A determination of the centre-of-mass energy at LEP2 using radiative two-fermion events

Using e⁺e^-→μ⁺μ^-(γ) and events radiative to the Z pole, DELPHI has determined the centre-of-mass energy, , using energy and momentum constraint methods. The results are expressed as deviations from the nominal LEP centre-of-mass energy, measured using other techniques. The results are found to be compatible with the LEP Energy Working Group estimates for a combination of the 1997 to 2000 data sets.