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81.
E.?Tomasi-GustafssonEmail author F.?Lacroix C.?Duterte G.?I.?Gakh 《The European Physical Journal A - Hadrons and Nuclei》2005,24(3):419-430
We perform a global analysis of the experimental data of the electromagnetic nucleon form factors, in space-like and time-like regions. We give the expressions of the observables in annihilation processes, such as p + ¯↦ℓ+ + ℓ-, ℓ = e or μ, in terms of form factors. We discuss some of the phenomenological models proposed in the literature for the space-like region, and consider their analytical continuation to the time-like region. After determining the parameters through a fit on the available data, we give predictions for the observables which will be experimentally accessible with large statistics, polarized annihilation reactions 相似文献
82.
83.
船舶碰撞危险度模型的构建 总被引:6,自引:0,他引:6
运用模糊数学的综合评判理论,把会遇中目标船的DCPA、TCPA两船距离、相对方位、船速比5个因素作为基本评判参数,建立碰撞危险度的评价模型.而将其它因素,如航行区域状况、能见度情况和船舶的操纵性能等,作为对上述因素的危险隶属度函数的修正加以考虑.引入了船舶领域、动界等概念,以对来船构成的本船危险度进行客观有效地评价,为安全避碰提供合理依据. 相似文献
84.
85.
We extract the neutron charge form factor G
n
E(Q
2) from the charge form factor of deuteron G
d
C(Q
2) obtained from T
20(Q
2) data at 0≤Q
2≤ 1.717 (GeV/c)2. The extraction is based on the relativistic impulse approximation in the instant form of the relativistic Hamiltonian dynamics.
Our results (12 new points) are compatible with existing values of the neutron charge form factor of other authors. We propose
a fit for the whole set (36 points) taking into account the data for the slope of the form factor at Q
2 = 0.
Received: 26 July 2002 / Accepted: 18 September 2002 / Published online: 4 February 2003
RID="a"
ID="a"e-mail: krutov@ssu.samara.ru
RID="b"
ID="b"e-mail: troitsky@theory.sinp.msu.ru
Communicated by V.V. Anisovich 相似文献
86.
On "Problems on von Neumann Algebras by R. Kadison, 1967" 总被引:1,自引:0,他引:1
LiMingGE 《数学学报(英文版)》2003,19(3):619-624
A brief summary of the development on Kadison‘s famous problems (1967) is given. A new set of problems in von Neumann algebras is listed. 相似文献
87.
88.
G. Pancheri O. Shekhovtsova G. Venanzoni 《The European Physical Journal A - Hadrons and Nuclei》2007,31(4):458-460
Effects due to the non-pointlike behaviour of pions in the process e
+
e
-→π
+
π
-
γ can arise for hard photons in the final state. By means of a Monte Carlo event generator, which also includes the contribution
of the direct decay φ→π
+
π
-
γ, we estimate these effects in the framework of the resonance perturbation theory. We consider angular cuts used in the KLOE
analysis of the pion form factor at threshold. A method to reveal the effects of the non-pointlike behaviour of pions in a
model-independent way is proposed. 相似文献
89.
D. Khalil A. Makhoute A. Maquet G. Rahali M. Zitane 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,41(2):287-295
The dynamics of laser-assisted elastic collisions in
helium is studied using the second-order Born approximation.
Detailed calculations of the scattering amplitudes are performed
by using the Sturmian basis expansion. Differential cross sections
for elastic scattering with the net absorption/emission of up to
two photons are calculated for collision energies of 5 eV, 10 eV,
and 20 eV. We discuss the influence of the low-energy electrons on
the differential cross section (DCS) as a function of the
scattering angle for selected choices of the laser frequency and
the number of photons exchanged between the external field and
electron-helium system. 相似文献
90.
David Salzmann 《Journal of Quantitative Spectroscopy & Radiative Transfer》2007,107(1):141-153
In this paper we present explicit formulas for the escape factors of strong spectral lines in spherical-symmetric plasmas. The plasma does not necessarily have a homogeneous density. The calculations include two new elements: the first incorporates an accurate calculation of the angle-averaged areal density of ions from any internal point to the edge of the sphere. The second is the use of a saddle point method to carry out the integration over the line profile. Approximate expressions for the asymptotic behavior of the escape factor are given for Gaussian, Lorentzian and Holtsmarkian line shapes. 相似文献