Makoto Nozawa, KEK
[理論宇宙物理グループセミナー] Black holes in an expanding universe
Meeting room 3, Kenkyu honkan 1F Black holes in the isolated and stationary spacetimes have been intensively studied so far. They are completely characterized by conserved charges and exhausted by Kerr family. Black holes in non-isolated and dynamical background, on the other hand, have been less understood. In particular, the black-hole spacetime which is asymptotically FLRW universe is of considerable importance when discussing formation and evaporation of primordial black holes. In this talk, I will give a talk on the study of `black hole candidate’ recently obtained by Ohta et al, which is specified by a set of harmonic functions. We established that this geometry indeed describes a black hole in a decelerating FLRW universe satisfying appropriate physical conditions. This solution can be generalized to a universe with an arbitrary power law expansion and to any number of spacetime dimensions. Furthermore, we show that in five dimensions this solution is pseudo-supersymmetric in fake supergravity coupled to arbitrary number of scalars and gauge fields. We discuss physical properties and causal structures in detail.
Black holes in the isolated and stationary spacetimes have been intensively studied so far. They are completely characterized by conserved charges and exhausted by Kerr family. Black holes in non-isolated and dynamical background, on the other hand, have been less understood. In particular, the black-hole spacetime which is asymptotically FLRW universe is of considerable importance when discussing formation and evaporation of primordial black holes. In this talk, I will give a talk on the study of `black hole candidate’ recently obtained by Ohta et al, which is specified by a set of harmonic functions. We established that this geometry indeed describes a black hole in a decelerating FLRW universe satisfying appropriate physical conditions. This solution can be generalized to a universe with an arbitrary power law expansion and to any number of spacetime dimensions. Furthermore, we show that in five dimensions this solution is pseudo-supersymmetric in fake supergravity coupled to arbitrary number of scalars and gauge fields. We discuss physical properties and causal structures in detail.
参考文献：Kei-ichi Maeda & Masato Nozawa, Phys.Rev. D81 (2010) 124038; D83 (2011) 024018
Sergey Ketov, Tokyo Metropolitan University
Cosmological Inflation in Supergravity: The Meeting Point of Cosmology and High-Energy Physics
Meeting room 3, Kenkyu honkan 1F
We propose a simple (most economic, based on gravity and supersymmetry only) and viable realization of cosmological (chaotic) inflation of early Universe. It is based on a new theory of supergravity that we call F(R) supergravity. The F(R) supergravity can be understood as the N=1 locally supersymmetric extension of popular theories of f(R) gravity in four spacetime dimensions. Our proposal to inflation uses the supersymmetric extension of the (R+R^2) inflationary model of Starobinsky. The F(R) supergravity theory was invented by me just for that purpose. In my talk I review the Starobinsky inflation, the F(R) supergravity and their applications to the Early Universe cosmology. However, those are not the only features of the proposed approach. The universal reheating and particle production after inflation in the context of F(R) supergravity are briefly discussed too.
Masato Yamanaka, KEK
Big-bang nucleosynthesis with a long-lived CHAMP including helium-4 spallation process
Meeting room 1, Kenkyu honkan 1F
Long-lived charged massive particle (CHAMP) plays a role as catalyzer of exotic nuclear reactions in the Big-bang nucleosynthesis era. I discuss the primordial abundances of light elements involving the helium-4 spallation processes, the catalyzed fusion processes, and the internal conversion processes. Furthermore, I show the cosmologically favored parameter space in the minimal supersymmetric standard model with long-lived stau via solving the Lithium-7 problem
山口康宏, 阪大RCNP
[原子核・ハドロングループセミナー] Exotic baryons from a heavy meson and a nucleon --Negative parity states --II
Meeting room 1, Kenkyu honkan 1F
我々はヘビーフレーバーを含む中間子であるDbarメソンまたはBメソンと核子の系におけるエキゾチックな散乱状態の解析を行う。粒子間の相互作用として、ヘビークォーク対称性に基づいたパイオン、ベクターメソン交換相互作用を用いる。系を非相対論的に取扱い、シュレディンガー方程式を解くことによってS行列を求め、その結果として(I,JP)=(0,3/2-)状態に共鳴があることを予言した。この共鳴はヘビーベクターメソンと核子の系(Dbar*-NまたはB*-N)とのチャンネル結合によって引き起こされるFeshbach共鳴であることがわかった。
大古田俊介, 阪大RCNP
[原子核・ハドロングループセミナー] Exotic baryons from a heavy meson and a nucleon --Negative parity states -- I
Meeting room 1, Kenkyu honkan 1F
我々はヘビーメソンと核子(DbarN 及び BN)によって構成される、エキゾチックなフレーバー量子数を持つヘビーバリオンの研究を行なった。ヘビーメソンと核子間の相互作用はヘビークォーク対称性を反映した1ボソン交換力として記述する。安井氏と須藤氏による先行研究では、パイオンによる長距離力のみ考慮されていたが、今回我々は短距離力の効果も取り入れる。このとき束縛状態は先行結果と同様に(I,J^P) = (0,1/2^-)状態で得られた。また、我々はSU(4)フレーバー対称性に基づく、ヘビーメソン-核子系の束縛状態についての解析も行なった。この解析からクォーク質量が軽い領域と重い領域での物理の違いを議論する。
Akira Mizuta, KEK
[理論宇宙物理グループセミナー] Photospheric thermal radiation for GRB promot emission
Meeting room 3, Kenkyu honkan 1F ガンマ線バーストの即時放射に関しての放射機構の一つとして光球面からの熱的放射モデルがあげられる。最近の理論的、数値シミュレーションから得られた結果に関して紹介する。
ガンマ線バーストの即時放射に関しての放射機構の一つとして光球面からの熱的放射モデルがあげられる。最近の理論的、数値シミュレーションから得られた結果に関して紹介する。
参考文献：
Lazzati et al. ApJ 732, 34 (2011)
Nagakura et al. ApJ 731, 80 (2011)
Pe’er ApJ 682, 463 (2008)
日高義将, 理研
場の量子論を用いた輸送係数の計算
Seminar room, Kenkyu honkan 3F
我々は相対論的場の量子論における輸送係数のダイアグラムを用いた新しい計算法を提案する． 我々の輸送係数の計算はBethe-Salpeter型の自己無撞着な方程式の計算に帰着し，その方程式の構造は線形化されたBoltzmann方程式と同様な形を持つことを示す．この計算の主要項は線形化されたBoltzmann方程式と完全に等価であり，高次の補正は頂点関数，スペクトル関数と衝突項に繰り込む事ができる事を見る．またこの方法を用いた相転移近傍での臨界現象についても議論する．特にモードカップリング理論や非線形Langevin方程式とダイアグラムの方法の対応を議論する．この方法を南部-Jona-Lasino模型に適用しカイラル相転移点での輸送係数について議論する．
Koji Hashimoto, RIKEN
Nuclear physics from String theory
Meeting room 1, Kenkyu honkan 1F
Describing nuclear properties directly from QCD is a long standing problem. I apply string theory technique called AdS/CFT correspondence, to solve this issue. With the technique, I can show a formation of atomic nuclei and their important properties such as nuclear density saturation, starting from strongly coupled QCD. This opens up an interdisciplinary interaction between nuclear physics, particle physics, and string theory.
Yasuhiro Sekino, KEK
CMB Fluctuations and String Compactification Scales
Meeting room 1, Kenkyu honkan 1F We propose a mechanism for the generation of temperature fluctuations of cosmic microwave background. We consider a large number of fields, such as Kaluza-Klein modes and string excitations. Each field contributes to the gravitational potential by a small amount, but an observable level of temperature fluctuations is achieved by summing up the contribution of typically of order 10^{14} fields. Tensor fluctuations are hardly affected by these fields. Our mechanism is based on purely quantum effects, and is different from the “slow-roll” or “curvaton” scenario. Using the observed data, we find constraints on the parameters of this model, such as the size of the extra dimensions and the string scale. Our model predicts a particular pattern of non-gaussianity with a small magnitude.
We propose a mechanism for the generation of temperature fluctuations of cosmic microwave background. We consider a large number of fields, such as Kaluza-Klein modes and string excitations. Each field contributes to the gravitational potential by a small amount, but an observable level of temperature fluctuations is achieved by summing up the contribution of typically of order 10^{14} fields. Tensor fluctuations are hardly affected by these fields. Our mechanism is based on purely quantum effects, and is different from the “slow-roll” or “curvaton” scenario. Using the observed data, we find constraints on the parameters of this model, such as the size of the extra dimensions and the string scale. Our model predicts a particular pattern of non-gaussianity with a small magnitude.
Reference: Yoshinobu Habara, Hikaru Kawai, Masao Ninomiya and Yasuhiro Sekino, [arXiv:1103.0299].
井元信之, 大阪大学大学院基礎工学研究科
量子測定の意外な側面
Room 345, 4 go-kan
