In a data sample of approximately four million hadronic Z decays recorded with the ALEPH detector from 1990 to 1995, a search for the strange b baryon Xi(b) is performed with a study of Xi-lepton correlations. Forty-four events with same sign Xi(-)l(-) combinations are found whereas 8.4 are expected based on the rate of opposite sign Xi(-)l(+) combinations. This significant excess is interpreted as evidence for Xi(b) semileptonic decays. The measured product branching ratio is Br(b-->Xi(b))xBr(Xi(b)-->X(c)Xl(-)<(nu)over bar (l)>)xBr(X(c)-->Xi(-)X')=(5.4+/-1.1(stat)+/-0.8(syst))x10(-4) per lepton species, averaged over electrons and muons, with X(c) a charmed baryon. The Xi(b) lifetime is measured to be tau(Xi b)=1.35(-0.28)(+0.37)(stat)(-0.17)(+0.15)(syst) ps.

Strange b baryon production and lifetime in Z decays

SELVAGGI, Giovanna;NUZZO, Salvatore Vitale;DE PALMA, Mauro
1996-01-01

Abstract

In a data sample of approximately four million hadronic Z decays recorded with the ALEPH detector from 1990 to 1995, a search for the strange b baryon Xi(b) is performed with a study of Xi-lepton correlations. Forty-four events with same sign Xi(-)l(-) combinations are found whereas 8.4 are expected based on the rate of opposite sign Xi(-)l(+) combinations. This significant excess is interpreted as evidence for Xi(b) semileptonic decays. The measured product branching ratio is Br(b-->Xi(b))xBr(Xi(b)-->X(c)Xl(-)<(nu)over bar (l)>)xBr(X(c)-->Xi(-)X')=(5.4+/-1.1(stat)+/-0.8(syst))x10(-4) per lepton species, averaged over electrons and muons, with X(c) a charmed baryon. The Xi(b) lifetime is measured to be tau(Xi b)=1.35(-0.28)(+0.37)(stat)(-0.17)(+0.15)(syst) ps.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11586/43859
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