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Miho Koma

Publications and source records attributed to Miho 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

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

Optimization of Lattice QCD codes for the AMD Opteron processor

We report our experience of the optimization of the lattice QCD codes for the new Opteron cluster at DESY Hamburg, including benchmarks. Details of the optimization using SSE/SSE2 instructions and the effective use of prefetch instructions are discussed.

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

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 is discussed in the nucleon-pion system.

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

String representation of the dual Ginzburg-Landau theory beyond the London limit

The effective string action of the color-electric flux tube in the dual Ginzburg-Landau (DGL) theory is studied by performing a path-integral analysis by taking into account the finite thickness of the flux tube. A modified Yukawa interaction appears as a boundary contribution and is reduced into the ordinary Yukawa interaction in the London Limit.

hep-ph↗