共查询到20条相似文献,搜索用时 687 毫秒
1.
2.
V. P. Ruban 《Journal of Experimental and Theoretical Physics》2010,111(5):776-785
We consider slow, compared to the speed of sound, motions of an ideal compressible fluid (gas) in a gravitational field in
the presence of two isentropic layers with a small specific-entropy difference between them. Assuming the flow to be potential
in each of the layers (v
1, 2 = ▿ϕ1, 2) and neglecting the acoustic degrees of freedom (div($
\bar \rho
$
\bar \rho
(z)▿ϕ1, 2) ≈ 0, where $
\bar \rho
$
\bar \rho
(z) is the average equilibrium density), we derive the equations of motion for the boundary in terms of the shape of the surface
z = η(x, y, t) itself and the difference between the boundary values of the two velocity field potentials: ψ(x, y, t) = ψ1 − ψ2. We prove the Hamilto nian structure of the derived equations specified by a Lagrangian of the form ℒ = ∫$
\bar \rho
$
\bar \rho
(η)η
t
ψdxdy − ℋ{η, ψ}. The system under consideration is the simplest theoretical model for studying internal waves in a sharply stratified
atmosphere in which the decrease in equilibrium gas density due to gas compressibility with increasing height is essentially
taken into account. For plane flows, we make a generalization to the case where each of the layers has its own constant potential
vorticity. We investigate a system with a model dependence $
\bar \rho
$
\bar \rho
(z) ∝ e
−2αz
with which the Hamiltonian ℋ{η, ψ} can be represented explicitly. We consider a long-wavelength dynamic regime with dispersion
corrections and derive an approximate nonlinear equation of the form u
t
+ auu
x
− b[−$
\hat \partial _x^2
$
\hat \partial _x^2
+ α2]1/2
u
x
= 0 (Smith’s equation) for the slow evolution of a traveling wave. 相似文献
3.
Utilizing the Baym-Kadanoff formalism with the polarization function calculated in the random phase approximation, the dynamics
of the ν = 0 quantum Hall state in bilayer graphene is analyzed. Two phases with nonzero energy gap, the ferromagnetic and
layer asymmetric ones, are found. The phase diagram in the plane ($
\bar \Delta _0
$
\bar \Delta _0
, B), where $
\bar \Delta _0
$
\bar \Delta _0
is a top-bottom gates voltage imbalance, is described. It is shown that the energy gap scales linearly, ΔE ∼ 14B [T] K, with magnetic field. 相似文献
4.
E. V. Gryzlova A. N. Grum-Grzhimailo A. I. Magunov S. I. Strakhova 《Optics and Spectroscopy》2010,109(1):59-65
Optical activity of xenon atoms in the vacuum UV range induced by circularly polarized laser light is studied theoretically.
The optical activity arises in the vicinity of the autoionizing state 5p
5(2
P
1/2)8s′$
\left[ {\frac{1}
{2}} \right]_1
$
\left[ {\frac{1}
{2}} \right]_1
as a result of its coupling via the laser field with the discrete state 5p
5(2
P
3/2)7p
$
\left[ {\frac{1}
{2}} \right]_1
$
\left[ {\frac{1}
{2}} \right]_1
. Polarization variations of the vacuum UV radiation upon its propagation through the atomic medium are calculated, and the
possibility of controlling this polarization is discussed. Manifestations of nonresonant coupling of the discrete state with
the broad autoionizing state 5p
5(2
P
1/2)6d′$
\left[ {\frac{1}
{2}} \right]_1
$
\left[ {\frac{1}
{2}} \right]_1
induced by the overlap of the Rydberg autoionizing series in xenon are studied. 相似文献
5.
G. V. Danilyan J. Klenke V. A. Krakhotin V. L. Kuznetsov V. V. Novitsky V. S. Pavlov P. B. Shatalov 《Physics of Atomic Nuclei》2009,72(11):1812-1817
Gamma rays probably emitted by the fissioning nucleus 236U* at the instant of the break of the neck or within the time of about 10−21 s after or before this were discovered in the experiment devoted to searches for the effect of rotation of the fissioning
nucleus in the process 235U($
\vec n
$
\vec n
, γf) and performed in a polarized beam of cold neutrons from the MEPHISTO Guideline at the FRM II Munich reactor. Detailed investigations
revealed that the angular distribution of these gamma rays is compatible with the assumption of the dipole character of the
radiation and that their energy spectrum differs substantially from the spectrum of prompt fission gamma rays. In the measured
interval 250–600 keV, this spectrum can be described by an exponential function at the exponent value of α = −5 × 10−3 keV−1. The mechanism of radiation of such gamma rays is not known at the present time. Theoretical models based on the phenomenon
of the electric giant dipole resonance in a strongly deformed fissioning nucleus or in a fission fragment predict harder radiation
whose spectrum differs substantially from the spectrum measured in the present study. 相似文献
6.
We present the measurement of directed flow (v
1) for the identified particles, namely, Λ, $
\bar \Lambda
$
\bar \Lambda
and K
s
0, as a function of rapidity and centrality in Au+Au collisions at $
\sqrt {s_{NN} }
$
\sqrt {s_{NN} }
= 200 GeV and 62.4 GeV. The measurement is based on the run IV data obtained by the STAR experiment at RHIC. In order to
enhance event plane resolution, we use tracks reconstructed from the Forward Time Projection Chambers (FTPCs), together with
the sideward deflection of spectator neutrons measured by the STAR’s Shower Maximum Detector at Zero Degree Calorimeters (ZDC-SMDs).
We find that for 200 GeV, proton and antiproton v
1 is less than 1%, the K
s
0
Λ, $
\bar \Lambda
$
\bar \Lambda
v
1 is less than 2%; for 62 GeV, proton v
1 is less than 1% and antiproton is less than 2%, v
1 for K
s
0, Λ, $
\bar \Lambda
$
\bar \Lambda
is less than 2% in Au+Au collisions at 200 GeV. 相似文献
7.
Yu. S. Surovtsev T. Branz T. Gutsche V. E. Lyubovitskij 《Physics of Particles and Nuclei》2010,41(6):990-993
In a model-independent approach the data on ππ → ππ, K
$
\bar K
$
\bar K
, ηη, ηη′ in the I
G
J
PC
= 0+0++ channel and on the Kπ scattering in the $
I\left( {J^P } \right) = \frac{1}
{2}\left( {0^ + } \right)
$
I\left( {J^P } \right) = \frac{1}
{2}\left( {0^ + } \right)
channel are analyzed jointly for studying the status and QCD nature of the f
0- and the K*0-mesons. It is shown that in the 1500-MeV region, there are two states, wide (interpreted as a glueball) and narrow (q
$
\bar q
$
\bar q
). In the Kπ-scattering data analysis, the proof for the K*0(900) is given. 相似文献
8.
N. G. Zaki 《Pramana》2010,75(4):719-726
The Weibel instability (WI) of relativistic electron beam (REB) penetrating an infinite collisional plasma was studied in
the following models: (i) REB model, where the total equilibrium distribution function f
0($
\vec p
$
\vec p
) is approximated by nonrelativistic background electron and REB distribution functions and (ii) relativistic monoenergetic
beam (RMB) model, where f
0($
\vec p
$
\vec p
) is approximated by nonrelativistic background electrons and RMB distribution functions. 相似文献
9.
The Blume-Emery-Griffiths model with the dipole-quadrupole interaction ($
\ell = \frac{I}
{J}
$
\ell = \frac{I}
{J}
) has been simulated using a cellular automaton algorithm improved from the Creutz cellular automaton (CCA) on the face centered
cubic (fcc) lattice. The finite-size scaling relations and the power laws of the order parameter (M) and the susceptibility (χ) are proposed for the dipole-quadrupole interaction (ℓ). The dipole-quadrupole critical exponent
δχ has been estimated from the data of the order parameter (M) and the susceptibility (χ). The simulations have been done in the interval $
0 \leqslant \ell = \frac{I}
{J}0 \leqslant 0.01
$
0 \leqslant \ell = \frac{I}
{J}0 \leqslant 0.01
for $
d = \frac{D}
{J} = 0,k = \frac{K}
{J} = 0
$
d = \frac{D}
{J} = 0,k = \frac{K}
{J} = 0
and $
h = \frac{H}
{J} = 0
$
h = \frac{H}
{J} = 0
parameter values on a face centered cubic (fcc) lattice with periodic boundary conditions. The results indicate that the
effect of the ℓ parameter is similar to the external magnetic field (h). The critical exponent δℓ are in good agreement with the universal value (δ
h
= 5) of the external magnetic field. 相似文献
10.
On the basis of quasipotential approach to the bound state problem in QED we calculate the vacuum polarization, relativistic,
recoil, structure corrections of orders α
5 and α
6 to the fine structure interval ΔE
fs = E(2P
3/2) − E(2P
1/2) and to the hyperfine structure of the energy levels 2P
1/2 and 2P
3/2 in muonic 23He ion. The resulting values ΔE
fs = 144 803.15 μeV, Δ$
\tilde E
$
\tilde E
hfs(2P
1/2) = −58 712.90 μeV, Δ$
\tilde E
$
\tilde E
hfs(2P
3/2) = −24 290.69 μeV provide reliable guidelines in performing a comparison with the relevant experimental data. 相似文献
11.
The BRAHMS measurement of proton-to-pion ratios in Au+Au and p+p collisions at $
\sqrt {s_{NN} }
$
\sqrt {s_{NN} }
= 62.4 GeV and $
\sqrt {s_{NN} }
$
\sqrt {s_{NN} }
= 200 GeV is presented as a function of transverse momentum and collision centrality within the pseudorapidity range 0 ≤
η ≤ 3. The baryo-chemical potential, μ
B
, for the indicated data spans from μ
B
≈ 26 MeV ($
\sqrt {s_{NN} }
$
\sqrt {s_{NN} }
200 GeV, η ≈ 0) to μ
B
∼ 260 MeV ($
\sqrt {s_{NN} }
$
\sqrt {s_{NN} }
= 62.4 GeV, η ≈ 3) [1]. The p/πratio measured for Au+Au system at $
\sqrt {s_{NN} }
$
\sqrt {s_{NN} }
62.4 GeV, η ≈ 3 reaches astounding value of 8–10 at p
T
> 1.5 GeV/c. For these energy and pseudorapidity interval no centrality dependency of p/π ratio is observed. Moreover, the baryon-to-meson ratio of nucleus-nucleus data are consistent with results obtained for p+p
interactions. 相似文献
12.
M. N. Zakharenkov 《Thermophysics and Aeromechanics》2009,16(3):391-396
The known problem of flow transition near a circular cylinder at Re = 40 from a symmetrical form to the Karman vortex street
can be considered as the problem of vortex wave development and intensification. Development of three bundles of vortex waves
of low intensity is observed in a wake of a cylinder; these bundles are easily visualized as the structures of relative vorticity
$
\bar \Omega
$
\bar \Omega
= Ω(t
1) − Ω(t
0): difference of vorticity Ω at two time moments, t
0 being fixed. In the field of $
\bar \Omega
$
\bar \Omega
the alternating structure of quadrupoles is characterized by linear parameter l = h/d: the ratio of the width of the central bundle of vortex waves to the distance between the centers of quadrupoles of a “single
sign”. When l = 0.281 is achieved, which coincides with the value of the same parameter of a stable Karman street, the transition from
symmetrical streamlining by viscous incompressible liquid to the vortex street occurs. 相似文献
13.
Abhijit Bhattacharyya Sanjay K. Ghosh Ritam Mallick Sibaji Raha 《Indian Journal of Physics》2010,84(12):1759-1763
We have studied the v+ $
\bar \nu
$
\bar \nu
→ e
+ + e
− energy deposition rate near a rotating compact star which is important for the study of gamma ray bursts (GRB). The General
relativistic (GR) and rotational effects increase the efficiency of the process immensely. The rotational effect also brings
about an asymmetry in the deposition rate of the star. 相似文献
14.
G. H. Arakelyan A. B. Kaidalov C. Merino Yu. M. Shabelski 《Physics of Atomic Nuclei》2011,74(3):426-436
The WA89 Collaboration experimental data on production of Λ, Σ−, Σ+, Ξ−, Ω− baryons, $
\bar \Lambda
$
\bar \Lambda
and $
\bar \Xi ^ +
$
\bar \Xi ^ +
antibaryons in Σ− collisions with C and Cu targets at 345 GeV/c ($
\sqrt {s_{\Sigma N} }
$
\sqrt {s_{\Sigma N} }
≈ 25.5 GeV) in the frame of the Quark-Gluon String Model is described. The comparison of the theoretical results with the
experimental data is discussed. Finally, some relations among the values of the model parameters obtained with the help of
quark combinatorics are presented. 相似文献
15.
S. G. Karshenboim 《Physics of Particles and Nuclei Letters》2009,6(6):450-454
Oscillations of neutral meson (K
0-$
\overline {K^0 }
$
\overline {K^0 }
, D
0-$
\overline {D^0 }
$
\overline {D^0 }
, and B
0-$
\overline {B^0 }
$
\overline {B^0 }
are extremely sensitive to the meson and antimeson energies at rest. This energy is determined as mc
2—with the corresponding inertial mass—and as the energy of gravitational interaction. Assuming that the CPT theorem is correct
for inertial masses and estimating the gravitational potential for which the largest contribution originates from the field
of the galaxy center, we obtain the estimate from experimental data on K
0-$
\overline {K^0 }
$
\overline {K^0 }
oscillations:
$
\left| {\left( {\frac{{m_g }}
{{m_i }}} \right)_{K^0 } - \left( {\frac{{m_g }}
{{m_i }}} \right)_{\overline {K^0 } } } \right| \leqslant 8 \times 10^{ - 13} , at C.L. = 90\%
$
\left| {\left( {\frac{{m_g }}
{{m_i }}} \right)_{K^0 } - \left( {\frac{{m_g }}
{{m_i }}} \right)_{\overline {K^0 } } } \right| \leqslant 8 \times 10^{ - 13} , at C.L. = 90\%
相似文献
16.
A general formalism for double and triple spin correlations of the reaction
is developed for the case of collinear kinematics. A complete polarization experiment allowing one to reconstruct all four
amplitudes describing this process is suggested. Furthermore, the spin observables of the inelastic charge-exchange reaction
(pp)(1
S
0 are analyzed in collinear kinematics within the single pN-scattering mechanism involving the subprocess pn → Δ0
p. The full set of spin observables, related to the polarization of one or two initial particles and one final particle, is
obtained in terms of three invariant amplitudes of the reaction pd → Δ(pp)(1
S
0) and the transition form factor d → (pp)(1
S
0). A complete polarization experiment for the reaction
(pp)(1
S
0) is suggested which allows one to determine three independent combinations of the four amplitudes of the elementary subprocess
.
The text was submitted by the authors in English. 相似文献
17.
A. I. Dmitriev V. M. Kaminski G. V. Lashkarev P. E. Butorin Z. D. Kovalyuk V. I. Ivanov A. I. Beskrovny 《Physics of the Solid State》2009,51(11):2342-2346
The neutron diffraction patterns have been analyzed for a layered single crystal and a powder of the γ-polytype of indium
selenide in the temperature range 10–300 K. In the temperature range 10–50 K, the excitation of bending vibrations due to
the charge density waves changes the phonon spectrum and gives rise to a negative thermal expansion in the plane of layers,
i.e., α‖c
= −2.2 × 10−6 K−1, which is characteristic of two-dimensional structures. The average (over the range T = 50–300 K) coefficients of thermal expansion along the principal crystallographic directions have been calculated: $
\bar \alpha _{ \bot c}
$
\bar \alpha _{ \bot c}
= 10.48 × 10−6 K−1 and $
\bar \alpha _{\parallel c}
$
\bar \alpha _{\parallel c}
= 12.97 × 10−6 K−1, which agree with the X-ray diffraction data previously obtained by the authors at T = 290 K. 相似文献
18.
I. A. Fomin 《JETP Letters》2011,93(3):144-146
It is shown that weak correlations between pair-breaking impurities in superconductors influence the temperature dependence
of the order parameter within the Ginzburg-Landau region if correlation radius of impurities R is greater than the coherence length of the superconductor ξ0. The dependence of the square of the average order parameter on a temperature difference T
c
− T changes its slope in a region $
\xi _0 \sqrt {{{T_c } \mathord{\left/
{\vphantom {{T_c } {\left( {T_c - T} \right)}}} \right.
\kern-\nulldelimiterspace} {\left( {T_c - T} \right)}}} \sim R
$
\xi _0 \sqrt {{{T_c } \mathord{\left/
{\vphantom {{T_c } {\left( {T_c - T} \right)}}} \right.
\kern-\nulldelimiterspace} {\left( {T_c - T} \right)}}} \sim R
. The influence of correlations of impurities on other thermodynamic properties of superconductors is discussed. 相似文献
19.
D. V. Shirkov 《Physics of Particles and Nuclei Letters》2010,7(6):379-383
The dimensional reduction, in a form of transition from four to two dimensions, was used in the 90s of the past century in
a context of the HE Regge scattering. Recently, it has got a new impetus in quantum gravity where it opens the way to renormalizability
and finite short-distance behaviour. We consider a QFT model gφ4 with running coupling defined in both domains of different dimensionality; the $
\bar g
$
\bar g
(q
2) evolutions being duly correlated at the reduction scale q ∼ M. Beyond this scale, in the deep UV 2-dimensional region, the running coupling does not increase any more. Instead, it slightly
decreases and tends to a finite value $
\bar g
$
\bar g
2(∞) < $
\bar g
$
\bar g
2(M
2) from above. As a result, the global evolution picture looks quite peculiar and proposes a base for the modified scenario
of gauge couplings behavior with UV fixed points provided by dimensional reduction instead of leptoquarks. 相似文献
20.
We used variationally improved perturbation theory (VIPT) in calculating the slope and curvature of Isgur-Wise (I-W) function
with the Cornell potential −$
\frac{{4\alpha _s }}
{{3r}}
$
\frac{{4\alpha _s }}
{{3r}}
+br + c instead of the usual stationary state perturbation theory as done earlier. We used −(4α
s
/3r), i.e. the Coulombic potential, as the parent and the linear one, i.e. br+c as the perturbed potential in the theory and calculated the slope and curvature of Isgur-Wise function including three states
in the summation involved in the first-order correction to wave function in the method. 相似文献
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