From 56 days of data taking in 2002, the NA48/1 experiment observed 6316 Ξ0 → Σ+ e- over(ν, ̄)e candidates (with the subsequent Σ+ → p π0 decay) and 555 over(Ξ0, -) → over(Σ+, -) e+ νe candidates with background contamination of 215 ± 44 and 136 ± 8 events, respectively. From these samples, the branching ratios BR (Ξ0 → Σ+ e- over(ν, ̄)e) = (2.51 ± 0.03stat ± 0.09syst) × 10-4 and BR (over(Ξ0, -) → over(Σ+, -) e+ νe) = (2.55 ± 0.14stat ± 0.10syst) × 10-4 were measured allowing the determination of the CKM matrix element | Vus | = 0.209-0.028+0.023. Using the Particle Data Group average for | Vus | obtained in semileptonic kaon decays, we measured the ratio g1 / f1 = 1.20 ± 0.05 of the axial-vector to vector form factors.
Measurement of the branching ratios of the decays Xi0 ---> Sigma+ e- anti-nu(e) and anti-Xi0 ---> anti-Sigma+ e+ nu(e).
ANZIVINO, Giuseppina;NAPPI, Aniello;VALDATA, Marisa
2007
Abstract
From 56 days of data taking in 2002, the NA48/1 experiment observed 6316 Ξ0 → Σ+ e- over(ν, ̄)e candidates (with the subsequent Σ+ → p π0 decay) and 555 over(Ξ0, -) → over(Σ+, -) e+ νe candidates with background contamination of 215 ± 44 and 136 ± 8 events, respectively. From these samples, the branching ratios BR (Ξ0 → Σ+ e- over(ν, ̄)e) = (2.51 ± 0.03stat ± 0.09syst) × 10-4 and BR (over(Ξ0, -) → over(Σ+, -) e+ νe) = (2.55 ± 0.14stat ± 0.10syst) × 10-4 were measured allowing the determination of the CKM matrix element | Vus | = 0.209-0.028+0.023. Using the Particle Data Group average for | Vus | obtained in semileptonic kaon decays, we measured the ratio g1 / f1 = 1.20 ± 0.05 of the axial-vector to vector form factors.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
