大木 洋 (オオキ ヒロシ)

Modular flavor symmetry on a magnetized torus
© 2020 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the "https://creativecommons.org/licenses/by/4.0/"Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP3. We study the modular invariance in magnetized torus models. The modular invariant flavor model is a recently proposed hypothesis for solving the flavor puzzle, where the flavor symmetry originates from modular invariance. In this framework, coupling constants such as Yukawa couplings are also transformed under the flavor symmetry. We show that the lowenergy effective theory of magnetized torus models is invariant under a specific subgroup of the modular group. Since Yukawa couplings as well as chiral zero modes transform under the modular group, the above modular subgroup (referred to as modular flavor symmetry) provides a new type of modular invariant flavor models with D4×Z2, (Z4×Z2)⋊Z2, and (Z8×Z2)⋊Z2. We also find that conventional discrete flavor symmetries which arise in magnetized torus model are noncommutative with the modular flavor symmetry. Combining both symmetries, we obtain a larger flavor symmetry, which is the semidirect product of the conventional flavor symmetry and the modular flavor symmetry for the nonvanishing Wilson line. For the vanishing Wilson line, we have additional Z2 symmetry, i.e., parity, which is the unique common element between the conventional flavor symmetry and the modular flavor symmetry., 2020年10月, Physical Review D, 102 (8), doi;scopus;scopus_citedby;rm:research_project_id研究論文（学術雑誌）
Gravitational waves from walking technicolor
© 2019, The Author(s). We study gravitational waves from the firstorder electroweak phase transition in the SU(Nc) gauge theory with Nf/Nc ≫ 1 (“large Nf QCD”) as a candidate for the walking technicolor, which is modeled by the U(Nf) × U(Nf) linear sigma model with classical scale symmetry (without mass term), particularly for Nf = 8 (“onefamily model”). This model exhibits spontaneous breaking of the scale symmetry as well as the U(Nf) × U(Nf) radiatively through the ColemanWeinberg mechanism à la GildenerWeinberg, thus giving rise to a light pseudo dilaton (technidilaton) to be identified with the 125 GeV Higgs. This model possess a strong firstorder electroweak phase transition due to the resultant ColemanWeinberg type potential. We estimate the bubble nucleation that exhibits an ultra supercooling and then the signal for a stochastic gravitational wave produced via the strong firstorder electroweak phase transition. We show that the amplitude can be reached to the expected sensitivities of the LISA., 2019年10月01日, Journal of High Energy Physics, 2019 (10), arxiv;doi;scopus;scopus_citedby;arxiv_url;arxiv_url研究論文（学術雑誌）
Novel Vus  Determination Using Inclusive Strange τ Decay and Lattice Hadronic Vacuum Polarization Functions
© 2018 authors. Published by the American Physical Society. We propose and apply a new approach to determining Vus using dispersion relations with weight functions having poles at Euclidean (spacelike) momentum which relate strange hadronic τ decay distributions to hadronic vacuum polarization (HVP) functions obtained from lattice quantum chromodynamics. We show examples where spectral integral contributions from the region where experimental data have large errors or do not exist are strongly suppressed but accurate determinations of the relevant lattice HVP combinations remain possible. The resulting Vus agrees well with determinations from K physics and threefamily CabibboKobayashiMaskawa unitarity. Advantages of this new approach over the conventional hadronic τ decay determination employing flavorbreaking sum rules are also discussed., 2018年11月16日, Physical Review Letters, 121 (20), arxiv;doi;pubmed;scopus;scopus_citedby;arxiv_url;arxiv_url研究論文（学術雑誌）
Nucleon charges with dynamical overlap fermions
© 2018 authors. Published by the American Physical Society. We calculate the scalar and tensor charges of the nucleon in 2+1flavor lattice QCD, for which the systematics of the renormalization of the disconnected diagram is well controlled. Numerical simulations are performed at a single lattice spacing a=0.11 fm. We simulate four pion masses, which cover a range of mπ∼290540 MeV, and a single strange quark mass close to its physical value. The statistical accuracy is improved by employing the socalled lowmode averaging technique and the truncated solver method. We study up, down, and strange quark contributions to the nucleon charges by calculating disconnected diagrams using the alltoall quark propagator. Chiral symmetry is exactly preserved by using the overlap quark action to avoid operator mixing among different flavors, which complicates the renormalization of scalar and tensor matrix elements and leads to possibly large contamination to the small strange quark contributions. We also study the nucleon axial charge with a contribution from the disconnected diagram. Our results are in reasonable agreement with experiments and previous lattice studies., 2018年09月25日, Physical Review D, 98 (5), arxiv;doi;scopus;scopus_citedby;arxiv_url;arxiv_url研究論文（学術雑誌）
 Vus  determination from inclusive strange tau decay and lattice HVP
We propose and apply a novel approach to determining Vus which uses inclusive strange hadronic tau decay data and hadronic vacuum polarization functions (HVPs) computed on the lattice. The experimental and lattice data are related through dispersion relations which employ a class of weight functions having poles at spacelike momentum. Implementing this approach using lattice data generated by the RBC/UKQCD collaboration, we show examples of weight functions which strongly suppress spectral integral contributions from the region where experimental data either have large uncertainties or do not exist while at the same time allowing accurate determinations of relevant lattice HVPs. Our result for Vus is in good agreement with determinations from K physics and 3family CKM unitarity. The advantages of the new approach over the conventional sum rule analysis will be discussed., 2018年03月26日, EPJ Web of Conferences, 175, doi研究論文（国際会議プロシーディングス）
Computing nucleon EDM on a lattice
2018年01月, EPJ, 175, 06027研究論文（国際会議プロシーディングス）
On Lattice Calculation of Electric Dipole Moments and Form Factors of the Nucleon
We analyze commonly used expressions for computing the nucleon electric dipole form factors (EDFF) $F_3$ and moments (EDM) on a lattice and find that they lead to spurious contributions from the Pauli form factor $F_2$ due to inadequate definition of these form factors when parity mixing of lattice nucleon fields is involved. Using chirally symmetric domain wall fermions, we calculate the proton and the neutron EDFF induced by the CPviolating quark chromoEDM interaction using the corrected expression. In addition, we calculate the electric dipole moment of the neutron using background electric field that respects time translation invariance and boundary conditions, and find that it decidedly agrees with the new formula but not the old formula for $F_3$. Finally, we analyze some selected lattice results for the nucleon EDM and observe that after the correction is applied, they either agree with zero or are substantially reduced in magnitude, thus reconciling their difference from phenomenological estimates of the nucleon EDM., 2017年01月26日, doi;arxiv;arxiv_url;arxiv_urlLight flavorsinglet scalars and walking signals in $N_f=8$ QCD on the lattice
Based on the highly improved staggered quark action, we perform lattice simulations of $N_f=8$ QCD and confirm our previous observation of a flavorsinglet scalar meson (denoted as $\sigma$) as light as the pion and various "walking signals" through lowlying spectra, with higher statistics, smaller fermion masses $m_f$, and larger volumes. We measure $M_\pi$, $F_\pi$, $M_\rho$, $M_{a_0}$, $M_{a_1}$, $M_{b_1}$, $M_N$, $M_\sigma$, $F_\sigma$, $\langle \bar{\psi} \psi\rangle$ (both directly and through the GMOR relation), and the string tension. The data are consistent with the spontaneously broken phase of the chiral symmetry, in agreement with the previous results: ratios of the quantities to $M_\pi$ monotonically increase in the smaller $m_f$ region towards the chiral limit similarly to $N_f=4$ QCD, in sharp contrast to $N_f=12$ QCD where the ratios become flattened. The hyperscaling relation holds with roughly a universal value of the anomalous dimension, $\gamma_m \simeq 1$, with a notable exception of $M_\pi$ with $\gamma_m \simeq 0.6$ as in the previous results. This is a salient feature ("walking signal") of $N_f=8$, unlike either $N_f=4$ which has no hyperscaling relation at all, or $N_f=12$ QCD which exhibits universal hyperscaling. We further confirm the previous observation of the light $\sigma$ with mass comparable to the pion in the studied $m_f$ region. In a chiral limit extrapolation of the $\sigma$ mass using the dilaton chiral perturbation theory and also using the simple linear fit, we find the value consistent with the 125 GeV Higgs boson within errors. Our results suggest that the theory could be a good candidate for walking technicolor model, having anomalous dimension $\gamma_m \simeq 1$ and a light flavorsinglet scalar meson as a technidilaton, which can be identified with the 125 GeV composite Higgs in $N_f=8$ onefamily model., 2016年10月22日, doi;arxiv;arxiv_url;arxiv_urlLattice Studies on 8Flavor QCD in The Light of Physics Beyond The Standard Model
We report the latest results of the LatKMI collaboration on 8flavor QCD using Monte Carlo simulations of the lattice gauge theory. The subject receives growing interest with regards to physics beyond the Standard Model (BSM). We show that a flavorsinglet scalar meson (sigma) emerges as one of the lightest bound states and can be a composite Higgs boson with mass 125 GeV. The light sigma may be a technidilaton, a pseudo NambuGoldstone boson of the approximate scale symmetry, which results from a slowly running (walking) coupling constant associated with an infrared fixed point. Consistently to this reasoning, a mass anomalous dimension gamma is found to be large gamma similar to 1. We discuss the applicability of 8flavor QCD to the BSM model building., 2016年01月, NUCLEAR AND PARTICLE PHYSICS PROCEEDINGS, 270, 242  246, web_of_science;doi研究論文（国際会議プロシーディングス）
Light composite scalar in eightflavor QCD on the lattice
We present the first observation of a flavorsinglet scalar meson as light as the pion in $N_f=8$ QCD on the lattice, using the Highly Improved Staggered Quark action. Such a light scalar meson can be regarded as a composite Higgs with mass 125 GeV. In accord with our previous lattice results showing that the theory exhibits walking behavior, the light scalar may be a technidilaton, a pseudo NambuGoldstone boson of the approximate scale symmetry in walking technicolor., 2014年03月19日, doi;arxiv;arxiv_url;arxiv_urlFlavor landscape of 10D SYM theory with magnetized extra dimensions
We study the flavor landscape of particle physics models based on a tendimensional super YangMills theory compactified on magnetized tori preserving fourdimensional ${\cal N}=1$ supersymmetry. Recently, we constructed a semirealistic model which contains the minimal supersymmetric standard model (MSSM) using an Ansatz of magnetic fluxes and orbifolding projections. However, we can consider more various configurations of magnetic fluxes and orbifolding projections preserving fourdimensional ${\cal N}=1$ supersymmetry. We research systematically such possibilities for leading to MSSMlike models and study their phenomenological aspects., 2013年07月07日, doi;arxiv;arxiv_url;arxiv_urlLight composite scalar in twelveflavor QCD on the lattice
Based on lattice simulations using highly improved staggered quarks for twelveflavor QCD with several bare fermion masses, we observe a flavorsinglet scalar state lighter than the pion in the correlators of fermionic interpolating operators. The same state is also investigated using correlators of gluonic interpolating operators. Combined with our previous study, that showed twelveflavor QCD to be consistent with being in the conformal window, we infer that the lightness of the scalar state is due to infrared conformality. This result shed some light on the possibility of a light composite Higgs boson ("technidilaton") in walking technicolor theories., 2013年05月26日, doi;arxiv;arxiv_url;arxiv_urlWalking signals in Nf=8 QCD on the lattice
We investigate chiral and conformal properties of the lattice QCD with eight flavors (Nf=8) through meson spectrum using the Highly Improved Staggered Quark (HISQ) action. We also compare our results with those of Nf=12 and Nf=4 which we study on the same systematics. We find that the decay constant F_pi of the pseudoscalar meson "pion" is nonzero, with its mass M_pi consistent with zero, both in the chiral limit extrapolation of the chiral perturbation theory (ChPT). We also measure other quantities which we find are in accord with the pi data results: The rho meson mass is consistent with nonzero in the chiral limit, and so is the chiral condensate, with its value neatly coinciding with that from the GellMannOakesRenner relation in the chiral limit. Thus our data for the Nf=8 QCD are consistent with the spontaneously broken chiral symmetry. Remarkably enough, while the Nf=8 data near the chiral limit are well described by the ChPT, those for the relatively large fermion bare mass m_f away from the chiral limit actually exhibit a finitesize hyperscaling relation, suggesting a large anomalous dimension gamma_m ~ 1. This implies that there exists a remnant of the infrared conformality, and suggests that a typical technicolor ("onefamily model") as modeled by the Nf=8 QCD can be a walking technicolor theory having an approximate scale invariance with large anomalous dimension gamma_m ~ 1., 2013年02月27日, doi;arxiv;arxiv_url;arxiv_urlKMI Lattice Projecct on 8Flavor QCD  Explortation of the Walking Technicolor
We present the report of the LatKMI collaboration on the lattice QCD simulation performed at the KMI computer, "phi", for the cases of 8 flavors, which is expected to be a candidate for the walking technicolor having an approximate scale invariance near the infrared fixed point. The simulation was carried out based on the highly improved staggered quark (HISQ) action. In this proceedings, we report preliminary results on the spectrum, analyzed through the chiral perturbation theory and the finitesize hyperscaling. We observe qualitatively different behavior of the 8flavor case in contrast to the 4flavor case which shows clear indication of the hadronic phase as in the usual QCD., 2013年, QUEST FOR THE ORIGIN OF PARTICLES IN THE UNIVERSE, 267  270, web_of_science研究論文（国際会議プロシーディングス）
KMI Lattice Project on 16Flavor QCD
It is well known that the SU(3) gauge theory with the fundamental 16flavor fermion is governed by a nontrivial infrared fixed point in the 2loop perturbation theory, while the theory has not been well investigated by nonperturbative lattice simulations. We investigate properties of 16flavor QCD by lattice simulation with highly improved action setup (HISQ/tree) at two lattice spacings. We present preliminary results for the mass of the lightest pseudoscalar meson at nonzero fermion mass. We discuss the (finitesize) hyperscaling of our data, the mass anomalous dimension extracted from the scaling, and comparison of the anomalous dimension with the perturbation theory., 2013年, QUEST FOR THE ORIGIN OF PARTICLES IN THE UNIVERSE, 275  278, web_of_science研究論文（国際会議プロシーディングス）
Analysis of the SchwingerDyson Equation in a box for the Study of Hyperscalling Relations
We study corrections to the finitesize hyperscaling relation in the conformal window of the large Nf QCD by using the ladder SchwingerDyson (SD) equation formulated in a finite spacetime with the periodic boundary condition. We find that the anomalous dimension, when identified through the hyperscaling relation neglecting the correction caused by the nonzero fermion mass, yields a value substantially lower than the one at the fixed point for large mass region., 2013年, QUEST FOR THE ORIGIN OF PARTICLES IN THE UNIVERSE, 279  282, web_of_science研究論文（国際会議プロシーディングス）
The KMI Lattice Project  Exploring for Technicolor from QCD
Investigation of the SU(3) gauge theory with many fermions for the quest for the walking technicolor theory as a KMI project is described. The theory, if it is successfully constructed, can supersede the standard model Higgs sector, and thus can be a candidate of the theory of new physics. We utilize the KMI highperformance computing system phi perform the numerical simulation adopting a stateoftheart lattice fermion formulation. A hint of the number of fermions for the candidate of the walking technicolor theory is emerging., 2013年, QUEST FOR THE ORIGIN OF PARTICLES IN THE UNIVERSE, 179  186, web_of_science研究論文（国際会議プロシーディングス）
Phenomenological aspects of 10D SYM theory with magnetized extra dimensions
We present a particle physics model based on a tendimensional (10D) super YangMills (SYM) theory compactified on magnetized tori preserving fourdimensional ${\cal N}=1$ supersymmetry. The lowenergy spectrum contains the minimal supersymmetric standard model with hierarchical Yukawa couplings caused by a wavefunction localization of the chiral matter fields due to the existence of magnetic fluxes, allowing a semirealistic pattern of the quark and the lepton masses and mixings. We show supersymmetric flavor structures at low energies induced by a modulimediated and an anomalymediated supersymmetry breaking., 2012年11月19日, doi;arxiv;arxiv_url;arxiv_urlNucleon strange quark content from N_f=2+1 lattice QCD with exact chiral symmetry
We calculate the strange quark content of the nucleon in 2+1flavor lattice QCD. Chirally symmetric overlap fermion formulation is used to avoid the contamination from up and down quark contents due to an operator mixing between strange and light scalar operators, \bar{s}s and \bar{u}u+\bar{d}d. At a lattice spacing a=0.112(1) fm, we perform calculations at four values of degenerate up and down quark masses, which cover a range of the pion mass M_pi \simeq 300540 MeV. We employ two different methods: one is a direct method where we calculate the strange quark content by directly inserting the strange scalar operator. The other is an indirect method where the quark content is extracted from a derivative of the nucleon mass in terms of the strange quark mass. With these two methods we obtain consistent results with each other. Our best estimate f_{T_s}=0.009(15)(16) is in good agreement with our previous studies in twoflavor QCD., 2012年08月21日, arxiv;arxiv_url;arxiv_urlLattice study of conformality in twelveflavor QCD
We study infrared conformality of the twelveflavor QCD on the lattice. Utilizing the highly improved staggered quarks (HISQ) type action which is useful to study the continuum physics, we analyze the lattice data of the mass and the decay constant of a pseudoscalar meson and the mass of a vector meson as well at several values of lattice spacing and fermion mass. Our result is consistent with the conformal hypothesis for the mass anomalous dimension $\gamma_m \sim 0.40.5$., 2012年07月12日, doi;arxiv;arxiv_url;arxiv_urlLattice study of infrared behaviour in SU(3) gauge theory with twelve massless flavours
We present details of a lattice study of infrared behaviour in SU(3) gauge theory with twelve massless fermions in the fundamental representation. Using the stepscaling method, we compute the coupling constant in this theory over a large range of scale. The renormalisation scheme in this work is defined by the ratio of Polyakov loops in the directions with different boundary conditions. We closely examine systematic effects, and find that they are dominated by errors arising from the continuum extrapolation. Our investigation suggests that SU(3) gauge theory with twelve flavours contains an infrared fixed point., 2012年05月28日, doi;arxiv;arxiv_url;arxiv_urlSuperfield description of 10D SYM theory with magnetized extra dimensions
We present a fourdimensional (4D) ${\cal N}=1$ superfield description of supersymmetric YangMills (SYM) theory in tendimensional (10D) spacetime with certain magnetic fluxes in compactified extra dimensions preserving partial ${\cal N}=1$ supersymmetry out of full ${\cal N}=4$. We derive a 4D effective action in ${\cal N}=1$ superspace directly from the 10D superfield action via dimensional reduction, and identify its dependence on dilaton and geometric moduli superfields. A concrete model for three generations of quark and lepton superfields are also shown. Our formulation would be useful for building various phenomenological models based on magnetized SYM theories or Dbranes., 2012年04月24日, doi;arxiv;arxiv_url;arxiv_urlStudy of the conformal hyperscaling relation through the SchwingerDyson equation
We study corrections to the conformal hyperscaling relation in the conformal window of the large Nf QCD by using the ladder SchwingerDyson (SD) equation as a concrete dynamical model. From the analytical expression of the solution of the ladder SD equation, we identify the form of the leading mass correction to the hyperscaling relation. We find that the anomalous dimension, when identified through the hyperscaling relation neglecting these corrections, yields a value substantially lower than the one at the fixed point \gamma_m^* for large mass region. We further study finitevolume effects on the hyperscaling relation, based on the ladder SD equation in a finite spacetime with the periodic boundary condition. We find that the finitevolume corrections on the hyperscaling relation are negligible compared with the mass correction. The anomalous dimension, when identified through the finitesize hyperscaling relation neglecting the mass corrections as is often done in the lattice analyses, yields almost the same value as that in the case of the infinite spacetime neglecting the mass correction, i.e., a substantially lower value than \gamma_m^* for large mass. We also apply the finitevolume SD equation to the chiralsymmetrybreaking phase and find that when the theory is close to the critical point such that the dynamically generated mass is much smaller than the explicit breaking mass, the finitesize hyperscaling relation is still operative. We also suggest a concrete form of the modification of the finitesize hyperscaling relation by including the mass correction, which may be useful to analyze the lattice data., 2012年01月19日, doi;arxiv;arxiv_url;arxiv_urlSpontaneous Parity Violation in SUSY Strong Gauge Theory
We suggest simple models of spontaneous parity violation in supersymmetric strong gauge theory. We focus on leftright symmetric model and investigate vacuum with spontaneous parity violation. Nonperturbative effects are calculable in supersymmetric gauge theory, and we suggest two new models. The first model shows confinement, and the second model has a dual description of the theory. The leftright symmetry breaking and electroweak symmetry breaking are simultaneously occurred with the suitable energy scale hierarchy. The second model also induces spontaneous supersymmetry breaking., 2011年04月28日, doi;arxiv;arxiv_url;arxiv_urlNonAbelian Discrete Flavor Symmetries on Orbifolds
We study nonAbelian flavor symmetries on orbifolds, $S^1/Z_2$ and $T^2/Z_3$. Our extra dimensional models realize $D_N$, $\Sigma(2N^2)$, $\Delta(3N^2)$ and $\Delta(6N^2)$ including $A_4$ and $S_4$. In addition, one can also realize their subgroups such as $Q_N$, $T_7$, etc. The $S_3$ flavor symmetry can be realized on both $S^1/Z_2$ and $T^2/Z_3$ orbifolds., 2010年09月27日, doi;arxiv;arxiv_url;arxiv_urlGeometric entropy and third order phase transition in d=4 N=2 SYM with flavor
We analyze the phase structure of $d=4$ $\mathcal{N}=2$ large $N$ SYM theory with flavor on $S^1\times S^3$ by using geometric entropy as an order parameter. We introduce chemical potential conjugate to global U(1) symmetry and find the third order phase transition at finite density by using the geometric entropy as the order parameter. We also find that the geometric entropy at the finite density has an interesting behavior at low temperature and for large $N_f$., 2010年06月02日, doi;arxiv;arxiv_url;arxiv_urlThreegeneration Models from E_8 Magnetized Extra Dimensional Theory
We study 10D super YangMills E8 theory on the 6D torus compactification with magnetic fluxes. We study systematically the possibilities for realizing 4D supersymmetric standard models with three generations of quarks and leptons. We also study quark mass matrices., 2010年02月15日, doi;arxiv;arxiv_url;arxiv_urlFlavor structure from magnetic fluxes and nonAbelian Wilson lines
We study the flavor structure of 4D effective theories, which are derived from extra dimensional theories with magnetic fluxes and nonAbelian Wilson lines. We study zeromode wavefunctions and compute Yukawa couplings as well as fourpoint couplings. In our models, we also discuss nonAbelian discrete flavor symmetries such as $D_4$, $\Delta(27)$ and $\Delta(54)$., 2010年01月12日, doi;arxiv;arxiv_url;arxiv_urlE6,7,8 Magnetized Extra Dimensional Models
We study 10D super YangMills theory with the gauge groups $E_6$, $E_7$ and $E_8$. We consider the torus/orbifold compacfitication with magnetic fluxes and Wilson lines. They lead to 4D interesting models with three families of quarks and leptons, whose profiles in extra dimensions are quasilocalized because of magnetic fluxes., 2009年08月04日, doi;arxiv;arxiv_url;arxiv_urlMagnetic flux, Wilson line and orbifold
We study torus/orbifold models with magnetic flux and Wilson line background. The number of zeromodes and their profiles depend on those backgrounds. That has interesting implications from the viewpoint of particle phenomenology., 2009年07月30日, doi;arxiv;arxiv_url;arxiv_urlNonAbelian Discrete Flavor Symmetries from Magnetized/Intersecting Brane Models
We study nonabelian discrete flavor symmetries, which can appear in magnetized brane models. For example, $D_4$, $\Delta(27)$ and $\Delta(54)$ can appear and matter fields with several representations can appear. We also study the orbifold background, where nonabelian flavor symmetries are broken in a certain way., 2009年04月17日, doi;arxiv;arxiv_url;arxiv_urlHigher Order Couplings in Magnetized Brane Models
We compute threepoint and higher order couplings in magnetized brane models. We show that higher order couplings are written as products of threepoint couplings. This behavior is the same as higher order amplitudes by conformal field theory calculations e.g. in intersecting Dbrane models., 2009年03月23日, doi;arxiv;arxiv_url;arxiv_urlA new scheme for the running coupling constant in gauge theories using Wilson loops
We propose a new renormalization scheme of the running coupling constant in general gauge theories using the Wilson loops. The renormalized coupling constant is obtained from the Creutz ratio in lattice simulations and the corresponding perturbative coefficient at the leading order. The latter can be calculated by adopting the zetafunction resummation techniques. We perform a benchmark test of our scheme in quenched QCD with the plaquette gauge action. The running of the coupling constant is determined by applying the stepscaling procedure. Using several methods to improve the statistical accuracy, we show that the running coupling constant can be determined in a wide range of energy scales with relatively small number of gauge configurations., 2009年02月22日, doi;arxiv;arxiv_url;arxiv_urlThree generation magnetized orbifold models
We study three generation models in the fourdimensional spacetime, which can be derived from the tendimensional N=1 super YangMills theory on the orbifold background with a nonvanishing magnetic flux. We classify the flavor structures and show possible patterns of Yukawa matrices. Some examples of numerical studies are also shown., 2008年12月18日, doi;arxiv;arxiv_url;arxiv_urlNucleon sigma term and strange quark content from lattice QCD with exact chiral symmetry
We calculate the nucleon sigma term in twoflavor lattice QCD utilizing the FeynmanHellman theorem. Both sea and valence quarks are described by the overlap fermion formulation, which preserves exact chiral and flavor symmetries on the lattice. We analyse the lattice data for the nucleon mass using the analytical formulae derived from the baryon chiral perturbation theory. From the data at valence quark mass set different from sea quark mass, we may extract the sea quark contribution to the sigma term, which corresponds to the strange quark content. We find that the strange quark content is much smaller than the previous lattice calculations and phenomenological estimates., 2008年06月29日, doi;arxiv;arxiv_url;arxiv_urlMagnetized orbifold models
We study (4+2n)dimensional N=1 super YangMills theory on the orbifold background with nonvanishing magnetic flux. In particular, we study zeromodes of spinor fields. The flavor structure of our models is different from one in magnetized torus models, and would be interesting in realistic model building., 2008年06月29日, doi;arxiv;arxiv_url;arxiv_urlSoft supersymmetry breaking terms from D4 x Z2 lepton flavor symmetry
We study the supersymmetric model with $D_4 \times Z_2$ lepton flavor symmetry. We evaluate soft supersymmetry breaking terms, i.e. soft slepton masses and Aterms, which are predicted in the $D_4$ flavor model. We consider constraints due to experiments of flavor changing neutral current processes., 2008年03月06日, doi;arxiv;arxiv_url;arxiv_urlD4 Flavor Symmetry for Neutrino Masses and Mixing
We present the $D_4\times Z_2$ flavor symmetry, which is different from the previous work by Grimus and Lavoura. Our model reduces to the standard model in the low energy and there is no FCNC at the tree level. Putting the experimental data, parameters are fixed, and then the implication of our model is discussed. The condition to realize the tribimaximal mixing is presented. The possibility for stringy realization of our model is also discussed., 2008年02月16日, doi;arxiv;arxiv_url;arxiv_urlDetermination of B*B pi coupling in unquenched QCD
The $B^* B\pi$ coupling is a fundamental parameter of chiral effective Lagrangian with heavylight mesons and can constrain the chiral behavior of $f_B$, $B_B$ and the $B\to \pi l \nu$ form factor in the soft pion limit. We compute the $B^* B \pi $ coupling with the static heavy quark and the $O(a)$improved Wilson light quark. Simulations are carried out with $n_f=2$ unquenched $12^3\times 24$ lattices at $\beta=1.80$ and $16^3\times 32$ lattices at $\beta=1.95$ generated by CPPACS collaboration. To improve the statistical accuracy, we employ the alltoall propagator technique and the static quark action with smeared temporal link variables following the quenched study by Negishi {\it et al.}. These methods successfully work also on unquenched lattices, and determine the $B^*B\pi$ coupling with 12% statistical accuracy on each lattice spacing., 2008年02月12日, doi;arxiv;arxiv_url;arxiv_urlNucleon sigma term from lattice QCD
There has been renewed interest in the nucleon sigma term since it determines the neutralino dark matter reaction rate with nucleon through the tchannel Higgs boson exchange. Despite its importance and its long history of theoretical studies, there are still substantial uncertainties. We present our recent studies of the nucleon sigma term based on the JLQCD project of Nf = 2 unquenched lattice QCD simulation with dynamical overlap fermion., 2008年, GRAND UNIFIED THEORIES: CURRENT STATUS AND FUTURE PROSPECTS, 1015, 52  66, web_of_science研究論文（国際会議プロシーディングス）
Discrete Rsymmetry anomalies in heterotic orbifold models
Anomalies of discrete Rsymmetries appearing in heterotic orbifold models are studied. We find that the mixed anomalies for different gauge groups satisfy the universal GreenSchwarz (GS) condition, indicating that these anomalies are canceled by the GS mechanism. An exact relation between the anomaly coefficients of the discrete Rsymmetries and oneloop betafunction coefficients is obtained. We also find that the discrete Rsymmetries have a good chance to be unbroken down to the supersymmetry breaking scale. Even below this scale a $Z_2$ subgroup is unbroken, which may be an origin of the Rparity of the minimal supersymmetric standard model. Relations between the Rsymmetry anomalies and Tduality anomalies are also investigated., 2007年05月22日, doi;arxiv;arxiv_url;arxiv_urlNonFactorisable Z2 times Z2 Heterotic Orbifold Models and Yukawa Couplings
We classify compactification lattices for supersymmetric Z2 times Z2 orbifolds. These lattices include factorisable as well as nonfactorisable sixtori. Different models lead to different numbers of fixed points/tori. A lower bound on the number of fixed tori per twisted sector is given by four, whereas an upper bound consists of 16 fixed tori per twisted sector. Thus, these models have a variety of generation numbers. For example, in the standard embedding, the smallest number of net generations among these classes of models is equal to six, while the largest number is 48. Conditions for allowed Wilson lines and Yukawa couplings are derived., 2006年12月06日, doi;arxiv;arxiv_url;arxiv_urlComputing Nucleon Electric Dipole Moment from lattice QCD
Sissa Medialab, 2020年04月22日, Proceedings of 37th International Symposium on Lattice Field Theory — PoS(LATTICE2019), 363 (290), 0  14, 国際誌, doi;arxiv;arxiv_url;arxiv_url;rm:research_project_id;rm:research_project_id記事・総説・解説・論説等（国際会議プロシーディングズ）
Calculation of Nucleon Electric Dipole Moments Induced by Quark ChromoElectric Dipole Moments and the QCD $θ$term
Electric dipole moments (EDMs) of nucleons and nuclei, which are sought as evidence of CP violation, require lattice calculations to connect constraints from experiments to limits on the strong CP violation within QCD or CP violation introduced by new physics from beyond the standard model. Nucleon EDM calculations on a lattice are notoriously hard due to large statistical noise, chiral symmetry violating effects, and potential mixing of the EDM and the anomalous magnetic moment of the nucleon. In this report, details of ongoing lattice calculations of proton and neutron EDMs induced by the QCD $\theta$term and the quark chromoEDM, the lowestdimension effective CPviolating quarkgluon interaction are presented. Our calculation employs chiralsymmetric fermion discretization. An assessment of feasibility of nucleon EDM calculations at the physical point is discussed., 2019年01月16日, arxiv;arxiv_url;arxiv_urlProgress in the Nucleon Electric Dipole Moment Calculations in Lattice QCD
Electric dipole moments (EDMs), which are sought as evidence of CP violation, require lattice calculations to connect constraints from experiments to limits on the strong CP violation within QCD or CP violation in new physics beyond the standard model. Nucleon EDM calculations on a lattice are notoriously hard due to large statistical noise, chiral symmetry violating effects, and potential mixing of the EDM and the anomalous magnetic moment of the nucleon. In this report, details of ongoing lattice calculations of proton and neutron EDMs induced by the QCD $\theta$term and the quark chromoEDM, the lowestdimension effective CPviolating quarkgluon interaction are presented. Our calculation employs chiralsymmetric fermion discretization. An assessment of feasibility of nucleon EDM calculations at the physical point is discussed., 2018年10月08日, arxiv;arxiv_url;arxiv_urlFlavorsinglet spectrum in multiflavor QCD
Studying SU(3) gauge theories with increasing number of light fermions is relevant both for understanding the strong dynamics of QCD and for constructing strongly interacting extensions of the Standard Model (e.g. UV completions of composite Higgs models). In order to contrast these manyflavors strongly interacting theories with QCD, we study the flavorsinglet spectrum as an interesting probe. In fact, some composite Higgs models require the Higgs boson to be the lightest flavorsinglet scalar in the spectrum of a strongly interacting new sector with a well defined hierarchy with the rest of the states. Moreover, introducing many light flavors at fixed number of colors can influence the dynamics of the lightest flavorsinglet pseudoscalar. We present the ongoing study of these flavorsinglet channels using multiple interpolating operators on highstatistics ensembles generated by the LatKMI collaboration and we compare results with available data obtained by the Lattice Strong Dynamics collaboration. For the theory with 8 flavors, the two collaborations have generated configurations that complement each others with the aim to tackle the massless limit using the largest possible volumes., 2017年10月18日, doi;arxiv;arxiv_url;arxiv_urlCalculation of Nucleon Electric Dipole Moments Induced by Quark ChromoElectric Dipole Moments
We present initial results of computing nucleon electric dipole moment induced by quark chromoEDM, CPviolating quarkgluon coupling. Using chirallysymmetric domain wall and M\"obius fermions with pion mass $m_\pi=172\text{ MeV}$, we calculate the connected part of the electric dipole form factor $F_3(Q^2)$. In addition, we perform an exploratory study of the method to calculate EDM using uniform background electric field on a lattice introduced without breaking the periodicity in the time direction., 2017年01月31日, arxiv;arxiv_url;arxiv_urlDeterminations of Vus using inclusive hadronic tau decay data
Two methods for determining Vus employing inclusive hadronic tau decay data are discussed. The first is the conventional flavorbreaking sum rule determination whose usual implementation produces results similar to 3 sigma low compared to threefamily unitary expectations. The second is a novel approach combining experimental strange hadronic tau distributions with lattice lightstrange currentcurrent twopoint function data. Preliminary explorations of the latter show the method promises Vus determinations competitive with those from Kl3 and Gamma[Kmu 2]/Gamma[(mu 2)]. For the former, systematic issues in the conventional implementation are investigated. Unphysical dependences of Vus on the choice of sum rule weight, w, and upper limit, s(0), of the weighted experimental spectral integrals are observed, the source of these problems identified and a new implementation which overcomes these problems developed. Lattice results are shown to provide a tool for quantitatively assessing truncation uncertainties for the slowly converging D = 2 OPE series. The results for Vus from this new implementation are shown to be free of unphysical w and s(0)dependences, and similar to 0.0020 higher than those produced by the conventional implementation. With preliminary new K pi branching fraction results as input, we find Vus in excellent agreement with that obtained from Kl3, and compatible within errors with expectations from threefamily unitarity., WORLD SCIENTIFIC PUBL CO PTE LTD, 2016年09月, MODERN PHYSICS LETTERS A, 31 (29), doi;web_of_science書評論文,書評,文献紹介等
Dark Side of the Standard Model: Dormant New Physics Awaken
We find that the nonperturbative physics of the standardmodel Higgs Lagrangian provides a dark matter candidate, "dormant skyrmion in the standard model", the same type of the skyrmion, a soliton, as in the hadron physics. It is stabilized by another nonperturbative object in the standard model, the dynamical gauge boson of the hidden local symmetry, which is also an analogue of the rho meson., 2016年08月12日, arxiv;arxiv_url;arxiv_urlSparameter and vector decay constant in QCD with eight fundamental fermions
SU(3) gauge theory with eight massless fundamental fermions seems to be near the conformal boundary, and is a candidate theory of walking technicolor. Along the series of study by LatKMI collaboration using HISQ fermions, Sparameter and vector decay constant, which provide important constraints in the model of electroweak symmetry breaking, are calculated for this theory. Use of various volumes allows a systematic investigation of finite volume effects. A strong sensitivity of the Sparameter to the volume is found., 2016年02月02日, arxiv;arxiv_url;arxiv_urlTopological observables in manyflavour QCD
SU(3) gauge theory with eight massless flavours is believed to be walking, while the corresponding twelve and fourflavour appear IRconformal and confining respectively. Looking at the simulations performed by the LatKMI collaboration of these theories, we use the topological susceptibility as an additional probe of the IR dynamics. By drawing a comparison with SU(3) pure gauge theory, we see a dynamical quenching effect emerge at larger number of flavours, which is suggestive of emerging nearconformal and conformal behaviour., 2016年01月18日, arxiv;arxiv_url;arxiv_urlWalking and conformal dynamics in manyflavor QCD
In the search for a realistic walking technicolor model, QCD with many flavors is an attractive candidate. From the series of studies by the LatKMI collaboration, we present updated results of the scaling properties of various hadron spectra, including the (pseudo)scalar, vector, and baryon channels, for $N_f=8$ QCD analyzed with the HISQ action. By comparing these with $N_f=12$ QCD, which has properties consistent with conformality, possible signals of walking dynamics are discussed. We also present a preliminary result of the flavorsinglet pseudoscalar mass in manyflavor QCD., 2016年01月11日, arxiv;arxiv_url;arxiv_urlSU(3) gauge theory with four degenerate fundamental fermions on the lattice
As a part of the project studying large $N_f$ QCD, the LatKMI Collaboration has been investigating the SU(3) gauge theory with four fundamental fermions (fourflavor QCD). The main purpose of studying fourflavor QCD is to provide a qualitative comparison to $N_f= 8$, $12$, $16$ QCD; however, a quantitative comparison to realworld QCD is also interesting. To make such comparisons more meaningful, it is desirable to use the same kind of lattice action consistently, so that qualitative difference of different theories are less affected by artifacts of lattice discretization. Here, we adopt the highlyimproved staggered quark action with the treelevel Symanzik gauge action (HISQ/tree), which is exactly the same as the setup for our simulations for $SU(3)$ gauge theories with $N_f=8$, $12$ and $16$ fundamental fermions~\cite{Aoki:2013xza, Aoki:2012eq, Aoki:2014oma}. In the next section, we show the fermion mass dependence of $F_\pi$, $\langle\bar{\psi}\psi\rangle$, $M_\pi$, $M_\rho$, $M_N$ and their chiral extrapolations. In section 3, preliminary results of the measurement of the mass of the flavorsinglet scalar bound state will be reported., 2015年12月03日, arxiv;arxiv_url;arxiv_urlNucleon axial and tensor charges with dynamical overlap quarks
We report on our calculation of the nucleon axial and tensor charges in 2+1flavor QCD with dynamical overlap quarks. Gauge ensembles are generated at a single lattice spacing 0.12 fm and at a strange quark mass close to its physical value. We employ the allmodeaveraging technique to calculate the relevant nucleon correlation functions, and the disconnected quark loop is efficiently calculated by using the alltoall quark propagator. We present our preliminary results for the isoscalar and isovector charges obtained at pion masses $m_\pi$ = 450 and 540 MeV., 2015年11月14日, arxiv;arxiv_url;arxiv_urlLattice study for conformal windows of SU(2) and SU(3) gauge theories with fundamental fermions
We present our investigation of SU(2) gauge theory with 8 flavours, and SU(3) gauge theory with 12 flavours. For the SU(2) case, at strong bare coupling, $\beta \lesssim 1.45$, the distribution of the lowest eigenvalue of the Dirac operator can be described by chiral random matrix theory for the Gaussian symplectic ensemble. Our preliminary result indicates that the chiral phase transition in this theory is of bulk nature. For the SU(3) theory, we use highprecision lattice data to perform the stepscaling study of the coupling, $g_{ { \rm GF } }$, in the Gradient Flow scheme. We carefully examine the reliability of the continuum extrapolation in the analysis, and conclude that the scaling behaviour of this SU(3) theory is not governed by possible infrared conformality at $g_{ { \rm GF } }^{2} \lesssim 6$., 2015年11月06日, arxiv;arxiv_url;arxiv_urlLattice study of the scalar and baryon spectra in manyflavor QCD
In the search for a composite Higgs boson in walking technicolor models, many flavor QCD, in particular with $N_f=8$, is an attractive candidate, and has been found to have a composite flavorsinglet scalar as light as the pion. Based on lattice simulations of this theory with the HISQ action, we will present our preliminary results on the scalar decay constant using the fermionic bilinear operator, and on the mass of the lightest baryon state which could be a dark matter candidate. Combining these two results, implications for dark matter direct detection are also discussed., 2015年10月26日, arxiv;arxiv_url;arxiv_urlTopological insights in manyflavor QCD on the lattice
LatKMI Collaboration discusses the topological insights in manyflavor QCD on the lattice. We explore walking/conformal/confining phase in $N_\mathrm{f}$ = 4, 8 and 12 (in particular $N_\mathrm{f}$ = 8) lattice QCD via the topological charge and susceptibility, eigenvalues and anomalous dimension., 2015年10月20日, arxiv;arxiv_url;arxiv_urlConformality in twelveflavour QCD
The spectrum of twelveflavor QCD has been studied in details by the LatKMI collaboration. In this proceeding we present our updated results for the spectrum obtained with the HISQ action at two lattice spacings, several volumes and fermion masses. In particular, we emphasize the existence of a flavorsinglet scalar state parametrically light with respect to the rest of the spectrum, first reported in our paper. This feature is expected to be present for theories in the conformal window, but the lattice calculation of such a state is difficult and requires noisereduction techniques together with large statistics, in order to evaluate disconnected diagrams. Being able to provide a robust observed connection between a light flavorsinglet scalar and (near)conformality is an important step towards observing a light composite Higgs boson in walking technicolor theories on the lattice. We also show updated results for the mass anomalous dimension $\gamma_m$ obtained from various spectral quantities, including the string tension, under the assumption that the theory is inside the conformal window., 2015年01月27日, arxiv;arxiv_url;arxiv_urlPhase Structure Study of SU(2) Lattice Gauge Theory with 8 Flavors
We present the investigation of the strong barecoupling regime of SU(2) lattice gauge theory with 8 fermion flavors in the fundamental representation. The simulations are performed with unimproved staggered fermions and the plaquette gauge action. One bulk phase transition is observed through the measurement of the plaquette. The results of coldstart and hotstart simulations, as well as the hysteresis study, indicate the order of this transition can be weakly first order. Using the smeared Polyakov loops, and a method inspired by the constraint effective potential, we study the vacuum structure near the confiningdeconfining phase transition. The Dirac operator eigenvalue spectrum is investigated, where further analysis is needed to clarify the properties of the chiral phase structure., 2014年10月31日, arxiv;arxiv_url;arxiv_urlSU(3) gauge theory with 12 flavours in a twisted box
We present preliminary result for the stepscaling study of the coupling constant with the YangMills gradient flow, in the twelvefavour SU(3) gauge theory. In this work, the lattice simulation is performed using unimproved staggered fermions and the Wilson plaquette gauge action, from which the gradient flow is also implemented. Imposing twisted boundary condition a'la t'Hooft and Parisi, our calculation is performed at zero fermion mass. The renormalised coupling constant is extracted via the computation of the energy density. In order to examine the reliability of the continuum extrapolation, we investigate this coupling constant using two different lattice discretisations. Our result shows that in order to control the systematic effects in the continuum extrapolation, it is necessary to implement a large enough gradientflow time. In the current calculation, the gaugefield averaging radius corresponding to the flow time has to be as large as 40% of the lattice size., 2014年10月31日, arxiv;arxiv_url;arxiv_urlNonAbelian discrete flavor symmetries of 10D SYM theory with magnetized extra dimensions
We study discrete flavor symmetries of the models based on a tendimensional supersymmetric YangMills (10D SYM) theory compactified on magnetized tori. We assume nonvanishing nonfactorizable fluxes as well as the orbifold projections. These setups allow modelbuilding with more various flavor structures. Indeed, we show that there exist various classes of nonAbelian discrete flavor symmetries. In particular, we find that S3 flavor symmetries can be realized in the framework of the magnetized 10D SYM theory for the first time., SPRINGER, 2014年06月, JOURNAL OF HIGH ENERGY PHYSICS, (6), arxiv;doi;web_of_science;url機関テクニカルレポート，技術報告書，プレプリント等
Composite flavorsinglet scalar in twelveflavor QCD
We report the calculation of the flavorsinglet scalar in the SU(3) gauge theory with the degenerate twelve fermions in the fundamental representation using a HISQtype action at a fixed $\beta$. In order to reduce the large statistical error coming from the vacuumsubtracted disconnected correlator, we employ a noise reduction method and a large number of configurations. We observe that the flavorsinglet scalar is lighter than the pion in this theory from the calculations with the fermion bilinear and gluonic operators. This peculiar feature is considered to be due to the infrared conformality of this theory, and it is a promissing signal for a walking technicolor, where a light composite Higgs boson is expected to emerge by approximate conformal dynamics., 2013年11月27日, arxiv;arxiv_url;arxiv_urlGluonic observables and the scalar spectrum of twelveflavour QCD
We measure glueball masses and the string tension in twelveflavour QCD, aiming at comparing the emerging gluonic spectrum to the mesonic one. When approaching the critical surface at zero quark mass, the hierarchy of masses in the different sectors of the spectrum gives a new handle to determine the existence of an infrared fixed point. We describe the details of our gluonic measurements and the results obtained on a large number of gauge configurations generated with the HISQ action. In particular, we focus on the scalar glueball and its mixing with a flavoursinglet fermionic state, which is lighter than the pseudoscalar (wouldbe pion) state. The results are interesting in view of a light composite Higgs boson in walking technicolor theories., 2013年10月03日, arxiv;arxiv_url;arxiv_urlA light composite scalar in eightflavor QCD on the lattice
In search for a composite Higgs boson (technidilaton) in the walking technicolor, we present our preliminary results on the first observation of a light flavorsinglet scalar in a candidate theory for the walking technicolor, the Nf=8 QCD, which was found in our previous paper to have spontaneous chiral symmetry breaking together with remnants of the conformality. Based on simulations with the HISQtype action on several lattice sizes with various fermion masses, we find evidence of a flavorsinglet scalar meson with mass comparable to that of the NambuGoldstone pion in both the small fermionmass region, where chiral perturbation theory works, and the intermediate fermionmass region where the hyperscaling relation holds. We further discuss its chiral limit extrapolation in comparison with other states studied in our previous paper: the scalar has a mass much smaller than that of the vector meson, which is compared to the NambuGoldstone pion having a vanishing mass in that limit., 2013年09月03日, arxiv;arxiv_url;arxiv_urlThe scalar spectrum of manyflavour QCD
The LatKMI collaboration is studying systematically the dynamical properties of N_f = 4,8,12,16 SU(3) gauge theories using lattice simulations with (HISQ) staggered fermions. Exploring the spectrum of manyflavour QCD, and its scaling near the chiral limit, is mandatory in order to establish if one of these models realises the Walking Technicolor scenario. Although lattice technologies to study the mesonic spectrum are well developed, scalar flavoursinglet states still require extra effort to be determined. In addition, gluonic observables usually require largestatistic simulations and powerful noisereduction techniques. In the following, we present useful spectroscopic methods to investigate scalar glueballs and scalar flavoursinglet mesons, together with the current status of the scalar spectrum in N_f = 12 QCD from the LatKMI collaboration., 2013年02月19日, doi;arxiv;arxiv_url;arxiv_urlExploring walking behavior in SU(3) gauge theory with 4 and 8 HISQ quarks
We present the report of the LatKMI collaboration on the lattice QCD simulation for the cases of 4 and 8 flavors. The Nf=8 in particular is interesting from the modelbuilding point of view: The typical walking technicolor model with the large anomalous dimension is the socalled onefamily model (FarhiSusskind model). Thus we explore the walking behavior in LQCD with 8 HISQ quarks by comparing with the 4flavor case (in which the chiral symmetry is spontaneously broken). We report preliminary results on the spectrum, analyzed through the chiral perturbation theory and the finitesize hyperscaling, and we discuss the availability of the Nf=8 QCD to the phenomenology., 2013年01月15日, doi;arxiv;arxiv_url;arxiv_urlLow energy spectra in many flavor QCD with Nf=12 and 16
We present our result of the manyflavor QCD. Information of the phase structure of manyflavor SU(3) gauge theory is of great interest, since the gauge theories with the walking behavior near the infrared fixed point are candidates of new physics for the origin of the dynamical electroweak symmetry breaking. We study the SU(3) gauge theories with 12 and 16 fundamental fermions. Utilizing the HISQ type action which is useful to study the continuum physics, we analyze the lattice data of the mass and the decay constant of the pseudoscalar meson and the mass of the vector meson as well at several values of lattice spacing and fermion mass. The finite size scaling test in the conformal hypothesis is also performed. Our data is consistent with the conformal scenario for Nf=12. We obtain the mass anomalous dimension $\gamma_m \sim 0.40.5$. An update of $N_f=16$ study is also shown., 2012年11月28日, arxiv;arxiv_url;arxiv_urlMany flavor QCD with N_f=12 and 16
Information of the phase structure of many flavor SU(3) gauge theory is of great interest for finding a theory which dynamically breaks the electroweak symmetry. We study the SU(3) gauge theory with fermions for $N_f=12$ and 16 in fundamental representation. Both of them, through perturbation theory, reside in the conformal phase. We try to determine the phase of each theory nonperturbatively with lattice simulation and to find the characteristic behavior of the physical quantities in the phase. HISQ type staggered fermions are used to reduce the discretization error which could compromise the behavior of the physical quantity to determine the phase structure at nonzero lattice spacings. Spectral quantities such as bound state masses of meson channel and meson decay constants are investigated with careful finite volume analysis. Our data favor the conformal over chiral symmetry breaking scenario for both $N_f=12$ and 16., 2012年02月22日, arxiv;arxiv_url;arxiv_urlMany flavor QCD as exploration of the walking behavior with the approximate IR fixed point
We present the first report of the LatKMI collaboration on the the lattice QCD simulation performed at the KMI computer, "$\varphi$", for the cases of 4 flavors and 8 flavors, the latter being expected to be a candidate for the walking technicolor having an approximate scale invariance near the infrared fixed point. The simulation was carried out based on the highly improved staggered quark (HISQ) action. In this proceedings, we report preliminary results on the spectrum, analyzed through the chiral perturbation theory and the finitesize hyperscaling. We observe qualitatively different behavior of the 8flavor case in contrast to the 4flavor case which shows clear indication of the hadronic phase as in the usual QCD., 2012年02月21日, arxiv;arxiv_url;arxiv_urlThe Infrared behavior of SU(3) Nf=12 gauge theory about the existence of conformal fixed point
Incorporated with twisted boundary condition, Polyakov loop correlators can give a definition of the renormalized coupling. We employ this scheme for the step scaling method (with step size s = 2) in the search of conformal fixed point of SU(3) gauge theory with 12 massless flavors. Staggered fermion and plaquette gauge action are used in the lattice simulation with six different lattice sizes, L/a = 20, 16, 12, 10, 8 and 6. For the largest lattice size, L/a = 20, we used a large number of Graphics Processing Units (GPUs) and accumulated 3,000,000 trajectories in total. We found that the step scaling function sigma (u) is consistent with u in the lowenergy region. This means the existence of conformal fixed point. Some details of our analysis and simulations will also be presented., 2011年11月07日, arxiv;arxiv_url;arxiv_urlConformal fixed point of SU(3) gauge theory with 12 fundamental fermions
We study the infrared properties of SU(3) gauge theory coupled to 12 massless機関テクニカルレポート，技術報告書，プレプリント等
Search for the IR fixed point in the Twisted Polyakov Loop scheme (II)
We measure the renormalized coupling in the Twisted Polyakov loop scheme for SU(3) gauge theory coupled with $N_f=12$ fundamental fermions. To find the infrared fixed point of this theory, we focus on the step scaling function for the renormalized coupling. We take the continuum limit using the linear function of $(a/L)^2$ and a constant fit function. We find that there is a sizeable systematic error due to the choice of the continuum extrapolation function in the low energy region. We will give some directions to reduce the systematic errors., 2010年11月02日, arxiv;arxiv_url;arxiv_urlStudy of the scaling properties in SU(2) gauge theory with eight flavors
We present our preliminary study of the SU(2) gauge theory with 8 flavors of fermions in fundamental representation. This theory could be a candidate of the gauge theory with conformal fixed point. By using Wilson/Polyakov loop in a finite volume with twisted boundary conditions, we study the renormalization group flow of the gauge coupling constant. Our calculation gives consistent result with the perturbative prediction of the running coupling in the weak coupling region. We investigate a possible signal for conformal behavior in the strong coupling region., 2010年11月01日, arxiv;arxiv_url;arxiv_urlChiral four dimensional field theory from superstring and higher dimensional super YangMills theory
We study four dimensional field theory from the lowenergy effective theory of Type I, II or heterotic string theories. Chiral fermions in four dimensions are obtained by several mechanisms. Especially, the background flux is one of the most interesting mechanisms for obtaining four dimensional chiral theories. Chiral matter fields have localized wavefunctions on extra dimensions. We discuss about the relations between background flux and lowenergy spectra which are counted by their zeromodes. Yukawa couplings are free parameters in the standard model and may be related to the underlying physics. In the string theory or its lowenergy limit, they are determined by overlap integral of wavefunctions on extra dimensions. We also study the higher order couplings based on the field theoretical approach. From the analysis of generic npoint couplings, we can discuss about flavor structures. We find that in such a construction some discrete flavor symmetries appear in the four dimensional effective theory. Their phenomenological implications are discussed. Furthermore we extend these constructions to orbifold background. Magnetic flux still plays an important role and leads to various types of lowenergy spectra different from that of toroidal compactifications. The orbifold models with heterotic string are also investigated., 2010年03月26日, arxiv;arxiv_url;arxiv_urlNonAbelian Discrete Symmetries in Particle Physics
We review pedagogically nonAbelian discrete groups, which play an important role in the particle physics. We show grouptheoretical aspects for many concrete groups, such as representations, their tensor products. We explain how to derive, conjugacy classes, characters, representations, and tensor products for these groups (with a finite number). We discussed them explicitly for $S_N$, $A_N$, $T'$, $D_N$, $Q_N$, $\Sigma(2N^2)$, $\Delta(3N^2)$, $T_7$, $\Sigma(3N^3)$ and $\Delta(6N^2)$, which have been applied for model building in the particle physics. We also present typical flavor models by using $A_4$, $S_4$, and $\Delta (54)$ groups. Breaking patterns of discrete groups and decompositions of multiplets are important for applications of the nonAbelian discrete symmetry. We discuss these breaking patterns of the nonAbelian discrete group, which are a powerful tool for model buildings. We also review briefly about anomalies of nonAbelian discrete symmetries by using the path integral approach., 2010年03月18日, doi;arxiv;arxiv_url;arxiv_urlSearch for the IR fixed point in the twisted Polyakov loop scheme
We present a nonperturbative study of the running coupling constant in the Twisted Polyakov Loop (TPL) scheme. We investigate how the systematic and statistical errors can be controlled {\it via} a feasibility study in SU(3) pure YangMills theory. We show that our method reproduces the perturbative determination of the running coupling in the UV. In addition, our numerical result agrees with the theoretical prediction of this coupling constant in the IR. We also present our preliminary results for $N_f=12$ QCD, where an IR fixed point may be present., 2009年10月21日, arxiv;arxiv_url;arxiv_urlNucleon sigma term and strange quark content in 2+1flavor QCD with dynamical overlap fermions
We study the sigma term and the strange quark content of nucleon in 2+1flavor QCD with dynamical overlap fermions. We analyze the lattice data of nucleon mass taken at two different strange quark masses with five values of up and down quark masses each. Using the reweighting technique, we study the strange quark mass dependence of the nucleon and extract the strange quark content., 2009年10月17日, arxiv;arxiv_url;arxiv_urlCalculation of the nucleon sigma term and strange quark content with two flavors of dynamical overlap fermions
We present a calculation of the nucleon sigma term on twoflavor QCD configurations with dynamical overlap fermions. We analyse the lattice data for the nucleon mass using the baryon chiral perturbation theory. Using partially quenched data sets, we extract the connected and disconnected contributions to the nucleon sigma term separately. Chiral symmetry on the lattice simplifies the determination of the disconnected contribution. We find that the strange quark content, which determines the neutralino dark matter reaction rate with nucleon through the Higgs boson exchange, is much smaller than the previous lattice results., 2008年10月23日, arxiv;arxiv_url;arxiv_urlA New Method of Calculating the Running Coupling Constant
We propose a new method to compute the running coupling constant of gauge theories on the lattice. We first give the definition of the running coupling in the new scheme using the Wilson loops in a finite volume, and explain how the running of the coupling constant is extracted from the measurement of the volume dependence. The perturbative calculation of the renormalization constant to define the scheme is also given at the leading order. As a benchmark test of the new scheme we apply the method the case of the quenched QCD. We show the preliminary result from our numerical simulations which are carried out with plaquette gauge action for various lattice sizes and bare lattice couplings. With techniques to improve the statistical accuracy, we show that we can determine the nonperturbative running of the coupling constant in a wide range of the energy scale with relatively small number of gauge configurations in our scheme. We compare our lattice data of the running coupling constant with perturbative renormalization group evolution at one and twoloop order, and confirm the consistency between them at high energy., 2008年08月21日, arxiv;arxiv_url;arxiv_urlHigh precision study of B*B pi coupling in unquenched QCD
The B* B pi coupling is a fundamental parameter of chiral effective Lagrangian with heavylight mesons and can constrain the B>pi l nu form factor in the soft pion limit which will be useful for precise determination of Vub. We compute the B* B pi coupling with the static heavy quark and the O(a)improved Wilson light quark. Simulations are carried out with n_f=2 unquenched 12^3x24 lattices at beta=1.80 generated by CPPACS collaboration. Following the quenched study by Negishi et al., we employ the alltoall propagator with 200 low eigenmodes as well as HYP smeared link to improve the statistical accuracy., 2007年11月02日, arxiv;arxiv_url;arxiv_url物理科学,この1年 2020
丸善出版, 2020年, vi, 157p, 26365944, cinii_books;rm:research_project_id (ISBN: 9784621304860)An Introduction to NonAbelian Discrete Symmetries for Particle Physicists
Springer, 2012年モジュラー FroggattNielsen 機構
日本物理学会2020年秋季大会, 2020年09月14日, 2020年09月14日テンソル繰り込み群におけるボンド次元の縮減法と誤差評価の改善
日本物理学会第76回年次大会, 2021年03月12日, 2021年03月12日口頭発表（一般）
Calculation of Electric Dipole Moments of the Nucleon
2019 Lattice X Intensity Frontier Workshop, 2019年09月23日, 2019年09月23日, 2019年09月23日Computing Nucleon Electric Dipole Moments from Lattice QCD
The 37th International Symposium on Lattice Field Theory, 2019年06月20日, 2019年06月16日, 2019年06月16日Computing Nucleon Electric Dipole Moments in Lattice QCD
International Moleculetype Workshop Frontiers in Lattice QCD and related topics, 2019年04月26日, 2019年04月15日, 2019年04月15日Gravitational Waves from Walking Technicolor
The 24th Regular Meeting of the New Higgs Working Group, 2018年12月22日, 2018年12月21日, 2018年12月21日Nucleon Electric Dipole Moments from Lattice QCD
基研研究会 素粒子物理の進展 2018, 2018年08月09日, 2018年08月06日, 2018年08月06日Nucleon Electric Dipole Moments from Lattice QCD
10 th International Workshop on Fundamental Physics Using Atoms (FPUA), 2018年01月08日, 2018年01月08日, 2018年01月08日Nucleon Electric Dipole Moments from Lattice QCD
The 7th KIAS Workshop on Particle Physics and Cosmology and The 2nd KEKNCTSKIAS Workshop on Particle Physics Phenomenology, 2017年11月10日, 2017年11月06日, 2017年11月06日格子QCDによる核子構造の研究と標準模型を越えた物理
日本物理学会2017年秋季大会, 2017年09月14日, 2017年09月12日, 2017年09月12日Vus determination from inclusive strange tau decay and lattice HVP
35th International Symposium On Lattice Field Theory, 2017年06月23日, 2017年06月18日, 2017年06月18日核子(chromo)EDM演算子の格子QCD計算
日本物理学会第72回年次大会, 2017年03月19日, 2017年03月17日, 2017年03月17日Determination of Vus from hadronic tau decays  New inclusive analysis using lattice QCD data 
The international workshop on future potential of high intensity accelerators for particle and nuclear physics (HINT2016), 2016年12月06日, 2016年12月05日, 2016年12月05日Lattice calculation of Vus from inclusive strangeness changing τ decay
The 14th International Workshop on Tau Lepton Physics (Tau2016), 2016年09月19日, 2016年09月18日, 2016年09月18日Vus from inclusive strange τ decay data and lattice HVPs
The 34th annual “International Symposium on Lattice Field Theory (Lattice 2016), 2016年07月28日, 2016年07月24日, 2016年07月24日物質優勢宇宙の謎解明のための核子構造精密計算
2016年理研シンポジウム「スーパーコンピューターHOKUSAIとShoubu, 研究開発の最前線」, 2016年06月08日, 2016年06月08日, 2016年06月08日Manyflavor QCD dynamics on the lattice
Lattice for Beyond the Standard Model Physics 2016, 2016年04月21日, 2016年04月21日, 2016年04月21日Inclusive τ decay analysis with lattice HVPs
RBRC Workshop on Lattice Gauge Theories 2016, 2016年03月10日, 2016年03月09日, 2016年03月09日数物特別セミナーD
数物特別セミナーＣ
素粒子論セミナーB
数物特別セミナーB
応用複素解析演習
素粒子論セミナーＡ
数物特別セミナーＡ
場の量子論Ⅱ
量子力学１演習
基礎量子力学
宇宙論入門
グローバル理系女性育成国際サマーキャンプ 2019
グローバル理系女性育成国際サマーキャンプ 2017
数物特別セミナーB
数物特別セミナーA
場の量子論B