An improved measurement of the forward-backward asymmetry in Z --> b (b) over bar decays is presented, based on a sample of 4.1 million hadronic Z decays collected by ALEPH between 1991 and 1995. Data are analysed as a function of polar angle of the event axis and b purity. The event tagging efficiency and mean b-jet hemisphere charge are measured directly from data. From the measured forward-backward jet charge asymmetry, the b quark asymmetry at root s= m(Z) is determined to be: A(FB)(b) = 0.1017 +/- 0.0032(syst.) +/- 0.0032(syst.). In the context of the Standard Model this corresponds to a value of the effective weak mixing angle of sin(2)theta(W)(eff)= 0.23109 +/- 0.00096.

Determination of A(FB)(b) using jet charge measurements in Z decays

BATIGNANI, GIOVANNI;BETTARINI, STEFANO;CIOCCI, MARIA AGNESE;FERRANTE, ISIDORO;FORTI, FRANCESCO;GIORGI, MARCELLO;MESSINEO, ALBERTO MARIA;RIZZO, GIULIANA;TONELLI, GUIDO EMILIO;
1998-01-01

Abstract

An improved measurement of the forward-backward asymmetry in Z --> b (b) over bar decays is presented, based on a sample of 4.1 million hadronic Z decays collected by ALEPH between 1991 and 1995. Data are analysed as a function of polar angle of the event axis and b purity. The event tagging efficiency and mean b-jet hemisphere charge are measured directly from data. From the measured forward-backward jet charge asymmetry, the b quark asymmetry at root s= m(Z) is determined to be: A(FB)(b) = 0.1017 +/- 0.0032(syst.) +/- 0.0032(syst.). In the context of the Standard Model this corresponds to a value of the effective weak mixing angle of sin(2)theta(W)(eff)= 0.23109 +/- 0.00096.
1998
R., Barate; D., Buskulic; D., Decamp; P., Ghez; C., Coy; J. P., Lees; A., Lucotte; E., Merle; M. N., Minard; J. Y., Nief; B., Pietrzyk; R., Alemany; G...espandi
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11568/829037
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