A sample of more than one million K-+/- -> pi(+)pi(-)e(+/-)v (K-e4) decay candidates with less than one percent background contamination has been collected by the NA48/2 experiment at the CERN SPS in 2003-2004, allowing a detailed study of the decay properties. The branching ratio, inclusive of K-e4 gamma decays, is measured to be BR(K-e4) = (4.257 +/- 0.016(exp) +/- 0.031(ext)) x 10(-5) with a total relative error of 0.8%. This measurement complements the study of S- and P-wave hadronic form factors by assigning absolute values to the relative hadronic form factors obtained earlier in a simultaneous analysis of the pi pi scattering lengths conducted on the same data sample. The overall form factor normalization f(s) = 5.705 +/- 0.017(exp) +/- 0.031(ext) is obtained with a total relative precision of 0.6%. (c) 2012 Elsevier B.V. All rights reserved.
New measurement of the K-+/- -> pi(+)pi(-)e(+/-)v (Ke4) decay branching ratio and hadronic form factors
LAMANNA, GIANLUCA;COSTANTINI, FLAVIO;GIUDICI, SERGIO;SOZZI, MARCO STANISLAO;
2012-01-01
Abstract
A sample of more than one million K-+/- -> pi(+)pi(-)e(+/-)v (K-e4) decay candidates with less than one percent background contamination has been collected by the NA48/2 experiment at the CERN SPS in 2003-2004, allowing a detailed study of the decay properties. The branching ratio, inclusive of K-e4 gamma decays, is measured to be BR(K-e4) = (4.257 +/- 0.016(exp) +/- 0.031(ext)) x 10(-5) with a total relative error of 0.8%. This measurement complements the study of S- and P-wave hadronic form factors by assigning absolute values to the relative hadronic form factors obtained earlier in a simultaneous analysis of the pi pi scattering lengths conducted on the same data sample. The overall form factor normalization f(s) = 5.705 +/- 0.017(exp) +/- 0.031(ext) is obtained with a total relative precision of 0.6%. (c) 2012 Elsevier B.V. All rights reserved.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
