Probing QCD via four-jet decays of theZ boson

For a quantitative analysis of the non-Abelian three-gluon vertex a continuous parameterisation of possible deviations from QCD is highly desirable. An almost unique extension of the three-gluon vertex is provided by the dimension-6 operator Tr(F _μ ^ν F _ν ^ρ F _ρ ^μ ). The effects of this interaction term on various observables ine ⁺ e ^?→γ,Z→4 jet production are studied in detail. Presente ⁺ e ^? data are expected to give rather weak bounds on such anomalous contributions to the triple gluon vertex.     

Quantum and quasiclassical studies of the O(3P)+HCl-->OH+Cl(2P) reaction using benchmark potential surfaces

We have performed quantum mechanical (QM) dynamics calculations within the independent-state approximation with new benchmark triplet A" and A' surfaces [B. Ramachandran et al., J. Chem. Phys. 119, 9590 (2003)] for the rovibronic state-to-state measurements of the reaction O(3P)+HCl(v=2,j=1,6,9)-->OH(v'j')+Cl(2P) [Zhang et al., J. Chem. Phys. 94, 2704 (1991)]. The QM and experimental rotational distributions peak at similar OH(j') levels, but the QM distributions are significantly narrower than the measurements and previous quasiclassical dynamics studies. The OH(low j) populations observed in the measurements are nearly absent in the QM results. We have also performed quasiclassical trajectory with histogram binning (QCT-HB) calculations on these same benchmark surfaces. The QCT-HB rotational distributions, which are qualitatively consistent with measurements and classical dynamics studies using other surfaces, are much broader than the QM results. Application of a Gaussian binning correction (QCT-GB) dramatically narrows and shifts the QCT-HB rotational distributions to be in very good agreement with the QM results. The large QCT-GB correction stems from the special shape of the joint distribution of the classical rotational/vibrational action of OH products. We have also performed QM and QCT calculations for the transition, O+HCl(v=0,T=300 K)-->OH(v'j')+Cl from threshold to approximately 130 kcal mol(-1) collision energy as a guide for possible future hyperthermal O-atom measurements. We find in general a mixed energy release into translation and rotation consistent with a late barrier to reaction. Angular distributions at high collision energy are forward peaked, consistent with a stripping mechanism. Direct collisional excitation channel cross sections, O+HCl(v=0,T=300 K)-->O+HCl(v'=1), in the same energy range are large, comparable in magnitude to the reactive channel cross sections. Although the (3)A" state dominates most collision processes, above approximately 48 kcal mol(-1), the (3)A' state plays the major role in collisional excitation.     

Large-angle inclusive production of charged pions at the CERN ISR with transverse moment a less than 1.0 GeV/c

The inclusive production of π^± in proton-proton collisons has been measured for the transverse momentum range 0.15 to 1.0 GeV/c over an angular range of 29° to 89° in the centre-of-mass system and for centre-of-mass energies √_s = 30.6 and 52.8 GeV. For each energy the invariant cross-section foe fixed transverse momentum was found to increase by about 15% as the centre-of-mass rapidity decreases from 1 to 0, i.e. the “central plateau” has not yet been reached.     

The use of triethanolamine in a buffer for the determination of fluoride in calcium and transition metal orthophosphates, using a fluoride-selective el

A method is described for the determination of fluoride in inorganic orthophosphates. Interference by complex-forming metal ions is avoided by the use of a citric acid-triethanolamine buffer, pH < 7.5.     

Diffusion Collisionnelle Induite Pour Les Bandes Rayleigh Et ν1 Raman Du Liquide Isotopique CCl4

We have studied the depolarized component of the ν₁ Raman band of the isotopic liquid C³⁵Cl₄ at 296 K. We compare the experimental Rayleigh and Raman depolarized scattering with theoretical spectra calculated using dipole induced dipole approximation.     

The bromination,debromination and debromosilylation of silylstyrenes and other vinylsilanes

The bromination of some vinylsilanes, and the debrominations and debromosilylations of their dibromides are stereospecific. Based on the crystal structure of the dibromide derived form trans-triphenylsilylstyrene, it is shown that bromination and debromination of silylstyrenes occur with syn stereochemistry, and that debromosilylation occurs with anti stereochemistry in polar solvents. Different stereochemistries may prevail with other vinylsilanes. Other elimination and substitution reactions are also described.