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

Using 1.63 fb−1 − 1 of integrated luminosity collected by the KLOE experiment about 7 × 104 4 K𝑆 S → π± ± e∓ ∓ ν decays have been reconstructed. The measured value of the charge asymmetry for this decay is A𝑆 S = (−4.9 ± 5.7𝑠𝑡𝑎𝑡 s t a t ± 2.6𝑠𝑦𝑠𝑡 s y s t ) × 10−3 − 3 , which is almost twice more precise than the previous KLOE result. The combination of these two measurements gives A𝑆 S = (−3.8 ± 5.0𝑠𝑡𝑎𝑡 s t a t ± 2.6𝑠𝑦𝑠𝑡 s y s t ) × 10−3 − 3 and, together with the asymmetry of the K𝐿 L semileptonic decay, provides significant tests of the CPT symmetry. The obtained results are in agreement with CPT invariance.