27 research outputs found
A nonperturbative calculation of the electron's magnetic moment
In principle, the complete spectrum and bound-state wave functions of a
quantum field theory can be determined by finding the eigenvalues and
eigensolutions of its light-cone Hamiltonian. One of the challenges in
obtaining nonperturbative solutions for gauge theories such as QCD using
light-cone Hamiltonian methods is to renormalize the theory while preserving
Lorentz symmetries and gauge invariance. For example, the truncation of the
light-cone Fock space leads to uncompensated ultraviolet divergences. We
present two methods for consistently regularizing light-cone-quantized gauge
theories in Feynman and light-cone gauges: (1) the introduction of a spectrum
of Pauli-Villars fields which produces a finite theory while preserving Lorentz
invariance; (2) the augmentation of the gauge-theory Lagrangian with higher
derivatives. In the latter case, which is applicable to light-cone gauge (A^+ =
0), the A^- component of the gauge field is maintained as an independent degree
of freedom rather than a constraint. Finite-mass Pauli-Villars regulators can
also be used to compensate for neglected higher Fock states. As a test case, we
apply these regularization procedures to an approximate nonperturbative
computation of the anomalous magnetic moment of the electron in QED as a first
attempt to meet Feynman's famous challenge.Comment: 35 pages, elsart.cls, 3 figure
Quantum Fields on the Light Front, Formulation in Coordinates close to the Light Front, Lattice Approximation
We review the fundamental ideas of quantizing a theory on a Light Front
including the Hamiltonian approach to the problem of bound states on the Light
Front and the limiting transition from formulating a theory in Lorentzian
coordinates (where the quantization occurs on spacelike hyperplanes) to the
theory on the Light Front, which demonstrates the equivalence of these variants
of the theory. We describe attempts to find such a form of the limiting
transition for gauge theories on the Wilson lattice.Comment: LaTeX 2e, 14 page
Comparison of quantum field perturbation theory for the light front with the theory in lorentz coordinates
The relationship between the perturbation theory in light-front coordinates
and Lorentz-covariant perturbation theory is investigated. A method for finding
the difference between separate terms of the corresponding series without their
explicit evaluation is proposed. A procedure of constructing additional
counter-terms to the canonical Hamiltonian that compensate this difference at
any finite order is proposed. For the Yukawa model, the light-front Hamiltonian
with all of these counter-terms is obtained in a closed form. Possible
application of this approach to gauge theories is discussed.Comment: LaTex 2.09, 20 pages, 5 figure
Application of Pauli-Villars regularization and discretized light-cone quantization to a single-fermion truncation of Yukawa theory
We apply Pauli-Villars regularization and discretized light-cone quantization
to the nonperturbative solution of (3+1)-dimensional Yukawa theory in a
single-fermion truncation. Three heavy scalars, including two with negative
norm, are used to regulate the theory. The matrix eigenvalue problem is solved
for the lowest-mass state with use of a new, indefinite-metric Lanczos
algorithm. Various observables are extracted from the wave functions, including
average multiplicities and average momenta of constituents, structure
functions, and a form factor slope.Comment: 21 pages, 7 figures, RevTeX; published version: more extensive data
in the tables of v
Hypoventilation and hypoxia in reversal of cardiogenic shock in an infant with congenital heart disease
When there is trouble brewing at the front, [first line]
Performance Medium: Piano and Voice (with lyrics