206 research outputs found
Backreaction of the Hawking radiation
Black holes create a vacuum matter charge to protect themselves from the
quantum evaporation. A spherically symmetric black hole having initially no
matter charges radiates away about 10% of the initial mass and comes to a state
in which the vacuum-induced charge equals the remaining mass.Comment: 8 pages, 1 figure. Latex 2.09. Figure PN
Radiation equations for black holes
It has been shown in the previous paper that the metric in the semiclassical
region of the collapse spacetime is expressed purely kinematically through the
Bondi charges. Here the Bondi charges are expressed through this metric by
calculating the vacuum radiation against its background. The result is closed
equations for the metric and the Bondi charges. Notably, there is a
nonvanishing flux of the vacuum-induced matter charge.Comment: 16 pages, 1 figure. Latex 2.09. Figure PN
Partial summation of the nonlocal expansion for the gravitational effective action in 4 dimensions
The vacuum action for the gravitational field admits a known expansion in
powers of the Ricci tensor with nonlocal operator coefficients (form factors).
We show that going over to a different basis of curvature invariants makes
possible a partial summation of this expansion. Only the form factors of the
Weyl-tensor invariants need be calculated. The full action is then uniquely
recovered to all orders from the knowledge of the trace anomaly. We present an
explicit expression for the partially summed action, and point out
simplifications resulting in the vertex functions. An application to the effect
of the vacuum gravitational waves is discussed.Comment: 12 pages, LaTe
The vacuum backreaction on a pair creating source
Solution is presented to the simplest problem about the vacuum backreaction
on a pair creating source. The backreaction effect is nonanalytic in the
coupling constant and restores completely the energy conservation law. The
vacuum changes the kinematics of motion like relativity theory does and imposes
a new upper bound on the velocity of the source.Comment: 9 pages including 2 figures. Latex 2.09. Figures by Metafont, 300
dpi. Keep all files in a separate director
Heat kernel expansion in the covariant perturbation theory
Working within the framework of the covariant perturbation theory, we obtain
the coincidence limit of the heat kernel of an elliptic second order
differential operator that is applicable to a large class of quantum field
theories. The basis of tensor invariants of the curvatures of a gravity and
gauge field background, to the second order, is derived, and the form factors
acting on them are obtained in two integral representations. The results are
verified by the functional trace operation, by the short proper time
(Schwinger-DeWitt) expansions, as well as by the computation of the Green
function for the two-dimensional scalar field model.Comment: LaTeX, 33 page
On electrodynamics of rapidly moving sources
Rapidly moving sources create pairs in the vacuum and lose energy. In consequence of this, the velocity of a charged body cannot approach the speed of light closer than a certain limit which depends only on the coupling constant. The vacuum back-reaction secures the observance of the conservation laws. A source can lose up to 50% of energy and charge because of the vacuum instability
Particle creation in the effective action method
The effect of particle creation by nonstationary external fields is
considered as a radiation effect in the expectation-value spacetime. The energy
of created massless particles is calculated as the vacuum contribution in the
energy-momentum tensor of the expectation value of the metric. The calculation
is carried out for an arbitrary quantum field coupled to all external fields
entering the general second-order equation. The result is obtained as a
functional of the external fields. The paper gives a systematic derivation of
this result on the basis of the nonlocal effective action. Although the
derivation is quite involved and touches on many aspects of the theory, the
result itself is remarkably simple. It brings the quantum problem of particle
creation to the level of complexity of the classical radiation problem. For
external fields like the electromagnetic or gravitational field there appears a
quantity, the radiation moment, that governs both the classical radiation of
waves and the quantum particle production. The vacuum radiation of an
electrically charged source is considered as an example. The research is aimed
at the problem of backreaction of the vacuum radiation.Comment: 129 pages including 7 figures. Latex 2.09. Figures by METAFONT, 300
DPI. Execute the file "arttotal.tex
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