6,483 research outputs found

### Zero-mode contribution to the light-front Hamiltonian of Yukawa type models

Light-front Hamiltonian for Yukawa type models is determined without the
framework of canonical light-front formalism. Special attention is given to the
contribution of zero modes.Comment: 14 pages, Latex, revised version with minor changes, Submitted to
J.Phys.

### Gauge Invariant Regularization of Quantum Field Theory on the Light-Front

Gauge invariant regularization of quantum field theory in the framework of
Light-Front (LF) Hamiltonian formalism via introducing a lattice in transverse
coordinates and imposing boundary conditions in LF coordinate $x^-$ for gauge
fields on the interval $|x^-|\le L$ is considered. The remaining ultraviolet
divergences in the longitudinal momentum $p_-$ are removed by gauge invariant
finite mode regularization. We find that LF canonical formalism for the
introduced regularization does not contain usual most complicated second class
constraints connecting zero and nonzero modes of gauge fields. The described
scheme can be used either for the regularization of conventional gauge theory
or for gauge invariant formulation of effective low-energy models on the LF.
The lack of explicit Lorentz invariance in our approach leads to difficulty
with defining the vacuum state. We discuss this difficulty, particulary, in the
connection with the problem of taking the limit of continuous space.Comment: LaTeX 2.09, 15 pages, Proceedings of "12th V.Fock School of Physics",
St-Petersburg 200

### Canonical formulation of the embedded theory of gravity equivalent to Einstein's General Relativity

We study the approach in which independent variables describing gravity are
functions of the space-time embedding into a flat space of higher dimension. We
formulate a canonical formalism for such a theory in a form, which requires
imposing additional constraints, which are a part of Einstein's equations. As a
result, we obtain a theory with an eight-parameter gauge symmetry. This theory
becomes equivalent to Einstein's general relativity either after partial gauge
fixing or after rewriting the metric in the form that is invariant under the
additional gauge transformations. We write the action for such a theory.Comment: LaTeX, 17 page

### Calculation of the Mass Spectrum of QED-2 in Light-Front Coordinates

With the aim of a further investigation of the nonperturbative Hamiltonian
approach in gauge field theories, the mass spectrum of QED-2 is calculated
numerically by using the corrected Hamiltonian that was constructed previously
for this theory on the light front. The calculations are performed for a wide
range of the ratio of the fermion mass to the fermion charge at all values of
the parameter \hat\theta related to the vacuum angle \theta. The results
obtained in this way are compared with the results of known numerical
calculations on a lattice in Lorentz coordinates. A method is proposed for
extrapolating the values obtained within the infrared-regularized theory to the
limit where the regularization is removed. The resulting spectrum agrees well
with the known results in the case of \theta=0; in the case of \theta=\pi,
there is agreement at small values of the fermion mass (below the
phase-transition point).Comment: LaTex 2.09, 20 pages, 7 figures. New improved expression for the
effective LF Hamiltonian was adde

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