375 research outputs found
Localized whistlers in magnetized spin quantum plasmas
The nonlinear propagation of electromagnetic (EM) electron-cyclotron waves
(whistlers) along an external magnetic field, and their modulation by
electrostatic small but finite amplitude ion-acoustic density perturbations are
investigated in a uniform quantum plasma with intrinsic spin of electrons. The
effects of the quantum force associated with the Bohm potential and the
combined effects of the classical as well as the spin-induced ponderomotive
forces (CPF and SPF respectively) are taken into consideration. The latter
modify the local plasma density in a self-consistent manner. The coupled modes
of wave propagation is shown to be governed by a modified set of nonlinear
Schr\"{o}dinger-Boussinesq-like equations which admit exact solutions in form
of stationary localized envelopes. Numerical simulation reveals the existence
of large-scale density fluctuations that are self-consistently created by the
localized whistlers in a strongly magnetized high density plasma. The
conditions for the modulational instability (MI) and the value of its growth
rate are obtained. Possible applications of our results, e.g., in strongly
magnetized dense plasmas and in the next generation laser-solid density plasma
interaction experiments are discussed.Comment: 9 pages, 4 figures; To appear in Physical Review E (2010
Mirror World and its Cosmological Consequences
We briefly review the concept of a parallel `mirror' world which has the same
particle physics as the observable world and couples to the latter by gravity
and perhaps other very weak forces. The nucleosynthesis bounds demand that the
mirror world should have a smaller temperature than the ordinary one. By this
reason its evolution should substantially deviate from the standard cosmology
as far as the crucial epochs like baryogenesis, nucleosynthesis etc. are
concerned. In particular, we show that in the context of certain baryogenesis
scenarios, the baryon asymmetry in the mirror world should be larger than in
the observable one. Moreover, we show that mirror baryons could naturally
constitute the dominant dark matter component of the Universe, and discuss its
cosmological implications
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