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Seyong Kim

Publications and source records attributed to Seyong Kim.

100 records · Page 6Linked to original sources
arXiv1997

Quenched staggered light hadron spectroscopy from $48^3\times64$ at $β= 6.5$

We report our light hadron mass calculation based on an increased statistics of 250 quenched gauge configurations on a (48^3 \times 64) lattice at (β= 6.5). Quark propagators are calculated for each of these configurations with staggered wall source and point sink at quark mass values of (m_q = 0.01, 0.005, 0.0025) and (0.00125). We also did additional calculations to improve our understanding of systematic biases arising from autocorrelation, source size, and propagator calculations. Our earlier conclusions that the flavor symmetry breaking is reduced and the ratio (m_N/m_ρ(\sim 1.25(4))) is small remains robust.

hep-lat↗
arXiv1996

Quenched KS light hadron mass at β=6.5 on a 64\times 48^3 lattice

We report our quenched staggered light hadron mass calculation at the coupling of β= 6.5 on a 48^3 \times 64 lattice, based on an increased statistics of two hundred gauge configurations. Staggered quark wall sources with mass of m_q a = 0.01, 0.005, 0.0025 and 0.00125 are used. Flavor symmetry is restored for pion and ρmeson. The lattice scale is estimated to be a^{-1} = 3.7(2) GeV.

hep-lat↗
arXiv1996

Chiral corrections to the axial charges of the octet baryons from quenched QCD

We calculate one-loop correction to the axial charges of the octet baryons using quenched chiral perturbation theory, in order to understand chiral behavior of the axial charges in quenched approximation to quantum chromodynamics (QCD). In contrast to regular behavior of the full QCD chiral perturbation theory result, $c_0+c_{l2}m_π^2\,\ln{m_π^2}+\cdots$, we find that the quenched chiral perturbation theory result, $c_0^Q+(c_{l0}^Q+c_{l2}^Qm_π^2)\ln{m_π^2}+c_2^Q m_π^2+\cdots$, is singular in the chiral limit.

hep-lat↗
arXiv1996

Lattice Gauge Theory of Three Dimensional Thirring Model

Three dimensional Thirring model with $N$ four-component Dirac fermions, reformulated as a lattice gauge theory, is studied by computer simulation. According to an $8^{3}$ data and preliminary $16^3$ data, chiral symmetry is found to be spontaneously broken for $N=2,\;4$ and 6. $N=2$ data exhibits long tail of the non-vanishing chiral condensate into weak coupling region, and $N=6$ case shows phase separation between the strong coupling region and the weak coupling region. Although the comparison between $8^3$ data and $16^3$ data shows large finite volume effects, an existence of the critical fermion flavor number $N_{\rm cr}$ $(2<N_{\rm cr}<6)$ for which the chiral behavior changes its character, is suggested by the current numerical data.

hep-lat↗
arXiv1995

Some properties of B_c from Lattice QCD

We discuss \(B_c\) mass (1S state) and decay constant \(f_{B_c}\) calculated by lattice non-relativistic quantum chromodynamcs(NRQCD) method. In leading order of \(v^2\), we found that \(M_{B_c} = 6.33(2)\) GeV and \(f_{B_c} = 395(2)\) MeV where the error bar is the statistical error only. Using these values, we estimate QCD effects to leptonic decay width of \(B_c\). The decay width is given by \(Γ(B_c \rightarrow l^+ν_l) = 0.86(15)m^2_l (1 - 0.0250(2)m^2_l)^2\times 10^{-14} ({\rm GeV})\), where \(m_l\) is in GeV. Relativistic correction and \(α_s\) correction to \(f_{B_c}\) have also been considered.

hep-lat↗
arXiv1995

Decay rates of various bottomonium systems

Using the Bodwin--Braaten--Lepage factorization theorem in heavy quarkonium decay and production processes, we calculated matrix elements associated with S- and P-wave bottomonium decays via lattice QCD simulation methods. In this work, we report preliminary results on the operator matching between the lattice expression and the continuum expression at one loop level. Phenomenological implications are discussed using these preliminary \(\overline{MS}\) matrix elements.

hep-lat↗
arXiv1995

Light hadron masses with 4-GeV cutoff and L=2.4fm

We discuss preliminary results from our quenched light hadron mass calculation on a $48^3 \times 64$ lattice at the coupling of $β= 6.5$. Staggered quarks with masses of $m_q = 0.01, 0.005, 0.0025$ and $0.00125$ are used.

hep-lat↗
arXiv1995

Evidence for hard chiral logarithms in quenched lattice QCD

We present the first direct evidence that quenched QCD differs from full QCD in the chiral ($m_q \rightarrow 0$) limit, as predicted by chiral perturbation theory, from our quenched lattice QCD simulations at $β= 6/g^2 = 6.0$. We measured the spectrum of light hadrons on $16^3 \times 64$, $24^3 \times 64$ and $32^3 \times 64$, using staggered quarks of masses $m_q=0.01$, $m_q=0.005$ and $m_q=0.0025$. The pion masses showed clear evidence for logarithmic violations of the PCAC relation $m_π^2 \propto m_q$, as predicted by quenched chiral perturbation theory. The dependence on spatial lattice volume precludes this being a finite size effect. No evidence was seen for such chiral logarithms in the behaviour of the chiral condensate $\langle\barψψ\rangle$.

hep-lat↗
arXiv1994

Looking for the Logarithms in Four-Dimensional Nambu-Jona-Lasinio Models

We study the problem of triviality in the four dimensional Nambu-Jona-Lasinio model with discrete chiral symmetry using both large-N expansions and lattice simulations. We find that logarithmic corrections to scaling appear in the equation of state as predicted by the large-N expansion. The data from $16^4$ lattice simulations is sufficiently accurate to distinguish logarithmically trivial scaling from power law scaling. Simulations on different lattice sizes reveal an interesting interplay of finite size effects and triviality. We argue that such effects are qualitatively different for theories based on fundamental scalar rather than fermion fields. Several lessons learned here can be applied to simulations and analyses of more challenging field theories.

hep-lat↗