In June 1996, the LEP centre-of-mass energy was raised to 161 GeV. Pair production of W bosons in e+e- collisions was observed for the first time by the LEP experiments. An integrated luminosity of 11 pb-1 was recorded in the ALEPH detector, in which WW candidate events were observed. In 6 events both Ws decay leptonically. In 16 events, one W decays leptonically, the other into hadrons. In the channel where both Ws decay into hadrons, a signal was separated from the large background by means of several multi-variate analyses. The W pair cross-section is measured to be σww = 4.23 +/- 0.73 (stat.) +/- 0.19 (syst.) pb. From this cross-section, the W mass is derived within the framework of the Standard Model: mw = 80.14 +/- 0.34 (stat.) +/- 0.09 (syst.) +/- 0.03 (LEP energy) GeV/c2
Measurement of the W mass in e+e− collisions at production threshold
GREGORIO, ANNA;BOSISIO, LUCIANO;GIANNINI, GIANROSSANO;
1997-01-01
Abstract
In June 1996, the LEP centre-of-mass energy was raised to 161 GeV. Pair production of W bosons in e+e- collisions was observed for the first time by the LEP experiments. An integrated luminosity of 11 pb-1 was recorded in the ALEPH detector, in which WW candidate events were observed. In 6 events both Ws decay leptonically. In 16 events, one W decays leptonically, the other into hadrons. In the channel where both Ws decay into hadrons, a signal was separated from the large background by means of several multi-variate analyses. The W pair cross-section is measured to be σww = 4.23 +/- 0.73 (stat.) +/- 0.19 (syst.) pb. From this cross-section, the W mass is derived within the framework of the Standard Model: mw = 80.14 +/- 0.34 (stat.) +/- 0.09 (syst.) +/- 0.03 (LEP energy) GeV/c2Pubblicazioni consigliate
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