20,546 research outputs found
Non-Quadratic Gauge Fixing and Global Gauge Invariance in the Effective Action
The possibility of having a gauge fixing term in the effective Lagrangian
that is not a quadratic expression has been explored in spin-two theories so as
to have a propagator that is both traceless and transverse. We first show how
this same approach can be used in spontaneously broken gauge theories as an
alternate to the 't Hooft gauge fixing which avoids terms quadratic in the
scalar fields. This "non-quadratic" gauge fixing in the effective action
results in there being two complex Fermionic and one real Bosonic ghost fields.
A global gauge invariance involving a Fermionic gauge parameter, analogous to
the usual BRST invariance, is present in this effective action.Comment: 4 pages, revtex4 (submitted to Phys. Rev. D
The long wavelength limit of hard thermal loop effective actions
We derive a closed form expression for the long wavelength limit of the
effective action for hard thermal loops in an external gravitational field. It
is a function of the metric, independent of time derivatives. It is compared
and contrasted with the static limit, and with the corresponding limits in an
external Yang-Mills field.Comment: 5 page
Etching of High Purity Zinc
A method of etching high purity zinc to reveal various etch figures on {101¯0} planes is presented in this
paper. Etch figures are formed by polishing in a dichromic acid solution after the introduction of mercury
to the crystal surface. No measurable aging time is required to form etch figures at newly formed dislocation
sites when mercury is on the surface prior to deformation. The mercury concentrates at the sites
where etch figures form and may be removed by vacuum distillation and chemical polishing before it appreciably
affects the purity of the bulk of the crystal
On Restricting to One Loop Order the Radiative Effects in Quantum Gravity
The dimensionful nature of the coupling in the Einstein-Hilbert action in
four dimensions implies that the theory is non-renormalizable; explicit
calculation shows that beginning at two loop order, divergences arise that
cannot be removed by renormalization without introducing new terms in the
classical action. It has been shown that, by use of a Lagrange multiplier field
to ensure that the classical equation of motion is satisfied in the path
integral, radiative effects can be restricted to one loop order. We show that
by use of such Lagrange multiplier fields, the Einstein-Hilbert action can be
quantized without the occurrence of non-renormalizable divergences. We then
apply this mechanism to a model in which there is in addition to the
Einstein-Hilbert action, a fully covariant action for a self-interacting scalar
field coupled to the metric. It proves possible to restrict loop diagrams
involving internal lines involving the metric to one-loop order; diagrams in
which the scalar field propagates occur at arbitrary high order in the loop
expansion. This model also can be shown to be renormalizable. Incorporating
spinor and vector fields in the same way as scalar fields is feasible, and so a
fully covariant Standard Model with a dynamical metric field can also be shown
to be renormalizableComment: 8 pages. This version contains more background materia
- …