Keh-Fei Liu

Glueball spectrum and matrix elements on anisotropic lattices

The glueball-to-vacuum matrix elements of local gluonic operators in scalar, tensor, and pseudoscalar channels are investigated numerically on several anisotropic lattices with the spatial lattice spacing ranging from 0.1-0.2 fm. These matrix elements are needed to predict the glueball branching ratios in J/{psi} radiative decays which will help identify the glueball states in experiments. Two types of improved local gluonic operators are constructed for a self-consistent check and the finite-volume effects are studied. We find that lattice spacing dependence of our results is very weak and the continuum limits are reliably extrapolated, as a result of improvement of the lattice gauge action and local operators. We also give updated glueball masses with various quantum numbers.

Stochastic estimation with Z2 noise

Abstract We introduce a Z 2 noise for the stochastic estimation of matrix inversion and discuss its superiority over other noises including the Gaussian noise. This algorithm is applied to the calculation of quark loops in lattice quantum chromodynamics that involves diagonal and off-diagonal traces of the inverse matrix. We will point out its usefulness in its applications to estimating determinants, eigenvalues, and eigenvectors, as well as its limitations based on the structure of the inverse matrix.

Scalar Glueball, Scalar Quarkonia, and their Mixing

The isosinglet scalar mesons f{sub 0}(1710), f{sub 0}(1500), f{sub 0}(1370) and their mixing are studied. We employ two recent lattice results as the starting point; one is the isovector scalar meson a{sub 0}(1450) which displays an unusual property of being nearly independent of quark mass for quark masses smaller than that of the strange, and the other is the scalar glueball mass at 1710 MeV in the quenched approximation. In the SU(3) symmetry limit, f{sub 0}(1500) turns out to be a pure SU(3) octet and is degenerate with a{sub 0}(1450), while f{sub 0}(1370) is mainly an SU(3) singlet with a slight mixing with the scalar glueball which is the primary component of f{sub 0}(1710). These features remain essentially unchanged even when SU(3) breaking is taken into account. We discuss the sources of SU(3) breaking and their consequences on flavor-dependent decays of these mesons. The observed enhancement of {omega}f{sub 0}(1710) production over {phi}f{sub 0}(1710) in hadronic J/{psi} decays and the copious f{sub 0}(1710) production in radiative J/{psi} decays lend further support to the prominent glueball nature of f{sub 0}(1710)

Study of pentaquarks on the lattice with overlap fermions

We present a quenched lattice QCD calculation of spin-

Flavor-singlet gA from lattice QCD.

1/2

Strangeness and charmness content of the nucleon from overlap fermions on 2+1-flavor domain-wall fermion configurations

five-quark states with

Lattice calculation of the strangeness magnetic moment of the nucleon

uudd\overline{s}

Lattice study of light scalar tetraquarks with I=0,2,1/2,3/2: Are \sigma and \kappa tetraquarks?

quark content for both positive and negative parities. We do not observe any bound pentaquark state in these channels for either

Lattice QCD at finite density via a new canonical approach

I=0

Role of nuclear binding in the EMC effect

or