From 56 days of data taking in 2002, the NA48/1 experiment observed 6316 Xi(0) -> Sigma(+)e(-)nu(e) candidates (with the subsequent Sigma(+) -> p pi(0) decay) and 555 (Xi(0)) over bar -> (Sigma(+)) over bare+nu(e) candidates with background contamination of 215 +/- 44 and 136 +/- 8 events, respectively. From these samples, the branching ratios BR(Xi(0) -> Sigma(+)e(-)nu(e)) = (2.51 +/- 0.03(stat) +/- 0.09(syst)) x 10(-4) and BR((Xi(0)) over bar -> (Sigma(+)) over bare(+)nu(e)) = (2.55 +/- 0.14(stat) +/- 0.10(syst)) x 10(-4) were measured allowing the determination of the CKM matrix element vertical bar V-us vertical bar = 0.209(-0.028)(+0.023) Using the Particle Data Group average for vertical bar V-us vertical bar obtained in semileptonic kaon decays, we measured the ratio g(1)/f(1) = 1.20 +/- 0.05 of the axial-vector to vector formfactors.
Measurement of the branching ratios of the decays Xi0 ---> Sigma+ e- anti-nu(e) and anti-Xi0 ---> anti-Sigma+ e+ nu(e)
VELTRI, MICHELE;
2007
Abstract
From 56 days of data taking in 2002, the NA48/1 experiment observed 6316 Xi(0) -> Sigma(+)e(-)nu(e) candidates (with the subsequent Sigma(+) -> p pi(0) decay) and 555 (Xi(0)) over bar -> (Sigma(+)) over bare+nu(e) candidates with background contamination of 215 +/- 44 and 136 +/- 8 events, respectively. From these samples, the branching ratios BR(Xi(0) -> Sigma(+)e(-)nu(e)) = (2.51 +/- 0.03(stat) +/- 0.09(syst)) x 10(-4) and BR((Xi(0)) over bar -> (Sigma(+)) over bare(+)nu(e)) = (2.55 +/- 0.14(stat) +/- 0.10(syst)) x 10(-4) were measured allowing the determination of the CKM matrix element vertical bar V-us vertical bar = 0.209(-0.028)(+0.023) Using the Particle Data Group average for vertical bar V-us vertical bar obtained in semileptonic kaon decays, we measured the ratio g(1)/f(1) = 1.20 +/- 0.05 of the axial-vector to vector formfactors.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
