セミナー 2011年

Tsubasa Ichikawa, Kinki U

系統的なエラーに耐性のあるユニタリ操作の設計

Seminar room, Kenkyu honkan 3F
量子情報処理では、系の正確な操作が不可欠である。一方、実際の実験環境ではノイズやエラーの影響により、実際に行った操作が所望の操作からずれてしまうことが一般的である。従って、所望の操作を実装するにあたっては、上手い工夫をして「ずれ」が少なくなるようにすることが望ましい。 本講演では、上述のずれの少ない量子操作をどのように設計すればよいかについて紹介する。近年の進展を概説した後に、二準位系に対する最近の我々のグループの取り組みについて述べる。

Kousuke Sumiyoshi, Numazu College of Technology / KEK

Progress of EOS tables for core-collapse supernovae & its applications to explosion dynamics and neutrino signals

Seminar room, Kenkyu honkan 3F
I would like to talk on the recent development of the EOS tables for core-collapse supernovae and their influence on the dynamics and the signal of neutrino bursts. I would like to describe the role of the equation of state in the neutrino-radiation hydrodynamics for supernova explosion. Some topics I try to cover include the mixture of light elements in supernova cores and the neutrino emission from the black hole formation.

Masahiro Ibe, ICRR

Recent Model Buildings of Gauge Mediation

Meeting room 1, Kenkyu honkan 1F
The models with gauge mediation are quite attractive to realize phenomenologically viable supersymmetric standard model. From the cosmological point of view, the models with the very light gravitino with a mass in the eV range is also motivated since it does not cause any cosmological problems. The models with such a light gravitino mass is, however, known to difficult to be realized. In this talk, I explain our recent models which realize such a very light gravitino mass. I also discuss a separate topic in gauge mediation, the lightest Higgs boson mass in gauge mediation. In the MSSM with gauge mediation, the Higgs boson mass is usually predicted at the lower edge of the experimental bound. We show however, the Higgs boson mass can be much enhanced even if we do not extend the models.

Naoki Yamamoto, Keio University

量子フィードバック制御理論の基礎

Seminar room, Kenkyu honkan 3F
量子系を制御する方策として、系を時間連続的に測定し、測定結果に基づいた操作を行う「フィードバック制御」によるものが容易に思いつく。しかし、古典系の場合と異なり、量子系については例えば非可換物理量を同時に測定することができないなど、測定に本質的な制限が課せられる。また、制御を考慮するにあたって、測定のバックアクションも見逃せない問題となる。本講演では、このような問題をクリアし新しい量子情報操作プロトコルを提供する「量子フィードバック制御理論」の基礎を説明する。とくに、この理論の実際的恩恵として、エンタングルの確定的生成法などについて説明する。

Yosuke Imamura, Tokyo Institute of Technology

Exact results in 3d gauge theories and M-theory

Meeting room 1, Kenkyu honkan 1F
Recently some exact results for gauge theories were obtained by using localizatuion. I will review a derivation of the superconformal index for 3d gauge theories, and apply it to Chern-Simons theories dual to M-theory in AdS_4xM_7. The obtained indices are consistent with the symmetry enhancement in gauge theory predicted by AdS/CFT.

Tatsu Takeuchi, Virginia Tech U

Ratchet Model of Baryogenesis

Meeting room 1, Kenkyu honkan 1F
Many models of baryogenesis, such as the Affleck-Dine model, utilize the coherent time-evolution of a baryon-number bearing scalar field to generate baryon-number. This this talk. I point out the resemblance of the problem to the theory of biological motors in which biassed motion is driven by ATP hydrolysis. I argue that a similar mechanism may be implementable in the particle theory context, and lead to interesting model building possibilities.

Hirotaka Yoshino, KEK

[理論宇宙物理グループセミナー] 粒子衝突における重力波放出の摂動解析:レビュー

Meeting room 3, Kenkyu honkan 1F
大きな余剰次元があるシナリオでは加速器においてブラックホールが形成される可能性があるが、その際に放出される重力波がどの程度のエネルギーを持ち去るかを計算することは重要な課題である。ひとつのアプローチは、数値相対論でシミュレーションすることであるが、技術的困難によりあまり進んでいない。一方で、重力波の一部については摂動の方法で解析することが可能である。これは4次元の場合には D’Eath and Payne によってなされたが、最近Herdeiro らによって高次元の場合に拡張された。今回はこの論文の概要と結果を紹介する。
参考文献: Herdeiro, Sampaio, and Rebelo, arXiv: 1105.2298.

Debajyoti Choudhury, Delhi U

Exploring Two Universal Extra Dimensions at the LHC

Meeting room 1, Kenkyu honkan 1F
UED models in 6 dimensions have several interesting features.
We discuss ways to look for such a model at the LHC, and the possibility of distinguishing it from the minimal UED scenario. Also discussed is the possibility of parameter determination.

Shohei Sugiyama, ICRR

Vacuum stability constraints on left-right mixing of stau's

Meeting room 1, Kenkyu honkan 1F
In the minimal supersymmetric standard model, large left-right mixing of stau’s is sometimes intriguing from phenomenological viewpoints. However, too large left-right mixing is not acceptable since the electroweak-breaking vacuum becomes metastable. In this talk the vacuum transition rate is evaluated by using semiclassical techniques, and constraints on parameters of the model are shown. In the calculation the bounce solution is derived in the multifield space. These constraints are also applied to the case of the low-energy minimal gauge mediation model.

Masaki Shigemori, Nagoya University

A Holographic Study of Thermalization in Strongly Coupled Plasmas

Meeting room 1, Kenkyu honkan 1F
Using the AdS/CFT correspondence, we probe the scale-dependence of thermalization in strongly coupled field theories following a quench via saddlepoint calculations of 2-point functions, Wilson loops and entanglement entropy in d=2,3,4. For homogeneous initial conditions, the entanglement entropy thermalizes slowest, and sets a timescale for equilibration that saturates a causality bound. In this strongly coupled setting, the UV thermalizes first.

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