Results For SU Research Articles

Associations among metabolic health, weight status, and various physical fitness components in Japanese adolescents: a cross-sectional study (NICE EVIDENCE study- Agano 3)

ABSTRACT Aim was to examine associations among metabolic health, weight status, and various physical fitness (PF) components in 1744 Japanese adolescents aged 13–14. Anthropometric measurements and PF tests (20 m shuttle run test [20mSRT], handgrip strength/body mass [HG], standing long jump [SLJ], and sit ups [SU]) were administered. The bottom sex-specific quintile of PF indicated “low fit”. Participants were classified as non-overweight (non-OW) or overweight/obese (OW) according to the International Obesity Task Force. Clustered metabolic risk was defined as the sum of Z scores for mean arterial pressure, non-high-density lipoprotein cholesterol, and HbA1c, divided by three, and ≥ 1 SD. Combination of weight status and scores for HG or SU were additively associated with clustered metabolic risk. Compared with the non-OW-moderate-high fit group, the OW-low HG group was 3.05 (95%CI: 1.88–4.97) times more likely to have clustered metabolic risk although risk was not significantly elevated in the OW-moderate-high HG group (1.52 [95%CI: 0.88–2.62]). A similar association was observed between OW and low SU scores but not between OW and low 20mSRT or SLJ scores. Adolescents with OW and moderate-high HG or SU scores had a lower prevalence of an unfavourable metabolic state than those with OW and low HG or SU results.

Monopoles of the Dirac type and color confinement in QCD

We present results of SU(3) Monte-Carlo studies of a new color confinement scheme proposed recently due to Abelian-like monopoles of the Dirac type corresponding in the continuum limit to violation of the non-Abelian Bianchi identities (VNABI). The simulations are done without any additional gauge-fixing smoothing the vacuum. We get for the first time, in pure SU(3) simulations, (1) the perfect Abelian dominance with respect to the static potentials on (12 ~ 16)4 at β = 5.6 − 5.8 using the multilevel method, (2) the monopole as well as Abelian dominances with respect to the static potentials by evaluating the Polyakov-loop correlators on 243 × 4 at β = 5.6. The Abelian photon part gives zero string tension. The new SU(3) as well as the previous SU(2) results are consistent with the new Abelian picture of color confinement that each one of eight colored electric flux is squeezed by the corresponding colored Abelian-like monopole of the Dirac type corresponding to VNABI.

Radiative transitions and magnetic moments of the charmed and bottom vector mesons in chiral perturbation theory

In this work, we systematically study the radiative decays and magnetic moments of the charmed and bottom vector mesons with chiral perturbation theory up to one-loop level. We present the results in SU(2) and SU(3) cases with the mass splitting in loop diagrams kept and unkept, respectively. The obtained decay rates for $D^\ast$ and $B^\ast$ mesons in SU(3) case with the mass splitting kept are: $\Gamma_{\bar{D}^{\ast 0}\to \bar{D}^0\gamma}=16.2^{+6.5}_{-6.0}$ keV, $\Gamma_{D^{\ast-}\to D^-\gamma}=0.73^{+0.7}_{-0.3}$ keV, $\Gamma_{D_s^{\ast-}\to D_s^-\gamma}= 0.32^{+0.3}_{-0.3}$ keV, and $\Gamma_{B^{\ast+}\to B^+\gamma}=0.58^{+0.2}_{-0.2}$ keV, $\Gamma_{B^{\ast0}\to B^0\gamma}=0.23^{+0.06}_{-0.06}$ keV, $\Gamma_{B_s^{\ast0}\to B_s^0\gamma}=0.04^{+0.03}_{-0.03}$ keV. The decay width for $D^{\ast-}\to D^-\gamma$ is consistent with the experimental measurement. As a byproduct, the full widths of $\bar{D}^{\ast0}$ and $D_s^{\ast-}$ are $\Gamma_{\mathrm{tot}}(\bar{D}^{\ast0})\simeq77.7^{+26.7}_{-20.5}~\mathrm{keV}$ and $ \Gamma_{\mathrm{tot}}(D_s^{\ast-})\simeq0.62^{+0.45}_{-0.50}~\mathrm{keV}$, respectively. We also calculate the magnetic moments of the heavy vector mesons. The analytical chiral expressions derived in our work shall be helpful for the extrapolations of lattice QCD simulations in the coming future.

Recent results from SU(2) with one adjoint Dirac fermion

We present some results for SU(2) with one adjoint Dirac flavour from the lattice studies. Data for the spectroscopy, the static potential, topological charge, and the anomalous dimension of the fermionic condensate are included. Our findings are found to be inconsistent with conventional confining behaviour, instead pointing tentatively towards a theory lying within or very near the onset of the conformal window, with an anomalous dimension of the fermionic condensate of almost 1. Implications of these findings on the building of models of strongly-interacting dynamics beyond the standard model are discussed.

Size of the pion from full lattice QCD with physicalu,d,sandcquarks

We present the first calculation of the electromagnetic form factor of the $\pi$ meson at physical light quark masses. We use configurations generated by the MILC collaboration including the effect of $u$, $d$, $s$ and $c$ sea quarks with the Highly Improved Staggered Quark formalism. We work at three values of the lattice spacing on large volumes and with $u$/$d$ quark masses going down to the physical value. We study scalar and vector form factors for a range in space-like $q^2$ from 0.0 to -0.1 $\mathrm{GeV}^2$ and from their shape we extract mean square radii. Our vector form factor agrees well with experiment and we find $\langle r^2 \rangle_V = 0.403(18)(6) \,\mathrm{fm}^2$. For the scalar form factor we include quark-line disconnected contributions which have a significant impact on the radius. We give the first results for SU(3) flavour-singlet and octet scalar mean square radii, obtaining: $\langle r^2 \rangle_S^{\mathrm{singlet}} = 0.506(38)(53) \mathrm{fm}^2$ and $\langle r^2 \rangle_S^{\mathrm{octet}} = 0.431(38)(46) \mathrm{fm}^2$. We discuss the comparison with expectations from chiral perturbation theory.

A different kind of string

In U(1) lattice gauge theory in three spacetime dimensions, the problem of confinement can be studied analytically in a semi-classical approach, in terms of a gas of monopoles with Coulomb-like interactions. In addition, this theory can be mapped to a spin model via an exact duality transformation, which allows one to perform high-precision numerical studies of the confining potential. Taking advantage of these properties, we carried out an accurate investigation of the effective string describing the low-energy properties of flux tubes in this confining gauge theory. We found striking deviations from the expected Nambu-Goto-like behavior, and, for the first time, evidence for contributions that can be described by a term proportional to the extrinsic curvature of the effective string worldsheet. Such term is allowed by Lorentz invariance, and its presence in the infrared regime of the U(1) model was indeed predicted by Polyakov several years ago. Our results show that this term scales as expected according to Polyakov's solution, and becomes the dominant contribution to the effective string action in the continuum limit. We also demonstrate analytically that the corrections to the confining potential induced by the extrinsic curvature term can be related to the partition function of the massive perturbation of a c=1 bosonic conformal field theory. The implications of our results for SU(N) Yang-Mills theories in three and in four spacetime dimensions are discussed.

Simulations at Fixed Topology: Fixed Topology Versus Ordinary Finite Volume Corrections

Lattice QCD simulations tend to get stuck in a single topological sector at fine lattice spacing, or when using chirally symmetric quarks. In such cases computed observables differ from their full QCD counterparts by finite volume corrections, which need to be understood on a quantitative level. We extend a known relation from the literature between hadron masses at fixed and at unfixed topology by incorporating in addition to topological finite volume effects, also ordinary finite volume effects. We present numerical results for SU(2) Yang-Mills theory.

Spin polarizability of hyperons

We review the recent progress of the theoretical understanding of spin polarizabilities of the hyperon in the framework of SU(3) heavy baryon chiral perturbation theory (HBChPT). We present the results of a systematic leading-order calculation of hyperon Compton scattering and extract the forward spin polarizability (γ0) of hyperons. The results obtained for γ0 in the case of nucleons agree with the known results of SU(2) HBChPT when kaon loops are not considered.

Hyperon forward spin polarizabiltyγ0

We present the results of a systematic leading-order calculation of hyperon Compton scattering and extract the forward spin polarizability---${\ensuremath{\gamma}}_{0}$---of hyperons within the framework of SU(3) heavy baryon chiral perturbation theory (HBChPT). The results obtained for ${\ensuremath{\gamma}}_{0}$ in the case of nucleons agree with that of the known results of SU(2) HBChPT when kaon loops are not considered.

Center vortices and the quark propagator in SU(2) gauge theory

We study the behavior of the AsqTad quark propagator in Landau gauge on quenched SU(2) gauge configurations under the removal of center vortices. In contrast to recent results in SU(3), we clearly see the infrared enhancement of the mass function disappear if center vortices are removed, a sign of the intimate relation between center vortices and chiral symmetry breaking in SU(2) gauge-field theory. These results provide a benchmark with which to interpret the SU(3) results. In addition, we consider vortex-only configurations. On those, the quark dressing function behaves roughly as on the full configurations, and the mass function picks up an almost linear momentum dependence.

Non-Abelian vortices and monopoles in [formula omitted] theories

Non-Abelian BPS vortex solutions are constructed in N = 2 theories with gauge groups SO ( N ) × U ( 1 ) . The model has N f flavors of chiral multiplets in the vector representation of SO ( N ) , and we consider a color-flavor locked vacuum in which the gauge symmetry is completely broken, leaving a global SO ( N ) C + F diagonal symmetry unbroken. Individual vortices break this symmetry, acquiring continuous non-Abelian orientational moduli. By embedding this model in high-energy theories with a hierarchical symmetry breaking pattern such as SO ( N + 2 ) → SO ( N ) × U ( 1 ) → 1 , the correspondence between non-Abelian monopoles and vortices can be established through homotopy maps and flux matching, generalizing the known results in SU ( N ) theories. We find some interesting hints about the dual (non-Abelian) transformation properties among the monopoles.

On the restoration of supersymmetry in twisted two-dimensional lattice Yang–Mills theory

We study a discretization of = 2 super Yang–Mills theory which possesses a single exact supersymmetry at non-zero lattice spacing. This supersymmetry arises after a reformulation of the theory in terms of twisted fields. In this paper we derive the action of the other twisted supersymmetries on the component fields and study, using Monte Carlo simulation, a series of corresponding Ward identities. Our results for SU(2) and SU(3) support a restoration of these additional supersymmetries without fine tuning in the infinite volume continuum limit. Additionally we present evidence supporting a restoration of (twisted) rotational invariance in the same limit. Finally we have examined the distribution of scalar field eigenvalues and find evidence for power law tails extending out to large eigenvalue. We argue that these tails indicate that the classical moduli space does not survive in the quantum theory.

Noncommutative [formula omitted] theories, the axial anomaly, Fujikawa's method and the Atiyah–Singer index

Fujikawa's method is employed to compute at first order in the noncommutative parameter the U(1)A anomaly for noncommutative SU(N). We consider the most general Seiberg–Witten map which commutes with hermiticity and complex conjugation and a noncommutative matrix parameter, θμν, which is of “magnetic” type. Our results for SU(N) can be readily generalized to cover the case of general nonsemisimple gauge groups when the symmetric Seiberg–Witten map is used. Connection with the Atiyah–Singer index theorem is also made.

Unification, multiplets, and proton decay

We make a detailed analysis of gauge-coupling unification in supersymmetry. When the standard model gauge group is embedded in a grand unified theory (GUT), new particles often appear below the GUT scale in order to predict the right phenomenology at low-energy. While these new particles are beyond the reach of accelerator experiments, they change the prediction of ${\ensuremath{\alpha}}_{s}$. Here we classify all the $\mathbf{(}\mathrm{S}\mathrm{U}(3{)}_{\mathrm{C}},\mathrm{S}\mathrm{U}(2{)}_{\mathrm{L}}{\mathbf{)}}_{\mathrm{U}(1{)}_{\mathrm{Y}}}$ representations which improve or worsen the prediction. Running experimentally determined values of the coupling constants at two loops we calculate the allowed range of masses of fields in these representations. We explore the implication of these results in SU(5) and $\mathrm{S}\mathrm{U}(3{)}^{3}$ (trinification) models. We discover that minimal trinification predicts light triplet Higgs particles which lead to proton decay with a lifetime in the vicinity of the current experimental bound.

Chiral condensate of lattice QCD with massless quarks from the probability distribution function method

We apply the probability distribution function method to the study of chiral properties of QCD with quarks in the exact massless limit. A relation among the chiral condensate, the zeros of the Bessel function, and the eigenvalue of the Dirac operator is also given. The chiral condensate in this limit can be measured with a small number of eigenvalues of the massless Dirac operator and without any ambiguous mass extrapolation. The results for SU(3) gauge theory with quenched Kogut-Susskind quarks on the ${10}^{4}$ lattice are shown.

Gluon propagator and confinement scenario in Coulomb gauge

We present numerical results in SU(2) lattice gauge theory for the instantaneous part of the gluon propagator in Coulomb gauge D 44,inst= V coul(R)δ(t) . Data are taken on lattice volumes 24 4 and 28 4 for 7 values of β in the interval2.2 ≤ β ≤ 2.8. The data are confronted with the confinement scenario in Coulomb gauge. They are consistent with a linearly rising color-Coulomb potential V coul(R) .

Logarithmic corrections to finite-size spectrum ofSU(N) symmetric quantum chains

We consider SU(N) symmetric one-dimensional quantum chains at finite temperature. For such systems the correlation lengths, ground state energy and excited state energies are investigated in the framework of conformal field theory. The possibility of different types of excited states is discussed. Logarithmic corrections to the ground state energy and different types of excited states in the presence of a marginal operator are calculated. The known results for SU(2) and SU(4) symmetric systems follow from our general formula.

The maximal abelian gauge, monopoles, and vortices in SU(3) lattice gauge theory

We report on calculations of the heavy quark potential in SU(3) lattice gauge theory. Full SU(3) results are compared to three cases which involve gauge-fixing and projection. All of these start from the maximal abelian gauge (MAG), in its simplest form. The first case is abelian projection to U(1)× U(1). The second keeps only the abelian fields of monopoles in the MAG. The third involves an additional gauge-fixing to the indirect maximal center gauge (IMCG), followed by center projection to Z(3). At one gauge fixing/configuration, the string tensions calculated from MAG U(1)× U(1), MAG monopoles, and IMCG Z(3) are all less than the full SU(3) string tension. The projected string tensions further decrease, by approximately 10%, when account is taken of gauge ambiguities. Comparison is made with corresponding results for SU(2). It is emphasized that the formulation of the MAG is more subtle for SU(3) than for SU(2), and that the low string tensions may be caused by the simple MAG form used. A generalized MAG for SU(3) is formulated.

Numerical study of the gluon propagator and confinement scenario in the minimal Coulomb gauge

We present numerical results in SU(2) lattice gauge theory for the space-space and time-time components of the gluon propagator at equal time in the minimal Coulomb gauge. It is found that the equal-time would-be physical 3-dimensionally transverse gluon propagator $D^{tr}(\vec{k})$ vanishes at $\vec{k} = 0$ when extrapolated to infinite lattice volume, whereas the instantaneous color-Coulomb potential $D_{44}(\vec{k})$ is strongly enhanced at $\vec{k} = 0$. This has a natural interpretation in a confinement scenario in which the would-be physical gluons leave the physical spectrum while the long-range Coulomb force confines color. Gribov's formula $D^{tr}(\vec{k}) = (|\vec{k}|/2)[(\vec{k}^2)^2 + M^4]^{1/2}$ provides an excellent fit to our data for the 3-dimensionally transverse equal-time gluon propagator $D^{tr}(\vec{k})$ for relevant values of $\vec{k}$.

A study of practical implementations of the overlap Dirac operator in four dimensions

We study three practical implementations of the overlap Dirac operator D ̵ 0 = 1 2 [1+γϵ( H w)] in four dimensions. Two implementations are based on different representations of ϵ( H w ) as a sum over poles. One of them is a polar decomposition and the other is an optimal fit to a ratio of polynomials. The third one is obtained by representing ϵ( H w ) using Gegenbauer polynomials and is referred to as the fractional inverse method. After presenting some spectral properties of the Hermitian operator H 0 = γ 5 D ̵ 0 , we study its spectrum in a smooth SU(2) instanton properties of the with the aim of comparing the three implementations of D 0. We also present some results in SU(2) gauge field backgrounds generated at β = 2.5 on an 8 4 lattice. Chiral properties have been numerically verified.