109 research outputs found
Light Quenched Hadron Spectrum and Decay Constants on different Lattices
We present a study of (quenched) lattice configurations from
the APE collaboration, for using both the Wilson and the
SW-Clover fermion action. We determine the light hadronic spectrum and meson
decay constants. We extract the inverse lattice spacing using data at the
simulated values of the quark mass. We find an agreement with the experimental
data of for mesonic masses and for baryonic masses and
pseudoscalar decay constants. A larger deviation is present for the vector
decay constants.Comment: 3 pages, Talk presented at LATTICE96(spectrum
Current Renormalisation Constants with an O(a)-improved Fermion Action
Using chiral Ward identities, we determine the renormalisation constants of
bilinear quark operators for the Sheikholeslami-Wohlert action lattice at
beta=6.2. The results are obtained with a high degree of accuracy. For the
vector current renormalisation constant we obtain Z_V=0.817(2)(8), where the
first error is statistical and the second is due to mass dependence of Z_V.
This is close to the perturbative value of 0.83. For the axial current
renormalisation constant we obtain Z_A = 1.045(+10 -14), significantly higher
than the value obtained in perturbation theory. This is shown to reduce the
difference between lattice estimates and the experimental values for the
pseudoscalar meson decay constants, but a significant discrepancy remains. The
ratio of pseudoscalar to scalar renormalisation constants, Z_P/Z_S, is less
well determined, but seems to be slightly lower than the perturbative value.Comment: 8 pages uuencoded compressed postscript file. Article to be submitted
to Phys.Rev.
RESULTS FOR THE B-MESON DECAY CONSTANT FROM THE APE COLLABORATION
The decay constant for the B-meson in the static limit is calculated using
the Wilson and clover actions at various lattice spacings. We show that both
the contamination of our results by excited states and the effects finite
lattice spacing are at most the order of the statistical uncertainties. A
comparison is made of our results and those obtained in other studies. Values
for and are also given.Comment: Contribution to Lattice'94, 3 pages PostScript, uuencoded compresse
Light Quark Mass Determinations from the Lattice
This paper is a review of recent lattice determinations of the light quark
masses. It describes the method employed to calculate quark masses in the
lattice formulation, and the extrapolations required to reach the physical
regime. This review is designed to be accessible to a general audience, not
specifically lattice theorists.Comment: Invited review talk at QCD97, Montpellier (July '97). 8 pages, 2
figures. Requires espcrc2.sty Minor changes: a reference added and a table
updated accordingl
Fluctuations in the vicinity of the phase transition line for two flavor QCD
We study the susceptibilities of quark number, isospin number and electric
charge in numerical simulations of lattice QCD at high temperature and density.
We discuss the equation of state for 2 flavor QCD at non-zero temperature and
density. Derivatives of with respect to quark chemical potential
are calculated up to sixth order. From this Taylor series, the
susceptibilities are estimated as functions of temperature and .
Moreover, we comment on the hadron resonance gas model, which explains well our
simulation results below .Comment: 3 pages, 5 figures, Talk presented at Lattice2004(non-zero
Where is the chiral critical point in 3-flavor QCD?
We determine the location of the second order endpoint of the line of first
order chiral phase transition in 3-flavor QCD at vanishing chemical potential.
Using Ferrenberg-Swendsen reweighting for two values of the quark mass we
determine the dependence of the transition line on the chemical potential and
locate the chiral critical point. For both quantities we find a significant
quark mass dependence.Comment: 3 pages, Lattice2003(nonzero), one reference exchange
QCD at non-zero temperature and density from the lattice
The study of systems as diverse as the cores of neutron stars and heavy-ion
collision experiments requires the understanding of the phase structure of QCD
at non-zero temperature, T, and chemical potential, mu_q. We review some of the
difficulties of performing lattice simulations of QCD with non-zero mu_q, and
outline the re-weighting method used to overcome this problem. This method is
used to determine the critical endpoint of QCD in the (mu_q,T) plane. We study
the pressure and quark number susceptibility at small mu_q.Comment: 5 pages, talk presented by C.R. Allton at the QCD Downunder
Conference, Barossa Valley and Adelaide, March 200
The quark mass and dependence of the QCD chiral critical point
In order to study the QCD chiral critical point we investigate Binder
Cumulants of the chiral condensate. The results were obtained from simulations
of 3 and 2+1 flavors of standard staggered fermions and 3 flavors of p4
improved staggered fermions. The quark masses used are close to the physical
quark mass. To extract the dependence on quark mass and chemical potential we
apply a new reweighting technique based on a Taylor expansion of the action.
The reweighting accuracy is for the standard and ,
for the p4 action.Comment: 3 pages, 6 figures, Lattice2002(nonzerot
Light quenched hadron spectrum and decay constants on different lattices
In this paper we study O(2000) (quenched) lattice configurations from the APE collaboration, for different lattice volumes and for 6.0 less than or equal to beta less than or equal to 6.4 using both the Wilson and the SW-Clover fermion actions, We determine the light hadronic spectrum and meson decay constants and study the mesonic dispersion relation. We extract the hadronic variable J and the strange quark mass in the continuum at the next-to-leading order obtaining m(s)()(mu = 2 GeV) = 122 +/- 20 MeV. A study is made of their dependence on lattice spacing, We implement a newly developed technique to extract the inverse lattice spacing using data at the simulated values of the quark mass (i.e. at masses around the strange quark mass)
The continuum limit of from the lattice in the static approximation
We present an analysis of the continuum extrapolation of in the static
approximation from lattice data. The method described here aims to uncover the
systematic effects which enter in this extrapolation and has not been described
before. Our conclusions are that we see statistical evidence for scaling of
for inverse lattice spacings \gtap 2 GeV but not for \ltap 2
GeV. We observe a lack of {\em asymptotic} scaling for a variety of quantities,
including , at all energy scales considered. This can be associated
with finite lattice spacing systematics. Once these effects are taken into
account, we obtain a value of 230(35) MeV for in the continuum
where the error represents uncertainties due to both the statistics and the
continuum extrapolation. In this method there is no error due to uncertainties
in the renormalization constant connecting the lattice and continuum effective
theories.Comment: 33 pages, latex text file and postscript figures all uuencoded into a
single file, ROME preprint 94/104
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