos via seesaw mechanism. There, Majorana masses of the right-handed neutrinos would be originated from spontaneous symmetry breaking of $U(1)_{B-L}$, which can lead to a Nambu-Goldstone boson called Majoron. We discuss a possiblitity that leptogenesis takes place in the primordial thermal bath due to the background Majoron field in motion.
（References)
・M.Ibe and K.Kaneta,“Spontaneous thermal Leptogenesis via Majoron oscillation,” arXiv:1504.04125 [hep-ph].
Shinya Aoki, Yukawa Institute for Theoretical Physics, Kyoto University
On the definition of entanglement entropy in lattice gauge theories
Meeting room 1, Kenkyu honkan 1F
We focus on the issue of proper definition of entanglement entropy in lattice gauge theories, and examine a naive definition where gauge invariant states are viewed as elements of an extended Hilbert space which contains gauge non-invariant states as well. Working in the extended Hilbert space, we can define entanglement entropy associated with an arbitrary subset of links, not only for abelian but also for non-abelian theories. We then derive the associated replica formula. We also discuss the issue of gauge invariance of the entanglement entropy.In the $Z_N$ gauge theories in arbitrary space dimensions, we show that all the standard properties of the entanglement entropy, e.g. the strong subadditivity, hold in our definition. We study the entanglement entropy for special states, including the topological states for the $Z_N$ gauge theories in arbitrary dimensions. We discuss relations of our definition to other proposals.
安井繁宏, 東工大
[近藤問題に関する連続セミナー] クォーク物質におけるQCD近藤効果
研究本館3階セミナー室
倉本義夫, KEK
[近藤問題に関する連続セミナー] 近藤効果の理論的意義と最近の発展
研究本館3階セミナー室
Anupam Mazumdar, Lancaster U
Understanding Gravity
Meeting room 1, Kenkyu honkan 1F
I will discuss how gravity in ultraviolet and infrared can be understood in such a way that it can ameliorate some of the singularity problems of nature and also provide some hints to the pertinent question of cosmological constant.
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
