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Intensive Lecture

DAY & TIME : Feb. 16th-18th 2015
SPEAKER : F. Takahashi　(Tohoku Univ.)
TITLE : Particle Cosmology

DAY & TIME : Fri. Feb. 27th 2015 10:30-
SPEAKER : K. Y. Choi (KASI)
TITLE : Dark matter production in the early Universe: beyond the thermal WIMP paradigm
E-PRINT : Howard Baer, Ki-Young Choi, Jihn E. Kim, Leszek Roszkowski, "Dark matter production in the early Universe: beyond the thermal WIMP paradigm " arXiv:1407.0017[hep-ph]
COMMENT : Seminar

DAY & TIME : Fri. Feb. 13th 2015 10:30-12:00
SPEAKER : O. Seto (Hokkai Gakuen Univ.)
TITLE : Helical Phase Inflation
E-PRINT : Tianjun Li, Zhijin Li, Dimitri V. Nanopoulos, "Helical Phase Inflation" arXiv:1409.3267[hep-th]
COMMENT : Journal Club

DAY & TIME : Fri. Feb. 6th 2015 10:30-

SPEAKER : W. Akutsu (Hokkaido Univ.)
TITLE : 弦の場の理論

SPEAKER : Y. Takano (Hokkaido Univ.)
TITLE :　"Toward the Standard Model from SO(32) Heterotic String"

SPEAKER : Y. Toda (Hokkaido Univ.)
TITLE : STRING THEORY AND STRING SYMMETRY

SPEAKER : H. Hattori (Hokkaido Univ.)
TITLE : TBA
COMMENT : Short Rehearsal of Master Thesis Presentation

DAY & TIME : Wed. Feb. 4th 2015 13:30-
SPEAKER : Y. Urakawa (Institute of Advanced Research, Nagoya university)
TITLE : "Infrared radiative stability and the initial state of the inflationary universe"
ABSTRACT :"Infrared radiative stability and the initial state of the inflationary universe" In this talk, after I give an introduction about the inflationary scenario and the primordial perturbations, which are generated during inflation, I discuss about the infrared (IR) radiative stability of the primordial perturbations, which has been in a debate in the last decades. Interestingly, the study of the IR stability may provide a stringent constraint on the possible initial state of the inflationary universe.
E-PRINT : T. Tanaka, Y. Urakawa, "Loops in inflationary correlation functions" DOI: 10.1088/0264-9381/30/23/233001
COMMENT : Afternoon Seminar

ANNOUNCEMENT From Urakawa san : Before the seminar, I'm going to give a brief notice on the consortium project which is in collaboration among Hokkaido university, Tohoku university, and Nagoya university. The primary purpose of this project is to encourage a collaboration and an interexchange among these three institutes. Participants of young students are very welcome.

DAY & TIME : Fri. Jan. 30th 2015 10:30-

SPEAKER : Y. Toda (Hokkaido Univ.)
TITLE : STRING THEORY AND STRING SYMMETRY
ABSTRACT : This review talk is about the closed string field symmetry. Quantized string mass spectrum is constructed the parameters,momentum and string winding mass,those are able to exchange each parameter. This string character shows the extra type massless states have SU(N) gauge symmetry. The SU(N) gauge symmetry are broken by S1/Z2 orbifold,and the orbifold makes the non-Abelian discrete symmetry. I explain that SU(N) gauge based on the string charactristic symmetry produses this discrete symmetry.

SPEAKER : H. Hattori (Hokkaido Univ.)
TITLE : Hybrid & thermal inflation
ABSTRACT : We first derive slow-roll parameters from RW-metric and the first order perturbation, and then calculate a model of hybrid infaltion. To fit observational valuse to these slow-roll parameters, we confront with a problem that e-folding number is too small than obserbvational one in this context. To avoid this, we can adopt "a thermal inflation" naturally to relax the tension between these. Then, using the quantum field theory at finite temperature, we'll get to know how to cause thermal inflation. We construct a new model that the thermal inflation is caused two times, which we call double thermal inflation, and analyse this model. This talk is based on my master's thesis.
COMMENT : Rehearsal of Master Thesis Presentation

DAY & TIME : Fri. Jan. 23rd 2015 10:30-12:00, 13:30-15:00

SPEAKER : W. Akutsu (Hokkaido Univ.)
TITLE : Tachyon Condensation in Bosonic Open String Field Theory
ABSTRACT : This talk is an review talk on construction of Erler-Schnabl solution and tachyon condensation in open string field theory. In 1999, A. Sen conjectured that the tachyonic mode contained bosonic open string states implies unstability of D-brane, and the D-brane will decay into "tachyon vacuum" through tachyon condensation. In this talk, after introducing some ingredients necessary for constructing exact solutions of EOM of Witten's open string field theory, we'll see that Erler-Schnabl solution is exact solution of the theory and it corresponds to "tachyon vacuum". This talk is based on my master's thesis.

SPEAKER : Y. Takano (Hokkaido Univ.)
TITLE : SM from SO(32) Magnetized Extra Dimensions
ABSTRACT : SM has a lot of problem or questions though it's great success. Supersting has a possibility to be BSM and to derive SM at low energy. In this talk, we wil see introducing magnetic flux in compact space breaks gauge symmetry and makes generations. We discuss which set of magnetic flux is permitted to derive gauge symmetries and generation of SM from SO(32) SYM.
COMMENT : Rehearsal of Master Thesis Presentation

DAY & TIME : Fri. Jan. 16th 2015 10:30-
SPEAKER : Y. Ookouchi (Kyushu Univ.)
TITLE : Introduction to solitons and dielectric branes
ABSTRACT : We firstly discuss a soliton in false vacuum then show its application to model building. Also, we review a dielectric brane in string theory which will be a main object in the second talk.
COMMENT :Seminar (Morning Session)

DAY & TIME : Fri. Jan. 16th 2015 13:30-
SPEAKER : A. Kasai (Kyushu Univ.)
TITLE : Decay of False vacuum via Fuzzy Monopole in String Theory
ABSTRACT We investigate dielectric branes in false vacua in Type IIB string theory. The dielectric branes are supported against collapsing by lower energy vacua inside spherical or tube-like branes. We claim that such dielectric branes can be seeds for semi-classical (or quantum mechanical) decay of the false vacua, which makes the life-time of the false vacua shorter. Also, we discuss a topology change of a bubble corresponding to the fuzzy monopole triggered by dissolving fundamental strings.
COMMENT :Seminar (Afternoon Session)

DAY & TIME : Fri. Jan. 16th 2015
SPEAKER : N. Omoto (Hokkaido Univ.)
TITLE : CP violation
ABSTRACT :In 1964, CP violation was discovered. CP symmetry is almost conserved, but there is a slight violation that can be seen from decay of neutral K mesons. In this presentation, I will introduce the CKM matrix which contains a CP violating phase, as well as quark mixing angle to predict at least 3 generations of quarks in KM theory. I will also introduce cosmological significance of the CP violation.
COMMENT :Rehearsal of M1 Journal Club

DAY & TIME : Fri. Jan. 9th 2015 10:30-12:00
SPEAKER : N. Shimode (Hokkaido Univ.)
TITLE : Towards p-Adic Matter in the Universe
E-PRINT : B. Dragovich, "Towards p-Adic Matter in the Universe" arXiv:1205.4409[hep-th]
COMMENT : Journal Club

DAY & TIME :Fri. Dec. 12th 10:30-12:00, 13:30-15:00
SPEAKER : T. Tsukioka
TITLE : Hydrodynamic Analysis in Gauge/Gravity Correspondence
ABSTRACT : Starting with explaining very elementally stuff in AdS/CFT correspondence, I would like to introduce hydrodynamic studies in the context of gauge/gravity dual. Some of the applications with which I have been involved could be also discussed.
COMMENT : Seminar

DAY & TIME : Fri. Dec. 5th
SPEAKER : I. Kishimoto (Niigata Univ.)
TITLE : Gauge invariants for identity-based solutions in string field theories
ABSTRACT :We consider modified KBc algebras in bosonic and super string field theories expanded around identity-based marginal and scalar solutions. By use of the algebra, classical solutions on the background are constructed and observables for them, including energy densities and gauge invariant overlaps, are calculable. These results are applied to evaluate observables analytically for both of the identity-based marginal and scalar solutions.
E-PRINT :
(1)"Observables for identity-based tachyon vacuum solutions," Isao Kishimoto, Toru Masuda, Tomohiko Takahashi, Prog. Theor. Exp. Phys. (2014) 103B02; doi: 10.1093/ptep/ptu136
(2)"Comments on observables for identity-based marginal solutions in Berkovits’ superstring field theory," Isao Kishimoto, Tomohiko Takahashi, Journal of High Energy Physics July 2014, 2014:31; doi: 10.1007/JHEP07(2014)031
(3)"Gauge invariant overlaps for identity-based marginal solutions," Isao Kishimoto, Tomohiko Takahashi, Prog. Theor. Exp. Phys. (2013) 093B07; doi: 10.1093/ptep/ptt073
COMMENT : Seminar

DAY & TIME : Fri. Nov. 28th 10:30-12:00, 13:30-15:00
SPEAKER : K. S. Jeong (CTPU)
TITLE : Constraints on axion in high scale inflation
ABSTRACT :The Peccei-Quinn (PQ) invariant extension of the Standard Model naturally explains why the strong interact ion does not break CP. In addition, the axion, which is a pseudo-Nambu-Goldstone boson in association with spontaneous breakdown of the global U(1) PQ symmetry, is a good candidate for cold dark matter of the Universe. The relic abundance of axion dark matter depends on when PQ phase transition occurs. We will discuss cosmological constraints on the axion dark matter in high scale inflation, where the axion can give a sizable contribution to isocurvature density perturbation.
E-PRINT :
Kiwoon Choi, Kwang Sik Jeong, Min-Seok Seo, "String theoretic QCD axions in the light of PLANCK and BICEP2," arxiv:1404.3880[hep-th]
Tetsutaro Higaki, Kwang Sik Jeong, Fuminobu Takahashi, "Solving the Tension between High-Scale Inflation and Axion Isocurvature Perturbations," arxiv:1403.4186[hep-ph]
COMMENT :Seminar

DAY & TIME :Fri. Nov. 28th
SPEAKER : T. Tatsuishi (Hokkaido Univ.)
TITLE : Quantum Field Theory and Anomalies
REFERENCE : M. E. Peskin, D. V. Shroeder, An Introduction to Quantum Field Theory, Westview Press, 1995.
COMMENT :Rehearsal of M1 Journal Club

DAY & TIME : Fri. Nov. 21st 10:30-12:00, 13:30-15:00
SPEAKER : S. Matsuura (Keio Univ.)
TITLE : Topologically Twisted N=(2,2) Supersymmetric Yang-Mills Theory on Arbitrary Discretized Riemann Surface
ABSTRACT : I will talk on a construction of supersymmetric Yang-Mills theory on an arbitrary two-dimensional lattice (polygon decomposition) with preserving one supercharge. When a smooth Riemann surface emerges as an appropriate continuum limit of the generic lattice, the discretized theory becomes topologically twisted N=(2,2) supersymmetric Yang-Mills theory on the surface. I will also discuss topological aspect of this discretized theory using the so-called localization.
E-PRINT : S. Matsuura, T. Misumi, K. Ohta, "Topologically Twisted N=(2,2) Supersymmetric Yang-Mills Theory on Arbitrary Discretized Riemann Surface " arXiv:1408.6998[hep-lat]
COMMENT :Seminar

DAY & TIME :Fri. Nov. 21st
SPEAKER : T. Suzuki (Hokkaido Univ.)
TITLE : Black hole thermodynamics and phase transition
E-PRINT : Brian P. Dolan, "Black holes and Boyle's law -- the thermodynamics of the cosmological constant," arxiv:1408.4023[gr-qc]
COMMENT :Rehearsal of M1 Journal Club

DAY & TIME :Fri. Nov. 14th 10:30-12:00
SPEAKER : I. Fujisawa (Hokkaido Univ.)
E-PRINT : A. Bagchi, R. Basu, D. Grumiller, M. Riegler, "Entanglement entropy in Galilean conformal field theories and flat holography," arxiv:1410.4089[hep-th]
COMMENT :Journal Club

DAY & TIME :Fri. Nov. 7th 10:30-12:00, 13:30-15:00
SPEAKER : A. Kusenko (UCLA)

TITLE : Cosmic connections: from cosmic rays to gamma rays, to cosmic backgrounds and magnetic fields
ABSTRACT : Combined data from gamma-ray telescopes, cosmic-ray detectors, and neutrino detectors have produced some surprising new insights regarding the most powerful sources in the universe, as well as intergalactic and galactic magnetic fields and extragalactic background light. I will discuss how a unified treatment of gamma rays, cosmic rays, and neutrinos reveals some intriguing connections between several seemingly unrelated phenomena.

TITLE : Higgs relaxation and leptogenesis.
ABSTRACT :The recent measurement of the Higgs boson mass implies a relatively slow rise of the Standard Model Higgs potential at large scales. A scalar field with such a potential develops a large vacuum expectation value at the end of inflation. The relaxation of the Higgs field from its large postinflationary value to the minimum of the effective potential represents an important stage in the evolution of the universe. During the Higgs relaxation, the time-dependent Higgs condensate can create an effective chemical potential for the lepton number, leading to a generation of the lepton asymmetry in the presence of some large right-handed Majorana neutrino masses. The electroweak sphalerons redistribute this asymmetry between leptons and baryons. The Higgs relaxation leptogenesis can explain the observed matter-antimatter asymmetry of the universe even if the Standard Model is valid up to the scale of inflation, and any new physics is suppressed by that high scale. The epoch of Higgs relaxation might have other observable consequences, for example, primordial magnetic fields.

DAY & TIME :Fri. Oct. 31st 10:30-12:00, 13:30-15:00
SPEAKER : K. Kohri (KEK)
TITLE : Inflation cosmology after BICEP2
COMMENT :Seminar

DAY & TIME :Fri. Oct. 31st
SPEAKER : A. Kaneko (Hokkaido Univ.)
TITLE : Quantization of Einstein Gravity
COMMENT :Rehearsal of M1 Journal Club

DAY & TIME :Fri. Oct. 24th 10:30-
SPEAKER : E. Park (Hokkaido Univ.)
TITLE : LHC signals from light mixed sneutrino dark matter
E-PRINT :
C. Arina and M. E. Cabrera, "Multi-lepton signatures at LHC from sneutrino dark matter" arXiv:1311.6549[hep-ph]
M. Chakraborti, U. Chattopadhyay, A. Choudhury, A. Datta, S. Poddar, "The Electroweak Sector of the pMSSM in the Light of LHC - 8 TeV and Other Data" arXiv:1404.4841[hep-ph]
COMMENT :Journal Club

DAY & TIME :Fri. Oct. 17th 10:30-12:00, 13:30-15:00
SPEAKER : N. Shiba (YITP)
TITLE : Entanglement between Two Interacting CFTs and Generalized Holographic Entanglement Entropy
ABSTRACT :We discuss behaviors of entanglement entropy between two interacting CFTs and its holographic interpretation using the AdS/CFT correspondence. We explicitly perform analytical calculations of entanglement entropy between two free scalar field theories which are interacting with each other in both static and time-dependent ways. We also conjecture a holographic calculation of entanglement entropy between two interacting N = 4 super Yang-Mills theories by introducing a minimal surface in the S^5 direction, instead of the AdS_5 direction. This offers a possible generalization of holographic entanglement entropy. In the first part of this talk, I will review the basics of the entanglement entropy in quantum field theory.
E-PRINT : A. Mollabashi, N. Shiba, T. Takayanagi, "Entanglement between Two Interacting CFTs and Generalized Holographic Entanglement Entropy" arXiv:1403.1393[hep-th]
COMMENT :Seminar

DAY & TIME :Fri. Oct 10th 10:30-12:00, 13:30-15:00
SPEAKER : H. Shimada (OIQP)
TITLE : Membranes from monopole operators in ABJM theory: Large angular momentum and M-theoretic AdS4/CFT3
ABSTRACT :In the talk, I will consider states with large angular momentum to facilitate the study of the M-theory regime of the AdS4/CFT3 correspondence (duality between M-theory on $AdS_4 \times S^7/Z_k$ and ABJM theory with gauge group $U(N)\times U(N)$ and level $k$, where $k$ is finite and $N$ is large). In particular I will discuss near-BPS operators in ABJM theory which correspond to states of membranes with large angular momenta on AdS. The talk will be based on my work with Stefano Kovacs(DIAS) and Yuki Sato (Wits University), arXiv:1310.0016.
COMMENT :Seminar

DAY & TIME :Fri. Oct. 3rd 10:30-
SPEAKER : R. Nakayama (Hokkaido Univ.)
TITLE : Gravitational Scattering in Asymptotically Flat Spacetime
E-PRINT : A. Strominger, "On BMS Invariance of Gravitational Scattering," arXiv:1312.2229[hep-th],
T. He, V. Lysov, P. Mitra, A. Strominger, "BMS supertranslations and Weinberg's soft graviton theorem," arXiv:1401.7026[hep-th],
D. Kapec, V. Lysov, S. Pasterski, A. Strominger, "Semiclassical Virasoro Symmetry of the Quantum Gravity S-Matrix," arXiv:1406.3312[hep-th]
COMMENT :Journal Club

DAY & TIME :Tue. Sept. 9th 10:30-12:00
SPEAKER : H. Abe (Waseda Univ.)
TITLE : Nonuniversal gaugino masses and MSSM fine-tuning revisited
ABSTRACT :The observed Higgs boson mass and no superparticles at the Large Hadron Collider (LHC) severely restrict the parameter space of the minimal supersymmetric standard model (MSSM). Certain class of nonuniversal gaugino mass spectra at the unification scale was identified, before the LHC experiments start, which drastically relaxes a fine-tuning required in the MSSM. We show such spectra are compatible with (even favored by) the Higgs boson mass observed at the LHC, and claim these observations are quite useful to prove models behind MSSM, such as supergravity/string models.
E-PRINT : H. Abe, J. Kawamura, "The 126 GeV Higgs boson mass and naturalness in (deflected) mirage mediation" arXiv:1405.0779[hep-ph]

arXiv:1208.5328[hep-ph]

arXiv:hep-ph/0703044[hep-ph]

arXiv:1405.3754[hep-ph]

COMMENT : Morning Seminar

DAY & TIME :Tue. Sept. 9th 13:30-
SPEAKER : H. Otsuka (Waseda Univ.)
TITLE : Moduli inflation in five-dimensional supergravity models
ABSTRACT :We propose a simple but effective mechanism to realize an inflationary early universe consistent with the observed WMAP, Planck and/or BICEP2 data, which would be incorporated in various supersymmetric models of elementary particles constructed in the (effective) fivedimensional spacetime. In our scenario, the inflaton field is identified with one of the moduli appearing when the fifth direction is compactified, and a successful cosmological inflation without the so-called problem can be achieved by a very simple moduli stabilization potential. We also discuss the related particle cosmology during and (just) after the inflation, such as the (no) cosmological moduli problem.
E-PRINT : H.Abe and H.Otsuka, "Moduli inflation in five-dimensional supergravity models" arXiv:1405.6520[hep-th]
COMMENT : Afternoon Seminar

DAY & TIME : Thu. Aug. 28th 10:30-12:00, 13:30-
SPEAKER : S. Nakamura (Chuo Univ.)
TITLE : Application of AdS/CFT Correspondence to Non-equilibrium Physics
ABSTRACT : Non-equilibrium physics is one of the challenging research areas in modern physics. The non-equilibrium steady states (NESS) are the states of the systems which are out of equilibrium but are time- independent in the macroscopic point of view. In this talk, we investigate the properties of NESS which are realized in the gravity dual in AdS/CFT. Typically, NESS are realized on a probe D-brane or a probe fundamental string in the dual geometry. There have been observations that an analogue black hole appears on the probe objects if the system is out of equilibrium and a notion of effective temperature --- a generalization of temperature in NESS --- appears from it. We study the behavior of the effective temperature systematically and will report its interesting properties. In the first talk in the morning, I am going to review the basics of the AdS/CFT correspondence for non-specialists, and the details of my research work will be reported in the second talk in the afternoon.
E-PRINT : S. Nakamura, H. Ooguri, "Out of Equilibrium Temperature from Holography," arXiv:1309.4089[hep-th]
COMMENT : Seminar

DAY & TIME : Fri. Aug. 1st 10:30-
SPEAKER : Y.Toda (Hokkaido Univ.)
TITLE : string T-duality

SPEAKER : W. Akutsu (Hokkaido Univ.)
TITLE : String field theory and its application
COMMENT : M2 Journal Club

DAY & TIME : Fri. Jul. 25th 10:30-
SPEAKER : Y. Takano (Hokkaido Univ.)
TITLE : String phenomenology
Reference: L.Ibanez, A.Uranga, String theory and particle physics, Cambridge University Press, 2012

SPEAKER : H. Hattori (Hokkaido Univ.)
TITLE : An introduction to modern Cosmology
Reference:辻川信二, 『現代宇宙論講義』. SGCライブラリ,サイエンス社, 2013
COMMENT : M2 Journal Club

DAY & TIME : Fri. Jul. 18th 10:30-12:00 13:30-
SPEAKER : T. Okazaki (Osaka Univ.)
TITLE : Membrane Quantum Mechanics
ABSTRACT :The BLG-model and the ABJM-model are expected to describe flat multiple M2-branes. We consider the situations where the M2-branes wrap a holomorphic Riemann surface in a Calabi-Yau space. We study the arising one-dimensional quantum mechanics by taking the limit where the size of the holomorphic curve goes to zero. The talk will be based on a joint work in progress with Hirosi Ooguri.
COMMENT : Seminar

DAY & TIME : Fri. Jul. 11th 10:30-12:00
SPEAKER : N. Kawamoto (Hokkaido Univ.)
TITLE : Perfect Action for Lattice Supersymmetry
ABSTRACT :We propose a lattice supersymmetry formulation which is equivalent to the continuum theory. A proposed lattice action has exact supersymmetry for not only continuum limit but at a finite lattice constant and the action corresponds to a perfect action.
COMMENT : Seminar

DAY & TIME :Fri. Jul. 4th 10:30-12:00, 13:30-
SPEAKER : K. Tsumura (Kyoto Univ.)
TITLE : Tau Lepton in Higgs Physics (Morning session)
ABSTRACT :In collider experiments, tau leptons are rather complicated objects due to the its prompt decay inside detectors. Its decay products always contain missing neutrinos, which makes analysis difficult. On the other hand, its decay provides a unique information of the chiral structure of interaction vertices. I will explain the basic techniques of the tau lepton analysis, and briefly review on Higgs physics with the latest update, i.e., Higgs decaying to tau lepton pair. Applications to the physics beyond the SM are also discussed.
TITLE : A Model with the Higgs Septet (Afternoon session)
ABSTRACT :We study a possibility of the Higgs boson, which consists of an SU(2) doublet and a septet. The vacuum expectation value of a septet with hypercharge Y=2 is known to preserve the electroweak rho parameter unity at the tree level. Due to the mixing between the doublet and a septet, the gauge coupling of the standard-model-like Higgs boson is larger than that in the standard model, i.e., K_V > 1. This is a typical feature of the model, which can be tested at collider experiments by measuring the Higgs coupling very precisely.
E-PRINT : J. Hisano , K. Tsumura "Higgs boson mixes with an SU(2) septet representation" Phys. Rev. D87, 053004 (2013)
COMMENT : Seminar

DAY & TIME : Fri. Jun. 27th 10:30-12:00, 13:30-
SPEAKER : Y. Omura (Nagoya Univ.)
TITLE : Study on two-Higgs-doublet models (with gauged U(1) symmetry)
ABSTRACT : It is well known that generic two-Higgs-doublet models (2HDMs) suffer from potentially large Higgs-mediated flavor-changing neutral current (FCNC) problem, unless additional symmetries are imposed on the Higgs fields thereby respecting the Natural Flavor Conservation Criterion (NFC) by Glashow and Weinberg. A common way to respect the NFC is to impose Z_2 symmetry which is softly broken by a dim-2 operator. Another new way is to introduce local U(1)_H Higgs flavor symmetry that distinguishes one Higgs doublet from the other. In this talk, we discuss the phenomenology in 2HDMs with not only the Z_2 but also U(1)_H symmetry. We also study dark matter (DM) physics in the Type-I inert 2HDM with local U(1)_H Higgs gauge symmetry. The lightest neutral scalar component H of the U(1)_H-charged Higgs doublet, which does not have Yukawa couplings with the Standard-Model (SM) fermions, is stable because of the remnant discrete symmetry, and it interacts with the SM particles through the U(1)_H gauge boson (Z_H) exchange as well as the SM boson exchange. We investigate the constraints on DM: thermal relic density, and direct/indirect detections. The additional U(1)_H gauge interaction plays a crucial role in reducing the DM thermal relic density. The most important result within the inert DM model with local U(1)_H symmetry is that ~ O(10) GeV dark matter scenario, which is strongly disfavored in the usual Inert Doublet Model (IDM) with Z_2 symmetry, is revived in our model because of newly open channels, H H -> Z_H Z_H , Z_H Z. Exotic Higgs decays, h -> Z_H Z_H, Z Z_H, would be distinctive signatures of the inert 2HDM with local U(1)_H symmetry. I also give a comment on the type-II 2HDM inspired by E_6 GUT, and introduce some results on DM physics.
COMMENT : Seminar

DAY & TIME : Fri. Jun. 20th 10:30-12:00
SPEAKER : T. Kobayashi (Hokkaido Univ.)
TITLE : Gaussian Froggatt-Nielsen mechanism on magnetized orbifolds
ABSTRACT: We study the structure of Yukawa matrices derived from the supersymmetric Yang-Mills theory on magnetized orbifolds, which can realize the observed quark and charged lepton mass ratios as well as the CKM mixing angles, even with a small number of tunable parameters and without any critical fine-tuning. As a reason behind this, we find that the obtained Yukawa matrices possess a Froggatt-Nielsen like structure with Gaussian hierarchies, which provides a suitable texture for them favored by the experimental data.
E-PRINT : H. Abe, T. Kobayashi, K. Sumita, Y. Tatsuta "Gaussian Froggatt-Nielsen mechanism on magnetized orbifolds," arXiv:1405.5012[hep-ph]
COMMENT : Seminar

DAY & TIME : Fri. Jun. 13th 14:00-
SPEAKER : H. Maeda (Hokkai Gakuen Univ.)
TITLE : Throat quantization of the Schwarzschild-Tangherlini(-AdS) Black Hole
ABSTRACT :Adopting the throat quantization pioneered by Louko and M\"akel\"a, we derive the mass and area spectra for the Schwarzschild-Tangherlini black hole and its anti-de~Sitter (AdS) generalization in arbitrary dimensions. We obtain exact spectra in three special cases: the three-dimensional BTZ black hole, toroidal black holes in any dimension, and five-dimensional Schwarzshild-Tangherlini(-AdS) black holes. For the remaining cases the spectra are obtained for large mass using the WKB approximation. For asymptotically flat black holes, the area/entropy has an equally spaced spectrum, as expected from previous work. In the asymptotically AdS case on the other hand, it is the mass spectrum that is equally spaced. Our exact results for the BTZ black hole with Dirichlet boundary conditions agree with those obtained previously via completely different methods.
E-PRINT :G. Kunstatter, H. Maeda, "Throat quantization of the Schwarzschild-Tangherlini(-AdS) Black Hole," arXiv:1311.4888[hep-qc]
COMMENT : Afternoon Seminar

DAY & TIME : Fri. Jun. 6th 10:30-12:00, 13:30-
SPEAKER : S. Mizoguchi (KEK)
TITLE : F-theory Family Unification
ABSTRACT : We propose a new geometric mechanism for naturally realizing unparallel three families of flavors in string theory, using the framework of F- theory. We consider a set of coalesced local 7-branes of a particular Kodaira singularity type and allow some of the branes to bend and separate from the rest, so that they meet only at an intersection point. Such a local configuration can preserve supersymmetry. Its matter spectrum is investigated by studying string junctions near the intersection, and shown to coincide, after an orbifold projection, with that of a supersymmetric coset sigma model whose target space is a homogeneous Kahler manifold associated with a corresponding painted Dynkin diagram. In particular, if one starts from the E7 singularity, one obtains the E7/(SU(5)xU(1)^3) model yielding precisely three generations with an unparallel family structure. Possible applications to string phenomenology are also discussed.
E-PRINT : S. Mizoguchi, "F-theory Family Unification," arXiv:1403.7066[hep-th]
COMMENT : Seminar

DAY & TIME : Fri. May 30th 13:30-
SPEAKER : 栗木雅夫（広島大）
TITLE : "ILC加速器と計画の現状"
ABSTRACT :ILC(International Linear Collider)は、二つの線形加速器からなる電子・陽電子コライダーであり、重心系エネルギーは第一期計画で５００GeV、第二期計画で1TeVである。日本の将来検討小委員会 (高エネルギー物理学研究者会議）、米国のSnowmass process およびP5, 欧州のEuropean Strategy for Particel　Physics などの検討委員会において、その高い物理的ポテンシャルから、将来計画として、その実現が強く望まれている。現在、LCC(Linear Collider Collaboration)のもと、国際的体制によって、加速器設計と検出器の検討が進められており、３年後の詳細技術設計とりまとめ、すなわち３年後にはすべての詳細図面が揃った「青信号」を灯すことを目指している。日本学術会議もILC物理の魅力を高く評価しており、日本誘致の妥当性を文部科学省の専門家会議が今後数年で評価する予定である。加速器としてみると、従来の円形のシンクロトロンとは異なり、線形加速器を利用することが最大の特徴である。線形加速器により、シンクロトロン放射とよばれる電磁放射によるエネルギー損失を実質的にゼロにし、 LEP などの円形コライダーのエネルギー限界を打ち破ることを目指している。そのための鍵は高い加速勾配と、高いルミノシティーのためのビームのナノメーターへの収束である。本講演では、計画の現状と、加速器の概要を述べる。

SPEAKER : 倉田正和（東京大）
TITLE : "ILC の物理"
COMMENT : ILC Seminar
ABSTRACT : 電子陽電子衝突によるクリーンな環境を生かして，どのように宇宙創生の謎にせまるのか？素粒子物理学の現状、特にヒッグス粒子や、その元となっている電弱対称性の破れの解明のためにILCができること、現在の標準理論を超える物理の直接・間接探索などを概観する。またLHCの最新結果を踏まえ、LHC・ILCの比較やLHC・ILCの相補性なども交えて、ILCの目指す物理を解説する。

DAY & TIME : Fri. May 23rd 10:30-12:30
SPEAKER : K. Ishikawa (Hokkaido Univ.)
TITLE : Large finite-size corrections to Fermi’s golden rule: Implications
ABSTRACT : In quantum mechanical transition process, the probability expressed in terms of the time interval T between the initial and final states, P=\Gamma T +P^{(d)}, where \Gamma given with Fermi’s golden rule has been known long time , but P^{(d)} was found recently. P^{(d)} has origins in wave characteristics caused by the overlap of wave functions, and is negligible at infinite T　in normal cases. Accordingly experiments and phenomena in nature have been studied with only \Gamma T. In this talk, I emphasize the important roles of P^{(d)} for various phenomena. (1) P^{(d)} gives large effects in processes of light particles such as neutrino and photon in T <{\hbar E \over m^2c^3}, where c,\hbar,m and E is the speed of light, Plank constant \over 2\pi, mass, and the energy of the observed particle. (2) The process reveals unexpected behaviors caused by overlap of waves which induces interaction energy and makes the final kinetic energy to have wide spectrum. (3) Various puzzling phenomena of neutrino and photon become understandable with P^{(d)}. Moreover, P^{(d)} can supply a new method for determining physical constant such as the absolute neutrino mass, which is an unknown physical constant, and gives finite probability to processes of vanishing \Gamma. (4) Examples of P^{(d)} in wide phenomena of physics, (and possibly chemical and biophysics) are presented.
E-PRINT : K. Ishikwa, Y. Tobita,"Finite-size corrections to Fermi's golden rule: I. Decay rates," Prog.Thoer.Exp.Physics. 2013,073B02
K. Ishikwa, Y. Tobita,"Long-range correlations of neutrinos in pion decays and neutrino diffraction," Ann. Physics. 344 (2014)118-178
K.Ishikawa, T.Nozaki, M.Sentoku, Y.Tobita, "Probing into decay products at finite distance in muon decay," arXiv:1405.0582[hep-ph]
K. Ishikwa, T. Tajima, Y. Tobita, preprint"Anomalous radiative transitions” in preparation. Others"
COMMENT : Seminar

DAY & TIME : Fri. May 16th 10:30-12:00, 13:30-
SPEAKER : T. Higaki (KEK)
TITLE :Supergravity/String cosmology after BICEP2
ABSTRACT :Recently the BICEP2 experiment has announced the detection of primordial gravitational wave. Following the result, we will discuss cosmology based on supergravity/string theory, focusing on axions as candidates of an inflaton or dark radiation.
E-PRINT : T. Higaki, F. Takahashi, "Dark Radiation and Dark Matter in Large Volume Compactifications," arXiv:1208.3563[hep-ph]
T. Higaki, K. Nakayama, F. Takahashi, "Moduli-Induced Axion Problem," arXiv:1304.7987[hep-ph]
M. Czerny, T. Higaki, F. Takahashi, "Multi-Natural Inflation in Supergravity," arXiv:1403.0410[hep-ph]
M. Czerny, T. Higaki, F. Takahashi, "Multi-Natural Inflation in Supergravity and BICEP2," arXiv:1403.5883[hep-ph]
T. Higaki, F. Takahashi, "Natural and Multi-Natural Inflation in Axion Landscape," arXiv:1404.6923[hep-ph]
COMMENT : Seminar

DAY & TIME : Fri. May 5th 10:30-12:00
SPEAKER : K. Hotta (Hokkaido Univ.)
TITLE : Gauge Theories, D-Branes and Holography
E-PRINT :F. Ferrari, ``Gauge Theories, D-Branes and Holography," arXiv:1310.6788[hep-th]
COMMENT : Journal Club

DAY & TIME : Fri. May 2nd 10:30-12:00, 13:30-
SPEAKER : T. Asaka (Nigata Univ.)
TITLE : Probing the origins of neutrino masses and baryon asymmetry of the universe
ABSTRACT :We consider the Standard Model extended by two quasi-degenerate right-handed neutrinos. Especially, we consider the case when they are lighter than charged kaon. This simple framework can account for the neutrino oscillations and the baryon asymmetry of the universe at the same time. In this talk we shall summarize the possible constraints on such right-handed neutrinos from direct search experiments and cosmology, and also discuss the strategy how to find and verify right-handed neutrinos by using the future experiments by using kaon.
E-PRINT : T. Asaka, S. Eijima, "Direct Search for Right-handed Neutrinos and Neutrinoless Double Beta Decay," arXiv:1308.3550[hep-ph]
T. Asaka, S. Eijima, A. Watanabe, "Heavy neutrino search in accelerator-based experiments," arXiv:1212.1062[hep-ph]
COMMENT : Seminar

DAY & TIME : Fri. Apr. 25th 10:30-12:00, 13:30-
SPEAKER : Y. Hyakutake (Ibaraki Univ.)
TITLE : Brief review on superstring theory and supergravity
COMMENT : Morning Seminar

TITLE : Holographic description of quantum black hole on a computer
ABSTRACT : The discovery of the fact that black holes radiate particles and eventually evaporate led Hawking to pose the well-known information loss paradox. This paradox caused a long and serious debate since it claims that the fundamental laws of quantum mechanics may be violated. A possible cure appeared recently from superstring theory, a consistent theory of quantum gravity: if the holographic description of a quantum black hole based on the gauge/gravity duality conjecture is correct, the information is not lost and quantum mechanics remains valid. However, the duality has not been tested at the level of quantum gravity for more than fifteen years since its proposal. In this seminar we do it for the first time on a computer. The black hole mass obtained by Monte Carlo simulation of the dual gauge theory reproduces precisely the quantum gravity effects in an evaporating black hole. This result opens up totally new perspectives towards quantum gravity since one can simulate quantum black holes through dual gauge theories.
E-PRINT : M. Hanada, Y. Hyakutake, G. Ishiki, J. Nishimura, "Holographic description of quantum black hole on a computer," arXiv:1311.5607[hep-th]
Y. Hyakutake, "Quantum Near Horizon Geometry of Black 0-Brane," arXiv:1311.7526[hep-th]
COMMENT : Afternoon Seminar

DAY & TIME : Fri. Apr. 18th 10:30-12:00
SPEAKER : E. Giguére (Hokkaido Univ.)
TITLE : Construction of SYM Theories for numerical simulation
E-PRINT : F. Sugino, "A Lattice Formulation of Super Yang-Mills Theories with Exact Supersymmetry," arXiv:0311021[hep-lat]

arXiv:0401017[hep-lat]

arXiv:0410035[hep-lat]

COMMENT : Journal Club

DAY & TIME : Fri. Apr. 11th 10:30-12:00
SPEAKER : I. Fujisawa (Hokkaido Univ.)
TITLE : The Amplituhedron
E-PRINT : N. Arkani-Hamed, J. Trnka, "The Amplituhedron," arXiv:1312.2007[hep-th]
N. Arkani-Hamed, J. Trnka, "Into the Amplituhedron," arXiv:1312.7878[hep-th]
COMMENT : Journal Club

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