Seminar Information

In the 2006 school year

TitleRadiatively-Induced Spontaneous Symmetry Breaking by Wilson-line in a Warped Extra Dimension
SpeakerHisaki Hatanaka (Chung-Yuan Christian University)
Date6 March (Tue) 14:00 H711
CommentWe investigate the dynamical gauge-Higgs unification(Hosotani mechanism) on Randall-Sundrum space-time. First, we study the Hosotani mechanism in the SU(2) gauge model with bulk fermion in the Randall-Sundrum space-time. We evaluate the one-loop effective potential for the Wilson-line phase for fermion loops. Second, We apply this mechanism into dynamical gauge-Higgs unification. We reconsider a 5D SU(3)w gauge model with or without an additional adjoint fermion and scalar fields as a toy model of electroweak gauge-Higgs unification in the Randall-Sundrum space-time. As a result, we found that the ratio of Z-boson mass to W-boson depends on the Wilson-line phase. We also propose a mechanism to tune the ratio to the experimental value (mZ/mW) \sim 1.13 by using some additional fields.

TitleFinite temperature string in AdS3
SpeakerToshihiro Matsuo
Date21 Feb. (Wed) 15:30 H711
CommentString theory in curved spacetime at finite temperature might be relevant for an early stage of the universe. We consider, as a concrete (though not realistic) example, string theory in AdS_3 described by the WZW model. Especially, we will focus on Hagedorn behavior which is read off from Euclidean one- loop path integral. We will also mention the correspondence principle of string/BH in AdS spacetime which would be confirmed by AdS_3 string/BTZ BH case.

TitleTopological aspects of gauge theory on noncommutative geometry
SpeakerHajime Aoki
Date30 Jan. (Tue) 15:30 H711
CommentWe define the Ginsparg-Wilson Dirac operator and its index on noncommutative geometry, such as fuzzy sphere and noncommutative torus. We then construct topologically nontrivial configurations in gauge theory on them, and study their properties and dynamics.

Date23 Jan. (Tue) 15:30 H711

TitleDiscrete Family Symmetry
SpeakerJisuke Kubo
Date16 Jan. (Tue) 15:30 H711
CommentWe consider a supersymmetric extension of the standard model, which possess a family symmetry based on a binary dihedral group Q6, and investigate the consequences of the family symmetry on the mixing of fermions, FCNCs and the stability of proton.

TitleHiggsless models and deconstruction
SpeakerMasaharu Tanabashi
Date9 Jan. (Tue) 15:30 H711
CommentDeconstruction (latticization) provides a powerful tool for analyzing electroweak properties of the five dimensional Higgsless models. Using the deconstruction technique, we construct a class of viable Higgsless models consistent with the present electroweak data. We also study one-loop structure in these models.

TitleHyper-Kahler nonlinear sigma models on (co)tangent bundle over Hermitian symmetric spaces
SpeakerMasato Arai (Helsinki U.)
Date19 Dec. (Fri) 15:30 H711
CommentWe construct four-dimensional N=2 nonlinear sigma models on tangent and cotangent bundles over Hermitian symmetric spaces of classical type by using the projective superspace formalism, which is an off-shell superfield formulation of N=2 supersymmetry.

TitleFlavor violation in ``minimal'' SUSY SU(5) model
SpeakerToshifumi Yamashita (SISSA)
Date8 Dec. (Fri) 12:10 H711 <------ Anntention!
CommentWe compare the patterns of the flavor violating effects which are radiatively induced via the neutrino Yukawa couplings in

TitleNeutrino masses in the economical 3-3-1 model
SpeakerHoang Ngoc Long (Institute of Physics, VAST(Vietnam Academy of Science & Technology))
Date5 Dec. (Tue) 15:30 H711
CommentThe model based on SU(3)_C X SU(3)_L X U(1)_X (3-3-1) with right-handed neutrinos and only two Higgs triplets is presented. The new lepton (flavor) number violating interactions through charged and neutral currents, are given. Radiative mechanism for quark and neutrino masses is also presented.

TitleLattice Formulation of Two Dimensional Topological Field Theory
SpeakerKazutoshi Ohta
Date28 Nov. (Tue) 15:30
CommentWe investigate an integrable property and observables of 2 dimensional N=(4,4) topological field theory defined on a discrete lattice by using the ``orbifolding'' and ``deconstruction'' methods. We show that our lattice model possess the integrability and make clear meaningful differences between the discrete lattice and differentiable manifold, which would be importanat to a study of topological quantities on the lattice. We also propose a new construction of N =(2,2) supersymmetric lattice theory, which is realized by a suitable truncation of scalar fields from the N =(4,4) theory.

TitleGraviton Propagators in Supergravity and Noncommutative Gauge Theory
SpeakerSatoshi Nagaoka
Date21 Nov. (Tue) 15:30
CommentタイプIIB行列模型で構成されるD3-ブレーンは4次元非可換空間上のゲージ理論として定式化される。行列模型の頂点演算子は、この非可換ゲージ理論において構成されたWilson lineと閉弦との結合の様子を表している。その中で重力モードは非可換ゲージ理論に特有な性質であるUV/IR混合の効果によって非常に特殊な振る舞いを示す。この研究では、非可換ゲージ理論とその双対な重力理論の双方の立場から重力子の頂点演算子の2点相関関数の解析を行ない、その振る舞いについて議論を行なった。この研究は共同研究hep-th/0512204,0611056に基づく。

TitleModuli: Stabilization, Phenomenology and Cosmology
SpeakerMasahiro Yamaguchi
Date7 Nov. (Tue) 15:30

TitleSupersymmetric Gauge Theories with Matters, Toric Geometries and Random Partitions
SpeakerYui NOMA
Date24 Oct. (Tue) 15:30

TitleAnomalies in Brane Tilings
SpeakerYosuke Imamura
Date17 Oct. (Tue) 15:30

TitleGravitino Production from Moduli Decay and Its Cosmological Implications
SpeakerMotoi Endo (DESY)
Date11 Sept. (Mon) 2006 16:00 <------ Anntention!
CommentWe study a scalar decay such as moduli (or an inflaton) into the gravitino as well as the standard model particles and their superpartners, and the supersymmetry breaking sector. The impacts of the new decay processes on cosmological scenarios are discussed; the modulus field generically produces too much gravitinos. We also comment on applications of the decay processes for the inflaton decay.

TitleGravitinos as a probe into inflation and SUSY breaking sectors
SpeakerFuminobu Takahashi (DESY and ICRR)
Date6 Sept. (Wed) 2006 15:30 <---- Attention!
CommentThe existence of the inflationary era is strongly supported by the recent observation by WMAP. It is therefore extremely important to investigate the reheating processes of the inflaton to reveal the thermal history of the universe. Recently, I have pointed out that too many gravitinos can be directly produced by the inflaton decay in many inflation models. The `new' gravitino overproduction problem sets severe bounds on both the inflation models and SUSY breaking scenarios. I will explain their implications on both inflation and SUSY breaking sectors in detail.

TitleTilings, Dimers and Quiver Gauge Theories
SpeakerAmihai Hanany (MIT)
Date18 Aug. (Fri) 2006 11:00 & 16:30 <------ Anntention!
CommentHanany.pdf(Local Only)

TitleTwo Loop Calculation of Higgs Mass in Gauge-Higgs Unification
SpeakerNobuhito Maru (University of Roma, Italy)
Date25 July (Tue) 15:30
CommentWe calculate the quantum corrections to the mass of the zero mode of the fifth component of the gauge field at two-loop level in a five dimensional massless QED compactified on S1. We discuss in detail how the divergences are exactly canceled and the mass becomes finite. The key ingredients to obtain the result are the shift symmetry and the Ward-Takahashi identity. We also evaluate the finite part of corrections. Maru.pdf(Local Only)

SpeakerNaoyuki Haba (Tokushima University)
Date19 July (Wed)
CommentHaba.pdf(Local Only)

TitleComments on Heterotic Flux Compactifications
SpeakerTetsuji Kimura (KIAS, Korea)
Date18 July (Tue) 15:30
CommentIn heterotic flux compactification with supersymmetry, three different connections with torsion appear naturally, all in the form \omega + aH. Supersymmetry condition carries a=-1, the Dirac operator has a=-1/3, and higher order term in the effective action involves a=1. With a view toward the gauge sector, we explore the geometry with such torsions. After reviewing the supersymmetry constraints and finding a relation between the scalar curvature and the flux, we derive the squared form of the zero mode equations for gauge fermions. With d H=0, the operator has a positive potential term, and the mass of the unbroken gauge sector appears formally positive definite. However, this apparent contradiction is avoided by a no-go theorem that the compactification with non-zero H and d H=0 is necessarily singular, and the formal positivity is invalid. With non-zero d H, smooth compactification becomes possible. We show that, at least near supersymmetric solution, the consistent truncation of action has to keep \alpha'R2 term in the effective action. A warp factor equation of motion is rewritten with \alpha' R2 contribution included precisely, and some limits are considered. Kimura.pdf(Local Only)

SpeakerKenzo Ishikawa (Hokkaido University)
Date14 July (Fri) 12:00 <---- Attention
Comment量子ホール効果は、様々な特異な量子現象や量子効果を示してきた。本セミナーでは、高いランダウ状態の量子ホール多体電子系における量子現象を議論する。高いランダウ状態では、低いランダウ状態における量子ホール効果とは全く異なる量子現象が発現する。フォンノイマン格子表現に基づいて電子場の理論を定式化し、非等方的性質をもつ圧縮性ガス状態や、Flux状態が平均場解として求まることを示す。さらに、これらの状態の特異な物理をしらべ、高移動度の量子ホール系で観測されている極めて異方性の強い物理現象と比較する。 Ishikawa.ppt(Local Only)

TitleConfined Phase In The Real Time Formalism And The Fate Of The World Behind The Horizon
SpeakerFuruuchi Kazuyuki (Harish-Chandra Research Institute, India)
Date4 July (Tue) 15:30
CommentIn the real time formulation of finite temperature field theories, one introduces an additional set of fields (type-2 fields) associated to each field in the original theory (type-1 field). In the context of the AdS-CFT correspondence, type-2 fields have been interpreted as living on a boundary behind the black hole horizon. However, below the Hawking-Page transition temperature, the thermodynamically preferred configuration is the thermal AdS without a black hole, and hence there are no horizon and boundary behind it. This means that when the dual gauge theory is in confined phase, the type-2 fields cannot be associated with the degrees of freedom behind the black hole horizon. In this case the role of the type-2 fields would be to make up bulk type-2 fields of classical closed string field theory on AdS at finite temperature in the real time formalism. I explained precisely how this happens by analyzing 't Hooft-Feynman diagrams in the gauge theory side and how the difference of the phases (confined/deconfined) changes the relevant diagrams.

TitleA Holographic Interpretation of Entanglement Entropy
SpeakerTadashi Takayanagi (Kyoto University)
Date27 June (Tue) 15:30
CommentA holographic interpretation of the entanglement entropy in quantum (conformal) field theories is discussed from the viewpoint of AdS/CFT correspondence. We propose that the entanglement entropy in d+1 dimensional conformal field theories can be obtained from the area of d dimensional minimal surfaces in AdS_{d+2}, analogous to the Bekenstein-Hawking formula for black hole entropy. We show that our proposal perfectly reproduces the correct entanglement entropy in 2D CFT when applied to AdS_3. We also discuss higer dimensional cases especially AdS_5/CFT_4 examples. We find that an important part of the entanglement entropy is related to the central charge of 4D CFT.Takayanagi.ppt(Local Only)

SpeakerMotohiko Yoshimura (Okayama University)
Date21 June (Tue) 16:30 <---- Attention
Commentニュートリノ研究は、標準理論のはるかかなたの物理を探究する現状ではほとんど唯一の手段である。また、宇宙のバリオン非対称性を理解する鍵でもある。従来の実験手法をこえて、ニュートリノの質量絶対値、マヨラナ粒子かどうか、CP の破れの有無を決める、新たな実験原理と手段の開拓が重要である。ここでは、マヨラナ粒子の同種粒子効果、レーザーまたはX線利用による反応促進の活用などを中心に、最近の研究を概観してみたい。Yoshimura.pdf(Local Only)

TitleN=4 SYM on R×S3 and Theories with 16 Supercharges
SpeakerGoro Ishiki (Osaka University)
Date13 June (Tue) 15:30
CommentIshiki.ppt(Local Only)

SpeakerKin-ya Oda (Riken)
Date6 June (Tue) 15:30
CommentTeVスケール重力シナリオにおいては、高次元空間における真のプランクスケールが文字通りTeVスケールとなり、来年末に稼働が予定されている加速器LHCで到達可能となる。このようなシナリオにおいてはLHCで高次元ブラックホールが多量に生成されることは確実である。今回のセミナーでは、TeV重力シナリオの簡単な紹介とともに、ブラックホール生成と蒸発の物理において何がわかっていて何がわかっていないのか、どのあたりに量子重力の補正が効いてくることが期待されるのか、等を議論する。Oda.pdf(Local Only)

TitleLittle Higgs Phenomenology
SpeakerC. -P. Yuan (Michigan State University)
Date30 May (Tue) 15:30
CommentYuan.pdf(Local Only)

Titlee+e- Linear Collider ILC : Central Physics Program
SpeakerP.M.Zerwas (DESY Hamburg & KEK Tsukuba)
Date24 May (Tue) 16:30 <-- Attention
CommentAn overview of the physics program will be presented for the e+e- linear collider ILC in the TeV energy range. At this facility, now in the design phase, central issues of physics can be addressed: electroweak symmetry breaking; the unification of the fundamental interactions; and the structure of space-time. In this context the talk will focus on analyses of the Higgs mechanism, supersymmetry and extra space dimensions. Combined with LHC results, a comprehensive picture of physics can eventually be developed from the Tera- to the Planck-scale -- a crucial range for unraveling the fundamental laws of nature.
Zerwas.pdf(Local Only)

TitleTriangle Anomaly from Einstein Manifolds
SpeakerYuji Tachikawa (University of Tokyo)
Date23 May (Tue) 15:30
CommentAdS/CFT対応においては、CFT側の三角量子異常はAdS側のChern-Simons項に対応する。そこで、type IIB超重力を五次元Einstein多様体X x 五次元AdS空間で考えた場合に、 AdS側のCS項をKaluza- Klein還元によって決定する方法を説明したい。 また、 Xが佐々木-Einstein 多様体の場合には対応するCFT を与える箙ゲージ理論が知られている。その三角量子異常を計算 し、 重力側の計算と完全に一致することを示したい。 この講演は共同研究 hep-th/0601054 に基づく。
Tachikawa.pdf (Local Only)

SpeakerZenro Hioki (University of Tokushima)
Date16 May (Tue) 15:30
Hioki.pdf Hioki2.pdf(Local Only)

TitleQuantum Brachistochrone
SpeakerAkio Hosoya (Tokyo Institute of Technology)
Date26 April (Wed) 16:30 <---- Attention!!
CommentWe present a general framework for finding the time-optimal evolution and the optimal Hamiltonian for a quantum system with a given set of initial and final states. Our formulation is based on the variational principle and is analogous to that for the brachistochrone in classical mechanics. We reduce the problem to a formal equation for the Hamiltonian which depends oncertain constraint functions specifying the range of available Hamiltonians. For some simple examples of the constraints, we explicitly find the optimal solutions.Recent development is also reported. 参考: PRL 96,060503(2006)
Hosoya.pdf(Local Only)

TitleSome recent ideas on confinement
SpeakerKenichi Konishi (Pisa U.)
Date17 April (Mon) 15:00 <---- Attention!!
CommentKonishi.pdf(Local Only)

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