Achard, P (reprint author), Univ Geneva, CH-1211 Geneva, Switzerland.
Neutral-current four-fermion production, e(+)e(-) f (f) over bar f'(f) over barf, is studied in 0.7 fb(-1) of data collected with the L3 detector at LEP at centre-of-mass energies root s = 183-209 GeV. Four final states are considered: q (q) over barv (v) over bar, q (q) over barl(+)l(-),l(+)l(-)l'(+)l'(-) and l(+)l(-)v (v) over bar, where l denotes either an electron or a muon. Their cross sections are measured and found to agree with the Standard Model predictions. In addition, the e(+)e(-) -> Z gamma* -> f (f) over barf'(f) over bar' process is studied and its total cross section at the average centre-of-mass energy (root s) = 196.6 GeV is found to be 0.29 +/- 0.05 +/- 0.03 pb, where the first uncertainty is statistical and the second systematic, in agreement with the Standard Model prediction of 0.22 pb. Finally, the mass spectra of the q (q) over barl(+)l(-) final states are analysed to search for the possible production of a new neutral heavy particle, for which no evidence is found. (c) 2005 Published by Elsevier B.V.