A precise measurement of the B+^+, B0^0 and mean b-hadron lifetime with the DELPHI detector at LEP I

DELPHIFinal results from the DELPHI Collaboration on the lifetime of B+ and B0 mesons and the mean b-hadron lifetime, are presented using the data collected at the Z0 peak in 1994 and 1995. Elaborate, inclusive, secondary vertexing methods have been employed to ensure a b-hadron reconstruction with good efficiency. To separate samples of B+ and B0 mesons, high performance neural network techniques are used that achieve very high purity signals. The results obtained are: tau_B+ = 1.624 +/- 0.014 (stat) +/- 0.018 (syst) ps tau_B0 = 1.531 +/- 0.021 (stat) +/- 0.031 (syst) ps tau_B+/tau_B0 = 1.060 +/- 0.021 (stat) +/- 0.024 (syst) and for the average b-hadron lifetime: tau_b = 1.570 +/- 0.005 (stat) +/- 0.008 (syst) ps

Human and climatic impact on mires: a case study of Les Amburnex mire, Swiss Jura Mountains

Modern period long-term human and climatic impacts on a small mire in the Jura Mountains were assessed using testate amoebae, macrofossils and pollen. This multiproxy data analysis permitted detailed interpretations of local and regional environmental change and thus a partial disentanglement of the different variables that influence long-term mire development. From the Middle Ages until a.d. 1700 the mire vegetation was characterised by ferns, Caltha and Vaccinium, but then abruptly changed into the modern vegetation characterised by Cyperaceae, Potentilla and Sphagnum. The cause for this change was most probably deforestation, possibly enhanced by climatic cooling. A decrease in trampling intensity by domestic animals from a.d. 1950 onwards allowed Sphagnum growth and climatic warming in the a.d. 1980s and 1990s may have been responsible for considerable changes in the species composition. The mire investigated is an example of the rapid changes in mire vegetation and peat development that occurred throughout the central European mountain region during the past centuries as a result of changing climate and land-use practice. These processes are still active today and will determine the future development of high-altitude mires

Masses, lifetimes and production rates of Ξ− and Ξ¯+ at LEP 1

AbstractMeasurements of the Ξ− and Ξ¯+ masses, mass differences, lifetimes and lifetime differences are presented. The Ξ¯+ sample used is much larger than those used previously for such measurements. In addition, the Ξ production rates in Z→bb¯ and Z→qq¯ events are compared and the position ξ∗ of the maximum of the ξ distribution in Z→qq¯ events is measured