Implications of a stochastic microscopic Finsler cosmology

Within the context of supersymmetric space-time (D-particle) foam in string/brane-theory, we discuss a Finsler-induced cosmology and its implications for (thermal) dark matter abundances. This constitutes a truly microscopic model of dynamical space-time, where Finsler geometries arise naturally. The D-particle foam model involves point-like brane defects (D-particles), which provide the topologically non-trivial foamy structures of space-time. The D-particles can capture and emit stringy matter and this leads to a recoil of D-particles. It is indicated how one effect of such a recoil of D-particles is a back-reaction on the space-time metric of Finsler type which is stochastic. We show that such a type of stochastic space-time foam can lead to acceptable cosmologies at late epochs of the Universe, due to the non-trivial properties of the supersymmetric (BPS like) D-particle defects, which are such so as not to affect significantly the Hubble expansion. The restrictions placed on the free parameters of the Finsler type metric are obtained from solving the Boltzmann equation in this background for relic abundances of a Lightest Supersymmetric Particle (LSP) dark matter candidate. It is demonstrated that the D-foam acts as a source for particle production in the Boltzmann equation, thereby leading to enhanced thermal LSP relic abundances relative to those in the Standard ??CDM cosmology. For D-particle masses of order TeV, such effects may be relevant for dark matter searches at colliders. The latter constraints complement those coming from high-energy gamma-ray astronomy on the induced vacuum refractive index that D-foam models entail. We also comment briefly on the production mechanisms of such TeV-mass stringy defects at colliders, which, in view of the current LHC experimental searches, will impose further constraints on their couplings.     

Bond-shift rearrangement during hydrogenolysis of neopentyl iodide on group VIII metal catalysts. An analogue of the mechanism of action of vitamin B12

The hydrogenolysis of neopentyl iodide on reduced Co or Pt dispersed on MgO support yields increasing amounts of 2-metylbutane and 2-methylbutenes in addition to neopentane, as the temperature is raised from 50 to 150°C. These results support the idea that a π-complexed half-reaction state is simultaneously involved in activation of the R---I bond and in the evident 1,2-methyl shift. This π-complex mechanism is the same as that first suggested almost a quarter of a century ago for neopentane isomerism during hydrogenolysis at 200°C on Pt catalysts. The present results also support the contention that similar π-complexes are responsible for analogous carbon skeleton rearrangement reactions mediated by coenzyme B₁₂.     

Molekulare Dimensionen von Polyneren,die in einer binären Mischung aus polaren und nichtpolaren Lösungsmitteln gelöst sind. 2. Mitt. PolymethyImethacrylat

Ohne Zusammenfassung     

Coherent optical manipulations of the fundamental state in a single quantum dot

By means of an original all-optical experimental technique using microphotoluminescence in a waveguiding geometry, resonant coherent manipulation of quantum states in a single quantum dot becomes possible now. Resonant Rabi oscillation of the fundamental exciton state in a single quantum dot has been realized. We present the results obtained on two different kinds of samples: InAs/GaAs self-assembled quantum dots and naturally formed GaAs quantum dots by thickness fluctuations.