Measurement of theZ0 line shape parameters and the electroweak couplings of charged leptons

We report on an improved measurement of the mass of theZ ⁰ boson, its total width and its partial decay widths into hadrons and leptons, as well as the effective axial vector and vector couplings to charged leptons. These measurements are based on a data set of approximately 160 000 hadronicZ ⁰ decays and 18 000 decays into electrons, muons and taus, recorded by the OPAL experiment at centre of mass energies near the mass of theZ ⁰. The total width and the partial widths to visible final states, derived from the measured cross sections, are used to extract the invisible width. The effective couplings of theZ ⁰ to charged leptons are studied using measurements of the lepton pair cross sections and forward-backward asymmetries at the different centre of mass energy points of theZ ⁰ scan. The implications of our results in the context of the Standard Model are discussed.On leave from Research Institute for Computer Peripherals, Hangzhou, China     

Thallium-205 NMR study of ti(I) macrocyclic complexes in nonaqueous solvents

Thallium-205 and carbon-13 NMR measurements were used to determine, in nonaqueous solvents, the stabilities of thallium(I) complexes with macrocyclic ligands of different structures but very nearly the same cavity sizes. In a given solvent the complexing abilities of the ligand vary in the order DA18C6 > 18C6 > DC18C6 > DB18C6 > DT18C6. In all cases the stabilities of the complexes varied inversely with the Gutmann donicities of the solvents.     

The prime at infinity and the rank of the class group in global function fields

In this paper we construct, for any integers m and n, and 2?g?m-1, infinitely many function fields K of degree m over F(T) such that the prime at infinity splits into exactly g primes in K and the ideal class group of K contains a subgroup isomorphic to (Z/nZ)^m-g. This extends previous results of the author and Lee for the cases g=1 and g=m.     

Complex mixture analysis based on gas chromatography-mass spectrometry with time array detection using a beam deflection time-of-flight mass spectrometer

A beam deflection time-of-flight mass spectrometer was developed in conjunction with an integrating transient recorder to provide time array detection, permitting high mass spectral scan file acquisition rates for complex mixture analysis by capillary gas chromatography-mass spectrometry (GC-MS). Results are presented for the analysis of a urinary organic acid mixture by GC-MS at a scan file acquisition rate of 10 scan files per second (sf/s), showing the advantages of such data collection in the deconvolution of partially resolved components. The reconstructed total ion current (RTIC) chromatogram available from data acquired at this scan file generation rate is shown to be comparable to the profile obtained from a flame ionization detector in representing the chromatography performed under identical experimental parameters. The RTIC chromatogram available from the database obtained at 10 sf/s is compared with that available from a database obtained at 1 sf/s, the latter representing that scan rate typically used with most GC-MS instruments. The advantages of the higher scan file acquisition rate in representing the chromatographic profile and in allowing mass spectral data to be obtained for components in the complex mixture that are unresolved chromatographically are discussed.     

Inclusive neutral vector meson production in hadronicZ0 decays

Results are reported of a study of neutral vector meson production in multihadronicZ ⁰ decays in the OPAL experiment at LEP. Pions and kaons have been identified by specific ionisation energy loss andK ^± andK ⁺ K ^– mass spectra have been fitted, in bins of the scaled momentum variablex _p , to combinations of resonance signals and non-resonant backgrounds. Rates are given forK ^*(892)° and ø(1020), and production cross sections are compared to the predictions of Monte Carlo models. Overall multiplicities have been determined as 0.76±0.07±0.06K ^*(892)° and 0.086±0.015±0.010 ø(1020) per hadronicZ ⁰ decay (the quoted errors are respectively statistical and systematic). Momentum dependent distortions of the mass spectra, possibly associated indirectly with Bose-Einstein effects, have prevented reliable measurement of the (770)° cross section in this study.     

A measurement of the forward-backward asymmetry of e+e?→bb by applying a jet charge algorithm to lifetime tagged events

The forward-backward asymmetry of has been measured using approximately 2.15 million hadronicZ ⁰ decays collected at the LEP e⁺e^– collider with the OPAL detector. A lifetime tag technique was used to select an enriched event sample. The measurement of the asymmetry was then performed using a jet charge algorithm to determine the direction of the primary quark. Values of:

The Compressibilities of Liquid Phase Host-Guest Systems

The compressibilities of seven liquidphase, macrocyclic host-guest systems were determinedat approximately 25 °C and 3.4 × 10⁷ Pa.Each two-component system consisted of a cyclodextrin,a calixarene, or a crown ether as host and anappropriate solvent as guest. In each case studied,the host-guest system was found to be lesscompressible than the pure solvent, with thedifferences ranging from 2 to 18% of the magnitudesof the pure solvent compressibilities. These findingshave enabled us to better understand how strong,ambient pressure, intermolecular host–guestinteractions influence the compressibility ofsolutions. Both inclusion and solvationcontribute.     

Hydro­gen bonding and C—H⋯O interactions in 3‐(3‐amino­phthal­imido)phthalic acid dihydrate

The title compound, C₁₆H₁₀N₂O₆·2H₂O, crystallized in the centrosymmetric triclinic space group P with one organic mol­ecule and two water mol­ecules as the asymmetric unit. Eight intermolecular hydrogen bonds have donor?acceptor distances in the range 2.602 (2)–3.289 (2) Å, with angles in the range 137 (2)–177 (2)°. These generate a three‐dimensional hydrogen‐bond network. There is a single intramolecular hydrogen bond. There are six significant intermolecular C—H?O interactions with H?O distances in the range 2.39–2.74 Å, and C—H?O angles in the range 131–157°.