9,088 research outputs found
A systematic approach to sketch Bethe-Salpeter equation
To study meson properties, one needs to solve the gap equation for the quark
propagator and the Bethe-Salpeter (BS) equation for the meson wavefunction,
self-consistently. The gluon propagator, the quark-gluon vertex, and the
quark--anti-quark scattering kernel are key pieces to solve those equations.
Predicted by lattice-QCD and Dyson-Schwinger analyses of QCD's gauge sector,
gluons are non-perturbatively massive. In the matter sector, the modeled gluon
propagator which can produce a veracious description of meson properties needs
to possess a mass scale, accordingly. Solving the well-known longitudinal
Ward-Green-Takahashi identities (WGTIs) and the less-known transverse
counterparts together, one obtains a nontrivial solution which can shed light
on the structure of the quark-gluon vertex. It is highlighted that the
phenomenologically proposed anomalous chromomagnetic moment (ACM) vertex
originates from the QCD Lagrangian symmetries and its strength is proportional
to the magnitude of dynamical chiral symmetry breaking (DCSB). The
color-singlet vector and axial-vector WGTIs can relate the BS kernel and the
dressed quark-gluon vertex to each other. Using the relation, one can truncate
the gap equation and the BS equation, systematically, without violating crucial
symmetries, e.g., gauge symmetry and chiral symmetry.Comment: 4 pages, 21st International Conference on Few-Body Problems in
Physic
A range extension for Haplomitrium mnioides (Lindb.) R.M.Schust.
Haplomitrium mnioides (Lindb.) R.M.Schust. is reported as new to Hainan Island. A continuous distribution of H. mnioides from west (Thailand) to east (Japan) is confirmed. Habitat pictures and a distribution map are provided
Charmonium Spectral Functions and Transport Properties of Quark-Gluon Plasma
We study vacuum masses of charmonia and the charm-quark diffusion coefficient
in the quark-gluon plasma based on the spectral representation for meson
correlators. To calculate the correlators, we solve the quark gap equation and
the inhomogeneous Bethe-Salpeter equation in the rainbow-ladder approximation.
It is found that the ground-state masses of charmonia in the pseudoscalar,
scalar, and vector channels can be well described. For ,
the value of the diffusion coefficient is comparable with that obtained by
lattice QCD and experiments: . Relating the diffusion
coefficient with the ratio of shear viscosity to entropy density of
the quark-gluon plasma, we obtain values in the range .Comment: 5 pages, 4 figure
Local Ideal Point Method for GIS-based Multicriteria Analysis: A Case Study in London, Ontario
GIS-based multicriteria analysis (GIS-MCA) is a procedure for transforming and combining geographic data and value judgments (preferences) to evaluate a set of alternatives with respect to relevant criteria. Ideal Point Method (IPM) is one of the most often used GIS-MCA techniques. It has been applied in many research/planning areas including environmental planning, urban/regional planning, waste management, water resource management and agriculture. One of the limitations of IPM is that it has conventionally been used as a global approach based on the implicit assumption that its parameters do not vary as a function of geographic space. The conventional IPM assumes a spatial homogeneity of its parameters within the whole study area. This thesis proposes a new IPM called local IPM. The local version of IPM is developed by localizing two parameters (criterion weights and ideal/nadir points) based on the range-sensitivity principle. The IPM methods are used to evaluate and analyse the spatial patterns of the quality of employment in London, Ontario. The case study shows that there are significant differences between the spatial patterns generated by the local and conventional IPM. The local IPM not only can display the general ‘spatial trend’ of the quality of employment in London, but also is able to highlight the areas with relatively high quality of employment in different neighborhoods. Furthermore, the local IPM provides a tool for visualizing and exploring spatial patterns. The parameters influencing the local IPM results can be mapped and further examined with GIS
Temperature Dependence of the Effective Bag Constant and the Radius of a Nucleon in the Global Color Symmetry Model of QCD
We study the temperature dependence of the effective bag constant, the mass,
and the radius of a nucleon in the formalism of the simple global color
symmetry model in the Dyson-Schwinger equation approach of QCD with a
Gaussian-type effective gluon propagator. We obtain that, as the temperature is
lower than a critical value, the effective bag constant and the mass decrease
and the radius increases with the temperature increasing. As the critical
temperature is reached, the effective bag constant and the mass vanish and the
radius tends to infinity. At the same time, the chiral quark condensate
disappears. These phenomena indicate that the deconfinement and the chiral
symmetry restoration phase transitions can take place at high temperature. The
dependence of the critical temperature on the interaction strength parameter in
the effective gluon propagator of the approach is given.Comment: 10 pages, 9 figure
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