## 2014年度のセミナー

Date/Place | Feb. 17 (Tues.) 15:00-16:00 / H711 |
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Name | Akira Shimizu (U. of Tokyo) |

Title | Pure state quantum statistical mechanics (slides) |

Abstract | A new formulation of quantum statistical mechanics is presented. An equilibrium state is represented by a pure quantum state, which replaces the Gibbs state in the ensemble formulation. Not only mechanical variables (given by quantum observables) but also genuine thermodynamic variables (such as entropy) are obtained from a single pure quantum state. If time allows I also discuss a squeezed equilibrium states. Refs. PRL108(2012)240401, PRL111(2013)010401, PRB90(2014)121110(R). |

Date/Place | Feb. 10 (Tues.) 15:30-16:30 / H711 |
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Name | Yoshiharu Kawamura (Shinshu U.) |

Title | Naturalness, Conformal Symmetry and Duality (slides) |

Abstract | We reconsider naturalness from the viewpoint of a high-energy physics or a fundamental theory, motivated by the alternative scenario that the standard model holds up to a high-energy scale such as the Planck scale. We propose a calculation scheme of radiative corrections utilizing a hidden duality relating integration variables, that justifies the subtraction of quadratic divergences and makes theories with scalar fields natural. If necessary and possible, we revisit the gauge hierarchy problem, too. We give a conjecture that theories with hidden fermionic symmetries can be free from the problem and become a candidate of physics behind and/or beyond the standard model, and present a prototype model for the grand unification. |

Date/Place | Feb. 3 (Tues.) 15:30-16:30 / H711 |
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Name | Mitsuhiro Nishida (Osaka U.) |

Title | Frustration in Holography (slides) |

Abstract | Frustration is an interesting phenomenon in condensed matter physics because it can introduce a new order parameter such as chirality. To study frustration, we consider a holographic superconductor model with three scalar fields and interband Josephson coupling. The Josephson coupling between scalar fields is important for frustration. We analyze free energy of solutions of the model to determine ground states. We find chiral ground states which break a chiral symmetry. |

Date/Place | Jan. 27 (Tues.) 15:30-16:30 / H711 |
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Name | Tomoki Ohtsuki (Kavli IPMU) |

Title | Bootstrapping controversies (slides) |

Abstract | d=3 O(n)xO(m) symmetric Landau-Ginzburg models have rich physical realizations including anti-ferromagnetic spin systems placed on triangular lattices and 2-flavor QCD chiral phase transitions (provided the axial anomaly is negligible). Despite their physical importance, studying the renormalization group (RG) flow of these systems are notoriously hard and there are serious controversies over the nature of their phase transitions: depending on the methods (e.g. perturbative RG series, functional RG equation, lattice Monte-Carlo, …), one obtains different answers regarding the presence of IR-stable fixed points. Recently the conformal bootstrap program has been gathering growing attention as a way to study d>2 conformal field theories (CFTs) in a completely non-perturbative fashion. Indeed the "solution" obtained by the method offers the most precise estimate for the 3d Ising model critical exponents. In this talk, I will discuss what we can learn about the above-mentioned problems - whether the fixed points exist or not - from bootstrap techniques, based on arXiv:1404.0489 and 1407.6195 with Yu Nakayama. |

Date/Place | Jan. 20 (Tues.) 15:30-16:30 / H711 |
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Name | Seiji Terashima (YITP, Kyoto U.) |

Title | A Localization Computation in Confining Phase (slides) |

Abstract | We show that the gaugino condensation of 4d N=1 supersymmetric gauge theories in the confining phase can be computed by the localization technique with an appropriate choice of a supersymmetry generator. |

Date/Place | Jan. 13 (Tues.) 15:30-16:30 / H711 |
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Name | Yutaka Sakamura (KEK) |

Title | 6D gauge-Higgs unification on T^2/Z_N with custodial symmetry (slides) |

Abstract | We investigate the gauge-Higgs unification models compactified on T^2/Z_N that have the custodial symmetry. We select possible gauge groups, orbifolds and representations of the matter fermions that are consistent with the custodial symmetry, by means of the group theoretical analysis. The best candidate we found is 6D SU(3)_C x U(4) gauge theory on T^2/Z_3 and the third generation quarks are embedded into bulk fermions that are the symmetric traceless rank-2 tensor of SO(6). |

Date/Place | Jan. 6 (Tues.) 15:30-16:30 / H711 |
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Name | Makoto Sakamoto (Kobe U.) |

Title | Non-renormalization theorem and cyclic Leibniz rule in lattice supersymmetry (slides) |

Abstract | We first show that full SUSY algebras cannot be realized on lattice but only nilpotent SUSY algebras on lattice. We then propose a lattice model of a complex SUSY quantum mechanics which realizes nilpotent SUSYs but the non-renormalization theorem on lattice. In our lattice model, the Leibniz rule in the continuum, which cannot hold on lattice due to a no-go theorem, is replaced by the cyclic Leibniz rule (CLR) for difference operators. It is shown that the CLR allows two of four supercharges of the continuum theory to preserve while a naive lattice model can realize one supercharge at the most. A striking feature of our lattice model is that there are no quantum corrections to potential terms in any order of perturbation theory. This is one of characteristic properties of SUSY theory in the continuum. It turns out that the CLR plays a crucial role in the proof of the non-renormalization theorem. This result suggests that the CLR grasps an essence of supersymmetry on lattice. |

Date/Place | Dec. 19 (Fri.) 11:00-12:00 / H711 (Informal) |
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Name | George T. Fleming (Yale U.) |

Title | Non-perturbative quantum field theory on curved manifolds |

Abstract | A challenging problem in quantum field theory is the study of conformal (or nearly-conformal) fixed points occurring in the non-perturbative regime of a quantum field theory. Using radial quantization, computation on curved manifolds is essential. We propose a new approach called Quantum Finite Elements (QFE), an extension of the usual Finite Element Method (FEM) to solving classical PDEs, where renormalization of couplings can play a key role in the restoration of rotational invariance. Some aspects of our approach can be found in earlier work related to Regge calculus and lattice quantum gravity, as well as the random lattice approach of Christ, Friedberg and Lee. |

Date/Place | Dec. 9 (Tues.) 15:30-16:30 / H711 |
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Name | Kiyoharu Kawana (Kyoto U.) |

Title | Multiverse and Maximum Entropy Principle (slides) |

Abstract | In this talk, we consider the quantum mechanics of Multiverse by using the Lorentzian path integral. We define the probability distribution P(λ) of the parameters of universes, and show that it has a maximum at the point where the radiation of a single universe becomes maximum. This is nothing but the Maximum Entropy Principle (MEP). As an example, we show that the Higgs expectation value vh is predicted to be O(200)GeV by this principle. |

Date/Place | Dec. 2 (Tues.) 15:30-16:30 / H711 |
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Name | Kenji Kadota (IBS CTPU) |

Title | 21cm probes on particle dark matter (slides) |

Abstract | The future prospects on the 21 cm constraints on the particle dark matter will be discussed. I will first discuss the 21 cm bounds on the ultra light scalar fields which can ubiquitously arise in the early Universe, such as pseudo-Goldstone bosons from the spontaneous breaking of an approximate symmetry. The effects of the dark matter interactions with the baryons on the 21 cm observables will also be discussed along with its comparison with the complementary bounds from the direct dark matter search experiments. |

Date/Place | Nov. 25 (Tues.) 15:30-16:30 / H711 |
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Name | Minoru Tanaka (Osaka U.) |

Title | Neutrino Physics with Atomic/Molecular Processes (slides) |

Abstract | The energy scale of atomic/molecular transitions is of the order of eV or less. It is close to the neutrino mass scale suggested by the neutrino oscillation and cosmological constraints. In this talk, I introduce a new approach to neutrino physics that uses atomic/molecular processes. It is expected that unknown neutrino properties such as the absolute mass are unveiled by this approach. In addition it has potential sensitivity to the cosmic neutrino background predicted by the big bang cosmology. In order for this approach to work, a macroscopic quantum coherence is essential. Our first experimental result that clearly exhibits the macrocoherence is also reported. |

Date/Place | Nov. 18 (Tues.) 15:30-16:30 / H711 |
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Name | Masahiro Nozaki (YITP, Kyoto U.) |

Title | Quantum Entanglement of Local Operators (slides) |

Abstract | We have introduced a new class of excited states which is defined by acting local operators on the ground state. We have investigated the time evolution of (Renyi) entanglement entropies for those locally excited states when the subsystem size is given by a half of the total space. We have found that they approach finite constants. We defined (Renyi) entanglement entropies of local operators by final values of those (Renyi) entanglement entropies. We have found that they depend on the details of local operators. We expect that they characterize local operators from the viewpoint of quantum entanglement. They help us study higher dimensional CFTs more. We also found the sum rule which those entropies obey. We also found that these results are interpreted in terms of the relativistic propagation of quasi-particles. We have investigated these quantities in strongly coupled theory. We obtained some interesting features of those quantities. We would like to talk about the results which we obtained as long as time allows. This talk is based on three papers (arXiv:1401.0539 [hep-th], arXiv:1405.5946 [hep-th], arXiv:1405.5875 [hep-th]). |

Date/Place | Nov. 11 (Tues.) 15:30-16:30 / H711 |
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Name | Kantaro Ohmori (U. of Tokyo) |

Title | Anomaly polynomial of general 6d SCFTs (slides) |

Abstract | 6d N=(2,0) theories are the source of many beautiful stories on supersymmetric field theories whose dimensions are lower than six. We hope similar and richer stories hold for 6d N=(1,0) theories, although it should be much harder to investigate with fewer supersymmetries. As a first step, we want better understanding of 6d theories and some calculable quantities of those theories. We found that the anomaly polynomials of 6d N=(2,0) or N=(1,0) SCFTs can be determined on their tensor branch using a kind of anomaly maching mechanism similar to the Green-Schwarz mechanism. In this talk, I will review 6d N=(1,0) SCFTs which can be constructed with branes of the M-thoery, and then talk about anomaly polynomials. Especially, I will focus on the world volume theories of M5-branes on the ALE-singularities of general type. If time permits, I will also talk about some on-going developments on T^2 compactifications of a certain class of 6d N=(1.0) theories. |

Date/Place | Nov. 6 (Thur.) 16:30-17:30 / H711 |
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Name | Eduard Massó (Universitat Autònoma de Barcelona) |

Title | Effective Higgs Lagrangians (slides) |

Abstract | The leading contributions from heavy new physics to Higgs processes can be captured in a model-independent way by dimension-six operators in an effective Lagrangian approach. In this talk we will discuss how these contributions affect Higgs couplings. In particular we will show that 8 CP-even plus 3 CP-odd Wilson coefficients parametrize the main impact in Higgs physics, as all other coefficients are constrained by non-Higgs SM measurements. We will discuss the issue of correlations (and non-correlations) among observables in the context of effective Lagrangians. |

Date/Place | Oct. 28 (Tues.) 15:30-16:30 / H711 |
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Name | Shinji Mukohyama (YITP, Kyoto U.) |

Title | Massive gravity and cosmology (slides) |

Abstract | The search for a consistent theory of finite-range gravity is a longstanding problem and well motivated by both theoretical and observational considerations. On the theoretical side, whether there exists such a consistent extension of general relativity by a mass term is a basic question of classical field theory. After Fierz and Pauli's pioneering attempt in 1939, this issue has been attracting a great deal of interest. On the observational side, continuing experimental probes of gravity have revealed new unexpected phenomena at large scales. One of the most profound discovery is the cosmic acceleration, which was found in 1998. The extremely tiny energy-scale associated with the cosmic acceleration hints that gravity might need to be modified in the infrared. The massive gravity is one of the most interesting attempts in this direction. In this talk, after reviewing the history and recent developments of massive gravity, I will describe cosmological solutions and their stability. |

Date/Place | Oct. 14 (Tues.) 15:30-16:30 / H711 |
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Name | Akinori Tanaka (Osaka U.) |

Title | Superconformal index on RP^2 x S^1 |

Abstract | We study N=2 supersymmetric gauge theories on RP^2 x S^1 and compute the superconformal index by using the localization technique. We apply our new superconformal index to the check of the simplest 3d mirror symmetry and prove it by using a mathematical formula called the q-binomial theorem. In this talk, I would like to explain the crucial points of our work and comment on some generalizations. This talk is based on [arXiv:1408.3371]. |

Date/Place | Oct. 7 (Tues.) 15:30-16:30 / H711 |
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Name | Nobuhito Maru (Osaka City U.) |

Title | Calculable Higgs Mass in Gauge-Higgs Unification (slides) |

Abstract | We address a question whether the recently observed Higgs mass 126 GeV is calculable as a finite value in the gauge-Higgs unification. In the 6-dimensional SU(3) model with a certain orbifold,\ it is known that a Higgs mass is predicted to be twice as large as the W-boson mass at the tree level. We demonstrate first by a general argument and secondly by explicit calculations that th\ e quantum correction to the deviation from this relation is calculable, with some similarity to the case of MSSM. |

Date/Place | Sep. 25 (Thur.) 15:30-16:30 / H711 |
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Name | Naoshi Sugiyama (Nagoya U.) |

Title |
Why is the B-mode Polarization measurement so important
for Cosmology? -BICEP2 as an example- (slides) |

Abstract | TBA |

Date/Place | July 15 (Tues.) 15:00～ / H711 |
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Name | Yuya Shimizu (RIKEN AICS) |

Title | Tensor Renormalization Group Study of Lattice Schwinger Model |

Abstract | The tensor renormalization group is one of the successful methods to avoid the numerical sign problem, though the practical calculations in higher dimensions are beyond the reach of current computer facilities. As a first step toward lattice QCD, we apply it to two-dimensional lattice QED (lattice-regularized Schwinger model). In this talk, I would like to show its validity through the numerical investigation on the phase structure with the theta vacuum term. |

Date/Place | July 8 (Tues.) 15:00～ / H711 |
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Name | Yukihiro Fujimoto (Osaka U.) |

Title | Magnetic flux meets orbifold (slides) |

Abstract |
It was known that generations and a fermion mass hierarchy appear in the context of higher dimensional gauge theories with a background magnetic flux. The number of generations directly depends on an integer value of the magnetic flux and the value of which is arbitrary in general. Amazingly, with (T^2×T^2)/ Z_{N} shifted orbifold, we found that the number of generations is restricted to mod N. The geometry of the extra dimensions, i.e. Z_{N} shifted orbifold, plays an important role to restrict the number of generations.
Another type of magnetized orbifold, e.g. T^2/Z_{N} twisted orbifold (N=2,3,4,6) with a magnetic flux, is also interesting because a complicated pattern appears to the generation structure with respect to Z_{N} eigenvalues. In the context of 6d gauge theories with T^2/Z_{N} (N=2,3,4,6) twisted magnetized orbifold, we obtained exact results for generation patterns by using the knowledge of 2d quantum mechanics.
Refs: ・Y. Fujimoto, T. Kobayashi, T. Miura, K. Nishiwaki and M. Sakamoto, ``Shifted orbifold models with magnetic flux,'' Phys. Rev. D 87,086001(2013) ・T-H Abe, Y. Fujimoto, T. Kobayashi, T. Miura, K. Nishiwaki and M. Sakamoto, ``Z_{N} twisted orbifold models with magnetic flux,'' JHEP01(2014)065 ・T-H Abe, Y. Fujimoto, T. Kobayashi, T. Miura, K. Nishiwaki and M. Sakamoto in preparation. |

Date/Place | July 1 (Tues.) 15:00～ / H711 |
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Name | Masafumi Fukuma (Kyoto U.) |

Title | Propagators in nonstationary spacetimes and a nonequilibrium-thermodynamics character of de Sitter space (slides) |

Abstract |
This talk consists of two parts.
The first half deals with the issue of defining a vacuum in a curved spacetime with no global timelike Killing vector. We propose to take as the vacuum the instantaneous ground state at each instant and develop a framework to calculate various Green's functions for such vacua. The second half is an application of the above framework, revealing a nonequilibrium-thermodynamics character of de Sitter space. We first introduce an Unruh-DeWitt detector coupled to scalar field in the instantaneous ground state at a finite past, and write down the master equation for the density matrix of the detector. We show that the density distribution exhibits a relaxation to the Gibbs distribution with the universal relaxation time of half the curvature radius of de Sitter space even when the detector is an ideal detector that can get adjusted to its environment instantaneously. This relaxation time gives an example of nonequilibrium thermodynamic quantities intrinsic to de Sitter space. [References] M. Fukuma, Y. Sakatani and S. Sugishita, "On propagators in de Sitter space" [PRD88 (2013) 024041, arXiv:1301.7352] M. Fukuma, Y. Sakatani and S. Sugishita, "Master equation for the Unruh-DeWitt detector and the universal relaxation time in de Sitter space" [PRD89 (2014) 064024, arXiv:1305.0256] |

Date/Place | June 24 (Tues.) 15:00～ / H711 |
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Name | Kengo Yamamoto (Osaka U.) |

Title | The dynamics of boundary conditions in S^1/Z_2 Gauge-Higgs Unification (slides(PDF), (slides(Keynote)) |

Abstract | Gauge-Higgs Unification is the candidate of Beyond Standard Model. The symmetry of Lagrangian density is spontaneously broken by the expectation values of gauge-field itself in Gauge-Higgs Unification. This mechanism allows we avoid the hierarchy problem of Higgs mass. This broken symmetry pattern depends on the boundary conditions of the extra-dimensions which are assumed in the system. But there is no criterion we select a set of boundary conditions in many possibility. In this research, we regard the boundary conditions as dynamical variables, and focus our attentions on SU(N) gauge theory on S^1/Z_2 times M^4. We can analyze this model by matrix model method. As performing the integrations of the partition function, we can get the nontrivial restriction for the set of boundary conditions. This restriction prefers the sets of boundary conditions which break Lagrangian symmetry. |

Date/Place | June 17 (Tues.) 15:00-16:00 / H711 |
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Name | Tatsuhiro Misumi (Keio U.) |

Title | Adjoint QCD on R^3 × S^1 with twisted fermonic boundary conditions (slides) |

Abstract | We discuss QCD with adjoint Dirac fermions on R^3 × S^1 with generic twisted boundary angles for fermions along S^1, with emphasis on its phase structure in the space spanned by the compactification scale L, the twisted angle \phi and the fermion mass m. By means of perturbation theory, semiclassical methods and a chiral effective model, we find various phases with or without chiral and center symmetry breaking, separated by first- and second-order phase transitions, which in specific limits (\phi = 0, \phi = \pi, L to 0 and m to \infty) reproduce known results in the literature. In the center-symmetric phase at small L (Hosotani-Unsal regime), we show that Unsal's bion-induced confinement mechanism is at work but is substantially weakened at \phi \not= 0 by a linear potential between monopoles. We argue that, due to interplay of the order parameters for center and chiral symmetries at \phi \not= 0, ``continuity" between a weak-coupling center-symmetric phase at small L and a strong-coupling one at large L can be intervened by the deconfined phase, depending on the ratio of the dynamical fermion mass to the energy scale of the Yang-Mills theory. We discuss implication of this possibility for resurgence in gauge theories. |

Date/Place | June 10 (Tues.) 15:00～ / H711 |
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Name | Sayaka Kawabata (Tohoku U.) |

Title | New method for precise determination of top quark mass at LHC (slides) |

Abstract | The mass of the top quark is an important input parameter to the Standard Model and models of new physics. Recently a measurement of the top quark mass with an accuracy of 0.8GeV has been reported. This mass, however, is not identical to the pole mass nor well-defined in perturbative QCD. On the other hand, the present error of the (theoretically more preferable) top quark MSbar mass is still large with 4-5GeV. In this study, we propose a new method to measure a theoretically well-defined top quark mass at the LHC. This method requires only lepton energy distribution and is basically independent of the production process of the top quark. We perform a simulation analysis of the top quark mass measurement with ttbar pair production and lepton+jets decay channel at the leading order. The estimated statistical error of the top quark mass is about 0.4GeV with an integrated luminosity of 100fb^{-1} at \sqrt{s}=14TeV. We also estimate some of the major systematic uncertainties and find that they are under good control. By including higher-order corrections, the MSbar mass of the top quark can be determined. |

Date/Place | June 4 (Wed.)13:30〜 /H711 |
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Name | Dongmin Gang (KIAS) |

Title | Holography of wrapped M5 branes and Chern-Simons theory (Keynote, PDF) |

Abstract | Large classes of interacting d-dimensional superconformal field theories(SCFTs) can be constructed from wrapped M5-branes on a manifold M of dimension (6-d). The lower dimensional SCFTs are labelled by M and will be denoted by T[M]. Recent studies on the wrapped M5-branes provides new physical insights : (1) AGT-like 'dualities' between T[M] and a (topological) theory on M, (2) Large classes of AdS_{d+1}/CFT_d involving T[M], (3) Quantitive understanding of some aspects of 6d (2,0) theory (such as superconformal index, N^3-behavior and etc). In this talk, we consider the case when d=3 where (1) 3d-3d relation relates supersymmetry partition function (ptn) of T[M] on a curved background to a Chern-Simons ptn on M and (2)T[M] theory is holographically dual to M-theory on AdS4xMxS4. Using the 3d-3d relation, we calculate the free energy of T[M] on a curved background and compare it to the corresponding gravity free energy and find an exact match modulo a non-trivial mathematical conjecture on perturbative CS invariants on M. We numerically check the conjecture for various Ms. From the calculation, we microscopically confirm the N^3 behavior of (2,0) theory. This talk is based on arXiv:1401.3595. |

Date/Place | June 3 (Tues.) 15:00～ / H711 |
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Name | Masakiyo Kitazawa (Osaka U.) |

Title | Thermodynamics of SU(3) gauge theory from gradient flow (slides) |

Abstract | We propose a novel method to study the bulk thermodynamics in lattice gauge theory on the basis of the Yang-Mills gradient flow. The energy density and the pressure of the SU(3) gauge theory at nonzero temperature are calculated on the lattice by directly measuring the thermal expectation values of the energy-momentum tensor (EMT) obtained by the gradient flow. Our numerical result on the lattice with spatial volume up to 64^3 shows that the method can be successfully used to define the EMT in lattice gauge theory with practically reasonable numerical costs. Applications of the method to the determination of lattice spacing and the measurement of the correlation functions of the EMT will also be addressed. |

Date/Place | May 27 (Tues.) 15:00～ / H711 |
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Name | Norikazu Yamada (KEK) |

Title | Revisiting epsilon-expansion analysis of UA(1) symmetry (slides) |

Abstract | We study the nature of phase transition of two-flavor QCD by analyzing the effective theory with the leading order epsilon-expansion. The RG flow of the effective theory is revisited with a mass dependent renormalization scheme, which clarifies the location of the attractive basin flowing into O(4) linear sigma model. I would like to present and discuss a subtlety that even if the flow starts from the inside the attractive basin the effective theory does not necessarily end up with O(4) theory. |

Date/Place | May 22 (Thur.) 13:00～ / H711 |
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Name | Hitoshi Murayama (Kavli IPMU / UC Berkeley) |

Title | What’s wrong with Goldstone? (Keynote, PDF) |

Abstract | Spontaneous Symmetry Breaking is a very universal concept applicable for a wide range of subjects: crystal, superfluid, neutron stars, Higgs boson, magnets, and many others. Yet there is a variety in the spectrum of gapless excitations even when the symmetry breaking patterns are the same. We unified all known examples in a single-line Lagrangian of the low-energy effective theory. In addition, we now have a better understanding of what happens with space-time symmetries, and predict gaps for certain states exactly based on symmetries alone. |

Date/Place | Date / Place:May 21 (Wed.) 16:20-17:20 / H711 |
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Name | Adam Pawel Falkowski(Laboratoire de Physique Théorique d’Orsay) |

Title | Exotic Higgs decays (slides) |

Abstract | I will discuss the possibility of the LHC observing Higgs decays that are not predicted within the Standard Model. I will describe some models where the branching fraction for exotic Higgs decays can be significant without violating any existing experimental constraints. The main focus will be on the sensitivity of the 4-lepton final state to exotic Higgs decays. I will show that the current ATLAS and CMS 4-lepton data already probe a non-trivial parameter space of certain new physics scenarios, and discuss the discovery reach in the coming LHC run. |

Date/Place | May 20 (Tues.) 15:00～ / H711 |
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Name | Yusuke Nishida (Tokyo Tech.) |

Title | Universality in quantum few-body physics (slides) |

Abstract | Physics is said to be universal when it emerges regardless of the underlying microscopic details. A prominent example is the Efimov effect, which predicts the emergence of an infinite tower of three-body bound states obeying discrete scale invariance when the particles interact resonantly. Because of its universality and peculiarity, the Efimov effect has been the subject of extensive research in chemical, atomic, nuclear and particle physics for decades. In this talk, I will give a pedagogical introduction to the Efimov effect and then discuss our recent studies on its emergence in condensed matter systems [arXiv:1208.6214] and a new universal phenomenon called super Efimov effect [arXiv:1301.4473]. |

Date/Place | 13 May. (Tue.) 13:00～ / H601 |
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Name | Masahide Yamaguchi (Tokyo tech univ.) |

Title | Non-Gaussianities of primordial perturbations and tensor sound speed (slides) |

Abstract | We investigate the relation between the non-Gaussianities of the primordial perturbations and the sound speed of the tensor perturbations, that is, the propagation speed of the gravitational waves. We find that the sound speed of the tensor perturbations is directly related not to the auto-bispectrum of the tensor perturbations but to the cross-bispectrum of the primordial perturbations, especially, the scalar-tensor-tensor bispectrum. This result is in sharp contrast with the case of the scalar (curvature) perturbations, where their reduced sound speed enhances their auto-bispectrum. Our findings indicate that the scalar-tensor-tensor bispectrum can be a powerful tool to probe the sound speed of the tensor perturbations. |

Date/Place | 9 May. (Fri.) 13:00～ / H711 |
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Name | Naoki Yamatsu (Osaka univ.) |

Title | A Vectorlike Supersymmetric Grand Unified Model with Noncompact Horizontal Symmetry (slides) |

Abstract | One of the most remarkable features in Nature is the existence of three generations of chiral quarks and leptons and their mass hierarchies. To understand the particle properties, I have been studying a supersymmetric vectorlike model with a noncompact group horizontal symmetry. The model has two good aspects: (1) Three chiral generations emerge as a result of the spontaneous horizontal symmetry breaking, called the mechanism of the spontaneous generation of generations. (2) The horizontal symmetry controls the structures of Yukawa couplings and they have hierarchical patterns naturally. Recently, I found an interesting feature in an SU(5) SUSY GUT model with the noncompact horizontal symmetry; when doublet-triplet mass splitting is naturally realized via the spontaneous horizontal symmetry breaking, the contribution to proton decay via the colored Higgses is highly suppressed. In this talk, I will give an introduction of this model and especially explain a related part of proton decay as far as possible. This talk is mainly based on a paper PTEP 2013, 123B01 (arXiv:1304.5215 [hep-ph]). |

Date/Place | 25 Apr. (Fri.) 16:00～ / H711 |
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Name | Yukihiro Fujimoto (Osaka univ.) |

Title | Generation, Quark/Lepton Flavor Structure from Point Interactions in an Extra Dimension (slides ) |

Abstract | In the context of 5d gauge theories on a circle, we found that three generations and quark/lepton mass hierarchy appear to the low energy effective theory from point interactions and a gauge singlet scalar. The point interactions are key ingredients to generate three generations of the chiral massless zero modes and the extra-dimension coordinate-dependent VEV of the gauge singlet scalar plays an important role to quark/lepton mass hierarchy. CP phases of the CKM matrix and the PMNS matrix CP phase show up from the twisted boundary condition for the Higgs doublet in this scenario and the flavor mixing structures are determined from the configuration of the point interactions. We also discuss stability of the system at the end. |

Date/Place | 25 Apr. (Fri.) 14:30～ / H711 |
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Name | Norihiro Iizuka (Osaka univ.) |

Title | What does condensed matter physics tell us about general relativity? |

Abstract | In this talk, we will discuss simple paradox where basics physical facts between condensed matter physics and general relativity (apparently) contradict through holography. |

Date/Place | 22 Apr. (Tue.) 15:00～ / H711 |
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Name | Noriaki Ogawa (IPMU) |

Title | On the Entanglement of Multiple CFTs via Rotating Black Hole Interior(slides) |

Abstract | We study the minimal surfaces between two of the multiple boundaries of 3d maximally extended rotating eternal black hole. Via AdS/CFT, this corresponds to investigating the behavior of entanglements of the boundary CFT with multiple sectors. Non-trivial time evolutions of such entanglements detect the geometry inside the horizon, and behave differently depending on the choice of the two boundaries. (Based on arXiv:1402.4548, with Norihiro Iizuka) |

Date/Place | 15 Apr. (Tue.) 15:00～ / H711 |
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Name | Masatoshi Yamada (Kanazawa univ.) |

Title | Non-perturbative renormalization group appproach to dynamical chiral symmetry breaking in extreme environments(slides) |

Abstract | We analyze dynamical chiral symmetry breaking (DchiSB) in various environments by using non-perturbative renormalization group (NPRG) . We start with the NPRG and the DχSB at zero temperature and zero density. We extend the system to take account of finite temperature and finite density using the Nambu-Jona-Lasinio model . Especially, we concentrate on renormaliztion flow structures of the four-fermi coupling constant, by which we judge the chiral symmetry breaking. Then taking the quark meson model, we impose an exernal magnetic field on the system, and investigate the so-called inverse magnetic catalysis. |

Date/Place | 8 Apr. (Tue.) 15:00～ / H711 |
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Name | Tadashi Okazaki (Osaka univ.) |

Title | Superconformal Mechanics and M2-branes |

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 on a holomorphic two-cycle 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. |