Back Numbers 2011-12
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- DAY & TIME : 3/2 (Fri.) 10:30-12:00
- SPEAKER : Keisuke Asaka (Hokkaido Univ.)
- TITLE : Complex Langevin method
- E-PRINT :
arXiv:1112.4655 [hep-lat].
- COMMENTS : Journal Club.
- DAY & TIME : 2/24 (Fri.) 10:30-12:00
- SPEAKER : Masahide Shimizu (Hokkaido Univ.)
- TITLE : String theory, Enumerative geometry, and Open mirror symmetry
- E-PRINT :
arXiv:1108.4766 [math.AG].
- DAY & TIME : 2/10 (Fri.) 10:30-12:00, 13:30-
- SPEAKER : Yu Nakayama (IPMU/Caltech)
- TITLE : Scale vs Conformal invariance from holography
- ABSTRACTS :
I discuss the (in)equivalence between scale invariance and
conformal invariance. In the first pedagogical part of the talk,
I start with the field theory criteria to understand the difference
between scale invariance and conformal invariance with many examples.
I also show the sketch of the proof of the equivalence in 1+1 dimension.
In the second part of the talk, I discuss the recent developments of
this subject including my work on the approach from the holography.
- DAY & TIME : 2/3 (Fri.) 10:30-12:00, 13:30-
- SPEAKER : M2 students (Eric Giguére, Sentoku Masashi, Wang Weichang)
- [Giguére]
TITLE : Numerical simulation of exact Supersymmetry in 1 dimension on the lattice
- [Sentoku]
TITLE : Interference of neutrino in muon decays
- [Wang]
TITLE : TBA
- COMMENTS : Rehearsal of Master Thesis Presentation (Short Version)
- DAY & TIME : 1/27 (Fri.) 10:30-12:00, 13:30-
- SPEAKER : M2 students (Eric Giguére, Sentoku Masashi, Wang Weichang)
- [Giguére]
TITLE : Numerical simulation of exact Supersymmetry in 1 dimension on the lattice
E-PRINT : arXiv:1107.1629 [hep-lat], e.t.c..
- [Sentoku]
TITLE : Interference of neutrino in muon decays
- [Wang]
TITLE : TBA
- COMMENTS : Rehearsal of Master Thesis Presentation (Long Version)
- DAY & TIME : 1/20 (Fri.) 10:30-12:00
- SPEAKER : Hisao Suzuki (Hokkaido Univ.)
- COMMENTS : Journal Club
- DAY & TIME : 1/13 (Fri.) 13:30-
- SPEAKER : Yutaka Tobita (Hokkaido Univ.)
- TITLE : Diffraction-corrected nuetrino flux and \nu N total cross section
- E-PRINT : arXiv:1111.6180 [hep-ph]
- COMMENTS : Seminar
- DAY & TIME : 1/13 (Fri.) 10:30-12:00
- SPEAKER : Kazuhiko Suehiro (Hokkaido Univ.)
- COMMENTS : Journal Club
- DAY & TIME : 12/16 (Fri.) 10:30-12:00, 13:30-
- SPEAKER : Masahiro Kuze (Tokyo Inst. of Tech.)
- TITLE :
[Morning] Neutrino Oscillation
[Afternoon] First Results from Double Chooz Reactor Neutrino Experiment
- COMMENTS : The final seminar in this year.
- DAY & TIME : 12/9 (Fri.) 10:30-12:00
- SPEAKER : Masahide Shimizu (Hokkaido Univ.)
- TITLE : Comments on Worldsheet Description of the Omega Background
- E-PRINT :
arXiv:1106.5503 [hep-th]
- COMMENTS : Journal Club
- DAY & TIME : 12/2 (Fri.) 10:30-12:00, 13:30-
- SPEAKER : Io Kawaguchi (Kyoto Univ.)
- TITLE : Classical integrability in sigma models on deformed AdS spaces
- E-PRINT :
arXiv:1107.3662 [hep-th],
arXiv:1109.0872 [hep-th]
- ABSTRACTS :
We present two descriptions to show
the classical integrability of the two-dimensional non-linear sigma model
defined on a three-dimensional warped AdS space.
The three-dimensional warped AdS space is a one-parameter deformation of a three-dimensional AdS space
and has SL(2,R)L x U(1)R symmetry. One descrition is related to the SL(2,R)L and called left description.
The other description is related to the U(1)R and called right description.
In each description, one can construct the Lax pair and read off the classical r-matrix from it.
The resulting r-matrix is of rational type in the left description and trigonometric type in the right description.
Two descriptions are equivalent and there exists a non-local map between them.
We show that a sigma model on a three-dimensional Schrodinger spacetime has a similar integrable structure.
- DAY & TIME : 11/25 (Fri.) 10:30-12:00, 13:30-
- SPEAKER : Masanori Hanada (KEK)
- TITLE : A large-N magic for the finite density QCD
- E-PRINT :
- ABSTRACTS :
Many miracles happen at large-N. As an example I introduce a so-called orbifold equivalence,
which claims a class of correlation functions in theories related by the orbifold projections coincides.
This equivalence was discovered through the study of the AdS/CFT correspondence and
later turned out to hold even in theories without gravity duals.
I explain how it was found and show that it can be understood as a generalization of the Eguchi-Kawai equivalence.
By applying this technique to QCD,
notorious "sign problem" at a finite baryon chemical potential can be solved at large-N.
In other words the sign problem is merely an illusion, up to a 1/N correction.
- DAY & TIME : 11/11 (Fri.) 10:30-12:00, 13:30-
- SPEAKER : M1 students (Yuki Takayasu, Kazuya Matsuda)
- COMMENTS : M1 Journal Club Rehearsal (Short Version)
- DAY & TIME : 11/18 (Fri.) 10:30-12:00, 13:30-
- SPEAKER : M1 students (Yuki Takayasu, Kazuya Matsuda)
- [Takayasu]
TITLE : CP-Violation in the Renormalizable Theory of Weak Interaction
PAPER :
"CP-Violation in the Renormalizable Theory of Weak Interaction", M.Kobayashi and T.Maskawa,
Prog.Theor.Phys.49:652-657,1973 .
ABSTRACTS :
To explain present Baryon world from big-bang, CP-violation is very essential.
To realize CP-violation, M.Kobayashi and T.Maskawa introduced the third generation of quark fields.
I will talk about the mechanism of CP-violation in the weak interaction theory.
- [Matsuda]
TITLE : The Chiral Anomaly and Effective Action in Low Energy Theory
PAPER :
"Consequences of anomalous ward identities", J.Wessa and B.Zumino,
Physics Letters Volume 37B (1971) 95 .
"Global aspects of current algebra", E. Witten,
Nuclear Physics B223 (1983) 422 .
ABSTRACT : TBA
- COMMENTS : M1 Journal Club Rehearsal (Long Version)
- SPEAKER : M1 students (Ippei Fujisawa, Naoki Yokomakura)
- COMMENTS : M1 Journal Club Rehearsal (Short Version)
- DAY & TIME : 11/4 (Fri.) 10:30-12:00, 13:30-
- SPEAKER : M1 students (Ippei Fujisawa, Naoki Yokomakura)
- [Fujisawa]
TITLE :
The Higgs Mechanism in Glashow-Weinberg-Salam Theory
PAPER :
"A Model of Leptons", S. Weinberg,
Phys.Rev.Lett.19:1264-1266 (1967). .
ABSTRACTS :
The Higgs mechanism consists of gauge theory and spontaneous symmetry breaking.
In this talk, I'd like to review these two concepts, and
explain the mechanism and an application, Glashow-Weinberg-Salam(GWS) Theory.
- [Yokomakura]
TITLE : Renormalization and Gravity
PAPER : "Short Distance Freedom of Quantum Gravity",
G. Narain and R. Anishetty.
arXiv:1109.3981 [hep-th].
ABSTRACT :
QED has great success with good consistency with experiments.
And also other two elementary forces,
weak and strong, have been described by QFT as gauge theory.
Gravity can be also described as a gauge theory,
but it is known that gravity is not renormalizable.
Therefore there are many ideas to deal with gravity in quantum
mechanically for example super string theory or super gravity.
In my talk, I will introduce higher derivative theory.
- COMMENTS : M1 Journal Club Rehearsal (Long Version)
- DAY & TIME : 10/28 (Fri.) 10:30-12:00, 13:30-
- SPEAKER : Hiroshi Suzuki (RIKEN)
- TITLE : Numerical simulation of the N=(2,2) Landau-Ginzburg model
- E-PRINT : arXiv:1107.1367 [hep-lat]
- ABSTRACTS :
The two-dimensional N=(2,2) Wess-Zumino (WZ) model with a cubic superpotential is
numerically studied with a momentum-cutoff regularization
that preserves supersymmetry.
A numerical algorithm based on the Nicolai map is employed and
the resulting configurations have no autocorrelation.
This system is believed to flow to an N=(2,2) superconformal field theory (SCFT) in the infrared (IR).
From a finite-size scaling of the susceptibility of the scalar field in the WZ model,
we measure the scaling dimension of a would-be chiral primary field.
We also measure the central charge in the IR region from a correlation function
between conserved supercurrents.
These results are consistent with the conjectured emergence of a SCFT,
and at the same time demonstrate that numerical studies can be complementary to analytical investigations
for this two-dimensional supersymmetric field theory.
- DAY & TIME : 10/21 (Fri.) 10:30-12:00, 13:30-
- SPEAKER : Tadashi Okazaki (Osaka Univ.)
- TITLE :
[Morning] BPS states and Wall-Crossing Phenomena
[Afternoon] Evidence for Duality of Conifold from Fundamental String
- E-PRINT :
arXiv:1107.3660 [hep-th]
- DAY & TIME : 10/14 (Fri.) 10:30-12:00, 13:30-
- SPEAKER : Tetsuji Kimura (KEK)
- TITLE :
[Morning] String theory and gauged supergravity
[Afternoon] Schwarzschild-AdS black holes in N=2 geometric flux compactification
- E-PRINT :
arXiv:1108.1113 [hep-th]
- DAY & TIME : 8/31 (Wed.) 14:00-
- SPEAKER : Ryu Sasaki (YITP)
- TITLE : Exactly Solvable Quantum Mechanics and Infinite Families of Multi-indexed Orthogonal Polynomials
- E-PRINT :
arXiv:1105.0508[math-ph]
- COMMENTS : Informal Seminar.
- DAY & TIME : 8/11 (Thu.) 10:30-
- SPEAKER : Issaku Kanamori (Regensburg Univ.)
- TITLE : TBA
- COMMENTS : Informal Seminar.
- DAY & TIME : 8/5 (Fri.) 10:30-12:00, 13:30-
- SPEAKER : Hidenori Fukaya (Osaka Univ.)
- TITLE :
[Morning] Numerical simulation of QCD on a lattice
[Afternoon] Chiral symmetry breaking on a lattice
- E-PRINT :
[Morning] (for Chiral perturbation part)
arXiv:1105.1606 [hep-lat],
arXiv:0812.2797 [hep-lat]
[Afternoon]
arXiv:0911.5555 [hep-lat],
arXiv:1012.4052 [hep-lat]
- ABSTRACTS :
[Morning]
Because of a strong coupling and non-linearlity
of its interactions, it is difficult to
study quantum chromo dynamics (QCD) in an analytic way.
In this talk, I'd like to review basics of
QCD and how to perform numerical simulation on a lattice,
including the latest results.
[Afternoon]
I will report on our recent numerical lattice QCD
study of the dynamical chiral symmetry breaking.
- DAY & TIME : 7/29 (Fri.) 10:30-12:00
- SPEAKER : Eun-Kyung Park (Hokkaido Univ.)
- TITLE : TBA
- COMMENTS : Journal Club
- DAY & TIME : 7/22 (Fri.) 10:30-12:00, 13:30-
- SPEAKER : Manabu Sakai (YITP)
- TITLE : Inflation in the SUSY breaking sector and gauge mediation
- E-PRINT : arXiv:1004.2099 [hep-ph],
arXiv:1103.5097 [hep-ph]
- COMMENTS :
We present an inflationary scenario based on a
phenomenologically viable model with direct gauge mediation of low-scale
supersymmetry breaking. Inflation can occur in the
supersymmetry-breaking hidden sector. Although the reheating temperature
from the inflaton decay is so high that the gravitino problem seems to
be severe, late time entropy production from the decay of the
pseudomoduli field associated with the supersymmetry breaking can dilute
gravitinos sufficiently. We show that gravitinos are also produced from
the pseudomoduli decay and there is a model parameter space where
gravitinos can be the dark matter in the present universe.
Morning seminar: Since I will talk about the inflation model which is
embedded in the SUSY breaking sector, I will explain how the SUSY
breaking parameters are given in gauge-mediated SUSY breaking models.
And I will also briefly review the inflation model.
- DAY & TIME & PLACE : 7/15 (Fri.) 15:00- 2-409
- SPEAKER : Tadashi Takayanagi (IPMU, The University of Tokyo)
- TITLE : D-brane and topological insulator
- COMMENTS :
This seminar is part of the intensive lecture.
Note that the time and place are quite irregular.
- DAY & TIME : 7/8 (Fri.) 10:30-12:00
- SPEAKER : Ryuichi Nakayama (Hokkaido Univ.)
- TITLE : Einstein Gravity from Conformal Gravity
- E-PRINT :
arXiv:1105.5632[hep-th]
- COMMENTS : Journal Club
- DAY & TIME : 7/1 (Fri.) 10:30-12:00
- SPEAKER : Osamu Seto (Hokkai Gakuen Univ.)
- TITLE : TBA
- COMMENTS : Seminar
- DAY & TIME : 7/1 (Fri.) 13:30-
- SPEAKER : Asao Arai (Department of Math., Hokkaido Univ.)
- TITLE : Mathematical Aspects of Time Operators
- References :
1. A. Arai, Rev. Math. Phys. 17(2005), 1071-1109.
2. A. Arai, Lett. Math. Phys. 80(2007), 211-221.
3. A. Arai, Lett. Math. Phys. 85(2008), 15-25.
4. A. Arai, Lett. Math. Phys. 87(2009), 67-80. Erratum: ibid 89(2009), 287.
5. A. Arai and Y. Matsuzawa, Lett. Math. Phys. 83(2008), 201-211.
6. A. Arai and Y. Matsuzawa, Rev. Math. Phys. 20(2008), 951-978.
7. A. Arai, RIMS Kokyuroku Bessatsu, B16 (2010), 1-13.
- COMMENTS :
A time operator in quantum mechanics is heuristically considered
to be a canonical conjugate operator to a Hamiltonian.
Mathematically speaking, the pair of a Hamiltonian and a time operator is a Hilbert space
representation of the canonical commutation relation (CCR) with one degree of freedom.
As is well known, in every Hilbert space representation of CCR,
there appears an unbounded linear operator, which makes mathematical
analysis of representations of CCR somewhat difficult. In this seminar,
a review is presented on some mathematical aspects of time operators and
their relevance to quantum physics.
- DAY & TIME : 6/24 (Fri.) 10:30-12:00
- SPEAKER : Noboru Kawamoto (Hokkaido Univ.)
- TITLE : A New Approach to Exact Lattice SUSY
- E-PRINT : arXiv:1006.2046[hep-lat] + to appear
- COMMENTS : Journal Club
- DAY & TIME : 6/10 (Fri.) 13:30-
- SPEAKER : Junji Kato (Hokkaido Univ.)
- TITLE : Mass deformation of twisted super Yang-Mills theory with fuzzy sphere solution
- E-PRINT : arXiv:1104.1252 [hep-th]
- COMMENTS : He will talk about his own work collaborated with Y. Kondo and A. Miyake.
- DAY & TIME : 6/3 (Fri.) 10:30-12:00, 13:30-
- SPEAKER : M2 students
- COMMENTS : M2 Journal Club Rehearsal (Short Version)
- DAY & TIME : 5/27 (Fri.) 10:30-12:00, 13:30-
- SPEAKER : M2 students (Eric Giguére, Sentoku Masashi, Wang Weichang)
- [Giguére]
TITLE : Including matter in a 3d latteice gravity model
E-PRINT : Ponzano-Regge model revisited
‡T,
‡U,
‡V.
- [Sentoku]
TITLE : Question of Parity Conservation in Weak Interactions
E-PRINT :
Question of Parity Conservation in Weak Wnteractions.
- [Wang]
TITLE : TBA
- COMMENTS : M2 Journal Club Rehearsal (Long Version)
- DAY & TIME : 5/20 (Fri.) 10:30-12:00, 13:30-
- SPEAKER : Shogo Kuwakino (Nagoya Univ.)
- TITLE :
[Morning]: Heterotic asymmetric orbifold
[Afternoon]: E6 grand unified theory with three generations from heterotic string
- E-PRINT : arXiv:1012.1690,
arXiv:1104.0765
- COMMENTS :
[Morning]:
In the morning session, we shall explain heterotic asymmetric orbifold construction.
Especially we will explain lattice engineering technique
which is the useful compactification method for constructing 4D models with various gauge symmetries.
[Afternoon]:
In the afternonn session, we discuss string GUT scenario,
realizing the standard model from string theory via SUSYGUT with adjoint Higgs fields.
We especially construct E6 SUSYGUT models in heterotic string theory.
We use diagonal embedding method to realize an adjoint Higgs field and
utilize lattice engineering technique for the model building.
In the framework of Z12 heterotic asymmetric orbifold construction,
we obtain two more three-family E6 models with an adjoint Higgs field.
- DAY & TIME : 5/17 (Tue.) 16:30-
- SPEAKER : Yukinari Sumino (Tohoku Univ.)
- TITLE : Family gauge symmetry as an origin of Koide's mass formula and charged lepton spectrum
- COMMENTS : (Informal Seminar)
We propose a mechanism to explain the origin of the charged lepton
spectrum as well as Koide's mass formula, on the basis of U(3)*O(3) family gauge symmetry.
We adopt a known scenario, in which the charged lepton spectrum is
determined by VEV of a scalar field that takes values on 3-by-3 matrix.
Within this scenario, we propose a mechanism, in which
the radiative correction induced by U(3) family gauge interaction
cancels the QED radiative correction to Koide's mass formula.
We consider SU(9)*U(1) symmetry broken down to U(3)*O(3) symmetry.
This leads to a potential model which predicts Koide's mass formula
as well as the charged lepton spectrum consistent with the experimental
values with high precision, by largely avoiding fine tuning of parameters.
- DAY & TIME : 5/13 (Fri.) 10:30-12:00, 13:30-
- SPEAKER : Yukinari Sumino (Tohoku Univ.)
- TITLE :
[Morning]: Introduction to the theory of non-relativistic bound-states based on perturbative QED/QCD
[Afternoon]: Development in theory of heavy quarkonia and precision determination of heavy quark masses
- E-PRINT :
- COMMENTS :
Before 1998, bound-state theories based on perturbative QCD
could hardly explain properties of heavy quarkonium systems
such as charmonium or bottomonium.
Owing to the discovery of renormalon cancellation around 1998,
it became possible to predict accurately various properties of
these bound-states.
Moreover, interpretations of the quark masses and perturbative
QCD potential have changed drastically.
I explain what has happened to our understandings at and since that time.
As an application, I review precision determinations of the masses
of the heavy quarks (b,c,t) using heavy quarkonium systems.
- DAY & TIME : 5/6 (Fri.) 10:30-12:00
- SPEAKER : Masao Jinzenji (Hokkaido Univ.)
- TITLE : Direct Proof of Generalized Mirror Transformation of Projective Space (Work in Progress)
- E-PRINT : arXiv:0902.3863[math.AG]
- COMMENTS : Journal Club
- DAY & TIME : 4/29 (Fri.)
- COMMENTS : No seminar and no group meeting (holiday)
- DAY & TIME : 4/22 (Fri.) 10:30-12:00, 13:30-
- SPEAKER : Yuki Sato (Nagoya Univ.)
- TITLE :
[Morning]: Basics of CDT
[Afternoon]: 2d Causal Dynamical Triangulation Coupled with "Ising Spins"
- E-PRINT :
[Morning]: hep-th/9805212
[Afternoon]: hep-th/0802.0719 ,
hep-th/9312047
- COMMENTS :
[Morning]:
I shall explain about the fundamental ideas around Causal Dynamical Triangulation (CDT).
CDT is a kind of regularization method based on a Lorentzian path-integral for gravity.
In this talk, I would like to focus on the 2-dimensional setup because
in that case the model can be calculated analytically.
[Afternoon]:
We constructed the 2d CDT coupled with "Ising spins"
borrowing the method in the non-critical string field theory constructed by Ishibashi and Kawai.
In the afternoon session, I am planning to talk about the subject above,
which is the collaborative work with H. Fuji and Y. Watabiki.
- DAY & TIME : 4/15 (Fri.) 10:30-12:00
- SPEAKER : Junji Kato (Hokkaido Univ.)
- TITLE : Introduction to projective superspace and kahler manifold
- E-PRINT : arXiv:1004.0880
- COMMENTS : Journal Club