The ντ-mass and the τ-decay modes

The behaviour of the different decay modes of the charged heavy lepton τ versus the neutrino ν_τ-mass is analyzed in detail. The τ→ν_τ A ₁ and τ→ν_τ K ^* decay rates have been evaluated using finite energy sum rules. The τ→ν_τ+ “Hadron Continuum” decay rate has been estimated within the framework of Quantum Chromodynamics (QCD). We find that the branching ratios of the semi-leptonic processes: τ→ν_τρ, τ→ν_τπ and τ→ν_τ+ “Hadron Continuum” are very sensitive to the value of the ν_τ-mass. Thus a more precise measurement of these branching ratios could provide an improved upper bound for the neutrino ν_τ-mass.     

Bildgarben und Fasercohomologie für Relativ Analytische Räume

Let : XY be a relative analytic space and an _X module. The object of this paper is to collect some results on the connection between the fibre cohomology groups Hⁱ(X(y),(y)) and the direct image sheaves Rⁱ _*. This generalizes results of Kodaira-Spencer and Grauert-Riemen-schneider giving a unified approach based on the methods of [9].     

NMR study of structure and dynamics of stereocomplexes of poly(methyl methacrylate) in C6D6 and CD3CN

Summary Stereocomplexes of isotactic (i) and syndiotactic (s) poly(methyl methacrylate)(PMMA), with different stereoregularity of thes-PMMA component, in C₆D₆ and CD₃CN solution were investigated by means of¹H NMR spectra measured with magic angle spinning (MAR-NMR), broadline (BL) NMR spectra and¹³C NMR spectra measured with strong proton decoupling. This study has shown that in associated segments of the stereocomplexes withp= 30–40% (p is the fraction of associated monomer units) the-CH₃ and CH₂ groups exhibit equal mobility as in solutions of onlyi ors PMMA, but in consequence of interaction of the ester groups these motions are restricted in space. In complexes with high density of interactions (p 75%) the motion of-CH₃ and CH₂ groups in associated segments is retarded. The network model of the stereocomplex, and the possibility of the formation of a double helix are discussed.

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Zusammenfassung Stereokomplexe von isotaktischem (i) und syndiotaktischem (s) Polymethylmethacrylat (PMMA), mit verschiedener Stereoregularität ders-PMMA Komponente, in C₆D₆ und CD₃CN Lösung, wurden durch¹H NMR Spektra mit Magisch-Winkel-Rotation (MAR-NMR), durch Breitband (BL) NMR Spektra und durch¹³C NMR Spektra mit starker Protonenentkopplung untersucht. Es wurde herausgefunden, daß in assoziierten Segmenten des Stereokomplexes mitp = 30–40% (p ist der Bruchteil der assoziierten Monomereinheiten) die-CH³ und CH²-Gruppen die gleiche Beweglichkeit wie in Lösungen von nur s oder nuri-PMMA ausweisen, aber infolge der Wechselwirkung der Estergruppen sind diese Bewegungen raumbehindert. In Komplexen mit einem hohen Grad von Wechselwirkungen (p 75%) ist die Beweglichkeit der-CH³ und CH²-Gruppen in assoziierten Segmenten verzögert. Das Netzwerkmodell des Stereokomplexes, sowohl als auch die Möglichkeit einer Doppelhelixform, werden diskutiert.

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Dedicated to Prof. Dr. G. Rehage on the occasion of his 60th birthday.

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With 2 figures and 1 table     

Zerlegbare Untergruppen affiner Gruppen

Ohne Zusammenfassung