328 research outputs found
Non-perturbative Analysis of Various Mass Generation by Gluonic Dressing Effect with the Schwinger-Dyson Formalism in QCD
As a topic of "quantum color dynamics", we study various mass generation of
colored particles and gluonic dressing effect in a non-perturbative manner,
using the Schwinger-Dyson (SD) formalism in (scalar) QCD. First, we review
dynamical quark-mass generation in QCD in the SD approach as a typical
fermion-mass generation via spontaneous chiral-symmetry breaking. Second, using
the SD formalism for scalar QCD, we investigate the scalar diquark, a
bound-state-like object of two quarks, and its mass generation, which is
clearly non-chiral-origin. Here, the scalar diquark is treated as an extended
colored scalar field, like a meson in effective hadron models, and its
effective size is introduced as a form factor. As a diagrammatical
difference, the SD equation for the scalar diquark has an additional 4-point
interaction term, in comparison with the single quark case. The diquark size
is taken to be smaller than a hadron, fm, and larger than a
constituent quark, fm. We find that the compact diquark with
fm has a large effective mass of about 900 MeV, and therefore
such a compact diquark is not acceptable in effective models for hadrons. We
also consider the artificial removal of 3- and 4-point interaction,
respectively, to see the role of each term, and find that the 4-point
interaction plays the dominant role of the diquark self-energy. From the above
two different cases, quarks and diquarks, we guess that the mass generation of
colored particles is a general result of non-perturbative gluonic dressing
effect.Comment: 17 pages, 15 figure
Quark tensor charge and electric dipole moment within the Schwinger-Dyson formalism
We calculate the tensor charge of the quark in the QCD-like theory in the
Landau gauge using the Schwinger-Dyson formalism. It is found that the dressed
tensor charge of the quark is significantly suppressed against the bare quark
contribution, and the result agrees qualitatively with the analyses in the
collinear factorization approach and lattice QCD. We also analyze the quark
confinement effect with the phenomenological strong coupling given by
Richardson, and find that this contribution is small. We show that the
suppression of the quark tensor charge is due to the superposition of the spin
flip of the quark arising from the successive emission of gluons which dress
the tensor vertex. We also consider the relation between the quark and the
nucleon electric dipole moments by combining with the simple constituent quark
model.Comment: 16 pages, 11 figures. arXiv admin note: text overlap with
arXiv:1401.285
Quark scalar, axial, and pseudoscalar charges in the Schwinger-Dyson formalism
We calculate the scalar, axial, and pseudoscalar charges of the quark in the
Schwinger-Dyson formalism of Landau gauge QCD. It is found that the dressed
quark scalar density of the valence quark is significantly enhanced against the
bare quark contribution, and the result explains qualitatively the
phenomenologically known value of the pion-nucleon sigma term and also that
given by lattice QCD. Moreover, we show that the Richardson's interquark
potential suppresses the quark scalar density in the Higashjima-Miransky
approximation. This fact suggests that the quark scalar density is an
observable that is sensitive to quark confinement. For the quark axial charge,
we find that it is suppressed due to the gluon dynamics. The result of the
quenched analysis agrees qualitatively with the experimental data of the
isovector axial coupling constant . We show that the suppression of the
quenched axial charge is due to a mechanism similar to that of the quark tensor
charge. In the Schwinger-Dyson equation with the leading unquenching quark-loop
contribution the quark axial charge is more suppressed, due to the anomaly
effect. The quark pseudoscalar density is found to be large, and is divergent
as the bare quark becomes massless. This result is in agreement with the
phenomenological current algebraic analysis, and explains well the dominance of
the pion-pole contribution.Comment: 28 pages, 22 figure
Microbiological Studies of Coli-aerogenee Bacteria. (I) : Convertion of the Lactic Acid Fermentation to α-Ketoglutaric Acid Fermentation
HISTOCHEMICAL STUDY ON THE CHANGE OF 17β-HYDROXYSTEROID DEHYDROGENASE ACTIVITY IN THE OYSTER DURING THE STAGES OF SEXUAL MATURATION AND SPAWNING
A Numerical Method for Distinction between Blow-up and Global Solutions of the Nonlinear Heat Equation
The famous one-dimensional nonlinear heat equation is considered.
To this equation a numerical method for distinction between blow-up
and global solutions is proposed. Difficulty is in the treatment of the
global solution which is defined in the infinite interval. The bounding
transform is used to overcome this difficulty. Numerical experiments
show the validity of our method
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