Scalar: Lattice
- : Scalar meson in dynamical and partially quenched two-flavor QCD: lattice
results and chiral loops
S. Prelovsek, C. Dawson, T. Izubuchi, K. Orginos and A. Soni
hep-lat/0407037
This is an exploratory study of the lightest non-singlet scalar $q\bar q$
state on the lattice with two dynamical quarks. Domain Wall fermions are used
for both sea and valence quarks on a 16^3*32 lattice with an inverse lattice
spacing of 1.7 GeV. We extract the scalar meson mass 1.58(34) GeV from the
exponential time-dependence of the dynamical correlators with $m_{val}=m_{sea}$
and N_f=2. Since this statistical error-bar from dynamical correlators is
rather large, we analyze also the partially quenched lattice correlators with
$m_{val}$ not equal $m_{sea}$. They are positive for $m_{val}>=m_{sea}$ and
negative for $m_{val}=m_{sea}$ and
negative for $m_{val}
- Scalar Mesons in Lattice QCD
SCALAR Collaboration: Teiji Kunihiro, Shin Muroya, Atsushi Nakamura,
Chiho Nonaka, Motoo Sekiguchi, Hiroaki Wada
hep-ph/0310312
We explore whether "f$_{0}$(600) or $\sigma$" exists as a pole in QCD, by a
full lattice QCD simulation on the $8^{3} \times 16$ lattice using the
plaquette action and Wilson fermions. It is shown that a low-mass $\sigma$ pole
exists owing to the disconnected diagram of the meson propagator. A discussion
is given on the physical content of the $\sigma$.
- Scalar Mesons as qbar^2 q^2? Insight from the Lattice
M. Alford, R.L. Jaffe
hep-lat/0306037
I describe some insight obtained from a lattice calculation on the
possibility that the light scalar mesons are \qbar^2 q^2 states rather than
\qbar q. First I review some general features of \qbar^2 q^2 states in QCD
inspired quark models. Then I describe a lattice QCD calculation of
pseudoscalar meson scattering amplitudes, ignoring quark loops and quark
annihilation, which finds indications that for sufficiently heavy quarks there
is a stable four-quark bound state with JPC=0{++} and non-exotic flavor quantum
numbers.
- Lattice study of "f$_{0}$(600) or $\sigma$"
SCALAR Collaboration: Teiji Kunihiro, Shin Muroya, Atsushi Nakamura,
Chiho Nonaka, Motoo Sekiguchi and Hiroaki Wada
hep-lat/0210012
We investigate the propagator of "f$_{0}$(600) or the $\sigma$" by the
full-QCD simulation with Wilson fermions. We calculate the mesonic correlator
in the I=0, $J^P=0^{+}$ channel on the $8^{3} \times 16$ lattice. Plaquet
action and Wilson fermion action are adopted. A coupling constant $\beta$ is
set to 4.8 and three kinds of hopping parameter, $\kappa$=0.1846, 0.1874 and
0.1891 are assayed. The disconnected diagram in the propagator is evaluated
through taking average over 500 or 1000 Z2 noise. Simulations with the larger
hopping parameter provide us with less noisy results. Though the statistics is
not yet enough, our results indicate the existence of a pole with a mass in
almost the same order as that of the $\rho$.
- Masses of singlet and non-singlet 0++ particles
UKQCD Collaboration: Alistair Hart, Craig McNeile, and Chris Michael
hep-lat/0209063
We compute the mass of the singlet 0++ state using both (psi_bar psi) and
Wilson loop operators from a N_f=2 lattice QCD calculation.
- Flavour Singlet Mesons in Full QCD on the Lattice
Authors: K. Schilling, H. Neff, N. Eicker, Th. Lippert, and J.W. Negele
hep-lat/0201009
We apply spectral methods to compute the OZI-rule suppressed loop-loop
correlators in the pseudoscalar meson flavour singlet channel. Using SESAM
configurations (obtained with two degenerate sea quark flavours on 16x16x16x32
lattices at beta = 5.6 with standard Wilson action), we find for the first time
clear evidence for mass plateau formation in the eta' channel of this theory.
As a consequence, we observe a clear signal of a mass gap persistent under
chiral extrapolation. This sets the stage for a more realistic two-channel
approach, where partially quenched strange quarks would be included, in
addition to u, d sea quarks.
- I=0 scalar channel
SCALAR Collaboration: S. Muroya, A. Nakamura, C. Nonaka, M. Sekiguchi
and H. Wada
hep-lat/0112012
Using lattice QCD with dynamical Wilson fermions, we study I=0 and
$J^{P}=0^{+}$ channel which is constructed by
$\frac{1}{\sqrt{2}}(\bar{u}u+\bar{d}d)|0>$, in order to search for the $\sigma$
meson. Our preliminary result shows that the connected and disconnected
diagrams contribute to the $\sigma$ meson propagator in the same order.
- The flavour singlet mesons in QCD
UKQCD Collaboration: C. McNeile, C. Michael and K. J. Sharkey
hep-lat/0107003
We study the flavour singlet mesons from first principles using lattice QCD.
We explore the splitting between flavour singlet and non-singlet for vector and
axial mesons as well as the more commonly studied cases of the scalar and
pseudoscalar mesons.
- Chiral Loops and Ghost States in the Quenched Scalar Propagator
W. Bardeen, A. Duncan, E. Eichten, N. Isgur and H. Thacker
hep-lat/0106008
The scalar, isovector meson propagator is analyzed in quenched QCD, using the
MQA pole-shifting ansatz to study the chiral limit. In addition to the expected
short-range exponential falloff characteristic of a heavy scalar meson, the
propagator also exhibits a longer-range, negative metric contribution which
becomes pronounced for smaller quark masses. We show that this is a quenched
chiral loop effect associated with the anomalous structure of the $\eta '$
propagator in quenched QCD. Both the time dependence and the quark mass
dependence of this effect are well-described by a chiral loop diagram
corresponding to an $\eta '- \pi$ intermediate state, which is light and
effectively of negative norm in the quenched approximation. The relevant
parameters of the effective Lagrangian describing the scalar sector of the
quenched theory are determined.
- The radial wavefunctions of a heavy-light meson calculated on a lattice
UKQCD Collaboration: A.M. Green, J. Koponen, P. Pennanen, C. Michael
hep-lat/0009015
A brief review is given of attempts to understand the energies of four-quark
systems calculated on a lattice in terms of nuclear-physics-inspired many-body
techniques involving interquark potentials. Results are given for the next
stage of this study where the wavefunctions of heavy-light mesons are also
calculated on a lattice.
- Insight into the Scalar Mesons from a Lattice Calculation
Mark Alford and R. L. Jaffe
hep-lat/0001023
We study the possibility that the light scalar mesons are (qbar qbar q q)
states rather than (qbar q). We perform a lattice QCD calculation of
pseudoscalar meson scattering amplitudes, ignoring quark loops and quark
annihilation, and find indications that for sufficiently heavy quarks there is
a stable four-quark bound state with J^{PC}=0^{++} and non-exotic flavor
quantum numbers.
- Flavour-singlet pseudoscalar and scalar mesons
C. Michael, M. S. Foster and C. McNeile (UKQCD Collaboration)
hep-lat/9909036
We measure correlations appropriate for favour-singlet mesons using dynamical
quark configurations from UKQCD. Improved methods of evaluating the
disconnected quark diagrams are presented. The scalar and pseudoscalar meson
channels are explored, with special reference to the mixing of scalar mesons
with scalar glueballs.
- Overview from lattice QCD
Gunnar S. Bali (Humboldt-Universitaet zu Berlin)
Plenary talk presented at
``Nuclear and Particle physics with CEBAF at Jefferson Lab'', Dubrovnik,
November 3-10, 1998
hep-lat/9901023
I review recent Lattice results. In particular, the confinement mechanism and
string breaking, glueballs and hybrid mesons as well as light hadron
spectroscopy are discussed.