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During 1993 and 1995 LEP was run at 3 energies near the Z\\(^0\\) peak in order to give improved measurements of the mass and width of the resonance. During 1994, LEP operated only at the Z\\(^0\\) peak. In total DELPHI accumulated data corresponding to an integrated luminosity of approximately 116 pb\\(^{-1}\\). Analyses of the hadronic cross-sections and of the cross-sections and forward-backward asymmetries in the leptonic channels used the most precise evaluations of the LEP energies. In the dimuon channel, events with a photon radiated from the initial state have been used to probe the cross-sections and asymmetries down to PETRA energies. Model independent fits to all DELPHI lineshape and asymmetry data from 1990 to 1995 have been carried out giving values of the resonance parameters:These values are significantly more precise than those previously published. The results are interpreted in terms of the Standard Model.

The transverse, longitudinal and asymmetric components of the fragmentation function are measured from the inclusive charged particles produced in collisions at LEP. As in deep inelastic scattering, these data are important for tests of QCD. The transverse and longitudinal components of the total hadronic cross section are evaluated from the measured fragmentation functions. They are found to be and respectively. The strong coupling constant is calculated from in next-to-leading order of perturbative QCD, giving Including non-perturbative power corrections leads to The measured transverse and longitudinal components of the fragmentation function are used to estimate the mean charged multiplicity, The fragmentation functions and multiplicities in and light quark events are compared. The measured transverse and longitudinal components of the fragmentation function allow the gluon fragmentation function to be evaluated.

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 s

An experimental study of the normalized three-jet rate of b quark events with respect to light quarks events (light=ℓ≡u,d,s) has been performed using the CAMBRIDGE and DURHAM jet algorithms. The data used were collected by the DELPHI experiment at LEP on the Z peak from 1994 to 2000. The results are found to agree with theoretical predictions treating mass corrections at next-to-leading order. Measurements of the b quark mass have also been performed for both the b pole mass: Mb and the b running mass: mb(MZ). Data are found to be better described when using the running mass. The measurement yields: \\(m_b(M_Z)=2.85\\pm0.18 (\\text{stat}) \\pm0.13 (\\text{exp}) \\pm0.19 (\\text{had}) \\pm0.12 (\\text{theo}) \\text{GeV}/c^2.\\)for the CAMBRIDGE algorithm.This result is the most precise measurement of the b mass derived from a high energy process. When compared to other b mass determinations by experiments at lower energy scales, this value agrees with the prediction of quantum chromodynamics for the energy evolution of the running mass. The mass measurement is equivalent to a test of the flavour independence of the strong coupling constant with an accuracy of 7 ‰.

Measurements are presented of R_(b), the ratio of the b bbar cross-section to the q qbar cross-section in e+e- collisions, and the forward-backward asymmetry Aᵇ_(F)B at twelve energy points in the range sqrt(s) = 130-207 GeV. These results are found to be consistent with the Standard Model expectations. The measurements are used to set limits on new physics scenarios involving contact interactions.

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/c², 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/c². These results supersede all values previously published by the DELPHI collaboration. This paper is dedicated to the memory of Carlo Caso.

Measurements of Zgamma* production are presented using data collected by the DELPHI detector at centre-of-mass energies ranging from 183 to 209 GeV, corresponding to an integrated luminosity of about 667 pb⁻1. The measurements cover a wide range of the possible final state four-fermion configurations: hadronic and leptonic (e+ e- q qbar, mu+ mu- q qbar, q qbar nu nubar), fully leptonic (l+ l- l'+ l'-) and fully hadronic final states (q qbar q qbar, with a low mass q qbar pair). Measurements of the Zgamma* cross-section for the various final states have been compared with the Standard Model expectations and found to be consistent within the errors. In addition, a total cross-section measurement of the l+ l- l'+ l'- cross-section is reported, and found to be in agreement with the prediction of the Standard Model.