250 research outputs found
Can the cosmological constant undergo abrupt changes?
The existence of a simple spherically symmetric and static solution of the
Einstein equations in the presence of a cosmological constant vanishing outside
a definite value of the radial distance is investigated. A particular
succession of field configurations, which are solutions of the Einstein
equations in the presence of the considered cosmological term and auxiliary
external sources, is constructed. Then, it is shown that the associated
succession of external sources tend to zero in the sense of the generalized
functions. The type of weak solution that is found becomes the deSitter
homogeneous space-time for the interior region, and the Schwartzschild space in
the outside zone.Comment: 10 pages, 1 figur
Gauge invariance properties and singularity cancellations in a modified PQCD
The gauge-invariance properties and singularity elimination of the modified
perturbation theory for QCD introduced in previous works, are investigated. The
construction of the modified free propagators is generalized to include the
dependence on the gauge parameter . Further, a functional proof of the
independence of the theory under the changes of the quantum and classical
gauges is given. The singularities appearing in the perturbative expansion are
eliminated by properly combining dimensional regularization with the Nakanishi
infrared regularization for the invariant functions in the operator
quantization of the -dependent gauge theory. First-order evaluations of
various quantities are presented, illustrating the gauge invariance-properties.Comment: 23 pages, 3 figure
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