We determine the chiral condensate from simulations of quenched lattice QCD with Wilson fermions. Our measurements have been obtained with high statistics at three values of the gauge coupling, ...corresponding to UV cutoffs in the range 2–4 GeV. Several improvements have been made with respect to earlier lattice computations. The most important are the non-perturbative renormalization of the condensate, the use of the tree-level improved Clover action and the reduction of the systematic error due to uncertainties in the lattice calibration. Our result for the chiral condensate in the
MS
scheme is
〈
ψψ〉
MS
(μ = 2
GeV) = −0.0147(8)(16)(12)
GeV
3 = −245(4)(9)(7)
MeV
3
, where the first error is statistical, the second is due to the non-perturbative renormalization and the third due to the lattice calibration.
This study evaluated the content of heavy metals in samples of eye shadows. Samples were manufactured in different countries (China, Italy, and USA). The content of Pb was measured by flame-atomic ...absorption spectrometry (F-AAS). The quantification of cadmium, cobalt, chromium, and nickel was performed by inductively coupled plasma-mass spectrometry (ICP-MS). The analyses were preceded by microwave-assisted acid digestion of the eye shadows. In many samples the lead was present within 20μgg−1, the value indicated as safe in good manufacturing practice, but it exceed this limit in four Chinese samples. The levels of cadmium, chromium and cobalt were always low and within acceptable and safe concentrations for the products made in Italy and USA, but the nickel concentrationexceeded the safe limit in many Chinese eye shadows. The overall results indicate that eye shadows are likely harmful when they are made according to current regulations, while products imported from China can be harmful. Therefore, major quality controls are recommended for products designed to enter in direct and long contact with the skin of eyelids when imported from countries with different regulations.
► Eye shadows are pigmented make-up products. ► Heavy metals are retained as impurities in the pigments of eye shadows. ► Continual exposure to heavy metals may entail adverse health effects. ► Content of heavy metals in commercial eye shadows is analyzed. ► Products imported from China could exceed safe limit imposed by European legislation.
We discuss the renormalization of different definitions of quark masses in the Wilson and the tree-level improved SW-Clover fermionic action. Using perturbative and non-perturbative renormalization ...constants, we study quark masses in the
MS
scheme from Lattice QCD in the quenched approximation at
β = 6.0,
β = 6.2 and
β = 6.4 for both actions. A reliable extrapolation to the continuum limit is however not yet possible. The most reliable results are
m
MS
(2
GeV) = 5.7±0.1±0.8
MeV
,
m
s
MS
(2
GeV) = 130±2±18
MeV and m
c
MS
(2
GeV) = 1662±30±230
MeV
.
In this paper we study
▪(2000) (quenched) lattice configurations from the APE collaboration, for different lattice volumes and for 6.0 ⩽
β ⩽ 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
MS
(μ = 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).
We compute non-perturbatively the renormalization constants of quark bilinears on the lattice in the quenched approximation at three values of the coupling
β = 6/
g
0
2 = 6.0, 6.2, 6.4 using both the ...Wilson and the tree-level improved SW-Clover fermion action. We perform a Renormalization Group analysis at the next-to-next-to-leading order and compute Renormalization Group invariant values for the constants. The results are applied to obtain a fully non-perturbative estimate of the vector and pseudoscalar decay constants.
We argue that there is strong experimental evidence in the data of
b- and
c-decays that the pattern of power suppressed corrections predicted by the short distance expansion, the heavy quark ...effective theory and the assumption of local duality is not correct for the non-leptonic inclusive widths. The data indicate instead the presence of
1
m
corrections that should be absent in the above theoretical framework. These corrections can be simply described by replacing the heavy quark mass by the mass of the decaying hadron in the
m
5 factor in front of all the non-leptonic widths.
The apeNEXT project Belletti, F.; Bodin, F.; Boucaud, Ph ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2006, Letnik:
559, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Numerical simulations in theoretical high-energy physics (Lattice QCD) require huge computing resources. Several generations of massively parallel computers optimised for these applications have been ...developed within the APE (array processor experiment) project. Large prototype systems of the latest generation,
apeNEXT, are currently being assembled and tested. This contribution explains how the
apeNEXT architecture is optimised for Lattice QCD, provides an overview of the hardware and software of
apeNEXT, and describes its new features, like the SPMD programming model and the C compiler.
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