2016年度のセミナー

Date/Place Feb. 24th(Fri.)(Informal) 15:30-16:30 / H711
Name Prof. Bohdan Grzadkowski (University of Warsaw)
Title Resonances in cosmology \\ - revisitation -(Slides)
Abstract I will revisit the issue of dark matter annihilation through a Breit-Wigner resonance. A few important and hitherto neglected effects will be discussed. For instance the resonance-enhanced early-universe annihilation cross section implies so small cross section for elastic scattering between dark matter and the Standard Model, that effects of early kinetic decoupling of dark matter are crucial for correct prediction of relic dark matter abundance. Also the standard Breit-Wigner parametrization of a resonance propagator must be corrected by including momentum dependence of the resonance width. Model independent discussion will be illustrated within a theory of Abelian vector dark matter. The momentum dependence of the scalar resonance introduces a gauge dependence of annihilation amplitudes. Also unitarity might be jeopardized. Both effects will be discussed. It turns out that the Fermi-LAT limits favours heavy dark matter, in the case of dark vector boson $M_{DM} \gsim 1.5 \tev$.

　

Date/Place Feb. 23rd(Thu.)(Informal) 15:30-16:30 / H711
Name Dr. Stanislav Rusak (Osaka U)
Title Aspects of SM Higgs and electroweak vacuum stability in the early universe(Slides)
Abstract If the Standard Model of particle physics is valid up to the inflationary scale, the Higgs field is expected to be a light field which obtains an expectation value comparable to the Hubble parameter during inflation. This has important implications for the physics of the Higgs during and immediately after the inflationary period. In the case of high scale inflation the field would be pushed into the true vacuum beyond 10^11 GeV during inflation and the universe would never end up in its current electroweak vacuum. This problem can be remedied by coupling the Higgs to the inflaton or to gravity. However, during preheating resonant production of Higgs quanta resulting from such couplings may again destabilize the vacuum putting new constraints on such models.

　

Date/Place Jan. 31th 15:30-16:30 / H711
Name Bum-Hoon Lee(Sogang University)
Title Gravity theory with the Gauss-Bonnet term, and Thermodynamic Black Hole stabilities(Slides)
Abstract We study the properties of the dilaton gravity theory with the Gauss-Bonnet term. The black holes in such a model have always scalar hairs, and also have the minimum mass for the existance. We investigate the nonperturbative stability under the possible fragmentation based on the thermodynamic property. Unlike black holes in the asymptotic flat spacetime which is stable under fragmentation, we found some parameter region showing the possible instability under the fragmentation. We will also briefly mention some implication of such a model to the cosmology.

　

Date/Place Jan. 24th 15:30-16:30 / H711
Name Hisaki Hatanaka(Osaka Univ.)
Title Collider signals of W′ and Z′ bosons in the gauge-Higgs unification(Slides)
Abstract In the SO(5)×U(1) gauge-Higgs unification (GHU), Kaluza-Klein (KK) excited states of charged and neutral vector bosons, W(1), W_R(1), Z(1), γ(1) and Z_R(1), can be observed as W’ and Z’ signals in collider experiments. In this paper we evaluate the decay rates of the W’ and Z’, and s-channel cross sections mediated by W’ and Z’ bosons with final states involving the standard model (SM) fermion pair (ℓν, ℓ+ℓ-, q-qbar), WH, ZH, WW and WZ. W' and Z' resonances appear around 6.0 TeV (8.5 TeV) for θ_H=0.115(0.0737) where θ_H is the Aharonov-Bohm phase in the fifth dimension in GHU. For decay rates we find Γ(W'→WH)≃Γ(W'→WZ) (W’=W(1), W_R(1)), Γ(W(1)→WH,WZ)∼Γ(W_R(1)→WH,WZ), Γ(Z(1)→ZH)≃∑_{Z’=Z(1),γ(1)} Γ(Z’→WW), and Γ(Z(1)_R→ZH)≃Γ(Z_R(1)→WW). W′ and Z′ signals of GHU can be best found at the LHC experiment in the processes pp→W′(Z′)+X followed by W′→tb¯,WH, and Z′→e+e−, μ+μ−, ZH near the W′and Z′ resonances. In the process with WZ in the final state, it is numerically confirmed with high accuracy that the unitarity is preserved, provided that all KK vector bosons and KK fermions in the intermediate states are taken into account. It is also shown that deviation of the WWZ coupling from the SM is very tiny. Exotic partners t_T(1) and b_Y(1) of the top and bottom quarks with electric charge +5/3 and −4/3 have mass M_{t_T(1),b_Y(1)}=4.6 TeV (5.4 TeV) for θ_H=0.115 (0.0737), becoming the lightest non-SM particles in GHU which can be singly produced in collider experiments. [This talk is based on my recent work (arXiv:1612.03378)]

　

Date/Place Jan. 17th 15:30-16:30 / H711
Name Kentaro Tanabe (Rikkyo Univ. )
Title Effective theory of black holes at large D(Slides)
Abstract In the infinite limit of the spacetime dimension D, the gravitational interaction by a black hole becomes very strong, and it is confined in very near region of the black hole horizon. Then, at large D, the dynamics of the black hole horizon is completely controlled by such confined low energy gravitons, which we call decoupled modes of large D black holes. We can construct an effective theory for the decoupled modes from the Einstein equation, and the effective theory describes the nonlinear dynamical evolution of black holes as some kinds of hydrodynamics. In this talk I will give some review on this large D effective theory method for dynamical black holes, and I will report recent progress in the understanding of the relation between decoupled modes and Goldstone modes coming from a spontaneous conformal symmetry breaking.

　

Date/Place Jan. 10th 15:30-16:30 / H711
Name Shuichi Yokoyama(YITP)
Title Matrix models of Chern-Simons matter theories beyond the spherical limit(Slides)
Abstract We study a class of matrix models which arises as partition function in U(N) Chern-Simons matter theories on three sphere. Employing the standard technique of the 1/N expansion developed in the study of ordinary hermitian matrix model, we solve the system beyond the planar limit. To test whether the proposed framework works correctly we confirm that the subleading correction in the free energy correctly reproduces the one obtained by expanding the past exact result in the case of pure Chern-Simons theory.

　

Date/Place Dec. 20th 15:30-16:30 / H711
Name Yuichi UESAKA(Osaka U. Nuclear Theory) (Slides)
Title Charged lepton flavor violating process, μ^-e^- -> e^-e^- in a muonic atom
Abstract The charged lepton flavor violation (CLFV) is a good probe to search for new physics beyond the standard model. Though various CLFV processes have been investigated, any singns of new physics have not yet found. In 2010, the CLFV decay of the muonic atom, $\mu^-e^-\rightarrow e^-e^-$, was proposed as one of the promising processes. In this talk, I report on our improved analysis of this process by taking into account the distortion of the out-going electrons in the nuclear Coulomb potential and the relativistic treatment of the muon and the electrons. These effects are important and modify the previous understanding of the mass dependence of transition rate. I also talk that the process has a capability to discriminate between contact and photonic CLFV interactions.

　

Date/Place Dec. 13th 15:30-16:30 / H711
Name Kazuya Yonekura(IPMU) (Slides)
Title Anomalies and SPT phases
Abstract I will talk about the relation between symmetry protected topological (SPT) phases and the anomalies of the theories which appear on the boundary. All anomalies of (anti-)unitary symmetries are believed to be classified by SPT phases, and they correspond to the (generalized version of) Berry phases of the ground state of the SPT phases. I also discuss some implications for chiral fermions as well as topological field theories.

　

Date/Place Nov. 29th 15:30-16:30 / H711
Name Ryuji Daido (Tohoku U.)
Title Gauge Coupling Unification with Hidden Photon, and Minicharged Dark Matter(Slides)
Abstract We show that gauge coupling unification is realized with a greater accuracy in the presence of a massless hidden photon which has a large kinetic mixing with hypercharge. We solve the renormalization group equations at two-loop level and find that the GUT unification scale is around $10^{16.5}$ GeV which sufficiently suppresses the proton decay rate, and that the unification is essentially determined by the kinetic mixing only, and it is rather insensitive to the hidden gauge coupling or the presence of vector-like matter fields charged under U(1)$_H$ and/or SU(5). Matter fields charged under the unbroken hidden U(1)$_H$ are stable and they contribute to dark matter. Interestingly, they become minicharged dark matter which carries a small but non-zero electric charge, if the hidden gauge coupling is tiny. The minicharged dark matter is a natural outcome of the gauge coupling unification with a hidden photon.

　

Date/Place Nov. 22nd 15:30-16:30 / H711
Name Masashi Hayakawa (Nagoya University)
Title Attempt to calculate the hadronic light-by-light scattering contribution to the muon g-2 from lattice QCD(Slides)
Abstract The standard model prediction to the muon g-2 slightly differs from its experimental value. However, it is not certain at all if one of the QCD contributions, so called, the hadronic light-by-light scattering (HLbL) contribution to the muon g-2 is correctly given by that obtained through hadronic model calculation, which is comparable in size to the difference currently observed between theory and experiment. Hence, in order to get a definite value of the HLbL contribution and to draw more reliable standard model prediction, the lattice QCD simulation is indispensable for this contribution. Here, I’d like to make the following three points clarify: (1) what must be done for the lattice QCD calculation of the HLbL contribution, (2) what has been attained so far, in particular, our procedure of calculation and preliminary result, and (3) challenging issues.

　

Date/Place Nov. 15th 15:30-16:30 / H711
Name Kento Watanabe (YITP)
Title From Path Integrals to Tensor Networks for AdS/CFT(Slides)
Abstract Tensor network descriptions are known in condensed matter physics as a useful tool to construct quantum (ground) states. Recently they have been considered as a toy model of holography or AdS/CFT.Toward better understanding of the connection between the tensor networks and AdS/CFT, we discuss it from two different viewpoints. First, we start with an Euclidean path-integral computation of ground state wave functions with a UV cut off. We consider its efficient optimization by making its UV cut off position dependent and define a quantum state at each length scale. We conjecture that this path-integral corresponds to a time slice of AdS. Next, we derive a flow of quantum states by rewriting the action of Killing vectors of AdS3 in terms of the dual 2d CFT. Both approaches support a correspondence between the hyperbolic time slice H2 in AdS3 and a version of continuous MERA (cMERA) network. We also give a heuristic argument why we can expect a sub-AdS scale bulk locality for holographic CFTs. (Ref: 1609.04645v2[hep-th] with Masamichi Miyaji and Tadashi Takayanagi)

　

Date/Place Nov. 8th 15:30-16:30 / H711
Name Mikito Koshino (Osaka University)
Title Physics of massless Dirac electrons ― from 2D to 3D(Slides)
Abstract Recently a great deal of attention has been focused on condensed matter systems having zero-gap electronic structures analogous to the massless relativistic particles. The most well-known example is graphene (2D graphite) where the low-energy band structure is described by the Weyl equation. Also, very recently, the 3D gapless materials called Weyl / Dirac semimetals have been discovered in real materials. In this talk, I introduce our recent works in exploring a new class of gapless electronic systems both in 2D and 3D. First I show that there is a certain family of zero-gap systems protected by the coexistence of chiral symmetry and spatial (e.g., reflection, inversion, and rotation) symmetries. The well-known examples such honeycomb lattice (= graphene) and half-flux square lattice can be explained in terms of the chiral and rotation symmetries, and also several examples of Dirac semimetals in 3D are presented. In the latter half, I introduce another approach from the material side, where I propose a class of graphene wound into three-dimensional periodic curved surfaces (“graphitic sponges”) and explore how to make a 3D Dirac system out of 2D massless electrons.

　

Date/Place Nov. 1st 15:30-16:30 / H711
Name Takumi Kuwahara (Nagoya U.)
Title Threshold Corrections to Dimension-Six Proton Decay Operators in SUSY SU(5) GUTs (Slides)
Abstract The supersymmetric grand unified theories (SUSY GUTs) are the promising models beyond the standard model for particle physics. The standard SUSY GUTs predict that there exist the baryon-number violating processes, such as proton decay. For precise determination of the proton lifetime, it is important to estimate quantum corrections on these processes since there exists a large scale running between the GUT scale and 1 GeV where the nucleon matrix elements are calculated. Corrections via the two-loop renormalization group equations (RGEs) have been already investigated. On the other hand, the one-loop threshold (finite) corrections whose size is comparable to that of the two-loop RGEs have not been evaluated so far. In this talk, we first discuss the derivation of the finite threshold correction to proton decay operators by using supergraph. Then, we show the effects of the threshold corrections on the decay rate in the minimal and non-minimal SUSY SU(5) GUTs numerically.

　

Date/Place Oct. 25th 15:30-16:30 / H711
Name Sinya Aoki (YITP)
Title Definition of entanglement entropy in lattice gauge theories and its application to pure gauge theories in 1+1 dimensions (Slides)
Abstract We focus on the issue of proper definition of entanglement entropy in lattice gauge theories, and examine a naive definition where gauge invariant states are viewed as elements of an extended Hilbert space which contains gauge non-invariant states as well. Working in the extended Hilbert space, we can define entanglement entropy associated with an arbitrary subset of links, not only for abelian but also for non-abelian theories. We then derive the associated replica formula. We also discuss the issue of gauge invariance of the entanglement entropy. As an application of this proposal, we study the entanglement entropy (EE) for pure gauge theories in 1+1 dimensions with the lattice regularization. We calculate the EE for arbitrary pure as well as mixed states in terms of eigenstates of the transfer matrix in 1+1 dimensional lattice gauge theory. We find that the EE of an arbitrary pure state does not depend on the lattice spacing, thus giving the EE in the continuum limit, and show that the EE for an arbitrary pure state is independent of the real (Minkowski) time evolution. We also explicitly demonstrate the dependence of EE on the gauge fixing at the boundaries between two subspaces.

　

Date/Place Oct. 18th 15:30-16:30 / H711
Name Hiroaki Sugiyama (Toyama U.)
Title Testing neutrino mass generation mechanisms via flavor physics (Slides)
Abstract There are many new physics models for generating neutrino masses, and it is important to consider how these models can be experimentally discriminated. Classification of models is useful for the efficient discrimination. In this talk, we classify simple models for each of Majorana and Dirac neutrino masses into some groups by concentrating on Yukawa interactions with leptons. We see these groups of models can be tested by e.g. lepton flavor violating (LFV) decays of the tau lepton. In addition, if a LFV decay of the Higgs boson is discovered, simple models for Majorana neutrino masses are excluded while some models for Dirac neutrino masses can survive.

　

Date/Place Oct. 11th 15:30-16:30 / H711
Name Kazunobu Maruyoshi (Seikei U.)
Title "Lagrangians" for N=2 SCFTs in 4d (Slides)
Abstract We study certain N=1 preserving deformations of four-dimensional N=2 superconformal field theories (SCFTs) with non-abelian flavor symmetry. The deformation is described by adding an N=1 chiral multiplet transforming in the adjoint representation of the flavor symmetry with a superpotential coupling, and giving the nilpotent vacuum expectation value to the chiral multiplet which breaks the flavor symmetry. Remarkably, we find classes of theories flow to enhanced N=2 supersymmetric fixed points in the infrared under the deformation. In particular, we find renormalization group flows from the deformed conformal SQCDs with gauge group SU(N) and Sp(N) to N=2 SCFT of Argyres-Douglas type. From these ``Lagrangian descriptions," we compute the full superconformal indices and find agreements with the previous results.

　

Date/Place Oct. 4th 15:30-16:30 / H711
Name Masafumi Kurachi (KEK)
Title Electroweak-Skyrmion as Topological Dark Matter (Slides)
Abstract We show the existence of a nontrivial topological configuration of the Higgs field in the Standard Model with the Skyrme term. It is shown that the current upper bound of the mass of the topological object is about 34 TeV. We discuss the impact of the existence of the topological object on cosmology.

　

Date/Place Aug. 30th 13:30-14:30 / H711
Name Teppei Kitahara (IKP)
Title Recent progress on CP violation in K to pi pi decays in the SM and SUSY solution
Abstract Recent progress in the determination of hadronic matrix elements has revealed a tension between the experimental value of epsilon’/epsilon, which quantifies direct CP-violation in K to pi pi decays, and the Standard-Model (SM) prediction. On the other hand, the standard analytic solution of the next-to-leading order (NLO) renormalization group (RG) evolution for the DeltaS = 1 Wilson coefficients suffers from several singularities. In the first part of this talk, we will introduce a singularity-free analytic solution of the RG evolution, and give a new prediction value of the epsilon’/epsilon in the SM at the NLO, which also implies the epsilon’ discrepancy. In the second part, we will show that it is possible to cure the epsilon’ discrepancy in the Minimal Supersymmetric Standard Model with squark masses above 3 TeV without overshooting epsilon. This solution exploits two features of supersymmetry, the possibility of large isospin-breaking contributions (enhancing epsilon’) and the Majorana nature of gluinos (permitting a suppression of epsilon). Our solution involves no fine-tuning of CP phases or other parameters. This talk is based on arXiv:1604.07400 and arXiv:1607.06727.

　

Date/Place July. 26th (Tues.) 15:30-16:30 / H711
Name Takahiro Nishinaka (YITP)
Title On 4d rank-one N=3 superconformal field theories (Slides)
Abstract We study the properties of 4d N=3 superconformal field theories whose rank is one, i.e. those that reduce to a single vector multiplet on their moduli space of vacua. We find that the moduli space can only be of the form C3/Z_k for k=1,2,3,4,6, and that the supersymmetry automatically enhances to N=4 for k=1,2. In addition, we determine the central charges a and c in terms of k, and construct the associated 2d chiral algebras, which turn out to be exotic N=2 supersymmetric W-algebras. This talk is based on arXiv:1602.01503 in collaboration with Yuji Tachikawa.

　

Date/Place July. 19th (Tues.) 15:30-16:30 / H711
Name Ryusuke Jinno (KEK)
Title Probing classically conformal B-L model with gravitational waves (Slides)
Abstract Recent gravitational-wave (GW) detection by LIGO has opened up the field of gravitational-wave "astronomy", and the era of gravitational-wave "cosmology" is expected to come next. In this talk, I focus on GWs as a probe to first-order phase transition in the early universe. Especially, I point out that, if the underlying particle physics model has so-called "classical conformal invariance", this property can lead to a very strong first-order phase transition in the early universe with large amount of GW production. I discuss how this occurs taking classically conformal B-L model as an example, and also discuss observational prospects in the future. If time permits, I will briefly discuss recent progress in so-called sound-wave enhancement of GWs during cosmic first-order phase transitions.

　

Date/Place July. 12th (Tues.) 15:30-16:30 / H711
Name Jun Nishimura (KEK)
Title Recent developments in the complex Langevin method for solving the sign problem (Slides)
Abstract The sign problem is a notorious problem that occurs in an attempt to apply Monte Carlo simulation to a theory with a complex action. In the context of particle physics, this occurs, for instance, in finite density QCD, theories with theta terms and supersymmetric gauge theories. Recently there have been remarkable developments in the complex Langevin method, which aims at solving the sign problem by extending the idea of stochastic quantization to a system with a complex action. In particular, we have established the argument for justification of the method extending the previous one by Aarts et al., which overlooked a few important issues. Our argument provides us with a simple criterion, which tells us whether the results obtained by the method are trustable or not. One can actually try to satisfy this criterion by using the so-called gauge cooling, which can be included in our argument explicitly. We also present some results demonstrating that the method is appplicable to interesting cases, which would be otherwise difficult to investigate. Ref.) Nagata-J.N.-Shimasaki, arXiv:1606.07627 [hep-lat], arXiv:1604.07717 [hep-lat]

　

Date/Place July. 7th (Thur.) (Informal) 15:30-16:30 / H711
Name Seong Chan Park (Yonsei-U)
Title Some thoughts on recent events in particle physics
Abstract I would discuss two issues in particle physics: one observational and one more theoretical. The former is about the 750 GeV excess in diphoton channel reported by ATLAS and CMS. The later is about the recent calculation of Sphaleron rate by Henry Tye and his company. My talk will be casual and meant to bring further discussion among participants.

　

Date/Place July. 5th (Tues.) 15:30-16:30 / H711
Name Tamiaki Yoneya (Tokyo U.)
Title Covariantized M(atrix) theory for D-particles (Slides)
Abstract The so-called BFSS M(atrix) theory for D-particles, proposed in 1996, has been the only known workable proposal towards concrete formulation of M theory, whose existence in 11 dimensional spacetime is conjectured to be a key feature in still-unknown non-perturbative definitions of string/M theory. However, its formulation has been restricted in a special light-front gauge. Whether and how the M(atrix) theory could be made fully Lorentz covariant in the sense of 11 dimensional Minkowski spacetime has long been one of the important unresolved issues in string/M theory. In this lecture, I discuss a possible resolution of this problem on the basis of my recent work.

　

Date/Place June. 30th (Thur.) 16:20-17:20 / H711
Name Fuminobu Takahashi (Tohoku U.)
Title Recent topics in axion cosmology -isocurvature perturbations and alignment- (Slides)
Abstract I will talk about two recent topics in the axion cosmology. One is the axionic isocurvature perturbation, which is tightly constrained by the recent CMB observation. I will mention various ways to suppress the isocurvature perturbations, particularly focusing on the recently proposed one using the Witten effect. The other is the so called aligned axion model, where the axion decay constant is hierarchically larger than the Peccei-Quinn symmetry breaking scale. I discuss cosmological implications of these scenarios.

　

Date/Place June. 28th (Tues.) 15:30-16:30 / H711
Name Yuya Tanizaki (RIKEN)
Title Lefschetz-thimble path integral for studying the sign problem and Silver Blaze phenomenon (Slides)
Abstract Lattice Monte Carlo method has been a powerful tool to study nonperturbative phenomenon even when analytical computation is not available. By regarding exp(-S) as a probability density, we can "solve" strongly correlated systems stochastically. Indeed, this method succeeds to explain many aspects of quantum chromodynamics (QCD) at finite temperatures. However, if the classical action takes complex values, this procedure does not work well. This is called the sign problem, and it has been one of the biggest obstacles in studying the strongly-correlated systems for theoretical physicists. Recently, Picard-Lefschetz theory gets much attention in this context, because it enables us to study the system with the complex classical action nonperturbatively associated with the semiclassical analysis. In this seminar, after its brief introduction, I will apply it to one-site Hubbard model. This model has a severe sign problem, which looks quite similar to that of the finite-density QCD at low temperatures. I will also try to give a qualitative picture about the early-onset problem of the baryon number density, called the baryon Silver Blaze problem, from the viewpoint of Lefschetz thimbles based on our computations. The complex Langevin method will also be discussed if time allows.

　

Date/Place June. 21st (Tues.) 15:30-16:30 / H711
Name Koji Nakamura (KEK)
Title Recent result at the LHC (Slides)
Abstract After the Higgs discovery, LHC accelerator has been upgraded to 13TeV center-of-mass energy and started taking data as "LHC run2" experiment since 2015. This upgraded experiment allows to access to the BSM physics in higher energy scale. In this seminar, I'll show the recent results at the LHC run2 and expected sensitivity of the future luminosity upgraded LHC.

　

Date/Place June. 21st (Tues.) 11:00-12:00 / H711
Name Enrico Brehm (Ludwig Maximilian U.)
Title Entanglement, Conformal Field Theory, and Interfaces (Slides)
Abstract Entanglement is a fundamental feature of quantum theories and as such plays an important role in theory and experiment. A measure thereof is called entanglement entropy. I want to present methods to derive this quantity in two-dimensional conformal field theories with interfaces, i.e. one-dimensional domain walls with suitable local gluing conditions. These may be seen as generalizations of boundaries and fall into two classes: topological interfaces that can be moved freely on the worldsheet of the theory, and non-topological interfaces whose deformation requires energy. Their effect on the entanglement entropy is highly different. I also want to address the question what we can learn about the interface itself when looking at entanglement through it.　

　

Date/Place June. 14th (Tues.) 15:30-16:30 / H711
Name Jiro Soda (Kobe U.)
Title Gauge Fields, Statistical Anisotropy, and Anisotropic Inflation (Slides)
Abstract In WMAP data, evidences of a preferred direction were found. Nowadays, it is called the statistical anisotropy. Many efforts had been made to find a physical mechanism for producing the statistical anisotropy and failed. In 2009, however, we invented anisotropic inflation and succeeded in explaining the quadratic statistical anisotropy. In anisotropic inflation, a gauge field produces a preferred direction and its coupling to an inflation filed induces the anisotropy in the CMB spectrum. In this talk, I will explain what is anisotropic inflation and why it can be a mechanism for producing the statistical anisotropy. I will also discuss Planck data from the perspective of the statistical anisotropy.

　

Date/Place June. 7th (Tues.) 15:30-16:30 / H711
Name Naoki Yamamoto (Keio U.)
Title Chirality, Topology, and Astrophysics (Slides)
Abstract Chirality of fermions has a topological nature. This microscopic property modifies the macroscopic hydrodynamic behavior and leads to unusual transport protected by topology in relativistic systems. We argue that these topological transport phenomena should play important roles in the evolution of supernovae and could potentially solve the problems in astrophysics, such as supernova explosions and the origin of magnetars.

　

Date/Place May. 31st (Tues.) 15:30-16:30 / H711
Name Hiroshi Suzuki (Kyushu U.)
Title Lattice energy-momentum tensor from the Yang-Mills gradient flow (Slides)
Abstract Generally speaking, it is difficult to construct a Noether current in QFT if one does not use (or does not know) regularization that preserves the symmetry under consideration. Such a situation occurs for the energy-momentum tensor (EMT) — a Noether current associated with the translational invariance — in lattice gauge theory which cannot preserve the translational invariance. In this work, we show how the notion of the Yang-Mills gradient flow can be useful to construct a lattice operator that automatically reproduces the correct EMT in the continuum limit. We also present our (preliminary) results for the thermodynamics of quenched and full QCD, obtained from the EMT constructed by our method.

　

Date/Place May. 24th (Tues.) 15:30-16:30 / H711
Name Mariko Kikuchi (Toyama U.)
Title Probing the extended Higgs sector from precision measurements of the Higgs boson decays (Slides)
Abstract We discuss how we are able to discriminate extended Higgs sectors by using precision measurements of the decays the discovered Higgs boson(h). To this end, we construct a full set of numerical codes for evaluating all the couplings of h at the one-loop level in various general extended Higgs sectors, such as the Higgs model with an isospin singlet scalar field, the two Higgs doublet models with four types of Yukawa interaction under the softly-broken discrete symmetry, the inert doublet model and the Higgs model with triplets. In these extended Higgs models, characteristic patterns of deviations in the couplings for h appear not only at the tree level but also at the one-loop level. We numerically evaluate the patterns at the one-loop level under theoretical constraints and the LHC Run-I data of h decays. Moreover, we examine how we can separate and identify extended Higgs models by detecting the patterns of the coupling deviations using the future precision data for the decays at the LHC Run-II, the HL-LHC and the ILC. This talk is based on the papers; 1. S. Kanemura, M. Kikuchi, K. Yagyu, Nucl. Phys. B 896, 80 (2015). 2. S. Kanemura, M. Kikuchi, K. Yagyu, Nucl. Phys. B to appear.

　

Date/Place May. 17th (Tues.) 15:30-16:30 / H711
Name Kazunori Nakayama (Tokyo U.)
Title Gravitational waves from the first order phase transition of the Higgs field at high energy scales (Slides)
Abstract In a wide class of new physics models, there exist scalar fields which obtain vacuum expectation values of high energy scales. We study the possibility that the standard model Higgs field has experienced first-order phase transition at the high energy scale due to the couplings with these scalar fields. We estimate the amount of gravitational waves produced by the phase transition, and discuss observational consequences.

　

Date/Place May. 10th (Tues.) 15:30-16:30 / H711
Name Kentaro Hori (IPMU)
Title Elliptic genera of N=2 gauge theories (Slides)
Abstract I will describe how to compute the Elliptic genus of 2d (0,2) and (2,2) supersymmetric gauge theories, and present a general exact formula written in terms of Jeffrey-Kirwan residues.

　

Date/Place Apr. 26th (Tues.) 15:30-16:30 / H711
Name Norihiro Tanahashi (Osaka U.)
Title Causality, hyperbolicity and shock formation in various theories of gravity (Slides)
Abstract We study gravitational wave propagation in Lovelock theories, which are extensions of Einstein's theory by higher-curvature corrections, to examine if these theories have good properties such as causality and hyperbolicity. We study the propagation on various background spacetime, and find that initial value problem may be ill-posed in some cases. We also show that the sound speed of gravitational wave depends on the background and it may cause shock formation in these theories. We discuss implications of these phenomena, and also examine if similar phenomena could occur in more general theories of gravity.

　

Date/Place Apr. 19th (Tues.) 15:30-16:30 / H711
Name Tohru Eguchi (Rikkyo U.)
Title Moonshine phenomena in string theory (Slides)
Abstract About five years ago we have found a curious phenomenon in string theory, i.e. appearance of exotic new symmetry M24 acting on the elliptic genus of K3 surface. Similar phenomena have been further discovered with various different symmetry groups and are now called moonshine phenomena. I will give a brief introduction to these moonshine phenomena which may play an interesting role in string theory in the future.

　

Date/Place Apr. 12th (Tues.) 15:30-16:30 / H711
Name Sotaro Sugishita (Osaka U.)
Title Holographic holes in higher dimensions (Slides)
Abstract Entropy of a black hole is proportional to the area of the event horizon (the Bekenstein-Hawking formula). In the context of the AdS/CFT correspondence, the Ryu-Takayanagi formula states that the leading term of entanglement entropy of a region in the boundary theory is given by the extremal area of the bulk surface which is homologous to the boundary region. These formulae seem to suggest that areas of codimension-two surfaces in gravitational theory have an interpretation in terms of quantum information. In this talk, we would like to discuss what quantities in the boundaries of asymptotically AdS spaces correspond to areas of general closed codimension-two surfaces in the bulk. Ref: arXiv:1403.3416

　

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