Study of B0_s anti-B0_s oscillations and B0_s lifetimes using hadronic decays of B0_s mesons

Oscillations of B0s mesons have been studied in samples selected from about 3.5 million hadronic Z decays detected by DELPHI between 1992 and 1995. One analysis uses events in the exclusive decay channels: B0s -> Ds- pi+ or Ds- a1+ and B0s -> anti-D0 K- pi+ or anti-D0 K- a1+, where the D decays are completely reconstructed. In addition, B0s anti-B0s oscillations have been studied in events with an exclusively reconstructed Ds accompanied in the same hemisphere by a high momentum hadron of opposite charge. Combining the two analyses, a limit on the mass difference between the physical B0s states has been obtained: Delta(m_B0s) > 4.0 ps^{-1} at the 95% C.L. with a sensitivity of Delta(m_B0s) = 3.2 ps^{-1}. Using the latter sample of events, the B0s lifetime has been measured and an upper limit on the decay width difference between the two physical B0s states has been obtained: tau(B0s) = 1.53^{+0.16}_{-0.15}(stat.) +/- {0.07}(syst.) ps \Delta\Gamma(B0s)/\Gamma(B0s) < 0.69 at the 95% C.L. The combination of these results with those obtained using Ds+- lepton-+ sample gives: Delta(m_B0s) > 4.9 ps^{-1} at the 95% C.L. with a sensitivity of Delta(m_B0s) = 8.7 ps^{-1}. tau(B0s) = 1.46 +/- 0.11 ps and \Delta\Gamma(B0s)/\Gamma(B0s) < 0.45 at the 95% C.L.Comment: 42 pages, 13 figure

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

Water Supply Act 2000: Proposal for implementing the quality requirement component of the EC Drinking-water Directive

Eind 1998 is een nieuwe EG-Drinkwaterrichtlijn in werkinggetreden (Richtlijn 98/83). Deze richtlijn dient binnen twee jaar na het inwerking treden van de nationale wetgeving zijn geimplementeerd Het uitgangspunt voor de kwaliteitseisen, meetfrequenties en meetmethoden voor het 'WLB 2000' is de EG-Drinkwaterrichtlijn. Het pakket aan stoffen is als basispakket overgenomen. Op basis van onderstaande criteria zijn parameters toegevoegd of is de kwaliteitseis aangescherpt ten opzichte van de EG-Drinkwaterrichtlijn. De richtlijn biedt de mogelijkheid hiertoe en verplicht hier zelfs toe in bepaalde gevallen. De meest in het oog springende verandering met het huidige WLB is de verlaging van de kwaliteitseis voor lood (van 50 naar 10 ug/l), arseen en nikkel (van 50 naar respectievelijk 10 en 20 ug/l). Het beleid van de overheid en de bedrijfstak anticipeert al enkele jaren op de veranderende eisen voor lood in de vorm van het opzetten en uitvoeren van saneringsprogramma's. De nieuwe kwaliteitseisen voor arseen en nikkel worden op een enkele uitzondering na op alle productielocaties nu al gehaald en hebben nauwelijks gevolgen voor de zuiveringsinspanning. Er zijn kwaliteitseisen gesteld voor desinfectiebijproducten als bromaat en trihalomethanen. Er wordt een voorstel gedaan om uitgaande van een aanvaardbaar infectierisico eisen te stellen aan pathogene micro-organismen (virussen en protozoa) daarnaast worden de bestaande indicator-organismen deels vernieuwd (bijvoorbeeld E.coli) en/of gehandhaafd. De IMH vervult een belangrijke rol bij het vaststellen en goedkeuren van de voorgenomen meetprogramma's. De EG-Drinkwaterrichtlijn geeft randvoorwaarden voor meetfrequenties en meetmethoden aan; de IMH heeft de bevoegdheid het uiteindelijke programma vast te stellen dan wel af te keuren.The EC Drinking-water Directive (98/83) was issued in December 1998 for implementation in the national legislation within two years. The Dutch Ministry of Housing, Spatial Planning and the Environment has established a number of working groups to facilitate the implementation process. The working group on "standards" has provided proposals for: drinking-water quality requirements, monitoring programme frequency, and requirements for analytical methods. The legislation on water for household purposes, hot water and individual water systems (with a collective character) included in the EC Directive is the task of other working groups. The proposed requirements conform to the EC Directive. However, where parameter values are more stringent, the EC Directive allows the addition of a number of parameters e.g. parameters included in the current legislation. After implementation the standard for lead will go from 50 to 10 ug/l. The government and the water supply companies have been preparing for this change for some years by introducing programmes for renewing lead pipes. One of the new proposals will be to set a requirement for pathogenic protozoa and viruses by introducing acceptable infection risks, the actual level of this acceptability still being a point of discussion. Of course, the parameters for microbiology conform to the EC Directive. The Inspectorate for the Environment will have to review the monitoring programmes of the water supply companies, who will, in turn, have to report deterioration of the standards to the Inspectorate.DGM/DW

Electroweak parameters of the z0 resonance and the standard model

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