4,198 research outputs found
A Display Calibration Technique based on Invariant Human Colour Mechanisms
When human observers are asked to adjust a coloured light such that it appears neither red nor green, or such that it appears neither yellow nor blue, most colour-normal observers have no difficulty in making these adjustments. These hue judgements are not significantly influenced by language or age [Saunders and van Brakel 1997] and individual differences in colour sensitivity are not reflected in the unique-hue settings [Webster et al. 2000]. The human colour system seems to be able to calibrate itself so that there is a remarkable agreement across observers in relation to these unique-hue judgements. Here we show how we can use the invariance of these unique-hue judgements to develop a colour calibration technique for display devices, which eliminates the need for an external calibration standard or a measurement device
Lattice QCD calculation of hadronic light-by-light scattering
We perform a lattice QCD calculation of the hadronic light-by-light
scattering amplitude in a broad kinematical range. At forward kinematics, the
results are compared to a phenomenological analysis based on dispersive sum
rules for light-by-light scattering. The size of the pion pole contribution is
investigated for momenta of typical hadronic size. The presented numerical
methods can be used to compute the hadronic light-by-light contribution to the
anomalous magnetic moment of the muon. Our calculations are carried out in
two-flavor QCD with the pion mass in the range of 270 to 450MeV, and contain so
far only the diagrams with fully connected quark lines.Comment: 5 pages, 5 figure
Nucleon average quark momentum fraction with Wilson fermions
We report on an analysis of the average quark momentum fraction of the
nucleon and related quantities using Wilson fermions.
Computations are performed on four CLS ensembles covering three values of the
lattice spacing at pion masses down to .
Several source-sink separations ( to ) are used to assess the excited-state contamination. To gain
further insight, the generalized pencil-of-functions approach has been
implemented to reduce the excited-state contamination in the relevant two- and
three-point functions. Preliminary results are shown for the isovector nucleon
charges from vector, axial vector and tensor derivative (twist-2) operators.Comment: 8 pages, 3 figures, 2 tables. Talk presented at the 35th
International Symposium on Lattice Field Theory, 18-24 June 2017, Granada,
Spai
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