Ch. Kourkoumelis

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Three jet events arising from decays of the Z boson, collected by the DELPHI detector, were used to measure differences in quark and gluon fragmentation. Gluon jets were anti-tagged by identifying b quark jets. Unbiased quark jets came from events with two jets plus one photon. Quark and gluon jet properties in different energy ranges were compared for the(More)
From the combined data of 1990 and 1991 of the DELPHI experiment at LEP, 13057 4-jet events are obtained and used for determining the contribution of the triple-gluon vertex. The relevant variables are the generalized Nachtmann Reiter angle 0* R and the opening angle of the two least energetic jets. A fit to their twodimensional distribution yields(More)
A study of the fragmentation properties of charm and bot tom quarks into D mesons is presented. From 263 700 Z ~ hadronic decays collected in 1991 with the DELPHI detector at the LEP collider, D ~ D + and D *+ are reconstructed in the modes K n + K n + n + and DOn + followed by D ~ + , respectively. The fractional decay widths F ( Z ~ are determined, and(More)
The measurement of the correlation between the transverse spin components of + ? pairs collected during 1992 to 1994 with the DELPHI detector at LEP1 is presented. A value ? 0:12 (syst.) was obtained for the correlation parameter, in agreement with the Standard Model expectation.
Distributions of event shape variables obtained from 120600 hadronic Z decays measured with the DELPHI detector are compared to the predictions of QCD based event generators. Values of the strong coupling constant c~ s are derived as a function of the renormalization scale from a quantitative analysis of eight hadronic distributions. The final result, c%(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)
  • E. G. Anassontzis, P. Ioannou, +15 authors P. Koske
  • 2002
NESTOR is a deep-sea water Cherenkov neutrino detector now under construction for deployment in the Mediterranean off Greece. Its key component is an optical module employing a photomultiplier tube with a 15 in. hemispherical photocathode in a transparent glass pressure housing. Extensive tests have been made on the sensitivity, uniformity, time resolution,(More)
An update of the searches for charginos and neutralinos in DELPHI is presented, based mainly on recent data collected at centre-of-mass energies of 161 GeV and 172 GeV. No signal is found. For a sneutrino with mass above 300 GeV/c and a mass di erence between the chargino and the lightest neutralino above 10 GeV/c, the lower limit at 95% con dence level on(More)
The transverse, longitudinal and asymmetric components of the fragmentation function are measured from the inclusive charged particles produced in e + e ? collisions at LEP. As in deep inelastic scattering, these data are important for tests of QCD. The transverse T and longitudinal L components of the total hadronic cross section tot are evaluated from the(More)
A new measurement of ~ is obtained from the distributions in thrust, heavy jet mass, energy-energy correlation and two recently introduced jet broadening variables following a method proposed by Catani, Trentadue, Turnock and Webber. This method includes the full calculation of ~y(~2) terms and leading and next-toleading logarithms resummed to all orders of(More)