Limits on the production of scalar leptoquarks from Z (0) decays at LEP

A search has been made for pairs and for single production of scalar leptoquarks of the first and second generations using a data sample of 392000 Z0 decays from the DELPHI detector at LEP 1. No signal was found and limits on the leptoquark mass, production cross section and branching ratio were set. A mass limit at 95% confidence level of 45.5 GeV/c2 was obtained for leptoquark pair production. The search for the production of a single leptoquark probed the mass region above this limit and its results exclude first and second generation leptoquarks D0 with masses below 65 GeV/c2 and 73 GeV/c2 respectively, at 95% confidence level, assuming that the D0lq Yukawa coupling alpha(lambda) is equal to the electromagnetic one. An upper limit is also given on the coupling alpha(lambda) as a function of the leptoquark mass m(D0)

Shift reagent spectra. The automatic determination of relative bound shifts and the automatic assignment of signals in the parent spectrum. Effects of concentration, temperature and solvent on relative bound shifts

In the use of a shift reagent as an aid in the structural elucidation of organic compounds, it is shown that accurate measurements of the shift reagent and substrate concentrations are not needed to determine the relative bound shifts of the substrate and the chemical shifts of the free substrate spectrum with good precision. This is possible whenever the induced shift ratios of nuclei of a given molecule are independent of the shift reagent concentration. This independence has been verified for all the monofunctional compounds described in this paper. The effect of absolute substrate concentration, solvent, temperature and the presence of water on the relative bound shifts is studied using the eight methyl group signals of β‐amyrin. The method is demonstrated by its use for structural determinations in the ketoandrostane series. Copyrigh

ATF2 Commissioning

International audienceATF2 is a final-focus test beam line that aims to focus the low-emittance beam from the ATF damping ring to a beam size of about 37 nm, and at the same time to demonstrate nm beam stability, using numerous advanced beam diagnostics and feedback tools. The construction has been finished at the end of 2008 and the beam commissioning of ATF2 has started in December of 2008. ATF2 is constructed and commissioned by ATF international collaborations with strong US, Asian and European participation

Measurement of the average lifetime of B hadrons

The average lifetime of B hadrons produced in hadronic Z0 decays has been measured with the DELPHI detector at LEP. The measurement is based on the analysis of the impact parameter distributions of high pt muons and hadrons. The resulting mean B lifetimes are τB=(1.30±0.10±0.08)ps and τB=(1.27±0.04±0.12)ps respectively, giving a combined value of τB=(1.28±0.10)ps. The hadronic sample was also used to measure the partial Z0 width Mathematical expression and gave a value of 0.222-0.031+0.033±0.017. © 1992 Springer-Verlag

A measurement of B meson production and lifetime using Dl- events in Z0 decays

A study of B meson decays into DlX final states is presented. In these events, neutral and charged D mesons originate predominantly from B+ and B0 decays, respectively. The dilution of this correlation due to D** production has been taken into account. From 263 700 hadronic Z0 decays collected in 1991 with the DELPHI detector at the LEP collider, 92 D0→K-π+, 35 D+→K-π+π+ and 61 D*0→D0π+ followed by D0→K-π+ or D0→K-π+π+π -, are found with an associated lepton of the same charge as the kaon. From the D0l- and D*+l-, the probability fd that a b quark hadronizes into a B- (or {Mathematical expression}) meson is found to be 0.44 ±0.08±0.09, corresponding to a total (Bs+Λb) hadronization fraction of 0.12-0.12+0.24. By reconstructing the energy of each B meson, the b quark fragmentation is directly measured for the first time. The mean value of the B meson energy fraction is: {Mathematical expression} Reconstructing D-lepton vertices, the following B lifetimes are measured: {Mathematical expression} and an average τ(B)=1.23-0.13+0.14(stat.)±0.15(syst.) ps is found. Allowing for decays into {Mathematical expression}, the B+ and B0 lifetimes are: {Mathematical expression} © 1993 Springer-Verlag