Talk Titles and Abstracts

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We investigate $SU(3)$ gauge theories in four dimensions with $N_f$ fundamental fermions, on a lattice using the Wilson fermion. We first introduce a new concept ``conformal theories with an IR cutoff', after pointing out that the following two categories in $SU(3)$ gauge theories with fundamental $N_f$ fermions possess an IR fixed point: Large $N_f (N_f^{c} \le N_f \le 16)$ QCD within the conformal window (referred as Conformal QCD) and small $N_f (1 \le N_f \le N_f^{c}-1)$ QCD at temperature $T/T_c > 1$ (referred as High Temperature QCD). In the case of Conformal QCD in the continuum limit, the compact space and/or time gives an IR cutoff. In the case of High Temperature QCD, the temperature $T$ plays a role of an IR cutoff together with a cutoff due to possible compact space, depending on how to take the continuum limit. We note any lattice calculation is performed on a finite lattice. Thus any calculation on a lattice possesses an IR cutoff. In the conformal theories with an IR cutoff there exists the ``conformal region'' together with the confining region and the deconfining region. We verify numerically on a lattice of the size $16^3\times 64$ the existence of the conformal region and the non-trivial $Z(3)$ structure of the vacuum and the Yukawa-type decay form of meson propagators in the conformal region. We stress that High Temperature QCD is intrinsically accompanied with an IR cutoff. Therefore the understanding the vacuum structure and the property of correlation functions is the key to resolve long standing issues in High Temperature QCD. We further argue that there is a precise correspondence between Conformal QCD and High Temperature QCD in the temporal propagators under the change of the parameters $N_f$ and $T/T_c$ respectively: the one boundary is close to meson states and the other is close to free quark states. In particular, we find the correspondence between Conformal QCD with $N_f = 7$ and High Temperature QCD with $N_f=2$ at $T\sim 2\, T_c$ being in close relation to a meson unparticle model. From this we estimate the anomalous mass dimension $\gamma^* = 1.2 (1)$ for $N_f=7$.

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Recent lattice efforts are reviewed to explain the Higgs particle in the framework of strongly coupled lattice gauge theories.

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One of the major scientific missions that KMI promotes is to conduct the computational research for the physics beyond the standard model. The high performance parallel computer phi was installed at KMI in early 2011 for that purpose. Lots of efforts have been put together for the operation and the utilization of phi since then. The research by LatKMI collaboration is the flagship project that have been using a large fraction of phi, exploring the possibility of composite description of the Higgs particle fond in LHC experiment. Their scientific achievements will be briefly discussed to initiate the following presentations.

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The many-flavor SU(3) gauge theory near the conformal phase boundary is of great interest with regard to the dynamical origin of the electroweak symmetry breaking. We study the infrared conformality of the twelve-flavor QCD on the lattice, utilizing the highly improved staggered quarks (HISQ) type action which is useful to study the continuum physics. The finite size scaling test in the conformal hypothesis is performed for our data of the mass and the decay constant of the pion and the mass of a vector meson. Our result is consistent with the conformal hypothesis for the mass anomalous dimension γ~0.4-0.5. Furthermore, the flavor-singlet scalar is found to be lighter than the pion in sharp contrast to the real-life QCD. It is encouraging result to explain Higgs boson mass in the walking technicolor that is an attractive candidate of theory beyond the standard model.

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We investigate walking signals of $N_f=8$ QCD through meson spectrum using the HISQ (highly improved staggered quark) action. Our data for the $N_f=8$ QCD are consistent with the spontaneously broken chiral symmetry in the chiral limit extrapolation of the chiral perturbation theory. Remarkably enough, those for the relatively large fermion bare mass $m_f$ away from the chiral limit actually exhibit a finite-size hyperscaling relation, suggesting a large anomalous dimension $\gamma_m \sim 1$. This implies that there exists a remnant of the infrared conformality, and suggests that a typical technicolor, ``one-family model'', as modeled by the $N_f=8$ QCD can be a walking technicolor theory.

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The existence of a light flavor-singlet scalar is expected in the walking technicolor as a pseduo Nambu-Goldstone boson of the scale symmetry breaking. The scalar in the walking technicolor corresponds to Higgs boson in the standard model, whose mass is relatively light, about 125 GeV, comparing to the electroweak scale. We study flavor-singlet scalar in the twelve- and eight-flavor QCD using non-perturbative lattice gauge simulation with a highly improved staggered action. In both the theories, we found a light scalar comparing with the pion measured at finite fermion mass. This property is much different from the usual QCD. We consider the lightness of the scalar is a reflection of the (approximate) infrared conformality in the theory. Since the eight-flavor QCD may be a candidate of the walking technicolor, this result could support a possibility of the composite Higgs boson.

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The next target of particle physics is to find the evidence of New Physics Beyond the Standard Model (BSM). The SuperKEKB/Belle II experiment, the next generation electron-positron B-factory experiment at KEK, aims to find evidence of New Physics by precision measurement of rare decay processes of B and D mesons, and also by searching for decays prohibited by the SM, such as the Lepton-Flavor-Violating (LFV) decays of the tau-lepton. In this talk, we present physics topics at the SuperKEKB/Belle II experiment, and the status of accelerator and detector construction.

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We consider the one-family technicolor model as the dynamical origin of the electroweak symmetry breaking. As low-energy degrees of freedom, we consider Techni-Pions (associated with the spontaneous breaking of global symmetry), Techni-Dilaton (which is identified as the 126 GeV scalar discovered at the LHC) as well as Techni-Rho mesons as typical resonances expected to appear in such model. The effective Lagrangian is constructed based on the formulation of the Hidden Local Symmetry, and we discuss implications for collider phenomenology based on that Lagrangian.

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An anomaly of the muon anomalous magnetic moment (muon g-2) has been reported. The discrepancies between the SM predictions and the measured value are about 3-4 σ. If this anomaly is an evidence of new physics beyond the SM, we expect new particles and interactions related with the muon sector. In this talk, we consider a model with an $L_\mu-L_\tau$ gauge symmetry. Since the muon couples to the $L_\mu-L_\tau$ gauge boson (called Z" boson) , its contributions to the muon g-2 can account for the discrepancy. On the other hand, the Z" boson does not interact with the electron and quarks, and hence there are no strong constraints from collider experiments even if the Z" boson mass is of the order of the electroweak scale. We show an allowed region of a parameter space in the model, taking into account consistency with the electroweak precision measurements as well as the muon g-2. We study the Large Hadron Collider (LHC) phenomenology, and show that the current and future data would probe the interesting parameter space for this model.

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In this talk we report our numerical work on the complete determination of the 10th-order contribution to the anomalous magnetic moment of leptons in the perturbation theory of quantum electrodynamics (QED). The large number of diagrams involved and the complexity of the renormalization procedure require the development of an automated code-generation algorithm for the numerical integrations. The systematic approach to these problems is described.

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In this talk I will describe various features of the time-dependent dynamics of strongly coupled plasma from the perspective of the AdS/CFT correspondence. I will concentrate on the properties of the hydrodynamic expansion, thermalization versus hydrodynamization and some features of nonequilibrium behaviour.

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In this talk I would like to explain our recent progress in understanding multiple M2-branes. In the former part, I will talk about the exact large N expansion of the ABJM partition function and its implication. In the latter part, I will explain how to study fractional membranes (branes) from Wilson loops (strings).

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The OPERA experiment is designed to perform the first observation of neutrino oscillations νμ→ντ through the direct detection of appearance of tau neutrinos. Thanks to the micrometric special resolution and three dimensional tracking by nuclear emulsion, Emulsion Cloud Chamber (ECC) detects decay topology of short lived tau particle emitted from ντ CC interactions. Combining with kinematical information measured in ECCs and muon ID by electronic detector provide the condition of low background events well below one after analysis of full statistics. The 1.25k ton of target, made by 150,000 ECC is exposed to the CERN Neutrinos to Gran Sasso beam with a 730 km distance and mean energy of 17 GeV pure νµ beam at the beam origin. So far, event sample of 5272 events have been done the detailed tau decay search around the neutrino interactions. 3 ντ events have been identified among them and the absence of a νμ→ντ oscillation signal is excluded with a significance of 3.4 σ.

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Nuclear emulsion detector is a 3D tracking detector with extreme high spatial resolution, and it continues growing in Nagoya University as a center of world. Recently, the device self-production and high-speed readout systems which are key technologies were upgraded in Nagoya University, and various projects are running using those just now. In this talk, I will introduce the recent activities and report the R&D project for directional dark matter search as a very unique activity.

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Recently so many dark matter direct search expriments have been conducted. Among them the detectors with noble liquids, especially LXe detectors, gave the best limit on the dark matter-nucleus cross section so far. In this talk I will review the principle of direct searches and noble liquid technologies. In particlar, I will explain the recent results of XMASS, the unique single phase LXe scintillator. I will also mention the future projects of noble liquid detectors.

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The dark matter is now widely accepted as a major ingredient of the Universe and considered to constitute 6 times as much as the ordinary matter. However, the nature the dark matter remains one of the biggest mysteries in the Universe. Since there is no plausible theory for the dark matter, we have variety of dark matter candidates, posing significant experimental challenges for detection and measurement of their properties. Among the dark matter candidates, Weakly Interacting Massive Particles (WIMPs) are the leading candidate since the scale of expected mass and cross section well matches the new physics expected in the weak scale such as supersymmetry and extra dimension. Gamma-ray observations aim at detecting gamma rays produced by WIMP annihilations or decays, and would provide direct constraints on the annihilation cross section which can be compared with the value expected from the thermal relic hypothesis. Current gamma-ray experiments exclude the WIMP mass mass below 30 GeV and Future observations will be sensitive up to a few TeV which covers large phase space expected from new physics.

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The X-ray sky is dominated by a diffuse extragalactic background radiation, which was resolved almost completely into discrete sources using the X-ray satellites ROSAT, Chandra and XMM-Newton - we observe the growth phase of the population of supermassive Black Holes throughout the history of the Universe. Indeed, the mass distribution of Black Holes in local galaxies is well traced by the evolution of the accreting Black Hole luminosity function. However, the maximum of high-luminosity objects occurs significantly earlier in the history of the universe (at redshifts 2-3), than that of low-luminosity objects, which have a peak at redshifts below unity. This anti-hierarchical evolution is similar to the down-sizing effect observed in the optical galaxy population and requires different feeding modes in the early and late Universe. Galaxy mergers are likely responsible for the early growth of black holes and bulges, while a different feeding mode - the re-juvenation of Black Holes in galaxies by the accretion of fresh gas from their environment - may be responsible for the late evolution of both the star formation and AGN activity. This is also confirmed by spatial correlation analyses, showing that AGN up to redshifts of z=2 live in relatively massive dark matter haloes, where the characteristic mass is not evolving with time. Recently the excitement has shifted to even higher redshifts where the objects are so faint that again only studies of their integrated emission - the background - can be performed. At this new X-ray background frontier, a correlation between the unresolved emission observed by Chandra with the residual near-infrared background observed by the Spitzer space telescope has revealed a significant signal which may well be emission of the first generation of Black Holes in the Universe. Prospects for future development in this field will be discussed.

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Large-scale structure in the Universe provides a key information of various fundamental issues in modern physics: dark energy, absolute mass of neutrinos, the origin of large-scale structure. Different galaxy imaging and spectroscopic surveys including Japan-led "SuMIRe" project using Subaru Telescope is ongoing or planned to unveil the evolution of the large-scale structure at a wide range of redshift. The largest source of systematic uncertainty in cosmological analysis using galaxy dataset is the challenge of modeling the complex relationship between galaxy redshift and the distribution of dark matter. I introduce a novel method to eliminate this systematics by combining different observables from galaxy spectroscopic and photometric data and also show how the measurement of cosmic growth rate is improved.

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We review different theories of modified gravity: F(R), F(G) and F(R) bigravity models. The possibility to unify early-time inflation with late-time acceleration in such theories is demonstrated. The description of neutron stars within F(R) gravity is given. Using perturbative approach it is shown that neutron stars from F(R) gravity maybe stable even for polytropic equations of state which seem to be totally non-realistic for standard GR.

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As a way of explaining the current cosmic accelerated expansion, there exists a way of modifying gravity at a long distance. In this presentation, among such gravity theories, we concentrate on an extended teleparallel gravity called ``$F(T)$ gravity'' with $T$ the torsion scalar in teleparallelism. In particular, we explore the four-dimensional effective $F(T)$ gravity coming from the higher-dimensional Kaluza-Klein (KK) and Randall-Sundrum (RS) theories. It is demonstrated that inflation and the dark energy dominated stage can be realized in the KK and RS models, respectively, due to the effect of only the torsion in teleparallelism without that of the curvature. Reference: Kazuharu Bamba, Shin'ichi Nojiri and Sergei D. Odintsov, Physics Letters B 725 (2013) 368-371 [arXiv:1304.6191 [gr-qc]].

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The Large Hadron Collider forward experiment was motivated to test the hadronic interaction models used to describe the cosmic-ray induced air showers. In this presentation, forward particle spectra measured in the LHC 0.9 and 7TeV p-p collisions and 5TeV p-Pb collisions are presented together with the future plan of the experiment.

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In 2013 KEK revised the roadmap of Japanese High Energy Physics (HEP) projects which had been developed in 2008. The new roadmap firms up three pillar research directions established in the original roadmap. They are the energy frontier physics, lepton flavor physics and quark flavor physics. Current status and plan for each recommended project are shown in this presentation.

Abstract:
After discovery of the Higgs boon, we have to face to a problem, where is physics beyond the standard model. I would like to review a strategy to serach for physics beyond the standard model on based on my personal view.