68 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
Thick-target yields of radioactive targets deduced from inverse kinematics
The thick-target yield (TTY) is a macroscopic quantity reflected by nuclear
reactions and matter properties of targets. In order to evaluate TTYs on
radioactive targets, we suggest a conversion method from inverse kinematics
corresponding to the reaction of radioactive beams on stable targets. The
method to deduce the TTY is theoretically derived from inverse kinematics. We
apply the method to the natCu(12C,X)24Na reaction to confirm availability. In
addition, it is applied to the 137Cs + 12C reaction as an example of a
radioactive system and discussed a conversion coefficient of a TTY measurement.Comment: 8 pages, 3 figures, Accepted to Nuclear Instruments and Methods in
Physics Research
Quark-Hadron Matter at Finite Temperature and Density in a Two-Color PNJL model
Quark-hadron matter at finite temperature and density is studied using a
two-flavor, color SU(2) (P)NJL model. The hadronic effective Lagrangian,
derived by bosonization of the quark fields and renormalized using the Eguchi
method, emerges in the form of an extended linear sigma model with meson and
diquark-baryon fields. Chiral and diquark condensates are studied as functions
of temperature and baryon density. Masses of mesons and diquark-baryons are
calculated with and without the Polyakov loop effect. We investigate the
equation of state of quark-hadron matter by taking into account the
contributions of mesons and diquark-baryons in addition to the quark
quasiparticles.Comment: 42 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
Thermodynamics of hadrons using the Gaussian functional method in the linear sigma model
We investigate thermodynamics of hadrons using the Gaussian functional method
(GFM) at finite temperature. Since the interaction among mesons is very large,
we take into account fluctuations of mesons around their mean field values
using the GFM. We obtain the ground state energy by solving the Schr\"{o}dinger
equation. The meson masses are obtained using the energy minimization
condition. The resulting mass of the Nambu-Goldstone boson is not zero even in
the spontaneous chiral symmetry broken phase due to the non-perturbative
effect. We consider then the bound state of mesons using the Bethe-Salpeter
equation and show that the Nambu-Goldstone theorem is recovered. We investigate
further the behavior of the meson masses and the mean filed value as functions
of temperature for the cases of chiral limit and explicit chiral symmetry
breaking.Comment: 5 pages, 8 figures, contribution to proceedings of XV International
Conference on Hadron Spectroscopy-Hadron 201
2カラー ナンブ ヨナラシニオ モケイ 二 オケル クォークハドロン ブッシツ ノ ケンキュウ
this is the author’s version of a work that was accepted for publication in Nuclear Physics A. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in PUBLICATION, [VOL913,(2 September 2013)] DOI:10.1016/j.nuclphysa.2013.06.00
Isotopic analysis of Ni, Cu, and Zn in freshwater for source identification
Nickel (Ni), copper (Cu), and zinc (Zn) are commonly used in human activities and pollute aquatic environments including rivers and oceans. Recently, Ni, Cu, and Zn isotope ratios have been measured to identify their sources and cycles in environments. We precisely determined the Ni, Cu, and Zn isotope ratios in rain, snow, and rime collected from Uji City and Mt. Kajigamori in Japan, and investigated the potential of isotopic ratios as tracers of anthropogenic materials. The isotope and elemental ratios suggested that road dust is the main source of Cu in most rain, snow, and rime samples and that some of the Cu may originate from fossil fuel combustion. Zinc in the rain, snow, and rime samples may be partially attributed to Zn in road dust. Zinc isotope ratios in the Uji rain samples are lower than those in the road dust, which would be emitted via high temperature processes. Nickel isotope ratios are correlated with V/Ni ratios in the rain, snow, and rime samples, suggesting that their main source is heavy oil combustion. Furthermore, we analyzed water samples from the Uji and Tawara Rivers and the Kakita River spring in Japan. Nickel and Cu isotope ratios in the river water samples were significantly heavier than those in rain, snow, and rime samples, while Zn isotope ratios were similar. This is attributed to isotopic fractionation of Cu and Ni between particulate-dissolved phases in river water or soil
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