Updated precision measurement of the average lifetime of B hadrons

The measurement of the average lifetime of B hadrons using inclusively reconstructed secondary vertices has been updated using both an improved processing of previous data and additional statistics from new data. This has reduced the statistical and systematic uncertainties and gives \tau_{\mathrm{B}} = 1.582 \pm 0.011\ \mathrm{(stat.)} \pm 0.027\ \mathrm{(syst.)}\ \mathrm{ps.} Combining this result with the previous result based on charged particle impact parameter distributions yields \tau_{\mathrm{B}} = 1.575 \pm 0.010\ \mathrm{(stat.)} \pm 0.026\ \mathrm{(syst.)}\ \mathrm{ps.

Measurement of Trilinear Gauge Couplings in e+e−e^+ e^- Collisions at 161 GeV and 172 GeV

Trilinear gauge boson couplings are measured using data taken by DELPHI at 161~GeV and 172~GeV. Values for $WWV$ couplings ($V=Z, \gamma$) are determined from a study of the reactions \eeWW\ and \eeWev, using differential distributions from the $WW$ final state in which one $W$ decays hadronically and the other leptonically, and total cross-section data from other channels. Limits are also derived on neutral $ZV\gamma$ couplings from an analysis of the reaction \eegi

Search for neutral heavy leptons produced in ZZ decays

Weak isosinglet Neutral Heavy Leptons (νm) have been searched for using data collected by the DELPHI detector corresponding to 3.3 × 106 hadronic Z0 decays at LEP1. Four separate searches have been performed, for short-lived νm production giving monojet or acollinear jet topologies, and for long-lived νm giving detectable secondary vertices or calorimeter clusters. No indication of the existence of these particles has been found, leading to an upper limit for the branching ratio BR(Z0 → νmν̄) of about 1.3 × 10-6 at 95% confidence level for νm masses between 3.5 and 50 GeV/c2. Outside this range the limit weakens rapidly with the νm mass. The results are also interpreted in terms of limits for the single production of excited neutrinos. © Springer-Verlag 1997

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)

Dépistage du cancer du sein chez les femmes à risque élevé (performances des stratégies de dépistage)

TOULOUSE3-BU Santé-Centrale (315552105) / SudocSudocFranceF

Differential spore production by <em>Botrytis cinerea</em> on agar medium and plant tissue under near-ultraviolet light-absorbing polyethylene film

International audiencePlastic films containing additives that alter their transmission of the light spectrum may be useful tools for the control of aerial plant pathogens of greenhouse crops. Several samples of polyethylene films containing additives that absorb near ultraviolet (nUV) light in the range 280 to 380 nm were compared for their ability to affect spore germination, mycelial growth, and sporulation of Botrytis cinerea on agar medium. One film was selected and further evaluated. The kinetics of spore production by the pathogen was similar on agar medium and on tomato stem tissue, and whether incubation took place under the nUV-absorbing film or under a control film. However, spore production on both types of substrates under the nUV film remained at less than 0.05% that of the control for several weeks after inoculation, demonstrating that the nUV film inhibited rather than delayed sporulation. A sharp reduction of spore production was also observed on other plant tissues. However, the efficiency of the nUV film appeared different for different plants, and it was lower on flowers and cotyledons than on stem tissue. Two of the five strains of B. cinerea tested on tomato stem tissue were less sensitive to sporulation inhibition by the nUV film. To clarify the potential of nUV films for the control of gray mold on greenhouse crops, the epidemiological significance of these results needs lo be further examined in light of the abundance of such strains in the environment

Entreprises, concurrence et Europe, 1re édition

International audienc

Entreprises, concurrence et Europe, 2e édition

International audienc

Electroweak parameters of the z0 resonance and the standard model

Contains fulltext : 124399.pdf (publisher's version ) (Open Access