20,790 research outputs found
Spin and angular momentum in the nucleon
Using the covariant spectator theory (CST), we present the results of a
valence quark-diquark model calculation of the nucleon structure function f(x)
measured in unpolarized deep inelastic scattering (DIS), and the structure
functions g1(x) and g2(x) measured in DIS using polarized beams and targets.
Parameters of the wave functions are adjusted to fit all the data. The fit
fixes both the shape of the wave functions and the relative strength of each
component. Two solutions are found that fit f(x) and g1(x), but only one of
these gives a good description of g2(x). This fit requires the nucleon CST wave
functions contain a large D-wave component (about 35%) and a small P-wave
component (about 0.6%). The significance of these results is discussed.Comment: 27 pages; 13 figure
Normalization of the covariant three-body bound state vertex function
The normalization condition for the relativistic three nucleon Bethe-Salpeter
and Gross bound state vertex functions is derived, for the first time, directly
from the three body wave equations. It is also shown that the relativistic
normalization condition for the two body Gross bound state vertex function is
identical to the requirement that the bound state charge be conserved, proving
that charge is automatically conserved by this equation.Comment: 24 pages, 9 figures, published version, minor typos correcte
Quark-Antiquark Bound States in the Relativistic Spectator Formalism
The quark-antiquark bound states are discussed using the relativistic
spectator (Gross) equations. A relativistic covariant framework for analyzing
confined bound states is developed. The relativistic linear potential developed
in an earlier work is proven to give vanishing meson decay
amplitudes, as required by confinement. The regularization of the singularities
in the linear potential that are associated with nonzero energy transfers (i.e.
) is improved. Quark mass functions that build chiral
symmetry into the theory and explain the connection between the current quark
and constituent quark masses are introduced. The formalism is applied to the
description of pions and kaons with reasonable results.Comment: 31 pages, 16 figure
Tropical eigenwave and intermediate Jacobians
Tropical manifolds are polyhedral complexes enhanced with certain kind of
affine structure. This structure manifests itself through a particular
cohomology class which we call the eigenwave of a tropical manifold. Other wave
classes of similar type are responsible for deformations of the tropical
structure.
If a tropical manifold is approximable by a 1-parametric family of complex
manifolds then the eigenwave records the monodromy of the family around the
tropical limit. With the help of tropical homology and the eigenwave we define
tropical intermediate Jacobians which can be viewed as tropical analogs of
classical intermediate Jacobians.Comment: 38 pages, 8 figure
Relativistic calculation of the triton binding energy and its implications
First results for the triton binding energy obtained from the relativistic
spectator or Gross equation are reported. The Dirac structure of the nucleons
is taken into account. Numerical results are presented for a family of
realistic OBE models with off-shell scalar couplings. It is shown that these
off-shell couplings improve both the fits to the two-body data and the
predictions for the binding energy.Comment: 5 pages, RevTeX 3.0, 1 figure (uses epsfig.sty
On the "Causality Paradox" of Time-Dependent Density Functional Theory
I show that the so-called causality paradox of time-dependent density
functional theory arises from an incorrect formulation of the variational
principle for the time evolution of the density. The correct formulation not
only resolves the paradox in real time, but also leads to a new expression for
the causal exchange-correlation kernel in terms of Berry curvature.
Furthermore, I show that all the results that were previously derived from
symmetries of the action functional remain valid in the present formulation.
Finally, I develop a model functional theory which explicitly demonstrates the
workings of the new formulation.Comment: 21 page
Covariant equations for the three-body bound state
The covariant spectator (or Gross) equations for the bound state of three
identical spin 1/2 particles, in which two of the three interacting particles
are always on shell, are developed and reduced to a form suitable for numerical
solution. The equations are first written in operator form and compared to the
Bethe-Salpeter equation, then expanded into plane wave momentum states, and
finally expanded into partial waves using the three-body helicity formalism
first introduced by Wick. In order to solve the equations, the two-body
scattering amplitudes must be boosted from the overall three-body rest frame to
their individual two-body rest frames, and all effects which arise from these
boosts, including the Wigner rotations and rho-spin decomposition of the
off-shell particle, are treated exactly. In their final form, the equations
reduce to a coupled set of Faddeev-like double integral equations with
additional channels arising from the negative rho-spin states of the off-shell
particle.Comment: 57 pages, RevTeX, 6 figures, uses epsf.st
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