Measured ratios of decay rates for RKe3/K2π, R Kμ3/K2π and RKμ3/Ke3 are presented. These measurements are based on K± decays collected in a dedicated run in 2003 by the NA48/2 experiment at CERN. The results obtained are R Ke3/K2π = 0.249±0.0009 (stat)±0.0004 (syst)and RKμ3/K2π = 0.1637±0.0006 (stat)±0.0003 (syst). Using the PDG average for the K±→π ±π0 normalisation mode, both values are found to be larger than the current values given by the particle data book and lead to a larger magnitude of the |Vus| CKM element than previously accepted. When combined with the latest particle data book value of |Vud|, the result is in agreement with unitarity of the CKM matrix. In addition, a new measured value of RKμ3/Ke3 = 0.656±0.003(stat)±0. 001(syst) is compared to the semi-empirical predictions based on the latest form factor measurements.
ASJC Scopus subject areas
- Engineering (miscellaneous)
- Physics and Astronomy (miscellaneous)