arXiv subjects

S. Ejiri

Publications and source records attributed to S. Ejiri.

101 records · Page 6Linked to original sources

arXiv1999

Heavy-light decay constants from clover heavy quark action in QCD with two flavors of dynamical quarks

We present results on an analysis of the decay constants f_B and f_Bs with two flavours of sea quark. The calculation has been carried out on 3 different bare gauge couplings and 4 sea quark masses at each gauge coupling, with m_pi/m_rho ranging from 0.8 to 0.6. We employ the Fermilab formalism to perform calculations with heavy quarks whose mass is in the range of the b-quark. A detailed comparison with a quenched calculation using the same action is made to elucidate the effects due to the sea quarks.

hep-lat↗

arXiv1999

Quenched QCD with domain-wall fermions on coarse lattices

We investigate the existence of chiral zero modes at a^{-1} \simeq 1 GeV in quenched domain-wall QCD. Simulations are carried out for the plaquette and an RG-improved gauge actions on a 12^3x24xN_s lattice with N_s=10-50. We find that the pion mass in the chiral limit remains non-vanishing as N_s\to\infty for both gauge actions. Possible origins of this non-vanishing pion mass are discussed.

hep-lat↗

arXiv1999

Eta meson mass and topology in QCD with two light flavors

We present results for the mass of the flavor singlet meson calculated on two-flavor full QCD configurations generated by the CP-PACS full QCD project. We also investigate topological charge fluctuations and their dependence on the sea quark mass.

hep-lat↗

arXiv1999

Hybrid Quarkonia on Asymmetric Lattices

We report on a study of heavy hybrid states using the NRQCD approach on coarse and asymmetric lattices, where we discard vacuum polarisation effects and neglect all spin-correction terms. We find a clear hybrid signal on all our lattices ($a_s= 0.15 ... 0.47$ fm). We have studied in detail the lattice spacing artefacts, finite volume effects and mass dependence. Within the above approximations we predict the hybrid excitation in Charmonium to be 1.323(13) GeV above its ground state. The bottomonium hybrid was found to be 1.542(8) GeV above its ground state.

hep-lat↗

arXiv1999

Quenched Light Hadron Spectrum

We present results of a large-scale simulation for the flavor non-singlet light hadron spectrum in quenched lattice QCD with the Wilson quark action. Hadron masses are calculated at four values of lattice spacing in the range $a \approx$ 0.1 - 0.05 fm on lattices with a physical extent of 3 fm at five quark masses corresponding to $m_π/m_ρ\approx 0.75$ - 0.4. The calculated spectrum in the continuum limit shows a systematic deviation from experiment, though the magnitude of deviation is contained within 11%. Results for decay constants and light quark masses are also reported.

hep-lat↗

arXiv1998

The static quark potential in full QCD

We report results on the static quark potential in two-flavor full QCD. The calculation is performed for three values of lattice spacing $a^{-1}\approx 0.9, 1.3$ and 2.5 GeV on $12^3{\times}24, 16^3{\times}32$ and $24^3{\times}48$ lattices respectively, at sea quark masses corresponding to $m_π/m_ρ\approx 0.8-0.6$. An RG-improved gauge action and a tadpole-improved SW clover quark action are employed. We discuss scaling of $m_ρ/\sqrtσ$ and effects of dynamical quarks on the potential.

hep-lat↗

arXiv1998

Quenched Light Hadron Spectrum with the Wilson Quark Action: Final Results from CP-PACS

We report the final results of the CP-PACS calculation for the quenched light hadron spectrum with the Wilson quark action. Our data support the presence of quenched chiral singularities, and this motivates us to use mass formulae based on quenched chiral perturbation theory in order to extrapolate hadron masses to the physical point. Hadron masses and decay constants in the continuum limit show unambiguous systematic deviations from experiment. We also report the results for light quark masses.

hep-lat↗

arXiv1998

Full QCD light hadron spectrum from the CP-PACS

We report on an on-going two-flavor full QCD study on CP-PACS using an RG-improved gauge action and a tadpole-improved SW quark action. Runs are made for three lattice spacings $a^{-1}\approx 0.9$, 1.3, and 2.5 GeV on $12^3\times24$, $16^3\times32$, and $24^3\times48$ lattices. Four sea quark masses having $m_{\rm PS}/m_{\rm V} \approx 0.8$--0.6 are simulated, for each of which hadron masses are evaluated for valence quark masses corresponding to $m_{\rm PS}/m_{\rm V} \approx 0.8$--0.5. Results for hadron and light quark masses are presented and compared with those obtained in quenched QCD.

hep-lat↗

arXiv1998

Non-perturbative determination of anisotropy coefficients and pressure gap at the deconfining transition of QCD

We propose a new non-perturbative method to compute derivatives of gauge coupling constants with respect to anisotropic lattice spacings (anisotropy coefficients). Our method is based on a precise measurement of the finite temperature deconfining transition curve in the lattice coupling parameter space extended to anisotropic lattices by applying the spectral density method. We determine the anisotropy coefficients for the cases of SU(2) and SU(3) gauge theories. A longstanding problem, when one uses the perturbative anisotropy coefficients, is a non-vanishing pressure gap at the deconfining transition point in the SU(3) gauge theory. Using our non-perturbative anisotropy coefficients, we find that this problem is completely resolved.

hep-lat↗

arXiv1998

Non-perturbative determination of anisotropy coefficients in lattice gauge theories

We propose a new non-perturbative method to compute derivatives of gauge coupling constants with respect to anisotropic lattice spacings (anisotropy coefficients), which are required in an evaluation of thermodynamic quantities from numerical simulations on the lattice. Our method is based on a precise measurement of the finite temperature deconfining transition curve in the lattice coupling parameter space extended to anisotropic lattices by applying the spectral density method. We test the method for the cases of SU(2) and SU(3) gauge theories at the deconfining transition point on lattices with the lattice size in the time direction $N_t=4$ -- 6. In both cases, there is a clear discrepancy between our results and perturbative values. A longstanding problem, when one uses the perturbative anisotropy coefficients, is a non-vanishing pressure gap at the deconfining transition point in the SU(3) gauge theory. Using our non-perturbative anisotropy coefficients, we find that this problem is completely resolved: we obtain $Δp/T^4 = 0.001(15)$ and $-0.003(17)$ on $N_t=4$ and 6 lattices, respectively.

hep-lat↗

arXiv1993

The (dual) Meissner effect in SU(2) and SU(3) QCD

After making an abelian projection in the maximally abelian gauge, we measure the distribution of abelian electric flux and monopole currents around an abelian Wilson loop in $SU(2)$ and $SU(3)$ QCD. The (dual) Meissner effect is observed clearly. The vacua in the confinement phases of $SU(2)$ and $SU(3)$ are both at around the border between type-1 and type-2 (dual) superconductor.

hep-lat↗