1,347 research outputs found
Zel'dovich states with very small mass and charge in nonlinear electrodynamics coupled to gravity
It is shown that in non-linear electrodynamics (in particular, Born-Infeld
one) in the framework of general relativity there exist "weakly singular"
configurations such that (i) the proper mass M is finite in spite of
divergences of the energy density, (ii) the electric charge q and Schwarzschild
mass m ~ q can be made as small as one likes, (iv) all field and energy
distributions are concentrated in the core region. This region has an almost
zero surface area but a finite longitudinal size L=2M. Such configurations can
be viewed as a new version of a classical analogue of an elementary particle.Comment: 11 pages. 1 reference added. To appear in Grav. Cosm
Bunch-excited wakefield in dielectric waveguide with hollow plasma channel
Wakefield excitation by a single relativistic electron bunch in a
plasma-dielectric accelerating structure has been studied both analytically and
numerically. The structure represents a dielectric-loaded cylindrical metal
waveguide, which has partially plasma-filled channel (the hollow plasma
channel) to transport charged particles. Assuming the linear regime of
excitation, analytical expressions have been derived for the longitudinal and
radial wakefields generated by a finite-size electron bunch. Axial profiles of
wakefield component amplitudes have been studied, and their mode and spectrum
analyses have been performed. Furthermore, the electron bunch-driven wakefield
excitation has been PIC-simulated numerically for the quasi-linear regime. The
comparative analysis of the data resulting from analytical studies and the ones
obtained by numerical simulation has demonstrated qualitative agreement between
the results
The banding in serpentinites and its influence on character of talc-magnesite and magnesite mineralization (natural and experimental data)
The geological setting of some banded talc-magnesite ores and magnesites was studied in the
field (Urals, Russia; Finland, East Iran). Talc-magnesite and magnesite ores occur in ultramafic
rocks. Experimental methods were used in order to determine the influence of physico-mechanical
parameters on the formation of banded structures in talc-magnesite rocks and magnesites.
Experiments were carried out with axial compression up to 10 kbar and confining pressure 2, 4, 6
and 8 kbars at room temperature.
The samples were chemically analyzed using a Philips Analytical PW 2400 authomatic XRF
Spectrometer and a scanning electron microscope (SEM).
Some analyses were made with a "Camebax SX-50" electron microprobe, using an accelerating
voltage of 20 kilovolts for all elements with a sample current of 20 nanoamps. X-ray method for
phase identification was used. Structure peculiarities of rocks prior to the experiment and after
were studied by optical methods in polished sections and thin sections.
It was shown, that banding in talc-magnesite stone and magnesites are inherited from banded
serpentinites and can affect on distribution and composition rock-forming minerals
The behaviours of Mg and Ca in some types of ultramaphic alkaline melts in the presence of H 2 O at high temperature and pressure (the experimental data)
The sample has been investigated, which was composed of olivine-melilite rock from the
south-western part of the Kugda intrusion, situated in the eastern margin of the Maimecha-Kotuiskay
alkaline- ultramaphic province (northern part of Siberia platform). The experiments were carried
out using a high-pressure apparatus of the "piston-cylinder" type. The pressure was 5-15 kb and
the temperature -800-1250 0 C. The water content in the system was 3 and 9 wt. All experiments
were carried out in hermetically sealed Pt or Au ampoules. The samples were chemically analyzed
using a scanning electron microscope (SEM). Besides, the chemical composition of the experimental
phases was determined by means of more than 40 electron microprobe in 20 experimental samples.
For phase identification the X-ray method was used too. The structural peculiarities of rocks and
mineral compositions were studied by optical methods in polished and thin sections prior and
after the experiment. It was shown that at pressures above 7.5-8 kb the olivine-melilite melt is
separated into two melts: pyroxenite and melilite. Most part of Mg in this system was concentrated
in a high temperature phase of diopside type. The remaining melt was depleted of Mg and enriched
by Ca. The mineralization vapour practically did not contain Mg. The main components of the
mineralization vapour were Ca, Na, Si and Fe
Parity violating cylindrical shell in the framework of QED
We present calculations of Casimir energy (CE) in a system of quantized
electromagnetic (EM) field interacting with an infinite circular cylindrical
shell (which we call `the defect'). Interaction is described in the only
QFT-consistent way by Chern-Simon action concentrated on the defect, with a
single coupling constant .
For regularization of UV divergencies of the theory we use % physically
motivated Pauli-Villars regularization of the free EM action. The divergencies
are extracted as a polynomial in regularization mass , and they renormalize
classical part of the surface action.
We reveal the dependence of CE on the coupling constant . Corresponding
Casimir force is attractive for all values of . For we
reproduce the known results for CE for perfectly conducting cylindrical shell
first obtained by DeRaad and Milton.Comment: Typos corrected. Some references adde
ΠΠ»ΠΈΡΠ½ΠΈΠ΅ ΡΠ΅Π»Π°ΠΊΡΠ°ΡΠΈΠΎΠ½Π½ΡΡ ΠΏΡΠΎΡΠ΅ΡΡΠΎΠ² ΠΏΡΠΈ Π΄Π΅ΡΠΎΡΠΌΠΈΡΠΎΠ²Π°Π½ΠΈΠΈ Π½Π° ΡΠ»Π΅ΠΊΡΡΠΈΡΠ΅ΡΠΊΠΎΠ΅ ΡΠΎΠΏΡΠΎΡΠΈΠ²Π»Π΅Π½ΠΈΠ΅ ΠΏΠΎΠ»ΠΈΠΏΡΠΎΠΏΠΈΠ»Π΅Π½ΠΎΠ²ΡΡ ΠΊΠΎΠΌΠΏΠΎΠ·ΠΈΡΠΎΠ² Ρ ΡΠ΅Ρ Π½ΠΈΡΠ΅ΡΠΊΠΈΠΌ ΡΠ³Π»Π΅ΡΠΎΠ΄ΠΎΠΌ
Objectives. To study the relationship between bending deformation and the change in the electrical resistance of carbon black polypropylene composites.Methods. Conductive polypropylene composites filled with carbon black UM-76 were investigated. The samples were deformed and kept under constant bending at temperatures of 20β155 Β°C.Results. The deformation of the samples led to a reversible increase in their electrical resistance, while subsequent holding of the samples in the deformed state was accompanied by an exponential drop in their electrical resistance. The average times and activation energies of the electrical relaxation of the deformed polypropylene composites were calculated (30β32 kJ/mol) and compared with similar characteristics of polyethylene composites (15β16 kJ/mol).Conclusions. The electrical resistance relaxation of deformed carbon black polypropylene composites at elevated temperatures is similar to their stress relaxation. The average times and activation energies of the electrical relaxation of deformed polypropylene composites are comparable with similar data on their mechanical relaxation. It was found that these electrical and mechanical phenomena are based on the same underlying physical processes.Π¦Π΅Π»ΠΈ. Π Π°Π±ΠΎΡΠ° ΠΏΠΎΡΠ²ΡΡΠ΅Π½Π° ΠΈΠ·ΡΡΠ΅Π½ΠΈΡ Π²Π»ΠΈΡΠ½ΠΈΡ Π΄Π΅ΡΠΎΡΠΌΠ°ΡΠΈΠΈ ΠΈΠ·Π³ΠΈΠ±Π° ΠΏΡΠΈ ΠΏΠΎΠ²ΡΡΠ΅Π½Π½ΡΡ
ΡΠ΅ΠΌΠΏΠ΅ΡΠ°ΡΡΡΠ°Ρ
Π½Π° ΠΈΠ·ΠΌΠ΅Π½Π΅Π½ΠΈΠ΅ ΡΠ»Π΅ΠΊΡΡΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ ΡΠΎΠΏΡΠΎΡΠΈΠ²Π»Π΅Π½ΠΈΡ ΡΠ»Π΅ΠΊΡΡΠΎΠΏΡΠΎΠ²ΠΎΠ΄ΡΡΠΈΡ
ΠΏΠΎΠ»ΠΈΠΏΡΠΎΠΏΠΈΠ»Π΅Π½ΠΎΠ²ΡΡ
ΠΊΠΎΠΌΠΏΠΎΠ·ΠΈΡΠΎΠ², Π½Π°ΠΏΠΎΠ»Π½Π΅Π½Π½ΡΡ
ΡΠ΅Ρ
Π½ΠΈΡΠ΅ΡΠΊΠΈΠΌ ΡΠ³Π»Π΅ΡΠΎΠ΄ΠΎΠΌ.ΠΠ΅ΡΠΎΠ΄Ρ. ΠΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π»ΠΈΡΡ ΠΏΠΎΠ»ΠΈΠΏΡΠΎΠΏΠΈΠ»Π΅Π½ΠΎΠ²ΡΠ΅ ΠΊΠΎΠΌΠΏΠΎΠ·ΠΈΡΡ Ρ ΡΠ΅Ρ
Π½ΠΈΡΠ΅ΡΠΊΠΈΠΌ ΡΠ³Π»Π΅ΡΠΎΠ΄ΠΎΠΌ Π£Π-76. ΠΠ±ΡΠ°Π·ΡΡ ΠΈΠ·Π³ΠΈΠ±Π°Π»ΠΈΡΡ ΠΈ Π²ΡΠ΄Π΅ΡΠΆΠΈΠ²Π°Π»ΠΈΡΡ ΠΏΡΠΈ Π·Π°Π΄Π°Π½Π½ΠΎΠΌ ΠΏΡΠΎΠ³ΠΈΠ±Π΅ Π² ΠΈΠ½ΡΠ΅ΡΠ²Π°Π»Π΅ 20β155 Β°C.Π Π΅Π·ΡΠ»ΡΡΠ°ΡΡ. ΠΡΠΈ Π΄Π΅ΡΠΎΡΠΌΠΈΡΠΎΠ²Π°Π½ΠΈΠΈ ΠΎΠ±ΡΠ°Π·ΡΠΎΠ² Π½Π°Π±Π»ΡΠ΄Π°Π»ΡΡ ΠΎΠ±ΡΠ°ΡΠΈΠΌΡΠΉ ΡΠΎΡΡ ΡΠ»Π΅ΠΊΡΡΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ ΡΠΎΠΏΡΠΎΡΠΈΠ²Π»Π΅Π½ΠΈΡ. ΠΠΎΡΠ»Π΅Π΄ΡΡΡΠ°Ρ Π²ΡΠ΄Π΅ΡΠΆΠΊΠ° ΠΎΠ±ΡΠ°Π·ΡΠΎΠ² Π² Π΄Π΅ΡΠΎΡΠΌΠΈΡΠΎΠ²Π°Π½Π½ΠΎΠΌ ΡΠΎΡΡΠΎΡΠ½ΠΈΠΈ ΡΠΎΠΏΡΠΎΠ²ΠΎΠΆΠ΄Π°Π»Π°ΡΡ ΡΠΊΡΠΏΠΎΠ½Π΅Π½ΡΠΈΠ°Π»ΡΠ½ΡΠΌ ΠΏΠ°Π΄Π΅Π½ΠΈΠ΅ΠΌ ΠΈΡ
ΡΠ»Π΅ΠΊΡΡΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ ΡΠΎΠΏΡΠΎΡΠΈΠ²Π»Π΅Π½ΠΈΡ. ΠΡΠ»ΠΈ ΡΠ°ΡΡΡΠΈΡΠ°Π½Ρ ΡΡΠ΅Π΄Π½ΠΈΠ΅ Π²ΡΠ΅ΠΌΠ΅Π½Π° ΠΈ ΡΠ½Π΅ΡΠ³ΠΈΡ Π°ΠΊΡΠΈΠ²Π°ΡΠΈΠΈ ΡΠ»Π΅ΠΊΡΡΠΈΡΠ΅ΡΠΊΠΎΠΉ ΡΠ΅Π»Π°ΠΊΡΠ°ΡΠΈΠΈ Π΄Π΅ΡΠΎΡΠΌΠΈΡΠΎΠ²Π°Π½Π½ΡΡ
ΠΏΠΎΠ»ΠΈΠΏΡΠΎΠΏΠΈΠ»Π΅Π½ΠΎΠ²ΡΡ
ΠΊΠΎΠΌΠΏΠΎΠ·ΠΈΡΠΎΠ² (30β32 ΠΊΠΠΆ/ΠΌΠΎΠ»Ρ), Π° ΡΠ°ΠΊΠΆΠ΅ ΠΏΡΠΎΠ²Π΅Π΄Π΅Π½ΠΎ ΠΈΡ
ΡΡΠ°Π²Π½Π΅Π½ΠΈΠ΅ Ρ Π°Π½Π°Π»ΠΎΠ³ΠΈΡΠ½ΡΠΌΠΈ Ρ
Π°ΡΠ°ΠΊΡΠ΅ΡΠΈΡΡΠΈΠΊΠ°ΠΌΠΈ ΠΏΠΎΠ»ΠΈΡΡΠΈΠ»Π΅Π½ΠΎΠ²ΡΡ
ΠΊΠΎΠΌΠΏΠΎΠ·ΠΈΡΠΎΠ² (ΠΎΠΊΠΎΠ»ΠΎ 14β16 ΠΊΠΠΆ/ΠΌΠΎΠ»Ρ).ΠΡΠ²ΠΎΠ΄Ρ. ΠΡΠΈ ΠΌΠ΅Ρ
Π°Π½ΠΈΡΠ΅ΡΠΊΠΎΠΌ Π΄Π΅ΡΠΎΡΠΌΠΈΡΠΎΠ²Π°Π½ΠΈΠΈ ΡΠ»Π΅ΠΊΡΡΠΎΠΏΡΠΎΠ²ΠΎΠ΄ΡΡΠΈΡ
ΠΏΠΎΠ»ΠΈΠΏΡΠΎΠΏΠΈΠ»Π΅Π½ΠΎΠ²ΡΡ
ΠΊΠΎΠΌΠΏΠΎΠ·ΠΈΡΠΎΠ² Ρ ΡΠ΅Ρ
Π½ΠΈΡΠ΅ΡΠΊΠΈΠΌ ΡΠ³Π»Π΅ΡΠΎΠ΄ΠΎΠΌ, Π² ΡΠΎΠΌ ΡΠΈΡΠ»Π΅ ΠΏΡΠΈ ΠΏΠΎΠ²ΡΡΠ΅Π½Π½ΡΡ
ΡΠ΅ΠΌΠΏΠ΅ΡΠ°ΡΡΡΠ°Ρ
, Ρ
Π°ΡΠ°ΠΊΡΠ΅Ρ ΡΠ΅Π»Π°ΠΊΡΠ°ΡΠΈΠΈ ΡΠ»Π΅ΠΊΡΡΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ ΡΠΎΠΏΡΠΎΡΠΈΠ²Π»Π΅Π½ΠΈΡ Π°Π½Π°Π»ΠΎΠ³ΠΈΡΠ΅Π½ Ρ
Π°ΡΠ°ΠΊΡΠ΅ΡΡ ΡΠ΅Π»Π°ΠΊΡΠ°ΡΠΈΠΈ ΠΌΠ΅Ρ
Π°Π½ΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ Π½Π°ΠΏΡΡΠΆΠ΅Π½ΠΈΡ. Π‘ΡΠ΅Π΄Π½ΠΈΠ΅ Π²ΡΠ΅ΠΌΠ΅Π½Π° ΠΈ ΡΠ½Π΅ΡΠ³ΠΈΡ Π°ΠΊΡΠΈΠ²Π°ΡΠΈΠΈ ΡΠ»Π΅ΠΊΡΡΠΈΡΠ΅ΡΠΊΠΎΠΉ ΡΠ΅Π»Π°ΠΊΡΠ°ΡΠΈΠΈ Π΄Π΅ΡΠΎΡΠΌΠΈΡΠΎΠ²Π°Π½Π½ΡΡ
ΠΏΠΎΠ»ΠΈΠΏΡΠΎΠΏΠΈΠ»Π΅Π½ΠΎΠ²ΡΡ
ΠΊΠΎΠΌΠΏΠΎΠ·ΠΈΡΠΎΠ² ΡΠΎΠΏΠΎΡΡΠ°Π²ΠΈΠΌΡ Ρ Π°Π½Π°Π»ΠΎΠ³ΠΈΡΠ½ΡΠΌΠΈ ΠΏΠΎΠΊΠ°Π·Π°ΡΠ΅Π»ΡΠΌΠΈ Π΄Π»Ρ ΠΌΠ΅Ρ
Π°Π½ΠΈΡΠ΅ΡΠΊΠΎΠΉ ΡΠ΅Π»Π°ΠΊΡΠ°ΡΠΈΠΈ. ΠΡΠΎ ΡΠΊΠ°Π·ΡΠ²Π°Π΅Ρ Π½Π° ΠΎΠ±ΡΠΈΠΉ ΠΌΠ΅Ρ
Π°Π½ΠΈΠ·ΠΌ ΡΡΠΈΡ
ΠΏΡΠΎΡΠ΅ΡΡΠΎΠ²
Hadron and Quark Form Factors in the Relativistic Harmonic Oscillator Model
Nucleon, pion and quark form factors are studied within the relativistic
harmonic oscillator model including the quark spin. It is shown that the
nucleon charge, magnetic and axial form factors and the pion charge form factor
can be explained with one oscillator parameter if one accounts for the scaling
rule and the size of the constituent quarks.Comment: 9 pages, Latex, 3 postscript figures, DFTT 8/9
The Boltzmann equation for colourless plasmons in hot QCD plasma. Semiclassical approximation
Within the framework of the semiclassical approximation, we derive the
Boltzmann equation describing the dynamics of colorless plasmons in a hot QCD
plasma. The probability of the plasmon-plasmon scattering at the leading order
in the coupling constant is obtained. This probability is gauge-independent at
least in the class of the covariant and temporal gauges. It is noted that the
structure of the scattering kernel possesses important qualitative difference
from the corresponding one in the Abelian plasma, in spite of the fact that we
focused our study on the colorless soft excitations. It is shown that
four-plasmon decay is suppressed by the power of relative to the process of
nonlinear scattering of plasmons by thermal particles at the soft momentum
scale. It is stated that the former process becomes important in going to the
ultrasoft region of the momentum scale.Comment: 41, LaTeX, minor changes, identical to published versio
Quark-antiquark composite systems: the Bethe-Salpeter equation in the spectral-integration technique
The Bethe-Salpeter equations for the light-quark composite systems, q q-bar,
are written in terms of spectral integrals. For the q q-bar -mesons
characterized by the mass M, spin J and radial quantum number n, the equations
are presented for the following (n,M^2)-trajectories: pi_J, eta_J, a_J, f_J,
rho_J, omega_J, h_J and b_J.Comment: 42 pages, 5 figures, typos correcte
- β¦