Measurement of the KL meson lifetime with the KLOE detector

We present a measurement of the KL lifetime using the KLOE detector. From a sample of ∼4×108KSKL pairs following the reaction e+e−→ϕ→KSKL we select ∼15×106KL→π0π0π0 decays tagged by KS→π+π− events. From a fit of the proper time distribution we find τL=(50.92±0.17stat±0.25syst)ns. This is the most precise measurement of the KL lifetime performed to date.