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1.
Rotating black holes in the brany universe of the Randall–Sundrum type with infinite additional dimension are described by
the Kerr geometry with a tidal charge b representing the interaction of the brany black hole and the bulk spacetime. For b < 0 rotating black holes with dimensionless spin a > 1 are allowed. We investigate the role of the tidal charge in the orbital resonance model of quasiperiodic oscillations
(QPOs) in black hole systems. The orbital Keplerian frequency v
K and the radial and vertical epicyclic frequencies v
r, v
θ
of the equatorial, quasicircular geodetical motion are given. Their radial profiles related to Keplerian accretion discs
are discussed, assuming the inner edge of the disc located at the innermost stable circular geodesic. For completeness, naked
singularity spacetimes are considered too. The resonant conditions are given in three astrophysically relevant situations:
for direct (parametric) resonances of the oscillations with the radial and vertical epicyclic frequencies, for the relativistic
precession model, and for some trapped oscillations of the warped discs, with resonant combinational frequencies involving
the Keplerian and radial epicyclic frequencies. It is shown, how the tidal charge could influence matching of the observational
data indicating the 3 : 2 frequency ratio observed in GRS 1915 + 105 microquasar with prediction of the orbital resonance
model; limits on allowed range of the black hole parameters a and b are established. The “magic” dimensionless black hole spin enabling presence of strong resonant phenomena at the radius,
where v
K: v
θ
: v
r = 3 : 2 : 1, is determined in dependence on the tidal charge. Such strong resonances could be relevant even in sources with
highly scattered resonant frequencies, as those expected in Sgr A*. The specific values of the spin and tidal charge are given
also for existence of specific radius where v
K : v
θ
: v
r = s : t : u with 5≥s >t >u being small natural numbers. It is shown that for some ratios such situation is impossible in the field of black holes. We
can conclude that analysing the microquasars high-frequency QPOs in the framework of orbital resonance models, we can put
relevant limits on the tidal charge of brany Kerr black holes. 相似文献
2.
EPR spectra of deep boron in 4H-SiC and 3C-SiC crystals have been observed and studied. Two sites in 4H-SiC produced deep-boron EPR signals, quasi-cubic k and hexagonal h. In both cases the deep-boron center symmetry is close to axial along the c crystal axis, and the g factor anisotropy is about an order of magnitude larger than that for shallow boron centers. In the 3C-SiC crystal, the deep-boron symmetry is also close to axial along one of the four 〈111〉 directions. The model proposed for
the deep boron center with acceptor properties is BSi-v
C, where BSi is the boron substituting for silicon, and v
C is the carbon vacancy, with the BSi-v
C direction coinciding in 4HSiC with the hexagonal axis of the crystal for both k and h positions. In the cubic 3C-SiC crystal, there are four equivalent deep boron centers, which represent BSi-v
C pairs with the bond directed along one of the four 〈111〉 crystal directions.
Fiz. Tverd. Tela (St. Petersburg) 40, 36–40 (January 1998) 相似文献
3.
Krzysztof Rȩbilas 《Foundations of Physics Letters》2006,19(4):337-351
The Coulomb force, established in the rest frame of a source-charge Q, when transformed to a new frame moving with a velocity V has a form F = q
E + q
v × B, where E = E′∥ + γE′⊥ and B = (1/c
2)v × E and E′ is the electric field in the rest frame of the source. The quantities E and B are then manifestly interdependent. We prove that they are determined by Maxwell's equations, so they represent the electric
and magnetic fields in the new frame and the force F is the well known from experiments Lorentz force. In this way Maxwell's equations may be discovered theoretically for this
particular situation of uniformly moving sources. The general solutions of the discovered Maxwell's equations lead us to fields
produced by accelerating sources. 相似文献
4.
I. Kolokolov V. Lebedev M. Stepanov 《Journal of Experimental and Theoretical Physics》1999,88(3):506-516
We consider advection of a passive scalar θ(t,r) by an incompressible large-scale turbulent flow. In the framework of the Kraichnan model all PDF’s (probability distribution
functions) for the single-point statistics of θ and for the passive scalar difference θ(r
1)−θ(r
2) (for separations r
1−r
2 lying in the convective interval) are found.
Zh. éksp. Teor. Fiz. 115, 920–939 (March 1999)
Published in English in the original Russian journal. Reproduced here with stylistic changes by the Translation Editor. 相似文献
5.
On the effect of a magnetic field on the yield point and kinetics of macroplasticity in LiF crystals
A strong effect of a static magnetic field B on active deformation kinetics (
=const) in LiF crystals is observed. This is a threshold effect with respect to B and
; it is observed only for B> B
c
(B≃0.4 T) and
. Magnetic sensitivity is exhibited by the yield stress τ
y
, which decreases by approximately a factor of 1.5 for B=0.48 T, and by the stage-II and stage-III hardening coefficients θII and θ III, the former decreasing and the latter increasing in a magnetic field. A physical interpretation is proposed for the observed
behavior.
Pis’ma Zh. éksp. Teor. Fiz. 65, No. 6, 470–474 (25 March 1997) 相似文献
6.
7.
A. I. Parkhomenko A. M. Shalagin 《Journal of Experimental and Theoretical Physics》1998,86(5):897-902
We derive a simple analytic formula that describes the relative difference of transport collision rates, Δv/v, for collisions of molecules and atoms in the rovibrational excitation of the former by light, as a function of the rotational
quantum numbers of the combining (i.e., affected by radiation) levels of the molecules. (The relative difference of transport
collision rates can be measured in light-induced drift, or LID, experiments and is proportional to the LID effect.) The formula
is valid in the energy sudden approximation and is based on the well-known factorization formula for cross sections of RT-transitions
in linear molecules that collide with atoms. We show that in this approximation the factor Δv/v is the sum of two independent terms, the vibrational term (Δv/v)vib and the rotational term (Δv/v)rot. Each term can be measured individually in LID experiments.
Zh. éksp. Teor. Fiz. 113, 1649–1660 (May 1998) 相似文献
8.
L. K. Aminov A. A. Ershova V. N. Efimov S. L. Korableva I. N. Kurkin B. Z. Malkin A. A. Rodionov 《Physics of the Solid State》2010,52(10):2070-2075
The EPR spectra of Ce3+ impurity ions in LiYF4, LiLuF4, and LiTmF4 double-fluoride single crystals have been investigated at a frequency of ∼9.3 GHz in the temperature range 5–25 K. The effective
g factors of the ground Kramers doublet of the cerium ions in three crystals are close to each other (g
‖ = 2.737, g
⊥ = 1.475 for LiYF4:Ce3+). A superhyperfine structure of the EPR spectrum of Ce3+ ions in the LiTmF4 Van Vleck paramagnet has been observed in the external magnetic field B oriented along the crystallographic axis c (B ‖ c). The superhyperfine structure of the EPR soectra of the Ce3+ ions in the LiYF4 and LiLuF4 diamagnetic matrices is resolved for B ⊥ c. Possible factors responsible for this pronounced difference in the properties of the systems studied have been discussed. 相似文献
9.
A. B. Voitkiv 《Journal of Experimental and Theoretical Physics》1997,85(6):1074-1080
Ionization of hydrogen and helium atoms is studied for the case of “soft” collisions with highly charged fast ions with v≲Z≪v2 and v≫v
0, where Z is the ion charge, v is the collision velocity, and v
0∼1 is the characteristic velocity of the electron in the ground state of the atom. Analytical expressions are derived for
the singly and doubly differential cross section for ionization of a hydrogen atom accompanied by the ejection of a slow electron
v
e≲v
0, where v
e is the velocity of the ejected electron with respect to the recoil ion). The results are generalized to the case of single
ionization of helium. It is shown that soft collisions provide the main contribution to the hydrogen ionization cross section
and for all practical purposes determine the cross section for single ionization of helium. The asymmetry in the angular distribution
of the ejected slow electrons and the properties of momentum exchange in such collisions are discussed. Finally, a formula
for the cross section for single ionization of helium is proposed.
Zh. éksp. Teor. Fiz. 112, 1966–1977 (December 1997) 相似文献
10.
The paper considers the effect of a magnetic field B on the transport of neutral composite particles, namely excitons, in weakly disordered two-dimensional (2D) systems. In the
case of classical transport (when the interference of different paths is neglected), the magnetic field suppresses exciton
transport, and the static diffusion constant D(B) monotonically drops with B. When quantum-mechanical corrections due to weak localization are taken into account, D(B) becomes a nonmonotonic function of B. In weak magnetic fields, where the magnetic length is much larger than the exciton Bohr radius, ℓB=(ℏc/eB)1/2≫a
B
=ε ℏ2/μe
2,a positive magnetodiffusion effect is predicted, i.e., the exciton mobility should increase with B.
Zh. éksp. Teor. Fiz. 114, 359–378 (July 1998) 相似文献
11.
M. Ya. Amusia R. Krivec E. Z. Liverts V. B. Mandelzweig 《Journal of Experimental and Theoretical Physics》2006,102(4):556-561
We discuss the results of the calculation of the photoionization with deexcitation of excited He and helium-like ions Li+ and B3+ at high but nonrelativistic photon energies θ. Several lower 1
S and 3
S states are considered. We present and analyze the ratios R
d
+
* of the cross sections of photoionization with deexcitation, σ
(d)
+
*(θ), and of the photoionization with excitation, σ+*(θ). The dependence of R
d
+
* on the excitation of the target object and the charge of its nucleus is presented. In addition to theoretical interest,
the results obtained can be verified using long-lived excited states such as 23
S of He.
The text was submitted by authors in English. 相似文献
12.
A. G. Lipson B. F. Lyakov D. M. Sakov V. A. Kuznetsov 《Physics of the Solid State》1997,39(12):1891-1894
An increase has been found in the electrical conductivity of electrochemically dehydrogenated palladium hydrides (deuterides)
as compared with original samples of pure palladium in a wide temperature range (75–300 K). It is shown that this effect is
due to the suppression of the scattering of conduction electrons by phonons in the palladium lattice for T⩾θ (θ is the Debye temperature) in the presence of clusters of quasimetallic hydrogen (deuterium).
Fiz. Tverd. Tela (St. Petersburg) 39, 2113–2117 (December 1997) 相似文献
13.
P. A. Alekseev E. S. Klement’ev V. N. Lazukov I. P. Sadikov M. N. Khlopkin M. Adams A. Yu. Muzychka I. L. Sashin N. B. Kol’chugina O. D. Chistyakov 《JETP Letters》1996,63(12):1000-1006
The effects of the crystal field (CF) on the paramagnetic Pr ion in a number of compounds of the type R1−x
PrxNi (R = Ce, La, Y), in which a transition of the cerium ions from an intermediate-valence into a Kondo state occurs as La
is substituted for Ce, are investigated. The level schemes of the Pr ion in the CF are reconstructed from inelastic neutron
scattering spectra and the temperature dependence of the heat capacity in different magnetic fields (B=0–8 T). The parameters of the low-symmetry CF in the compounds RNi are determined from the experimental data. It is established
that in the Kondo regime the hybridization of the f electrons with conduction electrons only gives a proportional increase in all the parameters of the CF potential. At the
same time, partial delocalization of the f electrons in the intermediate-valence state results in charge redistribution, which is manifested in different scales for
the changes in the different CF parameters.
Pis’ma Zh. éksp. Teor. Fiz. 63, No. 12, 947–952 (25 June 1996) 相似文献
14.
A new mechanism of a “Coulomb explosion,” where ions are accelerated by the electric field separating charges at the magnetic
Debye radius r
B∼B/4πen
e, is proposed on the basis of a nonquasineutral model of electronic vortices in a magnetic field. It is shown by means of
numerical calculations that in the process of acceleration of the ions a collisionless shock wave, whose front has an effective
width of the order of δ∼r
B, determined by the breakdown of quasineutrality, is formed in a time of the order of ω
pi
−1
, where ωpi is the ion plasma frequency. The origin of such explosive dynamics is the formation of “holes” in the electron density at
characteristic times of the order of ω
pe
−1
(ωpe is the electronic plasma frequency) as a result of the generation of electronic vorticity by the Weibel instability of an
electromagnetic wave. Calculations for a laser pulse with intensity J∼6×1018 W/cm2 show that the ions expand in the radial direction with velocities up to 3.5×108 cm/s.
Pis’ma Zh. éksp. Teor. Fiz. 70, No. 10, 669–674 (25 November 1999) 相似文献
15.
Guido Van Oost James P. Gunn Alexander Melnikov Jan Stöckel Michael Tendler 《Czechoslovak Journal of Physics》2001,51(10):957-975
Radial electric fields (E
r) and their role in the establishment of edge transport barriers and improved confinement have been studied in the tokamaks TEXTOR-94 and CASTOR, where E
r is externally applied to the plasma in a controlled way using a biased electrode, as well as in the tokamak T-10 where an edge transport barrier (H-mode) is obtained during electron-cyclotron resonance heating (ECRH) of the plasma.The physics of radial currents was studied and the radial conductivity in the edge of TEXTOR-94 (R = 1.75 m, a = 0.46 m) was found to be dominated by recycling (ion-neutral collisions) at the last closed flux surface (LCFS) and by parallel viscosity inside the LCFS. From a performance point of view (edge engineering), such electrode biasing was shown to induce a particle transport barrier, a reduction of particle transport, and a concomitant increase in energy confinement. An H-mode-like behaviour can be induced both with positive and negative electric fields. Positive as well as negative electric fields were shown to strongly affect the exhaust of hydrogen, helium, and impurities, not only in the H-mode-like regime.The impact of sheared radial electric fields on turbulent structures and flows at the plasma edge is investigated on the CASTOR tokamak (R = 0.4 m, a = 0.085 m). A non-intrusive biasing scheme that we call "separatrix biasing" is applied whereby the electrode is located in the scrape-off layer (SOL) with its tip just touching the LCFS. There is evidence of strongly sheared radial electric field and E×B flow, resulting in the formation of a transport barrier at the separatrix. Advanced probe diagnosis of the edge region has shown that the E×B shear rate that arises during separatrix biasing is larger than for standard edge plasma biasing. The plasma flows, especially the poloidal E×B drift velocity, are strongly modified in the sheared region, reaching Mach numbers as high as half the sound speed. The corresponding shear rates ( 5×106 s-1) derived from both the flow and electric field profiles are in excellent agreement and are at least an order of magnitude higher than the growth rate of unstable turbulent modes as estimated from fluctuation measurements.During ECRH in the tokamak T-10 (R = 1.5 m, a = 0.3 m), a regime of improved confinement is obtained with features resembling those in the H-mode in other tokamaks. Using a heavy ion beam probe, a narrow potential well is observed near the limiter together with the typical features of the L-H transition. The time evolution of the plasma profiles during L-H and H-L transitions is clearly correlated with that of the density profile and the formation of a transport barrier near the limiter. The edge electric field is initially positive after the onset of ECRH. It changes its sign during the L-H transition and grows till a steady condition is reached. Similar to the biasing experiments in TEXTOR-94 and CASTOR, the experimentally observed transport barrier is a barrier for particles. 相似文献
16.
Maury Goodman 《Pramana》2004,62(2):229-240
Following incredible recent progress in understanding neutrino oscillations, many new ambitious experiments are being planned
to study neutrino properties. The most important may be to find a non-zero value of θ13. The most promising way to do this appears to be to measurev
μ →v
e oscillations with anE/L near Δm
atmo
2
. Future neutrino experiments are great. 相似文献
17.
L. K. Aminov A. A. Ershova S. L. Korableva I. N. Kurkin B. Z. Malkin A. A. Rodionov 《Physics of the Solid State》2011,53(11):2240-2243
The superhyperfine structure of the EPR spectra of impurity Nd3+ and U3+ ions in LiYF4, LiLuF4, and LiTmF4 double-fluoride single crystals has been observed and discussed. In LiYF4: Nd (g
| = 1.987, g
⊥ = 2.554) and LiTmF4: Nd, the superhyperfine structure is observed at the orientation of the external magnetic field B in parallel to the c axis of the crystals and consists of nine components with a splitting of ∼15.4 MHz. In LiYF4: U (g
| = 1.149, g
⊥ = 2.508) and LiLuF4: U, the superhyperfine structure is observed at both B | c and B ⊥ c and consists of nine and eleven components, respectively, with a splitting of ∼21.5MHz. It should be noted that the resolution
of the superhyperfine structure of the EPR spectrum of LiLuF4: U3+ becomes significantly higher with a deviation from the orientation B ⊥ c. 相似文献
18.
Jun-ichi Kamoshita 《The European Physical Journal C - Particles and Fields》2007,52(2):451-457
The phenomenological investigation of noncommutative space-time in the laboratory frame is presented. We formulate the apparent
time variation of noncommutativity parameter θμν in the laboratory frame due to the earth’s rotation. Furthermore, in the noncommutative QED, we discuss how to probe the
electric-like component θ
E
=(θ01,θ02,θ03) by the process at future e-e+ linear collider. We may determine the magnitude and the direction of θ
E
by detailed study of the apparent time variation of the total cross-section. If no signal is observed, the upper limit on
the magnitude of θ
E
can be determined independent of its direction. 相似文献
19.
I. A. Smirnov L. S. Parfen’eva A. Jezowski H. Misiorek S. Krempel-Hesse F. Ritter W. Assmus 《Physics of the Solid State》1999,41(9):1418-1421
The electrical and thermal conductivities of an YbInCu4 polycrystalline sample have been measured within the 4.2–300-K range. The behavior of the heat conductivity has been found
to change sharply above and below T
v
=70–75 K, the temperature corresponding to an isostructural phase transition from a state with an integral valence (T>T
v
) to a mixed-valence state (T<T
v
) of Yb ions. A preliminary qualitative analysis of the results is presented.
Fiz. Tverd. Tela (St. Petersburg) 41, 1548–1551 (September 1999) 相似文献
20.
E. Torrente-Lujan 《Physics of Atomic Nuclei》2006,69(1):147-158
The interactions of fermions with the domain-wall bubbles produced during a first-order phase transition are considered. An
exact solution of the Dirac equation’s fermion propagation is obtained for a wall profile incorporating a position-dependent
CP-violating phase. The reflection coefficients through the wall are computed for particles and antiparticles. The asymmetry
in the reflection coefficients is especially high (a resonance effect) when the energy and mass of the incident particles
are E/m=Δθ/2, where Δθ is the phase variation across the wall width. We compute the chiral-charge flux through the wall surface and
the corresponding baryon asymmetry of the Universe. It agrees in sign and magnitude with the observed baryonic excess ϱB/s ≈ 10-10 for a larnge of parameters and CP violation. As a function of Δθ, the ratio ϱb/s reaches a maximum for large values of Δθ (m ≈ m
top).
The text was submitted by the author in English. 相似文献