Measurement of the charge asymmetry for the KS → πeν decay and test of CPT symmetry with the KLOE detector

Using 1.63 fb−1 of integrated luminosity collected by the KLOE experiment about 7 × 104 K S → π ± e ∓ ν decays have been reconstructed. The measured value of the charge asymmetry for this decay is A S = (−4.9 ± 5.7stat ± 2.6syst) × 10−3, which is almost twice more precise than the previous KLOE result. The combination of these two measurements gives A S = (−3.8 ± 5.0stat ± 2.6syst) × 10−3 and, together with the asymmetry of the K L semileptonic decay, provides significant tests of the CPT symmetry. The obtained results are in agreement with CPT invariance.