314 research outputs found
Effects of mode-mode and isospin-isospin correlations on domain formation of disoriented chiral condensates
The effects of mode-mode and isospin-isospin correlations on nonequilibrium
chiral dynamics are investigated by using the method of the time dependent
variational approach with squeezed states as trial states. Our numerical
simulations show that large domains of the disoriented chiral condensate (DCC)
are formed due to the combined effect of the mode-mode and isospin-isospin
correlations. Moreover, it is found that, when the mode-mode correlation is
included, the DCC domain formation is accompanied by the amplification of the
quantum fluctuation, which implies the squeezing of the state. However, neither
the DCC domain formation nor the amplification of the quantum fluctuation is
observed if only the isospin-isospin correlation is included. This suggests
that the mode-mode coupling plays a key role in the DCC domain formation.Comment: 10 pages, 11 figures; Correction of an error in Fig.
Time-Evolution of a Collective Meson Field by the Use of a Squeezed State
A time-evolution of quantum meson fields is investigated in a linear sigma
model by means of the time-dependent variational approach with a squeezed
state. The chiral condensate, which is a mean field of the quantum meson
fields, and quantum fluctuations around it are treated self-consistently in
this approach. The attention is payed to the description of the relaxation
process of the chiral condensate, where the energy stored in the mean field
configuration flows to the fluctuation modes. It is shown that the quantum
fluctuations play an important role to describe this relaxation process.Comment: 18 pages, 22 postscript figures, uses PTPTeX.st
Chaotic behaviour of nonlinear waves and solitons of perturbed Korteweg - de Vries equation
This paper considers properties of nonlinear waves and solitons of
Korteweg-de Vries equation in the presence of external perturbation. For
time-periodic hamiltonian perturbation the width of the stochastic layer is
calculated. The conclusions about chaotic behaviour in long-period waves and
solitons are inferred. Obtained theoretical results find experimental
confirmation in experiments with the propagation of ion-acoustic waves in
plasma.Comment: 7 pages, LaTeX, 2 Postscript figures, submitted to Reports on
Mathematical Physic
Nonequilibrium chiral dynamics by the time dependent variational approach with squeezed states
We investigate the inhomogeneous chiral dynamics of the O(4) linear sigma
model in 1+1 dimensions using the time dependent variational approach in the
space spanned by the squeezed states. We compare two cases, with and without
the Gaussian approximation for the Green's functions. We show that mode-mode
correlation plays a decisive role in the out-of-equilibrium quantum dynamics of
domain formation and squeezing of states.Comment: 5 pages, 4 figures. RevTex, version to appear in Phys. Rev. C. Rapid
Communicatio
Sufficient integral criteria for instability of the free charged surface of an ideal liquid
Applying the method of integral estimates to the analysis of three-wave
processes we derive the sufficient criteria for the hard loss of stability of
the charged plane surface of liquids with different physical properties. The
influence of higher-order wave interactions on the instability dynamics is also
discussed.Comment: 9 page
Normal modes of a quasi-one-dimensional multi-chain complex plasma
We studied equally charged particles, suspended in a complex plasma, which
move in a plane and interact with a screened Coulomb potential (Yukawa type)
and with an additional external confining parabolic potential in one direction,
that makes the system quasi-one-dimensional (Q1D). The normal modes of the
system are studied in the presence of dissipation. We also investigated how a
perpendicular magnetic field couples the phonon modes with each other. Two
different ways of exciting the normal modes are discussed: 1) a uniform
excitation of the Q1D lattice, and 2) a local forced excitation of the system
in which one particle is driven by e.g. a laser. Our results are in very good
agreement with recent experimental findings on a finite single chain system
(Phys. Rev. Lett. {\bf 91}, 255003 (2003)). Predictions are made for the normal
modes of multi-chain structures in the presence of damping.Comment: 15 pages, 14 figures, accepted for publication on PR
Spreading of waves in nonlinear disordered media
We analyze mechanisms and regimes of wave packet spreading in nonlinear
disordered media. We predict that wave packets can spread in two regimes of
strong and weak chaos. We discuss resonance probabilities, nonlinear diffusion
equations, and predict a dynamical crossover from strong to weak chaos. The
crossover is controlled by the ratio of nonlinear frequency shifts and the
average eigenvalue spacing of eigenstates of the linear equations within one
localization volume. We consider generalized models in higher lattice
dimensions and obtain critical values for the nonlinearity power, the
dimension, and norm density, which influence possible dynamical outcomes in a
qualitative way.Comment: 24 pages, 3 figures. arXiv admin note: text overlap with
arXiv:0901.441
Ion-beam-driven resonant ion cyclotron instability
The resonant ion-beam-driven electrostatic ion cyclotron instability is identified. Measured dispersion relation and onset vs. beam energy and density agree with numerical calculations based on a theory which includes beam acoustic terms. After amplitude saturation, velocity space diffusion of the beam ions is observed. (auth
Photon emission by an ultra-relativistic particle channeling in a periodically bent crystal
This paper is devoted to a detailed analysis of the new type of the undulator
radiation generated by an ultra-relativistic charged particle channeling along
a crystal plane, which is periodically bent by a transverse acoustic wave, as
well as to the conditions limiting the observation of this phenomenon. This
mechanism makes feasible the generation of electromagnetic radiation, both
spontaneous and stimulated, emitted in a wide range of the photon energies,
from X- up to gamma-rays
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