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. (C) 1998 Published by Elsevier Science B.V, All rights reserved.
|Autori interni:||CREANZA, Donato Maria|
MAGGI, Giorgio Pietro
|Titolo:||Determination of A(FB)(b) using jet charge measurements in Z decays|
|Rivista:||PHYSICS LETTERS. SECTION B|
|Data di pubblicazione:||1998|
|Digital Object Identifier (DOI):||10.1016/S0370-2693(98)00345-1|
|Appare nelle tipologie:||1.1 Articolo in rivista|