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.

Kazunori Kohri, KEK

[理論宇宙物理グループセミナー] 速度依存する対消滅散乱断面積をもつダークマターモデルの宇宙論的検証

Meeting room 3, Kenkyu honkan 1F

Naoki Yamatsu, Kyushu University

Chiral Generations in Vectorlike Model with Noncompact Horizontal Symmetry

Meeting room 1, Kenkyu honkan 1F
One of the most remarkable features in Nature is the existence of three generations of chiral quarks and leptons and these mass hierarchy. To understand the particle properties, I have been studying the supersymmetric vectorlike model with a noncompact group horizontal symmetry. The model has two aspects: (1) Three chiral generations emerge as a result of spontaneous breaking of the horizontal symmetry in the vectorlike model. (2) The structure of Yukawa couplings is constrained by the horizontal symmetry and become hierarchical naturally. In this talk, I will mainly discuss the above two characters. I will also introduce some other aspects of the model.

Hideo Kodama, KEK

[理論宇宙物理グループセミナー] Introduction to the toric CY compactification

Meeting room 3, Kenkyu honkan 1F
E. Witten: “Strong coupling expansion of Calabi-Yau compactification”, NPB471:135 (1996)
M. Kreuzer: “Toric Geometry and Calabi-Yau Compactifications”, hep-th/0612307.
Seung-Joo Lee: “Combinatorics in N = 1 Heterotic Vacua”, arXiv:1105.3462
Lara B. Anderson, James Gray, Andre Lukas, Burt Ovrut: “Stabilizing All Geometric Moduli in Heterotic Calabi-Yau Vacua”, arXiv:1102.0011

Ken'ichiro Nakazato, Tokyo University of Science

Exploring Hadron Physics in Black Hole Formations: a New Promising Target of Neutrino Astronomy

Room 345, 4 go-kan
Recently, we have performed several sets of core-collapse simulation of a non-rotating star with 40Msolar by a general relativistic neutrino-radiation-hydrodynamics code so as to compute quantitatively the dynamics up to the black hole formation as well as the neutrino luminosities and spectra. Employing different hadronic equations of state (EOS), we have demonstrated that the duration of neutrino emissions from this event is sensitive to the stiffness of EOS at supra-nuclear densities and, therefore, that the observation of neutrinos from such an event will provide us with valuable information on the properties of dense and hot hadronic matter. While this approach can not distinguish EOS’s with a similar stiffness: a soft nucleonic EOS and a hyperonic EOS, for example, we find that we can break this degeneracy by analyzing more in detail the time variation of neutrino numbers observed at a terrestrial detector. Performing the Kolmogolov-Smirnov test, which is free from the ambiguity of the distance to the progenitor, we show that the break-up of the degeneracy of hadronic EOS’s is indeed feasible for Galactic events. Ref. Nakazato et al. Physical Review D 81 (2010) 083009

Thomas Durt, Institut Fresnel, Marseille

Fundamental aspects of Time in Quantum Mechanics and Meson Phenomenology

Seminar room, Kenkyu honkan 3F
Mesons illustrate fundamental quantum properties such as the superposition principle (for instance in kaon oscillations), and their phenomenology also appeared very useful in the past for measuring CP-violation related effects. More recently, mesons were also useful for testing decoherence and entanglement related effects. The aim of our talk is to show that mesons could also be useful for revealing and/or studying fundamental aspects of Time in the quantum theory, such as the existence of a Time Operator (and also of the so-called Time Superoperator).

1 77 78 79 80 81 82