Measurement of the branching ratio and search for a CP violating asymmetry in the eta -> pi+pi-e+e-(gamma) decay at KLOE
Abstract
We have studied the eta->pi+pi-e+e-(gamma) decay using about 1.7 fb-1 collected by the KLOE experiment at the DAFNE phi-factory. This corresponds to about 72 millions eta mesons produced in phi radiative decays. We have measured the branching ratio, inclusive of radiative effects, with 4% accuracy: BR(eta->pi+pi-e+e-(gamma)) = (26.8 +/- 0.9Stat. +/- 0.7Syst.) x 10-5. We have obtained the first measurement of the CP-odd pipi-ee decay planes angular asymmetry, Aphi = (-0.6 +/- 2.5Stat. +/- 1.8Syst.) x 10-2.
0