Related papers: Cherenkov radiation as ghost instability
We theoretically study the effect of ultraslow group velocities on the emission of Vavilov-Cherenkov radiation in a coherently driven medium. We show that in this case the aperture of the group cone on which the intensity of the radiation…
We study the problem of the instability of inhomogeneous radiation universes in quadratic lagrangian theories of gravity written as a system of evolution equations with constraints. We construct formal series expansions and show that the…
Modified theories of electrodynamics that include violations of Lorentz symmetry often allow for the possibility of vacuum Cerenkov radiation. This phenomenon has previously been studied in a number of Lorentz-violating theories, but none…
The Cherenkov effect is a well known phenomenon in the electrodynamics of fast charged particles passing through transparent media. If the particle is faster than the light in a given medium, the medium emits a forward light cone. This…
The energy in the ghost-free massive gravity theory is calculated via explicitly resolving the initial value constraints for spherically symmetric deformations of flat space. It turns out that the energy is positive in some cases, but in…
Generalized Super-Cherenkov Radiations (SCR), as well as their SCR-signatures are investigated. Two general SCR-coherence conditions are found as two natural extremes of the same spontaneous particles decays in (dielectric, nuclear or…
For usual radiation the integral of the electric field strength over the time is zero. First time the possibility of unipolar radiation generation has been considered theoretically in the paper [EG.Bessonov. Preprint No 76 of the Lebedev…
Many theories of modified gravity with higher order derivatives are usually ignored because of serious problems that appear due to an additional ghost degree of freedom. Most dangerously, it causes an immediate decay of the vacuum. However,…
We explore an idea put forward many years ago by Zeldovich and Novikov concerning the existence of compact objects endowed with arbitrarily small mass. The energy-density of such objects, which we call ``Ghost stars'', is negative in some…
Similar to electromagnetic forces, strong interactions might induce such collective effects as Cherenkov and Mach waves. Their conical structure would be responsible for specific ring-like events. The theoretical and experimental arguments…
Some part of the microwave Cherenkov radiation from a particle-in-flight from vacuum to semi-infinite layered medium is redirected by the periodical structure of medium in the backward direction. This part of radiation is…
We revisit the theory of Cherenkov radiation in uniaxial crystals. Historically, a number of flawed attempts have been made at explaining this radiation phenomenon and a consistent error-free description is nowhere available. We apply our…
A theory of pulsar radio emission generation, in which the observed waves are produced directly by maser-type plasma instabilities operating at the anomalous cyclotron-Cherenkov resonance $\omega- k_{\parallel} v_{\parallel} + \omega_B/…
The effect of light refraction in a galaxy halo of dark matter, described by profiles of Navarro-Frenk-White and Burkett, was considered. Powers of the Cherenkov radiation for the refractive indexes of gravitational fields with these…
Classical Cherenkov radiation is a celebrated physics phenomenon of electromagnetic (EM) radiation stimulated by an electric charge moving with constant velocity in a three dimensional dielectric medium. Cherenkov radiation has a wide…
Some characteristic features in the radiation from a relativistic electron uniformly rotating along an equatorial orbit around a dielectric ball have been studied. It was shown that at some harmonics, in case of weak absorption of radiation…
Lorentz- and CPT-violating models of electrodynamics with Chern-Simons terms are typically plagued by various sorts of instabilities. However, when the Chern-Simons term arises from a slow time variation in a pseudoscalar field with an…
Theories which contain ghost fields are considered to be invalid. It is assumed that for such theories the energy is unbounded from below, and the theory will be unstable, allowing the creation of particle pairs with arbitrarily large…
Recent work has shown that non-local modifications of the Einstein equations can have interesting cosmological consequences and can provide a dynamical origin for dark energy, consistent with existing data. At first sight these theories are…
In the context of a Planck scale underpinning for the universe, we argue that both gravitation and electromagnetism can be characterized in a unified way, in a Sakharov like description. We also consider the issue of observed gamma…