Showing papers by "S. O. Holmgren published in 1999"
TL;DR: In this paper, infrared and collinear safe event shape distributions and their mean values are determined using the data taken at five different centre of mass energies above MZ with the DELPHI detector at LEP from the event shapes, the strong coupling αs is extracted in View the MathML source(αs2), NLLA and a combined scheme using hadronisation corrections evaluated with fragmentation model generators as well as using an analytical power ansatz
54 citations
TL;DR: In this article, the DELPHI measurements at 130, 136, 161, 172 and 183 GeV are presented as a function of the variables rapidity, ξp, p and transversal momenta.
34 citations
TL;DR: In this paper, a search event with one jet and at most one isolated lepton used data taken at LEP-2 by the DELPHI detector at a center-of-mass energy of 183 GeV.
31 citations
TL;DR: In this article, the trilinear gauge boson couplings WWgamma and WWZ were measured using the data taken by DELPHI in 1998 at a centre-of-mass energy of 189 GeV.
27 citations
TL;DR: The DELPHI results on the inclusive production of the neutral mesons ρ0, f0(980), f2(1270), KView the MathML source and f′2(1525) in hadronic Z0 decays were presented in this paper.
22 citations
TL;DR: The cross-section for the process e(+)e(-) --> W+ W- has been measured with the data sample collected by DELPHI at an average centre-of-mass energy of 189 GeV and corresponding to an integrated...
15 citations
TL;DR: A search for pair produced charged Higgs bosons has been performed in the high energy data collected by DELPHI at LEP with View the MathML source, 172 and 183 GeV as mentioned in this paper.
15 citations
24 Oct 1999
TL;DR: In this paper, a readout system designed to serve the 9728 PMT channels of the ATLAS Tile calorimeter at LHC is described. But the system is located immediately outside the Calorimeter with limited accessibility and moderate radiation levels, making reliability an important issue in the design.
Abstract: We describe a readout system designed to serve the 9728 PMT channels of the ATLAS Tile calorimeter at LHC. The system will be located immediately outside the calorimeter with limited accessibility and moderate radiation levels, making reliability an important issue in the design. Six or eight boards per calorimeter module each receive and digitize high and low gain signals from six PMTs every 25 ns. Two custom designed gate arrays on each board store the data in digital pipelines until validated by the first level trigger. Selected data are formatted and read out for use by the DAQ and second level trigger systems. Configuration and control commands are distributed to the digitizer boards via the TTC clock distribution system. The current digitizer design was developed for test beam tests during summer 1999, and the final system is scheduled for volume production in the beginning of 2000.
13 citations
TL;DR: In this article, an update of the searches for charginos and neutralinos is presented, based on a data sample corresponding to the 53.9 pb−1 recorded by the DELPHI detector in 1997, at a centre-of-mass energy of 183 GeV.
12 citations
TL;DR: In this article, the DELPHI data were used to search for the supersymmetric partners of electron, muon and tau leptons and of top and bottom quarks.
Abstract: Data taken by DELPHI during the 1995 and 1996 LEP runs have been used to search for the supersymmetric partners of electron, muon and tau leptons and of top and bottom quarks. The observations are in agreement with standard model predictions. Limits are set on sfermion masses. Searches for long lived scalar leptons from low scale supersymmetry breaking models exclude stau masses below 55 GeV/c2 at the 95% confidence level, irrespective of the gravitino mass.
7 citations
TL;DR: In this article, the DELPHI detector was used to search for processes of the type e+e- → YY with the subsequent decay Y → X7, where X is an undetectable neutral particle.
Abstract: The events with two photons and missing (transverse) energy collected by the DELPHI detector at centre-of-mass energies between 130 GeV and 183 GeV have been studied to search for processes of the type e+e- → YY with the subsequent decay Y → X7, where X is an undetectable neutral particle. Reactions of this kind are expected in supersymmetric models, where the Y particle can be either the lightest neutralino, decaying to a photon and a gravitino, or the next-to-lightest neutralino, decaying to a photon and the lightest neutralino. To study the case of long-lived Y particles, a search for single-photon events with the reconstructed photon axis pointing far from the beam interaction region has also been performed. No evidence for a deviation from Standard Model expectations has been observed in the data and upper limits have been derived on the signal cross-section as a function of the the X and Y masses and of the Y mean decay path.
TL;DR: In this article, the mass of charginos was found to be greater than 85.5~GeV/$c^2$ for $m{ ilde{chi}^+_1}-m_{ ilde { au}_ 1}geq 0.3
TL;DR: In this paper, the four-jet events collected by DELPHI during the special LEP run at center-of-mass energies of 130 and 136 View the MathML source in 1997 with an integrated luminosity of View-the-MathML source are analyzed.
TL;DR: In this paper, the mass of the neutral Higgs boson with either an on-shell Z boson or a neutral pseudo-scalar Higgs particle was analyzed at DELPHI with an integrated luminosity of 54 pb-1.
Abstract: Neutral Higgs bosons were searched for in the data collected by DELPHI at a centre-of-mass energy of 183 GeV, corresponding to an integrated luminosity of 54 pb-1. The production of the lightest neutral Higgs boson with either an on-shell Z boson or a neutral pseudo-scalar Higgs boson was analysed. Lower limits at the 95% confidence level were obtained on the Higgs boson masses. The limits are 85.7 GeV/c2 for the Standard Model Higgs boson and 74.4 GeV/c2 for the scalar and 75.3 GeV/c2 for the pseudo-scalar Higgs bosons as predicted by the minimal super-symmetric extension of the Standard Model with commonly used assumptions on the model parameters, plus the assumption that the mass of the pseudo-scalar boson is greater than 20 GeV/c2. These results significantly improve the limits reached with previous data.