Glueball relevant study on isoscalars from Nf = 2 lattice QCD

We perform a glueball-relevant study on isoscalars based on anisotropic Nf = 2 lattice QCD gauge configurations. In the scalar channel, we identify the ground state obtained through gluonic operators to be a single-particle state through its dispersion relation. When qq operator is included, we find the mass of this state does not change, and the qq operator couples very weakly to this state. So this state is most likely a glueball state. For pseudoscalars, along with the exiting lattice results, our study implies that both the conventional qq state η2 (or η' in flavor SU(3)) and a heavier glueball-like state with a mass of roughly 2.6 GeV exist in the spectrum of lattice QCD with dynamical quarks.

Quarkonia-Glueball Structure of the Ground Pseudoscalar Mesons

Considering corrections due to SU(3) flavor symmetry breaking, non-ideal ω - ϕ mixing, double OZI and electromagnetic amplitudes of J/ψ decays into a vector and a pseudo-scalar meson, and three-gluon-annihilation amplitudes of radiative decays of J/ψ into a pseudoscalar meson, we investigate two-photon decays of pseudoscalar mesons, radiative decays between pseudoscalar and vector mesons, decays of J/ψ into a vector and a pseudoscalar meson, and radiative decays of J/ψ into a pseudoscalar meson. The quarkonia-glueball structure of η, η′ and η(1440) is phenomenologically deduced from the fit to the updated world average data concerning the above mentioned decays. We find that η (η′) contains about 48.7%, 47.6%, 3.7% (32.9%, 48.8%, 18.3%) non-strange quarkonium, strange quarkonium and glueball components, respectively, and that η(1410) is mainly a glueball state (about 78% glueball component), mixed with 18.5% non-strange quarkonium and 3.5% strange quarkonium. We predict that Br (J/ψ→γη) : Br (J/ψ→γη′) : Br (J/ψ→γη(1410)) = 1.0:5.2:8.0, which can be tested at BEPC/BES with 50 million J/ψ events.

THE FIRST CALCULATION FOR THE MASS OF THE GROUND 4++ GLUEBALL STATE ON LATTICE

Under the quenched approximation, we perform a lattice calculation for the mass of the ground 4++ glueball state in E++ channel on a D =3 + 1 lattice. Our calculation shows that the mass of this state is MG (4++) = 3.65(6)(18) GeV , which rules out the 4++ or mainly 4++ glueball state interpretation for ξ(2230).