3,670 research outputs found
Advection of a passive scalar field by turbulent compressible fluid: renormalization group analysis near
The field theoretic renormalization group (RG) and the operator product
expansion (OPE) are applied to the model of a density field advected by a
random turbulent velocity field. The latter is governed by the stochastic
Navier-Stokes equation for a compressible fluid. The model is considered near
the special space dimension . It is shown that various correlation
functions of the scalar field exhibit anomalous scaling behaviour in the
inertial-convective range. The scaling properties in the RG+OPE approach are
related to fixed points of the renormalization group equations. In comparison
with physically interesting case , at additional Green function
has divergences which affect the existence and stability of fixed points. From
calculations it follows that a new regime arises there and then by continuity
moves into . The corresponding anomalous exponents are identified with
scaling dimensions of certain composite fields and can be systematically
calculated as series in (the exponent, connected with random force) and
. All calculations are performed in the leading one-loop
approximation.Comment: 11pages, 6 figures, LATEX2e. arXiv admin note: substantial text
overlap with arXiv:1611.00327; text overlap with arXiv:1611.0130
Stochastic Navier-Stokes equation and advection of a tracer field: One-loop renormalization near d
Advection of a passive scalar field by turbulent compressible fluid: renormalization group analysis near d
Conversion of recoilless gamma-radiation into a periodic sequence of ultrashort pulses in a set of dispersive and absorptive resonant media
An efficient technique to produce a periodic sequence of ultrashort pulses of
recoilless gamma-radiation via its transmission through the optically thick
vibrating resonant absorber was demonstrated recently [Nature, 508, 80 (2014)].
In this work we extend the theoretical analysis to the case of a set of
multiple absorbers. We consider an analytical model describing the control of
spectral content of a frequency modulated gamma-radiation by selective
correction of amplitudes and initial phases of some spectral components, using,
respectively, the resonant absorption or dispersion of nuclei. On the basis of
the analytical solutions we determine the ultimate possibilities of the
proposed technique.Comment: 16 pages, 6 figure
Generator Coordinate Method Calculations for Ground and First Excited Collective States in He, O and Ca Nuclei
The main characteristics of the ground and, in particular, the first excited
monopole state in the He, O and Ca nuclei are studied
within the generator coordinate method using Skyrme-type effective forces and
three construction potentials, namely the harmonic-oscillator, the square-well
and Woods-Saxon potentials. Calculations of density distributions, radii,
nucleon momentum distributions, natural orbitals, occupation numbers and
depletions of the Fermi sea, as well as of pair density and momentum
distributions are carried out. A comparison of these quantities for both ground
and first excited monopole states with the available empirical data and with
the results of other theoretical methods are given and discussed in detail.Comment: 15 pages, LaTeX, 6 Postscript figures, submitted to EPJ
Exploration of Novel Ordering Mechanism in Titanium Alloys Using Atom Probe Tomography and Aberration-corrected Scanning Transmission Electron Microscopy
String Nature of Confinement in (Non-)Abelian Gauge Theories
Recent progress achieved in the solution of the problem of confinement in
various (non-)Abelian gauge theories by virtue of a derivation of their string
representation is reviewed. The theories under study include QCD within the
so-called Method of Field Correlators, QCD-inspired Abelian-projected theories,
and compact QED in three and four space-time dimensions. Various
nonperturbative properties of the vacua of the above mentioned theories are
discussed. The relevance of the Method of Field Correlators to the study of
confinement in Abelian models, allowing for an analytical description of this
phenomenon, is illustrated by an evaluation of field correlators in these
models.Comment: 100 pages, LaTeX2e, no figures, 1 table, based on the Ph.D. thesises
at the Humboldt University of Berlin (1999) (available under
http://dochost.rz.hu-berlin.de) and the Institute of Theoretical and
Experimental Physics, Moscow (2000), new results are included, extended with
respect to the journal versio
- …