Mariusz Witek

Learn More
This Technical Design Report is dedicated to Tom Ypsilantis. Tom conceived the Ring Imaging Cherenkov detectors for particle identification in LHCb and he made an inestimable contribution to the LHCb RICH project. Tom would have wished to see these detectors in operation. He was totally dedicated to the project. He will be missed by the RICH group for his(More)
The study of quark jets in e + e − reactions at LEP has demonstrated that the hadronisation process is reproduced well by the Lund string model. However, our understanding of gluon fragmentation is less complete. In this study enriched quark and gluon jet samples of different purities are selected in three-jet events from hadronic decays of the Z collected(More)
A measurement of the branching fractions of the b-quark into charged and neutral b-hadrons Abstract The production fractions of charged and neutral b-hadrons in b-quark events from Z 0 decays have been measured with the DELPHI detector at LEP. An algorithm has been developed, based on a neural network, to estimate the charge of the weakly-decaying b-hadron(More)
The main features of the Cloud Computing system developed at IFJ PAN are described. The project is financed from the structural resources provided by the European Commission and the Polish Ministry of Science and Higher Education (Innovative Economy, National Cohesion Strategy). The system delivers a solution for carrying out computer calculations on a(More)
During LEP running in 1995 and 1996, DELPHI accumulated data at centre-of-mass energies ranging from 130 GeV to 172 GeV. Searches were performed for events containing four nal-state fermions in the l + l ? q q, q q and l + l ? l + l ? channels. The number of events detected was found to be consistent with Standard Model predictions.
The pseudoscalar meson η b has been searched for in two-photon interactions at LEP II. The data sample corresponds to a total integrated luminosity of 617 pb −1 at centre-of-mass energies ranging from 161 to 209 GeV. Upper limits at a confidence level of 95% on the product Γ γ γ (η b) × BR(η b) are 190, 470 and 660 eV/c 2 for the η b decaying into 4, 6 and(More)
A search for unstable heavy fermions with the DELPHI detector at LEP is reported. Sequential and non-canonical leptons, as well as excited leptons and quarks, are considered. The data analysed correspond to an integrated luminos-ity of about 48 pb 1 at an e + e centre-of-mass energy of 183 GeV and about 20 pb 1 equally shared between the centre-of-mass(More)
  • 1