Showing papers by "Tord Ekelof published in 2003"
TL;DR: In this paper, the results of each search were used to derive limits on production cross-sections and particle masses and the combined result of all searches excluded regions in the parameter space of the constrained MSSM, leading to limits on the mass of the Lightest Supersymmetric Particle and other supersymmetric particles.
Abstract: DELPHI data collected at centre-of-mass energies up to 208 GeV have been analysed to search for charginos, neutralinos and sfermions in the framework of the Minimal Supersymmetric Standard Model (MSSM) with R-parity conservation. No evidence for a signal was found in any of the channels. The results of each search were used to derive limits on production cross-sections and particle masses. In addition, the combined result of all searches excludes regions in the parameter space of the constrained MSSM, leading to limits on the mass of the Lightest Supersymmetric Particle and other supersymmetric particles.
251 citations
TL;DR: In this article, a search for pair-produced doubly charged Higgs bosons has been performed using the data collected by the DELPHI detector at LEP at centre-of-mass energies between 189 and 209 GeV.
55 citations
17 Nov 2003
TL;DR: The present status and short term plans of the Nordic grid infrastructure are reported on and the available and foreseen resources, grid services and forming user base are described.
Abstract: Nordugrid offers reliable grid services for academic users over an increasing set of computing & storage resources spanning through the Nordic countries Denmark, Finland, Norway and Sweden. A small group of scientists has already been using the Nordugrid as their daily computing utility. In the near future we expect a rapid growth both in the number of active users and available resources thanks to the recently launched Nordic grid projects.We report on the present status and short term plans of the Nordic grid infrastructure and describe the available and foreseen resources, grid services and our forming user base.
42 citations
TL;DR: In this paper, a study of the event shapes of different types of gammagamma processes in the PYTHIA program was conducted, and it was shown that (74+/-22) % of the observed J/psi events are due to resolved photons.
32 citations
TL;DR: Innovative middleware solutions are key to the NorduGrid testbed, which spans academic institutes and supercomputing centers throughout Scandinavia and Finland and provides continuous grid services to its users.
Abstract: Innovative middleware solutions are key to the NorduGrid testbed, which spans academic institutes and supercomputing centers throughout Scandinavia and Finland and provides continuous grid services to its users.
24 citations
TL;DR: In this article, a neural network was used to estimate the charge of the weakly-decaying b-hadron by distinguishing its decay products from particles produced at the primary vertex.
20 citations
TL;DR: In this article, neutral B meson oscillations in the B-s(0) -, and B-d(0)- systems were studied using a sample of about 4.0 million hadronic Z decays recorded by the DELPHI detector between 1992 and 2000.
Abstract: Neutral B meson oscillations in the B-s(0) - , and B-d(0) - systems were studied using a sample of about 4.0 million hadronic Z decays recorded by the DELPHI detector between 1992 and 2000. Events with a high transverse momentum lepton were removed and a sample of 770 k events with an inclusively reconstructed vertex was selected. The mass difference between the two physical states in the B-d(0) - system was measured to be: Deltam(d) = (0.531 +/- 0.025(stat.) +/- 0.007(syst.))ps(-1). The following limit on the width difference of these states was also obtained: DeltaGamma(Bd)/Gamma(Bd) oscillations was found, a limit on the mass difference of the two physical states was given:, Deltam(s) > 5.0 ps(-1) at 95% CL. The corresponding sensitivity of this analysis is equal to 6.6 ps(-1).
18 citations
TL;DR: In this paper, measurements of on-shell ZZ production are described, using data from the DELPHI experiment at LEP in e(+)e(-) collisions at centre-of-mass energies between 183 and 209 GeV, corresponding to an integrated luminosity of about 665 pb(-1).
Abstract: Measurements of on-shell ZZ production are described, using data from the DELPHI experiment at LEP in e(+)e(-) collisions at centre-of-mass energies between 183 and 209 GeV, corresponding to an integrated luminosity of about 665 pb(-1). Results obtained in each of the final states q (q) over barq (q) over bar, nu(ν) over barq (q) over bar, mu(+)mu(-) q (q) over bar, e(+)e(-) r(+)r(-) q (q) over bar, l(+)l(-)l(+)l(-), and nu(ν) over barl(+)l(-) (with l = e, mu) are presented. The measured production cross-sections are consistent with the Standard Model expectations. These results update and supersede those already published at 183 and 189 GeV.
15 citations
TL;DR: In this article, the authors studied the production of wrong sign charmed mesons over bar X-(s), D-(s) = (D-0, D+, D-s, D-S, D+S), and D-X = (10.1 +/- 1.0(stat) +/- 0.6(syst) +/- 2.8(B))% where the first error is statistical, the second and third errors are systematic.
4 citations
11 Apr 2003-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: Tom Ypsilantis played the leading role in the initial phase of development of the RICH technique around 1980 as well as in many of its continued development projects during the following two decades as discussed by the authors.
Abstract: Tom Ypsilantis played the leading role in the initial phase of development of the RICH technique around 1980 as well as in many of its continued development projects during the following two decades. An account is given of the initial phase of development as well as of the AQUA-RICH project developed during the 1990s.
1 citations
11 Apr 2003-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this article, a simulation study of the feasibility of an earlier proposed tau-neutrino appearance experiment based on a RICH with liquid radiator (C6F14) has been performed.
Abstract: A comprehensive simulation study of the feasibility of an earlier proposed tau-neutrino appearance experiment based on a RICH with liquid radiator (C6F14) has been performed. Tau leptons, that are created in charged current interactions of incident tau neutrinos with the same momentum spectrum as that of the planned Gran Sasso beam (average 17 GeV /c ), have an average track length of about 0.5 mm . Cherenkov photons emitted in the liquid radiator from the short track of the tau lepton provide a characteristic pattern for tau-neutrino appearance. In the present report it is shown, on the basis of simulations performed with the GEANT4 code, that Cherenkov radiation from delta electrons, originating from the interaction of the long-lived tau decay products with the Cherenkov radiator, constitutes a severe background that renders the detection of the millimeter-short tau track unfeasible. Increasing the incident neutrino beam momentum results in longer tau tracks and therefore more signal photons, but this does not solve the background problem since the kink angle between the tau track and the secondary decay particle decreases with increasing neutrino momentum, leading to an increased overlap between the Cherenkov rings of these two particles.