セミナー情報 (2017年度)

首都大学東京素粒子理論研究室では、学外の研究者を招いて様々な内容のセミナーを開催しています。

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12月13日(水)14:40より @8号館308

" Dynamical scalegenesis via bosonic seesaw mechanism "

松崎 真也 氏(名古屋大学)

We propose a model which accounts for the dynamical origin of the electroweak symmetry breaking, directly linking to the mass generation of dark matter candidate and active neutrinos. This dynamical scale generation is triggered by a couple of seesaw mechanisms (bosonic seesaws) induced from a newly introduced vectorlike confinement sector (hypercolor). Phenomenological consequences (including dark matter physic and LHC signals) derived from this scenario are discussed.

11月29日(水)14:40より @8号館308

" Belle II 実験の概要 "

角野 秀一 氏(首都大学東京)

Belle II 実験が始まり、Belle II実験装置の建設から Belle II 実験の物理解析 へと移行していく時期に差し掛かりつつある。本セミナーでは、Belle II 実験装置 の概要と、BelleII実験の物理の概要について述べる。

11月22日(水)14:40より @8号館308

" Neutrino physics in the minimal gauged U(1) L_mu - L_tau model "

永田 夏海 氏(東京大学)

In the minimal gauged U(1)_{L_mu - L_tau} model, the neutrino mass structure is tightly restricted because of the gauge symmetry. In particular, it is found that for the observed values of the neutrino squared mass differences and the mixing angles, all of the CP phases in the neutrino mass matrix as well as the light neutrino mass eigenvalues are fully determined with great accuracy. I will discuss this prediction and the prospects for testing it in the future neutrino experiments. I will also show the implication for leptogenesis in this minimal setup.

10月18日(水)14:40より @8号館308

" B中間子系におけるインスタントン効果へのアプローチ "

酒井 裕企 氏(首都大学東京)

非可換ゲージ理論におけるトポロジカルな真空構造に起因する非摂動効果である インスタントン効果は幅広い分野にわたり応用されている。 しかしながら、この効果は実験を通じて直接確認がされておらず、 その検証は重要な課題であるといえる。 本セミナーでは低エネルギー有効理論におけるQCDインスタントン効果の大きさへの制限について述べる。 インスタントン効果は中間子の質量スペクトラムやダイナミクスに寄与するが、 今回は特にインスタントン効果によって誘起される軽いクォーク(アップ、ダウン、ストレンジ)の 6点相互作用、いわゆる 't Hooft vertex、がクォークの質量に与える非摂動的な量子補正の大きさについて議論する。 軽い中間子系における6点相互作用によるクォーク質量への補正について先行研究がされており、 アップクォークのカレント質量を0にとることで、strong CP問題を避けることができないことが知られている。 このことは、インスタントン効果が小さいことを示唆している。 今回は、重い中間子系について議論する。 特にB中間子の質量スペクトラムからインスタントン効果によって誘起される質量補正の大きさに制限を与え、 軽い中間子系における制限と同程度の強さが見込まれることが分かった。 将来予定されているB-factory実験からの精密なデータやlattice計算の発展により、この制限はより改善され得る。

7月5日(水)14:40より @8号館300

" Tensions in neutrino oscillation experiments and nonstandard interactions "

安田 修 氏(首都大学東京)

Despite the success of the standard scenario with three flavor neutrino mixing, there have been a couple of anomalies, which may imply the deviation from the standard neutrino oscillation scenario. (i) a non-zero best-fit value of the non-standard oscillation parameters in the the global analysis of the solar and KamLAND data which rules out the standard oscillation scenario at 90% C.L, (ii) the measurement of the non-maximal value of theta_{23} by nova which excludes the maximal mixing at 2.5 sigma C.L. In this talk, I will discuss the possibility to explain these anomalies by introducing the flavor dependent nonstandard interactions of neutrinos. Also I will briefly discuss other possibility to explain the non-maximal mixing of the nova data by introducing larger systematic errors in the neutrino energy.

6月28日(水)14:40より @8号館300

" Quartic gauge boson couplings and the Electroweak Skyrmion "

倉知 昌史 氏(高エネルギー加速器研究所)

Topological objects play important roles in various areas of physics, and the physics of the dark matter might be no exception. In this talk, I will discuss the existence of a dark matter candidate in the Higgs sector of the Standard Model with a minimal addition of higher derivative operators. The talk is based on JHEP 1607 037 (2016) [arXiv:1605.07355] and JHEP 1704 150 (2017) [arXiv:1703.06397].

6月14日(水)14:40より @8号館300

" Prospects of the T2HKK experiment "

Dr. Monojit Ghosh (首都大学東京)

T2HKK is the proposed long-baseline experiment to determine the unknown neutrino oscillation parameters in standard three flavour framework i.e., (i) the mass ordering of the neutrinos and (ii) the information of the leptonic CP phase. The unique two detector setup of this experiment will be helpful to determine both these quantities with high precision. In this talk I will discuss the configuration of T2HKK experiment and its physics capabilities in both standard and non-standard scenarios.

5月31日(水)14:40より @8号館300

" Quantum Entanglement and Emergent Geometry "

渡邊 賢人 氏(基礎物理学研究所)

The gauge/gravity correspondence developed in string theory gives us an interesting insight. It links quantum entanglement and gravitational spacetime. Using measures of quantum information, for example entanglement entropy, we can probe emergent geometries encoded in quantum states. Moreover, tensor networks, which efficiently describes quantum states with proper quantum entanglement, suggest the emergent geometries. In this seminar, I would like to review some developments in this context and our recent works.

5月17日(水)14:40より @8号館300

" A Model of Black Hole Evaporation and 4D Weyl Anomaly "

横倉 祐貴 氏(理化学研究所)

We analyze time evolution of a spherically-symmetric collapsing matter from a point of view that black holes evaporate by nature. We consider conformal matters and solve the semi-classical Einstein equation by using the 4-dimensional Weyl anomaly with a large c coefficient. Here the energy-momentum tensor contains the contribution from both the collapsing matter and Hawking radiation. The solution indicates that the collapsing matter forms a dense object and evaporates without horizon or singularity, and it has a surface but looks like an ordinary black hole from the outside. Any object we recognize as a black hole should be such an object. [arXiv: 1701.03455]

4月26日(水)14:40より @8号館300

" Probing Pre-inflationary Physics From Cosmic Microwave Background "

北澤 敬章 氏 (首都大学東京)

The possible physics of the beginning of inflation will be discussed by taking a model in string theory as an example. The physics gives some imprints in primordial scalar perturbations which were created through the accelerated expansion of the Universe during inflation. One of the typical imprint is the dumping of the amplitude or power of the Cosmic Microwave Background (CMB) at long wave lengths. Next we will discuss whether such an imprint has been observed by PLANC and WMAP experiments. The observational data show the dumping of the power of the CMB at long wave lengths about 3-sigma level with larger galactic mask than the standard one. The observational data also show that we have to take larger galactic mask because of some unknown contaminations in the region closer to the galactic surface.

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