Showing papers by "S. O. Holmgren published in 1994"
01 Dec 1994
259 citations
TL;DR: In this article, the decays into hadrons and charged leptons have been analysed to give values for the cross sections and leptonic forward-backward asymmetries which are significantly improved with respect to those previously published by the DELPHI collaboration.
34 citations
TL;DR: In this article, the DELPHI experiment was used to reconstruct J/psi mesons from their decay to mu(+)mu(-) and e(+)e(-), using the data collected by the Delphi experiment during 1991 and 1992.
31 citations
TL;DR: In this article, two-particle correlations in invariant mass are studied separately for like-sign and unlike-sign pions, and good agreement is obtained with the mass correlations, both for the unlike sign and for the like sign pairs if the production of the η′ and ρ0 mesons is reduced and Bose-Einstein correlations are included in the model.
Abstract: Two-particle correlations in invariant mass are studied separately for like-sign and unlike-sign pions. Strong correlations are observed only at small masses. The correlations decrease very rapidly for like-sign pions and slowly for unlike-sign pions, manifesting different particle dynamics. The like-sign correlations exhibit a power-law behaviour as a function of mass, compatible with the previously observed intermittency effect. The predictions of the parton shower model (JETSET 7.3) deviate significantly from the data. However, good agreement is obtained with the mass correlations, both for the unlike-sign and for the like-sign pairs if the production of the η′ and ρ0 mesons is reduced and Bose-Einstein correlations are included in the model. The value of the Bose-Einstein correlation strength is consistent with unity for pions which are produced directly or in the decays of short-lived resonances.
14 citations
15 Jan 1994-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this article, the analog response of proportional counters is determined by the local charge density distribution on an insulating sense-wire surface, which depends on a number of parameters such as spatial distribution of irradiation, counting rate, gas gain and surface conductivity of the insulating layer.
Abstract: The analog response of aged proportional counters is shown to be determined by the local charge density distribution on an insulating sense-wire surface. It therefore depends on a number of parameters such as spatial distribution of irradiation, counting rate, gas gain and surface conductivity of the insulating layer. Typical charge response time constants are derived from a dynamic model of the surface charge density. Experimental consequences such as charging-up effects, time dependence of amplitude in irradiation burst environments, fluctuations of detector resolution as a function of rate, and the influence of water admixtures on counting gases are described. The problem of deriving specific ageing parameters is quantified in a typical example.
12 citations
TL;DR: In this article, the DELPHI detector at the LEP collider has been used to identify charged kaons over a large momentum range by the barrel ring imaging Cherenkov detector.
12 citations
TL;DR: In this paper, the production of multihadronic states in γγ collisions at LEP has been studied with the DELPHI detector, and the analyzed data correspond to an integrated luminosity of about 32pb−1.
Abstract: The production of multihadronic states in γγ collisions at LEP has been studied with the DELPHI detector. The analyzed data correspond to an integrated luminosity of about 32pb−1, collected in the LEP runs of 1990–1992. Minimum bias data and a sample of events with jets at highpT have been selected under the requirement that no scattered electron or positron is observed. The two data sets have been compared to Monte Carlo predictions. The non-perturbative contribution described by the vector meson dominance Model and direct\(q\bar q\) production from pointlike photons described by the quark parton model were found to be insufficient to reproduce the data. It has been necessary to include a third interaction component, which is due to perburbative hard scattering of the partonic constituents of the photon. Several parametrisations of the quark and gluon densities of the photon have been tested. The interplay with the cut in jet transverse momentum, which is necessary for the separation of the perturbative and non-perturbative regions, is discussed. The data favour parametrisations with rather soft partonic content of the photon.
11 citations
TL;DR: In this paper, a total of about View the MathML source decays have been analyzed to measure the view-the-MathML source mixing probability, and two different b tagging techniques have been used: events with two leptons and events with one lepton and one Λ.
9 citations
TL;DR: In this article, the DELPHI detector at LEP recorded 46497 events having a high-momentum muon in hadron jets in the years 1991-1992.
8 citations
TL;DR: In this paper, the authors used the flight distance distributions of D mesons and of (ϕ-lepton) secondary vertices, with the lepton emitted at high transverse momentum relative to the jet axis, to obtain two values for the B or D meson lifetime.
Abstract: The study of the properties of inclusive production ofDs mesons and of events in which a ϕ and a muon are present in the same jet provides two independent measurements of the probability,fsw, for a heavy quark to hadronize into a strangeB orD meson. The data sample analysed corresponds to 243,000 hadronicZ0 decays. The combined value of these measurements isfsw=0.19±0.06±0.08. From the flight distance distributions ofDs and of (ϕ-lepton) secondary vertices, with the lepton emitted at high transverse momentum relative to the jet axis, two values are obtained for theBs0 meson lifetime. Combining these measurements with a previous result based on the study ofDs-μ events, theBs0 meson lifetime is measured to be: 0.96±0.37 ps.
4 citations