Measurement of the Tau Lepton Polarisation at LEP2

A first measurement of the average polarisation P_tau of tau leptons produced in e+e- annihilation at energies significantly above the Z resonance is presented. The polarisation is determined from the kinematic spectra of tau hadronic decays. The measured value P_tau = -0.164 +/- 0.125 is consistent with the Standard Model prediction for the mean LEP energy of 197 GeV.A first measurement of the average polarisation Pτ of tau leptons produced in e + e − annihilation at energies significantly above the Z resonance is presented. The polarisation is determined from the kinematic spectra of tau hadronic decays. The measured value Pτ=−0.164±0.125 is consistent with the Standard Model prediction for the mean LEP energy of 197 GeV.A first measurement of the average polarisation P_tau of tau leptons produced in e+e- annihilation at energies significantly above the Z resonance is presented. The polarisation is determined from the kinematic spectra of tau hadronic decays. The measured value P_tau = -0.164 +/- 0.125 is consistent with the Standard Model prediction for the mean LEP energy of 197 GeV

Measurement of the Mass and Width of the W Boson in e+e−e^{+}e^{-} Collisions at s\sqrt{s} = 161 - 209 GeV

A measurement of the W boson mass and width has been performed by the DELPHI collaboration using the data collected during the full LEP2 programme (1996-2000). The data sample has an integrated luminosity of 660 pb^-1 and was collected over a range of centre-of-mass energies from 161 to 209 GeV. Results are obtained by applying the method of direct reconstruction of the mass of the W from its decay products in both the W+W- -> lvqq and W+W- -> qqqq channels. The W mass result for the combined data set is M_W = 80.336 +/- 0.055 (Stat.) +/- 0.028 (Syst.) +/- 0.025 (FSI) +/- 0.009 (LEP) GeV/c^2, where FSI represents the uncertainty due to final state interaction effects in the qqqq channel, and LEP represents that arising from the knowledge of the collision energy of the accelerator. The combined value for the W width is Gamma_W = 2.404 +/- 0.140 (Stat.) +/- 0.077 (Syst.) +/- 0.065 (FSI) GeV/c^2. These results supersede all values previously published by the DELPHI collaboration. This paper is dedicated to the memory of Carlo Caso.A measurement of the W boson mass and width has been performed by the DELPHI collaboration using the data collected during the full LEP2 programme (1996-2000). The data sample has an integrated luminosity of 660 pb^-1 and was collected over a range of centre-of-mass energies from 161 to 209 GeV. Results are obtained by applying the method of direct reconstruction of the mass of the W from its decay products in both the W+W- -> lvqq and W+W- -> qqqq channels. The W mass result for the combined data set is M_W = 80.336 +/- 0.055 (Stat.) +/- 0.028 (Syst.) +/- 0.025 (FSI) +/- 0.009 (LEP) GeV/c^2, where FSI represents the uncertainty due to final state interaction effects in the qqqq channel, and LEP represents that arising from the knowledge of the collision energy of the accelerator. The combined value for the W width is Gamma_W = 2.404 +/- 0.140 (Stat.) +/- 0.077 (Syst.) +/- 0.065 (FSI) GeV/c^2. These results supersede all values previously published by the DELPHI collaboration. This paper is dedicated to the memory of Carlo Caso

B* production in Z decays

The decay B*→Bγ has been observed with the DELPHI detector at LEP, where the B* meson is produced in Z boson decays. The combination of inclusively reconstructed B mesons with well-measured converted photons yields a measurement of the flavour-averaged B*-B mass difference of 45.5±0.3 (stat.) ±0.8 (syst.) MeV/c2. 95% confidence level upper limits at 6 MeV/c2 are placed on both the isospin (i.e. B+-B0) and the Bs-Bud splitting of the mass difference. The production ratio of B* to B mesons in Z decays is measured to be 0.72±0.03 (stat.) ±0.06 (syst.). Limits on the production cross-section of other hypothetical excited B hadron states decaying radiatively are established. The differential B* cross section has been measured to be in good agreement with the average b fragmentation, yielding an average fractional B* energy of 〈xE〉=0.695±0.009 (stat.) ±0.013 (syst.). From the decay angular distribution the relative contribution of longitudinal B* polarisation states is measured to be σL/(σL + σT) = 0.32 ± 0.04 (stat.) ±0.03 (syst.). © 1995 Springer-Verlag

Charged particle multiplicity in e(+)e(-) interactions at root s=130 GeV

From the data collected by DELPHI at LEP in autumn 1995, the multiplicity of charged particles at a hadronic energy of 130 GeV has been measured to be = 23:84 0:51(stat) 0:52(syst). When compared to lower energy data, the value measured is consistent with the evolution predicted by QCD with corrections at next-to-leading order, for a value s(130GeV) = 0:105 0:003(stat) 0:008(syst)

Search for pair produced heavy scalars in Z0 decays

A search for charged Higgs bosons decaying into quarks is described, based on statistics of around 1.7 million hadronic Zo decays detected in DELPHI. Despite the very high background from standard hadronic decays of the Zo, masses in the range up to 43.5 GeV/c2 are excluded at the 95% confidence level. After combination with a search for leptonic decays, this mass limit is extended to cover all branching ratios. A similar analysis sets new limits on the possible production of any pair-produced heavy scalar decaying into a pair of jets, such as neutral Higgs bosons in a two doublet scheme and diquarks. © 1994 Springer-Verlag.0SCOPUS: ar.jinfo:eu-repo/semantics/publishe