The forward-backward asymmetry of the process e(+)e(-) --> Z --> b ($) over bar b has been measured using events collected ee by the DELPHI experiment during the 1991 and 1992 LEP runs. This data sample corresponded to 884 000 hadronic Z decays at a centre-of-mass energy root s similar to M(Z). The tagging of b-quark events was performed using two approaches; the first was based on the semileptonic decay channels b --> X + mu and b --> X + e, the second used a lifetime tag with jet-charge reconstruction. The results of these two methods were combined to give A(FB)(b ($) over bar b) = 0.107 +/- 0.011(stat. + syst. + mixing). With the semileptonic sample, the forward-backward asymmetry of the process e(+)e(-) --> Z --> c ($) over bar c was also measured to be A(FB)(c ($) over bar c) = 0.083 +/- 0.022(stat.) +/- 0.016(syst.). The effective value of the Weinberg mixing angle derived from these measurements was sin(2) theta(eff)(lep) = 0.2294 +/- 0.0021.

Measurement of the forward-backward asymmetry of e(+)e(-)-]Z-]B(B)over-bar using prompt leptons and a lifetime tag

CACCIA, MASSIMO;PREST, MICHELA;
1995-01-01

Abstract

The forward-backward asymmetry of the process e(+)e(-) --> Z --> b ($) over bar b has been measured using events collected ee by the DELPHI experiment during the 1991 and 1992 LEP runs. This data sample corresponded to 884 000 hadronic Z decays at a centre-of-mass energy root s similar to M(Z). The tagging of b-quark events was performed using two approaches; the first was based on the semileptonic decay channels b --> X + mu and b --> X + e, the second used a lifetime tag with jet-charge reconstruction. The results of these two methods were combined to give A(FB)(b ($) over bar b) = 0.107 +/- 0.011(stat. + syst. + mixing). With the semileptonic sample, the forward-backward asymmetry of the process e(+)e(-) --> Z --> c ($) over bar c was also measured to be A(FB)(c ($) over bar c) = 0.083 +/- 0.022(stat.) +/- 0.016(syst.). The effective value of the Weinberg mixing angle derived from these measurements was sin(2) theta(eff)(lep) = 0.2294 +/- 0.0021.
1995
DELPHI; forward-backward asymmetry; b-tagging; jet reconstruction
Abreu, P; Adam, W; Adye, T; Agasi, E; Ajinenko, I; Aleksan, R; Alekseev, Gd; Allport, Pp; Almehed, S; Almeida, Fml; Alvsvagg, Sj; Amaldi, U; Andreazza...espandi
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11383/1791221
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