2009.2.20 updated
Seminar *1号館116号室にて.
| 4/9(WED) | 15:30- | 古城徹(理研) | Tetraquark core in the sigma meson |
| The sigma meson is analyzed through the tetraquark correlators. The general 1/Nc arguments enable to reduce the complicated spectrum of the sigma channel into the bare pole plus continuum ones but without the pipi scattering components. Comparing the large Nc results for the 2q and pipi molecule picture with the sum rule results for the reduced sigma spectrum, we conclude that the sigma meson can have the bare tetraquark core with the mass about 700 MeV. | |||
| 4/16(WED) | 15:00- | 藤井宏次(東大駒場) | Expanding color flux tubes and instabilities (pdf) |
| We present an analytic study of the physics of the glasma which is a strong classical gluon field created at early stage of high-energy heavy-ion collisions. Our analysis is based on the picture that the glasma just after the collision is made of color electric and magnetic flux tubes extending in the longitudinal direction with their diameters of the order of 1/Q_s (Q_s is the saturation scale of the colliding nuclei). We find that both the electric and magnetic flux tubes expand outwards and the field strength inside the flux tube decays rapidly in time. Next we investigate whether there exist instabilities against small rapidity-dependent perturbations for a fixed color configuration. We find that the magnetic background field exhibits an instability induced by the fluctuations in the lowest Landau level, and it grows in the time scale of 1/Q_s. For the electric background field we find no apparent instability while the possible relation to the Schwinger mechanism for particle pair creations is suggested. | |||
| 5/7(WED) | 15:00- | 前沢祐(理研) | Magnetic and electric screening masses from Polyakov-loop correlation in two-flavor lattice QCD (ppt) |
| Screening properties of quark-gluon plasma are induced by thermal fluctuation of electric (longitudinal) and magnetic (transverse) gluons. We calculate the screening masses from Polyakov-loop correlation in two-flavor lattice QCD simulation. Using symmetries of the Euclidean-time reflection and charge conjugation on the Polyakov-loop correlator, we can decompose the Polyakov-loop correlation to various combinations of the Polyakov-loop operators with a gauge fixing, and extract the screening masses. We find that the magnitude of the magnetic screening mass turns out to be smaller than that of the electric screening mass, in accordance with an expectation of the thermal perturbation theory. We will also show comparisons of the screening masses with AdS/CFT correspondence and quenched lattice QCD. | |||
| 5/21(WED) | 15:00- | 八田佳孝(筑波大) | Jets in N=4 SYM from AdS/CFT (ppt) |
| After a brief review of jet physics in perturbative QCD, I discuss various aspects of jets in N=4 supersymmetric Yang-Mills theory at strong coupling using gauge/string correspondence. I also talk about the energy loss of jets in a finite temperature plasma and discuss its relation to the previous works on jet quenching. | |||
| 6/11(WED) | 15:00- | Alexander Rothkopf(本郷) | Non-thermal Fixed Points: weak coupling description of strongly correlated systems |
| We present numerical and analytical findings, showing that strongly correlated systems far from equilibrium can exhibit scaling solutions with a dynamically generated weak coupling. The employed model systems are relativistic scalar quantum field theories with initial conditions, which lead to non-equilibrium instabilities, such as parametric resonance or spinodal decomposition. The non-thermal fixed points are found to prevent fast thermalization if classical-statistical fluctuations dominate over quantum fluctuations. These non-equilibrium phenomena may be of interest for the thermalization in both early universe cosmology and relativistic heavy-ion collisions. | |||
| 6/25(WED) | 15:00- | 野秋淳一(KEK) | Chiral properties of light mesons with Nf=2 overlap fermions |
| 近年の格子QCDにおける大きな進展として, 格子上で厳密なカイラル対称性を保つ数値シミュレーションが実現したことが挙げられる. 特に我々JLQCD Collaboration では, 業界最大の計算機資源を投入することで動的クォークの効果を取り入れた格子計算を初めて達成した. すなわち計算結果と連続理論, 特にカイラル摂動論との整合性を直接的に問うことが可能となった. 我々はまず中間子の質量と崩壊定数のカイラル特性に着目し, これまでの格子計算ではあいまいにされてきた いくつかの問題点を議論した. 今回はその成果を発表する. | |||
| 7/2(WED) | 14:30- | 肥山詠美子(理研) | ハイパー核物理の現状と今後の展望 |
| 近年のハイパー核物理研究の発展は目覚しい. また来年にはJ-PRAC施設において, Day-1実験が実施される予定であり, 今後のハイパー核物理研究の発展は大いに期待されるところである. セミナーでは, 近年のハイパー核物理の発展と今後の展望について, 少数粒子系物理の観点から講演をする予定である. | |||
| 9/25(THU) | 14:30- | 森田健司(延世大学, ソウル) | QCD sum ruleによるTc付近におけるチャーモニウムの性質 (ppt) |
| チャーモニウムはQCDにおける閉じ込めの性質に敏感であり, 近年の高エネルギー 重イオン衝突においては, 閉じ込め－非閉じ込め相転移のシグナルの有力な候補と して活発に研究されている. 本研究では, QCD sum rule(QCDSR)を用いた有限温度媒質中でのチャーモニウムを 解析した. QCDSRでは, カレント相関関数の演算子積展開(OPE)を通じて スペクトル関数の情報を得ることができるが, 有限温度の場合には, 凝縮項の温度依存性を通じて温度の効果を取り入れることが出来る. 重クォーク系の場合には次元４グルーオン凝縮が支配的であり, 我々は格子ＱＣＤの結果からグルーオン凝縮の温度依存性を決定し, それがどのようにチャーモニウムのスペクトル変化を引き起こすかを調べた. J/psi, eta_cならびに, chi_cについての計算結果も報告する. | |||
| 10/29(WED) | 16:00- | F. Lenz (Institute for Theoretical Physics III, University of Erlangen-Nurnberg) | Quantum fields in accelerated frames |
| In this talk I will present studies of quantized fields in accelerated frames (Rindler spaces) with emphasis on gauge fields. Important properties of the dynamics in Rindler spaces are shown to follow from the scale invariance of the corresponding Hamiltonians. Origin and consequences of this extraordinary property of Hamiltonians in Rindler spaces are elucidated. Characteristics of the Unruh radiation, the appearance of a photon condensate and the interaction energy of vector and scalar static charges are discussed and implications for Yang-Mills theories and QCD in Rindler spaces are indicated. | |||
| 11/26(WED) | 15:00- | 赤松幸尚(本郷) | Heavy Quark Diffusion in the Quark-Gluon Fluid (pptx) |
| In the relativistic heavy ion collisions, it is suggested that thermal medium is produced in a very short time after the collision. However, the heavy quarks such as charm and bottom quarks are expected to be still on their way to thermalization and require a different treatment than hydrodynamics. Relativistic diffusion process is one of the candidates for the description of heavy quarks in the quark-gluon plasma. In this talk, I will review the heavy quark energy loss very briefly, construct heavy quark diffusion model in the quark-gluon plasma, and combine it with hydrodynamic model. I will also discuss the profile of heavy quark diffusion, heavy quark spectra, and the spectra of single electrons decayed from heavy quarks. The recent analyses of heavy quark correlations will also be discussed. | |||
| 12/10(WED) | 16:00- | 金澤拓也(本郷) | 閉じ込め四方山話 (pptx) |
| 格子シミュレーションを介して非可換ゲージ理論の 閉じ込めに関する知見を得ようとする最近の試みのいくつかに ついてレビューする. 準備が間に合えばpreliminaryな数値計算 結果も提示する予定. | |||
| 1/21(WED) | 15:00- | 石井理修(筑波大学計算科学研究センター) | 格子QCDによる核力 |
| 最近進めている格子QCDによる核力の研究について説明する. この方法では格子QCDによりまずBethe-Salpeter(BS)波動関数を生成し, そこから核子間ポテンシャルを逆算する. 最大の特徴は, BS波動関数の長距離部分に 埋め込まれた散乱位相差の情報も同時に再現できるようなポテンシャルが得られる という点である. これによりNN散乱実験に忠実な核子間ポテンシャルを 格子QCDを用いて研究することに道が開かれる. また, quenched QCDを用いて 実際に得られた結果には, 現象論的核子間ポテンシャルが共通に持つ性質(i)近距離の斥力芯 (ii)中間距離の引力が同時に再現されており, 非常に有望な方法であることが期待される. このセミナーでは, テンソル力, ハイペロン力, 核力のエネルギー依存性, PACSCSゲージ配位を使った2+1 flavor full QCD result等の最近の進展にも触れる. |
Journal Club *3号館101号室にて.
| 4/18(FRI) | 16:00- | 佐野 | Signatures of S-wave bound-state formation in finite volume
S.Sasaki and T.Yamazaki PRD74 114507 (2006) http://arxiv.org/abs/hep-lat/0610081 |
| 5/2(FRI) | 15:00- | 井上 | Jet quenching in high energy heavy ion collision by QCD synchrotron-like radiation
E.V.Shuyak and I.Zahed PRD67 054025 (2007) |
| 5/16(FRI) | 16:00- | 大西 | Coupled Hartree-Fock-Bogoliubov kinetic equation for a trapped Bose gas Milena Imamovi-Tomasovi and Allan Griffin PRA60 494 (1999) |
| 5/23(FRI) | 16:00- | 丹治 | Nonequilibrium Quantum Breakdown in a Strongly Correlated System T.Oka and H.Aoki arXiv:0803.0422v1 [cond-mat.str-el] |
| 5/30(FRI) | 16:00- | 藤井 | Chiral phase transition in the presence of spinodal decomposition C. Sasaki, B. Friman, K. Redlich, Phys.Rev.D77,034024 Transverse Rapidity Dependence of the p-pbar ratio as a Signature of the QCD Critical Point M. Asakawa, S.A. Bass, B. Muller and C. Nonaka, arXiv:0803.2449 And also, just mentioned about A QCD chiral critical point at small chemical potential: is it there or not? Ph.de Forcrand, S.Kim and O. Philipsen, POS(LAT2007)178 Phases of dense quarks at large Nc L. McLerran and R. Pisarski, Nucl.Phys.A796, 83 |
| 6/6(FRI) | 16:00- | 服部 | Onset of J/ psi Melting in Quark-Gluon Fluid at RHIC T. Gunji, H. Hamagaki, T. Hatsuda and T. Hirano Phys.Rev.C76:051901(2007), [hep-ph/0703061] |
| 6/20(FRI) | 16:00- | 西山 | The Azimuthal decorrelation of jets widely separated in rapidity as a test of the BFKL kernel A.S. Vera and F. Schwennsen Nucl.Phys.B776 170 (2007), [hep-ph/0702158] Phenomenology of jet physics in the BFKL formalism at NLO F. Schwennsen hep-ph/0703198 |
| 7/4(FRI) | 16:00- | 松井 | Real-time static potential in hot QCD M. Laine, O. Philipsen, P. Romatschke and M. Tassler JHEP 0703:054(2007), [hep-ph/0611300] A Resummed perturbative estimate for the quarkonium spectral function in hot QCD Mikko Laine JHEP 0705:028(2007), [arXiv:0704.1720 [hep-ph]] Real and imaginary-time Q anti-Q correlators in a thermal medium A. Beraudo, J.-P. Blaizot and C. Ratti arXiv:0712.4394 [nucl-th] |
| 9/29-30 | @3-108 | QCD Daze | |
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1 佐野 "Minimaly-doubled fermions" 2 井上 "Energy loss of charm quarks in the QGP: collisional vs radiative" M.G.Mustafa, hep-ph/0412402 3 大西 "Landau theory of relativistic Fermi liquids" G.Baym and S.A.Chin, Nucl.Phys.A262,527(1976) 4 藤井 "The QCD critical point" 5 丹治 "Review on the spaghetti vacuum" 6 服部 "The effects of topological charge in heavy ion collisions: event by event P and CP violation" D.K.Kharzeev et al, Nucl.Phys.A803,227(2008) 7 西山 "Prethermalization" J.Berges et al, PRL93,142002(2004) 8 松井 "Summary (CTP)" | |||
| 11/7(FRI) | 16:00- | 佐野 | QCD critical point and complex chemical potential singularities M. A. Stephanov Phys.Rev.D73,094508(2006) |
| 11/21(FRI) | 16:00- | 井上 | Mach cones in QGP J. Casalderrey-Solana hep-ph/0701257 |
| 11/28(FRI) | 16:00- | 大西 | Magnetic susceptibility of quark matter within Fermi-liquid theory T. Tatsumi and K. Sato Phys.Lett.B663(2008)322 |
| 12/5(FRI) | 16:00- | 丹治 | Quantum field theoretical description of unstable behavior of trapped Bose-Einstein condensates with complex eigenvalues of Bogoliubov-de Gennes equations M. Mine, M. Okumura, T. Sunaga and Y. Yamanaka, Ann.Phys.322(2007)2327 Appendix of "Aspects of Quantum Field Theory in Curved Space-Time" S.A.Fulling, Cambridge Univ. Press |
| 12/12(FRI) | 14:30- | 服部 | Tilted pion sources from azimuthally sensitive HBT interferometry M. Lisa, U. Heinz and U. Wiedemann Phys.Lett.B489(2000)287 Azimuthally Sensitive Hanbury Brown-Twiss Interferometry in Au+Au Collisions at sqrt[sNN]=200 GeV J. Adams et al. STAR Collaboration PRL93(2004)012301 |
| 1/16(FRI) | 16:00- | 西山 | Fluctuation-dissipation-relation-preserving field theory of the glass transition in terms of fluctuating hydrodynamics T. Nishino and H. Hayakawa PRE78(2008)061502 |
| 2/6(FRI) | 15:00- | 藤井 | Non-Gaussian Fluctuations near the QCD Critical Point M. A. Stephanov PRE102(2009)032301 |
| 2/20(FRI) | 15:00- | 松井 | Broken Symmetries (link) the Royal Swedish Academy of Sciences (2008) Quasi-Particles and Gauge Invariance in the Theory of Superconductivity Y. Nambu, Physical Review 117(1960)648 The Collective Description of Many-Particle Systems (A Generalized Theory of Hartree Fields) T. Kinishita and Y. Nambu, Physical Review 94(1954)598 |
