72 research outputs found
Comment on `A simple explanation of the non-appearance of physical gluons and quarks'
In a recent paper by Johan Hansson [hep-ph/0208137] it is claimed that the
non-appearance of quarks and gluons as physical particles is an automatic
result of the nonabelian nature of the color interaction in quantum
chromodynamics. It is shown that the arguments given by Hansson are
insufficient to support his claim by giving simple counter arguments.Comment: 3 pages, LATE
Aspects of the derivative coupling model in four dimensions
A concise discussion of a 3+1-dimensional derivative coupling model, in which
a massive Dirac field couples to the four-gradient of a massless scalar field,
is given in order to elucidate the role of different concepts in quantum field
theory like the regularization of quantum fields as operator valued
distributions, correlation distributions, locality, causality, and field
operator gauge transformations.Comment: 17 pages, LaTeX, corresponding to the published versio
Bound-free pair production cross section in heavy-ion colliders from the equivalent photon approach
Exact calculations of the electron-positron pair production by a single
photon in the Coulomb field of a nucleus with simultaneous capture of the
electron into the K-shell are discussed for different nuclear charges. Using
the equivalent photon method of Weizsaecker and Williams, a simple expression
for the bound-free production of electron-positron pairs by colliding
very-high-energy fully stripped heavy ions is derived for nuclei of arbitrary
charge.Comment: 4 pages, 2 figures, style file include
Coulomb distortion effects in quasi-elastic (e,e') scattering on heavy nuclei
The influence of the Coulomb distortion for quasi-elastic (e,e') scattering
on highly charged nuclei is investigated in distorted wave Born approximation
for electrons. The Dirac equation is solved numerically in order to obtain
exact electron continuum states in the electrostatic field generated by the
charge distribution of an atomic nucleus. Different approximate models are used
to describe the nucleon current in order to show that, at high electron
energies and energy-momentum transfer, the influence of Coulomb distortions on
(e,e') cross sections can be reliably described by the effective momentum
approximation, irrespective of details concerning the description of the
nuclear current.Comment: 34 pages, 11 figures, LATEX, style file include
Scalar models of formally interacting non-standard quantum fields in Minkowski space-time
For decades, a lot of work has been devoted to the problem of constructing a
non-trivial quantum field theory in four-dimensional space time. This letter
addresses the attempts to construct an algebraic quantum field theory in the
framework of non-standard theories like hyperfunction or ultra-hyperfunction
quantum field theory. For this purpose model theories of formally interacting
neutral scalar fields are constructed and some of their characteristic
properties like two-point functions are discussed. The formal self-couplings
are obtained from local normally-ordered analytic redefinitions of the free
scalar quantum field, mimicking a non-trivial structure of the resulting
Lagrangians and equations of motion.Comment: 4 pages, 6 references and a conclusion section added, abstract
slightly modifie
Coulomb solutions from improper pseudo-unitary free gauge field operator translations
Fundamental problems of quantum field theory related to the representation
problem of canonical commutation relations are discussed within a gauge field
version of a van Hove-type model. The Coulomb field generated by a static
charge distribution is described as a formal superposition of time-like
pseudo-photons in Fock space with a Krein structure. In this context, a
generalization of operator gauge transformations is introduced to generate
coherent states of abelian gauge fields interacting with a charged background.Comment: 19 pages, two sections extende
- …