arXiv subjects

D. I. Sadekov

Publications and source records attributed to D. I. Sadekov.

4 recordsLinked to original sources

arXiv2025

Lessons from the Klein paradox

We re-examine the Klein paradox from a many-particle perspective in quantum field theory. Specifically, we compute the expectation value of the particle current induced by a sufficiently strong step-like electric potential in 1+1 dimensions. First, for a constant (eternal) potential, we calculate the current for different Fock space ground states corresponding to distinct mode bases. While one basis yields a zero current, another produces the standard nonzero value. We then consider a potential that is rapidly switched on, recovering the standard current in the asymptotic future. This result is generalized to potentials that interpolate between different constant values at spatial infinity. Finally, we analyze a potential acting for a finite duration and again reproduce the standard current. A physical interpretation of these results is provided.

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arXiv2024

Light fields in various patches of de Sitter space-time

We start with the consideration of the loop effects for light fields with non-zero mass in the expanding Poincaré patch of de Sitter space-time. We derive the Dyson-Schwinger equation, which sums up the leading infrared (growing with time) loop corrections in certain limit for small initial perturbations above the Bunch-Davies state. The solution of this equation shows the destiny of the initial state at the future infinity. Then we discuss the case of the contracting Poincaré patch and global de Sitter space-time and briefly the case of different initial conditions in the expanding Poincaré patch.

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arXiv2023

Loop corrections to the current of created pairs in the lengthy electric pulse

We discuss loop-corrections to the electric current produced by strong and lengthy electric pulse. Namely we calculate one loop contribution to the electric current, distinguishing terms which depend on the pulse duration. We show that one loop correction does not lead to a strong modification of the tree-level current, which linearly grows with the pulse duration. Meanwhile, the correction to the photon propagator does contain the additional secular growth with the pulse duration. Based on the latter observation we argue that higher loop corrections will strongly modify the tree-level current, but that will demand a longer duration of the pulse than if the growth was at the first loop level.

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arXiv2021

Currents of created pairs in strong electric fields

We calculate tree--level currents of created particles in strong background electric fields in 4D QED for various initial states. Namely, we do that in pulse background for initial vacuum and thermal states at past infinity. In both cases we find that the current grows linearly with the length of the pulse with coefficients of proportionality containing the characteristic Schwinger's factor. For the constant electric field background we calculate the current for several different initial states. We observe that in such a case the current is either zero or linearly divergent. We explain the reason for such a behaviour and compare the situation in ordinary and scalar QED. Finally, we calculate the current in two--dimensional situation in the presence of such settings when the so called Klein paradox can be observed.

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