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The semileptonic decay width of heavy baryons such as (Λ
b
→ Λcev) has been estimated in the framework of a nonrelativistic field theoretic quark model where four component quark field
operators along with a harmonic oscillator wave function are used to describe translationally invariant hadronic states. The
present estimation does not make an explicit use of heavy quark symmetry and has a reasonable agreement with the experimentally
measured decay width, polarisation ratio and form factors with the harmonic oscillator radii and quark momentum distribution
inside the hadron as free parameters. 相似文献
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C. Poulain N. Mazellier L. Chevillard Y. Gagne C. Baudet 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,53(2):219-224
We present the results of an experimental study of the spatial Fourier modes of the vorticity in a turbulent jet flow.
By means of an acoustic scattering setup we have recorded the evolution in time of Fourier modes of the vorticity field, characterized
by well defined wavevectors k.
By computing the auto-correlation of the amplitude of the Fourier modes we evidence that, whatever the length scale (or equivalently
k), the dynamic evolution of
the vorticity field involves two well separated time scales.
We have also performed the simultaneous acquisitions of pairs of Fourier modes with two wavevectors k and k'.
Whatever the spectral gap k- k', any pair of Fourier modes exhibits a significant cross-correlation over long time delays, indicating a strong statistical
dependence between
scales. 相似文献
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S. Sankar MR. Manikandan S.D. Gopal Ram T. Mahalingam G. Ravi 《Journal of Crystal Growth》2010,312(19):2729-2733
The microbial free single crystals of α and γ glycine were grown from gel at room temperature in a new chemical route. These crystals showed a superior quality than the solution grown crystals. The metastable α-form and the stable γ-form of glycine were crystallized in silica gel by solubility reduction method. The form of crystallization is confirmed by single crystal and powder X-ray diffraction analyses. The crystals of α and γ glycine were found to crystallize in monoclinic and hexagonal crystal systems, respectively. For analyzing the functional group and thermal stability of α and γ glycine crystals, spectroscopic and thermal analyses have been carried out. The dielectric studies were performed to find the dielectric constant of the grown crystals and the results are discussed. Second harmonic generation efficiency of the crystal was measured by Kurtz’s powder method using Nd:YAG laser and it was found to be 2.68 times that of potassium dihydrogen phosphate crystals. 相似文献
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Raman and resonance-Raman spectra of the I?3 ion isolated within CsI crystals have been studied using 647 nm and 488 nm exciting radiation. Sample temperatures between 300 and 20 K have been used. Eleven overtones of the symmetric stretching mode (nν1) have been observed in the resonance-Raman spectrum excited by the 488 nm Ar+ laser line. Bands centred at 153, 170, 264 and 304 cm?1 have been assigned as ν3, 2ν2, ν1+ν3 and 2ν3(Σ+) respectively. The remaining structure between the nν1 lines has been assigned as due to combinations of these lines with the lattice vibrations of the CsI crystal. 相似文献
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Mixed alkoxide/aryloxide clusters are long-lived and milder than previously reported ester interchange catalysts. They completely transform difficult substrates in a single synthetic operation with lower catalyst and reagent ester loadings. In addition to superior activities, these mixed clusters are kinetically less basic toward enolizable esters. 相似文献
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In this paper exact asymptotic formulae are found for singularvalues of the Cauchy operator and the logarithmic potentialtype operator (on a bounded domain), as well as their productswith Bergman's projection. It is shown that these spectral characteristicsdetect geometric properties of a domain (area and the lengthof the boundary). The hypothesis "can we hear the shape of adrum", from a paper by J.M. Anderson, D. Khavinson, and V. Lomonosov[Spectral properties of some integral operators arisingin potential theory, Quart. J. Math. Oxford (2) 43 (1992)387-407], is correct in the above sense. 1991 Mathematics SubjectClassification: 47B10. 相似文献