arXiv subjects
Publications and source records attributed to Sergey V. Sushkov.
An analitical approximation of $<ϕ^2>$ for a scalar field in a static spherically symmetric wormhole spacetime is obtained. The scalar field is assumed to be both massive and massless, with an arbitrary coupling $ξ$ to the scalar curvature, and in a zero temperature vacuum state.
An analitical approximation of $<ϕ^2>$ for a massive scalar field in a zero temperature vacuum state in static spherically symmetric spacetimes is obtained. The calculations are based on the method for computing vacuum expectations values for scalar fields in general static spherically symmetric spacetimes derived by Anderson, Hiscock and Samuel [Phys. Rev. D {\bf 51}, 4337 (1995)]. The analitical approximation is used to compute $<ϕ^2>$ in Schwarzschild and wormhole spacetimes.
We analyse in details the problems which one faces trying to quantize a scalar field on the spacelike cylinder being the simple example of a spacetime with closed timelike curves. Our analysis brings to light the fact that the usual set of positive and negative frequency solutions of the field equation turns out to be incomplete. The consequence of this fact is that the usual formulation of quantum field theory breaks down on such a spacetime. We postulate the completeness principle and build on its basis the modified quantization procedure. As an example, the Hadamard function and $<ϕ^2>$ for the scalar field on the spacelike cylinder are calculated. It is shown that the ``naive'' method of images gives the same results of calculation.
We investigate the phenomenon of particle creation of the massless scalar field in the model of spacetime in which, depending on the model's parameter $\aout$, the chronology horizon could be formed. The model represents a two-dimensional curved spacetime with the topology $R^1 \times S^1$ which is asymptotically flat in the past and in the future. The spacetime is globally hyperbolic and has no causal pathologies if $\aout<1$, and closed timelike curves appear in the spacetime if $\aout\ge 1$. We obtain the spectrum of created particles in the case $\aout<1$. In the limit $\aout \to 1$ this spectrum gives the number of particles created into mode $n$ near the chronology horizon. The main result we have obtained is that the number of scalar particles created into each mode as well as the full number of particles remain finite at the moment of forming of the chronology horizon.
We present the first results of a self-consistent solution of the semiclassical Einstein field equations corresponding to a Lorentzian wormhole coupled to a quantum scalar field. The specific solution presented here represents a wormhole connecting two asymptotically spatially flat regions. In general, the diameter of the wormhole throat, in units of the Planck length, can be arbitrarily large, depending on the values of the scalar coupling $ξ$ and the boundary values for the shape and redshift functions. In all cases we have considered, there is a fine-structure in the form of Planck-scale oscillations or ripples superimposed on the solutions.
An approximate form for the vacuum averaged stress-energy tensor of a conformal spin-2 quantum field on a black hole background is employed as a source term in the semiclassical Einstein equations. Analytic corrections to the Schwarzschild metric are obtained to first order in $ε= {\hbar}/M^2$, where $M$ denotes the mass of the black hole. The approximate tensor possesses the exact trace anomaly and the proper asymptotic behavior at spatial infinity, is conserved with respect to the background metric and is uniquely defined up to a free parameter $\hat c_2$, which relates to the average quantum fluctuation of the field at the horizon. We are able to determine and calculate an explicit upper bound on $\hat c_2$ by requiring that the entropy due to the back-reaction be a positive increasing function in $r$. A lower bound for $\hat c_2$ can be established by requiring that the metric perturbations be uniformly small throughout the region $2M \leq r < r_o$, where $r_o$ is the radius of perturbative validity of the modified metric. Additional insight into the nature of the perturbed spacetime outside the black hole is provided by studying the effective potential for test particles in the vicinity of the horizon.