Measurement of the W-pair cross-section and of the W mass in {\mathrm{e^+ e^-}} interactions at 172 GeV

From a data sample of integrated luminosity, collected by DELPHI at a centre-of-mass energy of 172 GeV, 118 events were selected as W-pair candidates. From these, the branching fraction was measured to be and the cross-section for the doubly resonant process to be pb. The mass of the W boson, obtained from direct reconstruction of the invariant mass of the fermion pairs in the decays and , was determined to be , where “int.” denotes the uncertainty from interconnection effects like colour reconnection and Bose-Einstein interference. Combined with the W mass obtained from the cross-sections measured by DELPHI at threshold, a value of was found. Received: 12 December 1997 / Published online: 10 March 1998