arXiv subjects

Yoshiaki Koma

Publications and source records attributed to Yoshiaki Koma.

At least 19 recordsLinked to original sources

arXiv2025

Finite-length flux tube in the dual Ginzburg-Landau theory on the dual lattice

The dual Ginzburg-Landau (DGL) theory is one of the nonperturbative effective field theories of quantum chromodynamics (QCD). The DGL theory describes the QCD vacuum as a dual superconductor and possesses electric flux-tube solutions via the dual Meissner effect, which applies to the quark confinement mechanism. We demonstrate a powerful numerical method for solving the field equations in the DGL theory with U(1) dual gauge symmetry. An essential aspect of our method is to formulate the DGL theory on the dual lattice, which enables us to investigate any system composed of finite-length flux tubes in a systematic manner. Taking full advantage of the dual lattice formulation, we investigate the finite-length flux-tube solution corresponding to the quark-antiquark system in detail, which exposes the significant terminal effects absent in the infinitely long flux-tube solution. We also study the flux-tube interaction in the two-flux-tube and multiflux-tube systems, providing new insights into the nonperturbative properties of QCD.

hep-lat↗

arXiv2017

Precise determination of the three-quark potential in SU(3) lattice gauge theory

We investigate the static interquark potential for the three-quark system in SU(3) lattice gauge theory at zero temperature by using Monte Carlo simulations. We extract the potential from the correlation function of the three Polyakov loops, which are computed by employing the multilevel algorithm. We obtain remarkably clean results of the three-quark potential for O(200) sets of the three-quark configurations of various sizes and geometries including not only the cases that three quarks are put at the vertices of acute, right, and obtuse triangles, but also the extreme cases such that three quarks are put in line. We find several new interesting features of the three-quark potential and then discuss its possible functional form.

hep-lat↗

arXiv2012

Heavy quarkonium spectroscopy in pNRQCD with lattice QCD input

The charmonium and bottomonium mass spectra are investigated in potential nonrelativistic QCD (pNRQCD) with the heavy quark potential computed by lattice QCD simulations. The potential consists of a static potential and relativistic corrections classified in powers of the inverse of heavy quark mass m, and the effects of the O(1/m) and O(1/m^{2}) spin-orbit corrections on the mass spectra are examined systematically. The pattern of the mass spectra is found to be in fairly good agreement with experimental data, in which the O(1/m) correction gives an important contribution.

hep-lat↗

arXiv2010

Momentum dependence of the topological susceptibility with overlap fermions

Knowledge of the derivative of the topological susceptibility at zero momentum is important for assessing the validity of the Witten-Veneziano formula for the eta' mass, and likewise for the resolution of the EMC proton spin problem. We investigate the momentum dependence of the topological susceptibility and its derivative at zero momentum using overlap fermions in quenched lattice QCD simulations. We expose the role of the low-lying Dirac eigenmodes for the topological charge density, and find a negative value for the derivative. While the sign of the derivative is consistent with the QCD sum rule for pure Yang-Mills theory, the absolute value is overestimated if the contribution from higher eigenmodes is ignored.

hep-lat↗

arXiv2009

Scaling study of the relativistic corrections to the static potential

The relativistic corrections to the static potential, i.e. the O(1/m) correction, the O(1/m^2) spin-dependent and momentum-dependent corrections are investigated in SU(3) lattice gauge theory. These corrections are relevant ingredients of an effective field theory for heavy quarkonium called potential nonrelativistic QCD. Utilizing the multilevel algorithm for the field strength correlator on the quark-antiquark source, these corrections are determined at the distances ranged from 0.25 to 1.2 fm. A reasonable scaling behavior and long-range nonperturbative contributions are observed.

hep-lat↗

arXiv2007

Relativistic corrections to the static potential at O(1/m) and O(1/m^2)

We investigate the relativistic corrections to the static potential, i.e. the O(1/m) potential and the O(1/m^2) velocity-dependent potentials, in SU(3) lattice gauge theory. They are important ingredients of potential nonrelativistic QCD for heavy quarkonium. Utilizing the multi-level algorithm, we obtain remarkably clean signals of these potentials up to r=0.9 fm. We observe long range nonperturbative contributions to these corrections.

hep-lat↗

arXiv2007

Gauge-independent Abelian mechanism of color confinement in gluodynamics

Abelian mechanism of non-Abelian color confinement is observed in a gauge-independent way by high precision lattice Monte Carlo simulations in gluodynamics. An Abelian gauge field is extracted with no gauge-fixing. A static quark-antiquark potential derived from Abelian Polyakov loop correlators gives us the same string tension as the non-Abelian one. The Hodge decomposition of the Abelian Polyakov loop correlator to the regular photon and the singular monopole parts also reveals that only the monopole part is responsible for the string tension. The investigation of the flux-tube profile then shows that Abelian electric fields defined in an arbitrary color direction are squeezed by monopole supercurrents with the same color direction, and the quantitative features of flux squeezing are consistent with those observed previously after Abelian projections with gauge fixing. Gauge independence of Abelian and monopole dominance strongly supports that the mechanism of non-Abelian color confinement is due to the Abelian dual Meissner effect.

hep-lat↗

arXiv2007

Abelian dominance and the dual Meissner effect in local unitary gauges in SU(2) gluodynamics

Performing highly precise Monte-Carlo simulations of SU(2) gluodynamics, we observe for the first time Abelian dominance in the confining part of the static potential in local unitary gauges such as the F12 gauge. We also study the flux-tube profile between the quark and antiquark in these local unitary gauges and find a clear signal of the dual Meissner effect. The Abelian electric field is found to be squeezed into a flux tube by the monopole supercurrent. This feature is the same as that observed in the non-local maximally Abelian gauge. These results suggest that the Abelian confinement scenario is gauge independent. Observing the important role of space-like monopoles in the Polyakov gauge also indicates that the monopoles defined on the lattice do not necessarily correspond to those proposed by 't Hooft in the context of Abelian projection.

hep-lat↗

arXiv2007

Spin-dependent potentials from lattice QCD

The spin-dependent corrections to the static inter-quark potential are phenomenologically relevant to describing the fine and hyperfine spin splitting of the heavy quarkonium spectra. We investigate these corrections, which are represented as the field strength correlators on the quark-antiquark source, in SU(3) lattice gauge theory. We use the Polyakov loop correlation function as the quark-antiquark source, and by employing the multi-level algorithm, we obtain remarkably clean signals for these corrections up to intermediate distances of around 0.6 fm. Our observation suggests several new features of the corrections.

hep-lat↗

arXiv2006

Nonperturbative determination of the QCD potential at O(1/m)

The relativistic correction to the QCD static inter-quark potential at O(1/m) is investigated nonperturbatively for the first time by using lattice Monte Carlo QCD simulations. The correction is found to be comparable with the Coulombic term of the static potential when applied to charmonium, and amounts to one-fourth of the Coulombic term for bottomonium.

hep-lat↗

arXiv2005

Determination of the spin-dependent potentials with the multi-level algorithm

The spin-dependent corrections to the static interquark potential are relevant to describing the fine and hyper-fine splittings of the heavy quarkonium spectra. We investigate these corrections in SU(3) lattice gauge theory with the Polyakov loop correlation function as the quark source by applying the multi-level algorithm. We observe remarkably clean signals for the spin-dependent potentials up to intermediate distances.

hep-lat↗

arXiv2005

More on the finite size mass shift formula for stable particles

The next to leading order (NLO) contribution of the generalized finite size mass shift formula for an interacting two stable particle system in a periodic $L^{3}$ box is discriminated with maintaining its model independent structure and validity to all orders in perturbation theory. The influence of the NLO contribution is examined for the nucleon mass shift in the realistic nucleon-pion system.

hep-lat↗

arXiv2005

On the finite size mass shift formula for stable particles

Luescher's finite size mass shift formula in a periodic finite volume, involving forward scattering amplitudes in the infinite volume, is revisited for the two stable distinguishable particle system. The generalized mass shift formulae for the boson and fermion are derived in the boson-boson and fermion-boson systems, respectively. The nucleon mass shift formula is given in the nucleon-pion system and the relation to the computation within chiral perturbation theory is discussed.

hep-lat↗

arXiv2004

Finite size mass shift formula for stable particles revisited

hep-lat↗

arXiv2004

Static potential, force, and flux-tube profile in 4D compact U(1) lattice gauge theory with the multi-level algorithm

The long range properties of four-dimensional compact U(1) lattice gauge theory with the Wilson action in the confinement phase is studied by using the multi-level algorithm. The static potential, force and flux-tube profile between two static charges are successfully measured from the correlation function involving the Polyakov loop. The universality of the coefficient of the 1/r correction to the static potential, known as the Luescher term, and the transversal width of the flux-tube profile as a function of its length are investigated. While the result supports the presence of the 1/r correction, the width of the flux tube shows an almost constant behavior at a large distance.

hep-lat↗

arXiv2003

Glueball masses in 4d U(1) lattice gauge theory using the multi-level algorithm

We take a new look at plaquette-plaquette correlators in 4d compact U(1) lattice gauge theory which are separated in time, both in the confined and the deconfined phases. From the behaviour of these correlators we extract glueball masses in the scalar as well as the axial-vector channels. Also in the deconfined phase, the non-zero momentum axial-vector correlator gives us information about the photon which appears as a massless particle in the spectrum. Using the Luescher - Weisz multi-level algorithm, we are able to go to large time separations which were not possible previously.

hep-lat↗

arXiv2002

Casimir scaling hypothesis on the nonperturbative force in QCD vs. dual superconducting scenario of confinement

We discuss the Casimir scaling hypothesis on the nonperturbative force in terms of the dual superconducting picture of the QCD vacuum by calculating the string tensions of flux tubes associated with static charges in various SU(3) representations in the dual Ginzburg-Landau (DGL) theory.

hep-ph↗

arXiv2002

Electric magnetic duality of the confining flux tube in Abelian-projected gluodynamics

The structure of the Abelian-projected (AP) flux tube in SU(2) gauge theory in the maximally Abelian gauge is studied by applying the Hodge decomposition to the Abelian Wilson loop. It is shown that the profile of the AP flux tube has the same structure as the classical flux tube solution in the dual Abelian Higgs model, which is composed of a Coulombic and a solenoidal electric field linked by monopole supercurrent.

hep-ph↗