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排序方式: 共有620条查询结果,搜索用时 31 毫秒
161.
Robert Harlander 《Pramana》2006,67(5):875-884
Recent theoretical developments concerning Higgs production at the large hadron collider are reviewed, both in the standard
model and in the MSSM. Emphasis is put on the inclusive and exclusive cross-sections for gluon fusion, as well as on the associated
production with bottom quarks. 相似文献
162.
S. Fumeron P. Ben-Abdallah 《Journal of Quantitative Spectroscopy & Radiative Transfer》2005,95(1):33-47
A theoretical study of unsteady radiative heat transfer inside refractive heterogeneous participating media is presented. In the approximation of space-time geometrical optics, some new properties for propagating waves are exhibited. Physically, it is shown that the time dependency of refractive index can give rise to an effect of spectral bounce, whereas space dependency is responsible for the existence of confined trajectories for light. Then, the problem of energy transport is studied: from the shape of Clausius Invariant in unsteady processes, the transient radiative transfer equation is built and the existence of amplification effects for specific intensity is presented. 相似文献
163.
在自旋轨道劈裂阵模型下,考虑组态间的耦合,计算出类铜钽激光等离子体的跃迁组态的波长和对应的波数,通过组态平均分析了其自电离与辐射跃迁特性,得出相关的自电离系数和辐射衰减系数,这些参数为分析高离化钽激光等离子体的双电子复合过程提供了重要的理论依据. 相似文献
164.
We have used the quantum electrodynamic theory of moments and the S-matrix formalism of Gell-Mann and Low to carry out numerical
modeling of the characteristics (shift, width) of radiative multiphoton absorption lines for an atom in the field of a multimodal
laser pulse with gaussian and soliton-like shapes. We have studied the effect of multimode character on the characteristics
of multiphoton resonances, using as an example the 6S-6F transition in the cesium atom at the wavelength 1059 nm.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 2, pp. 271–274, March–April, 2007. 相似文献
165.
J. T. Londergan 《The European Physical Journal A - Hadrons and Nuclei》2007,32(4):415-419
The NuTeV neutrino measurement of the Weinberg angle differs by 3 standard deviations from measurements at the Z pole. We review the status of various possibilities to explain this result, including contributions from physics outside
the standard model; effects of radiative corrections; nuclear corrections to parton distributions; isospin-violating effects;
and effects due to strange quarks. 相似文献
166.
F. J. Cao 《The European Physical Journal A - Hadrons and Nuclei》2007,31(4):883-885
The quantum dynamics of the symmetry-broken λ(Φ
2)2 scalar-field theory in the presence of an homogeneous external field is investigated in the large-N limit. We consider an initial thermal state of temperature T for a constant external field J. A subsequent sign flip of the external field, J→ - J, gives rise to an out-of-equilibrium nonperturbative quantum field dynamics. We review here the dynamics for the symmetry-broken
λ(Φ
2)2 scalar N component field theory in the large-N limit, with particular stress in the comparison between the results when the initial temperature is zero and when it is finite.
The presence of a finite temperature modifies the dynamical effective potential for the expectation value, and also makes
that the transition between the two regimes of the early dynamics occurs for lower values of the external field. The two regimes
are characterized by the presence or absence of a temporal trapping close to the metastable equilibrium position of the potential.
In the cases when the trapping occurs it is shorter for larger initial temperatures. 相似文献
167.
Effect of lithium-potassium mixed alkali on spectroscopic properties of Er^3+-doped aluminophosphate glasses
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Er^3+-doped lithium-potassium mixed alkali aluminophosphate glasses belonging to the oxide system xK2O-(15-x)Li2O-4B2O3-11Al2O3-5BaO-65P2O5 are obtained in a semi-continuous melting quenching process. Spectroscopic properties of Er^3+-doped glass matrix have been analysed by fitting the experimental data with the standard Judd-Ofelt theory. It is observed that Judd-Ofelt intensity parameters Ωt(t = 2, 4 and 6) of Er^3+ change when the second alkali is introduced into glass matrix. The variation of line strength Sed[^4I13/2,^4I15/2] follows the same trend as that of the/26 parameter. The effect of mixed alkali on the spectroscopic properties of the aluminophosphate glasses, such as absorption cross-section, stimulated emission cross-section, spontaneous emission probability, branching ratio and the radiative lifetime, has also been investigated in this paper. 相似文献
168.
A. Battaglia C.P. Davis C. Simmer 《Journal of Quantitative Spectroscopy & Radiative Transfer》2007,105(1):55-67
Three different numerical methods capable of solving the radiative transfer of microwave radiation within 3-D dichroic media are compared. A case study, represented by an intense rain shaft populated by perfectly oriented oblate raindrops, is analysed in detail, including a discussion of the behaviour of all four Stokes components.Results demonstrate an acceptable agreement between all Monte Carlo methods. The method based on a discrete ordinates scheme agrees only qualitatively with the Monte Carlo outputs. Because of its lower computational cost the backward Monte Carlo technique based on importance sampling represents the most efficient way to face passive microwave radiative transfer problems related to optically thick 3-D structured clouds including non-spherical preferentially oriented hydrometeors. 相似文献
169.
B. Metsch 《The European Physical Journal A - Hadrons and Nuclei》2008,35(3):275-280
The scope of a relativistically covariant constituent quark model of baryons based on the Bethe-Salpeter equation in instantaneous
approximation is illustrated by a discussion of various baryon resonance observables such as static electromagnetic moments
--including a novel calculational procedure-- form factors and helicity amplitudes, semileptonic decays as well as the systematics
of two-body strong decay widths. 相似文献
170.
D.W. Mueller JrA.L. Crosbie 《Journal of Quantitative Spectroscopy & Radiative Transfer》2002,75(4):423-453
Three-dimensional vector radiative transfer in a semi-infinite, Rayleigh scattering medium exposed to a polarized, Gaussian laser beam directed perpendicular to the surface is studied. The focus of this investigation is the 4×4, spatially varying reflection matrix that can be used to determine the normally backscattered radiation when the polarization of the incident radiation is specified. An inverse integral transform is used to construct the spatially varying reflection matrix from the generalized reflection matrix found in a previous study. The elements of this matrix depend on location specified by optical radius and azimuthal angle. The azimuthal variation is found by performing part of the inverse transform analytically, while the radial variation is described by five functions that are calculated numerically via an inverse Hankel transform. Benchmark numerical results for these five functions are presented, and the effects of beam radius and particle concentration are discussed. Expressions that describe the behavior of the reflection functions at small and large optical radii are developed, and comparisons are made to the one-dimensional and scalar situations. The scalar approximation fails to predict the three-dimensional effects produced by the polarized beam, and even when the incident radiation is unpolarized, the error in the scalar reflection function can be as high as 20%. 相似文献