QCD corrections to the forward-backward asymmetries of c and b quarks at the Z pole

Measurements of the forward-backward production asymmetry of heavy quarks in Z decays provide a precise determination of . The asymmetries are sensitive to QCD effects, in particular hard gluon radiation. In this paper QCD corrections for and are discussed. The interplay between the experimental techniques used to measure the asymmetries and the QCD effects is investigated using simulated events. A procedure to estimate the correction needed for experimental measurements is proposed, and some specific examples are given. Received: 26 February 1998 / Published online: 2 June 1998     

Chemical reaction studies in CH4/Ar and CH4/N2 gas mixtures of a dielectric barrier discharge

Chemical reactions in a dielectric barrier discharge at medium pressure of 250-300 mbar have been studied in CH(4)/Ar and CH(4)/N(2) gas mixtures by means of mass spectrometry. The main reaction scheme is production of H(2) by fragmentation of CH(4), but also production of higher order hydrocarbon molecules such as C(n)H(m) with n up to 9 including formation of different functional CN groups is observed. Formation of C(2)H(2), C(2)H(4), and C(2)H(6) molecules has been investigated in some detail. Significant differences are noted in comparison to a theoretical estimate.     

On Auslander modules of normal surface singularities

Abstract We study thefundamental sequences of normal surface singularities. Our main result asserts that for rational singularities (with a technical side-condition) and for minimally elliptic singularities the middle termA, theAuslander module, is isomorphic to the module of Zariski differentials if and only if the singularity is quasihomogeneous.     

Self-Consistent Model of a Positive Column in an Inert Gas Discharge at Low Pressures and Small Currents

A formalism of the self-consistent solution of the kinetic equation and the field equation is described for the positive plasma column in an inert gas discharge. The model considers the presence of electrons trapped in the potential well transfering the discharge current and of free electrons which reach the walls in a free diffusion regime supporting the required ionization level in the discharge. The calculations have been carried out for neon. In the model application range the comparison is made with experimental data of axial fields, wall potentials, wall currents and in some cases with distribution functions. A good correspondence takes place.     

Ground-state energy of the exciton-phonon system in a magnetic field

Upper bounds for the ground-state energy of the exciton-phonon system in a magnetic field are calculated variationally using a wavefunction whose symmetry is suited both to low and high magnetic fields. The displacement amplitudes for the exciton-phonon interaction are those known from the free field case. The results compare satisfactorily with experimental data for TlCl and TlBr.