Based on a sample of four million events collected by ALEPH from 1991 to 1995, a measurement of the forward-backward asymmetry in Z --> b (b) over bar decays using inclusive final states is presented. High-performance tagging of b (b) over bar events in a wide angular range is achieved using neural network techniques. An optimal hemisphere charge estimator is built by merging primary and secondary vertex information, leading kaon identification and jet charge in a neural network. The average charge asymmetry, the flavour tagging efficiencies and mean b-hemisphere charges are measured from data and used to extract the pole b asymmetry in the Standard Model A(FB)(o,b) = 0.1011 +/- 0.0012 (syst), corresponding to a value of the effective weak mixing angle of sin(2)theta(W)(eff) = 0.23189 +/- 0.00056.
Measurement of A(FB)(b) using inclusive b-hadron decays
SELVAGGI, Giovanna;NUZZO, Salvatore Vitale;DE PALMA, Mauro
2001-01-01
Abstract
Based on a sample of four million events collected by ALEPH from 1991 to 1995, a measurement of the forward-backward asymmetry in Z --> b (b) over bar decays using inclusive final states is presented. High-performance tagging of b (b) over bar events in a wide angular range is achieved using neural network techniques. An optimal hemisphere charge estimator is built by merging primary and secondary vertex information, leading kaon identification and jet charge in a neural network. The average charge asymmetry, the flavour tagging efficiencies and mean b-hemisphere charges are measured from data and used to extract the pole b asymmetry in the Standard Model A(FB)(o,b) = 0.1011 +/- 0.0012 (syst), corresponding to a value of the effective weak mixing angle of sin(2)theta(W)(eff) = 0.23189 +/- 0.00056.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
