2,218 research outputs found
Remarks on the f_0(400-1200) scalar meson as the dynamically generated chiral partner of the pion
The quark-level linear sigma model is revisited, in particular concerning the
identification of the f_0(400-1200) (or \sigma(600)) scalar meson as the chiral
partner of the pion. We demonstrate the predictive power of the linear sigma
model through the pi-pi and pi-N s-wave scattering lengths, as well as several
electromagnetic, weak, and strong decays of pseudoscalar and vector mesons. The
ease with which the data for these observables are reproduced in the linear
sigma model lends credit to the necessity to include the sigma as a fundamental
q\bar{q} degree of freedom, to be contrasted with approaches like chiral
perturbation theory or the confining NJL model of Shakin and Wang.Comment: 15 pages, plain LaTeX, 3 EPS figure
SU(3) Mass Splittings for Mesons and Baryons
By comparing SU(3)-breaking scales of linear mass formulae, it is shown that
the lowest vector, axial-vector, and scalar mesons all have a
configuration, while the ground-state octet and decuplet baryons are .
Also, the quark-level linear model is employed to predict similar
and states. Finally, the approximate mass degeneracy of the
scalar (980) and (980) mesons is demonstrated to be accidental.Comment: 8 Pages, AIP Proc. Style; Contribution to the High-Energy Physics
Workshop "Scalar Mesons: an Interesting Puzzle for QCD", May 16-18, 2003,
SUNY Institute of Technology, Utica (NY
Images in Christmas Balls
We describe light-reflection properties of spherically curved mirrors, like
balls in the Christmas tree. In particular, we study the position of the image
which is formed somewhere beyond the surface of a spherical mirror, when an eye
observes the image of a pointlike light source. The considered problem,
originally posed by Abu Ali Hasan Ibn al-Haitham -- alias Alhazen -- more than
a millennium ago, turned out to have the now well known analytic solution of a
biquadratic equation, being still of great relevance, e.g. for the
aberration-free construction of telescopes. We do not attempt to perform an
exhaustive survey of the rich historical and engineering literature on the
subject, but develop a simple pedagogical approach to the issue, which we
believe to be of continuing interest in view of its maltreating in many
high-school textbooks.Comment: 13 pages, 7 figures plain LaTeX; Also see
http://cft.fis.uc.pt/eef/mirrors.htm, revised version has simplified
formulas, more transparent for a wider audience, one reference adde
The Separable Kernel of Nucleon-Nucleon Interaction in the Bethe-Salpeter Approach
The dispersion relations for nucleon-nucleon (NN) T-matrix in the framework
of Bethe-Salpeter equation for two spin one-half particle system and with
separable kernel of interaction are considered in the paper. The developed
expressions are applied for construction of the separable kernel of interaction
for S partial-waves in singlet and triplet channels. We calculate the low
energy scattering parameters and the phase shifts and also the deuteron binding
energy with the separable interaction. The approach can be easily extended to
higher partial-waves for NN-scattering and other reactions (anti N N-, pi
N-scattering).Comment: RevTex 4 style, 9 pages, 1 figur
Cadmiumtoxizität bei Weinreben
Toxicity of cadmium to grapevineCultings of the cv. Riesling were cultivated in nutrient solutions with different amounts of cadmium.Cadmium inhibited the growth of shoot and of leaf area and produced chlorosis, necroses and leaf deformations. Old leaves showed no symptoms at all, but with high cadmium levels leaf fall occurred.The threshold of cadmium damage was beneath a level of 0.1 ppm Cd of the nutrient solution.The dry matter production of the plants was reduced by cadmium: 0.66 mg Cd/l of nutrient solution caused an inhibition of 50 %.Cadmium reduced the chlorophyll content of the leaves.The transport of iron from roots to leaves was inhibited nearly complete ly by medium to high levels of cadmium {1.0, 3.0, 10.0 ppm). Iron was accumulated in the roots. Thus cadmium may have caused an iron deficiency chloros is in grapevines.The uptake of cadmium showed a clear dependence on the amount of cadmium in the nutrient solution . Within the plants, decreasing amounts of cadmium were found following the pattern roots - stem - leaves
Relativistic three-particle scattering equations
We derive a set of relativistic three-particle scattering equations in the
three-particle c.m. frame employing a relativistic three-particle propagator
suggested long ago by Ahmadzadeh and Tjon in the c.m. frame of a two-particle
subsystem. We make the coordinate transformation of this propagator from the
c.m. frame of the two-particle subsystem to the three-particle c.m. frame. We
also point out that some numerical applications of the Ahmadzadeh and Tjon
propagator to the three-nucleon problem use unnecessary nonrelativistic
approximations which do not simplify the computational task, but violate
constraints of relativistic unitarity and/or covariance.Comment: 5pages, text and one ps figure (in revtex) include
Relativistic Contributions to Deuteron Photodisintegration in the Bethe-Salpeter Formalism
In plane wave one-body approximation the reaction of deuteron
photodisintegration is considered in the framework of the Bethe-Salpeter
formalism for two-nucleon system. Results are obtained for deuteron vertex
function, which is the solution of the homogeneous Bethe-Salpeter equation with
a multi-rank separable interaction kernel, with a given analytical form. A
comparison is presented with predictions of non-relativistic, quasipotential
approaches and the equal time approximation. It is shown that important
contributions come from the boost in the arguments of the initial state vertex
function and the boost on the relative energy in the one-particle propagator
due to recoil.Comment: 29 pages, 6 figure
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