Download or read book Precise Measurement of the K - to Pi -E E- Decay written by and published by . This book was released on 2011 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: A sample of 7253 K{sup ±} 2![pi]{sup ±}ee−([gamma]) decay candidates with 1.0% background contamination has been collected by the NA 48/2 experiment at the CERN SPS, which allowed a precise measurement of the decay properties. The branching ratio in the full kinematic range was measured to be BR = (3.11 {+-} 0.12) x 10−7, where the uncertainty includes also the model dependence. The shape of the form factor W(z), where z = (M{sub ee}/M{sub K})2, was parameterized according to several models, and, in particular, the slope [delta] of the linear form factor W(z) = W0(1 + [delta]z) was determined to be [delta] = 2.32 {+-} 0.18. A possible CP violating asymmetry of K+ and K− decay widths was investigated, and a conservative upper limit of 2.1 x 10−2 at 90% CL was established.