Precise measurement of Γ(KS → π+π-(γ))/Γ(KS → π0π0) with the KLOE detector at DAφNE

Using a sample of over 400 million phi -> KSKL decays produced during the years 2001 and 2002 at the DA Phi NE e(+)e(-) collider, the ratio R-S(pi) = Gamma(K-S -> pi(+) pi(-)(gamma))/Gamma (K-S -> pi(0)pi(0)) has been measured with the KLOE detector. The result is R-pi(S) = 2.2555 +/- 0.0012(stat)+/- 0.0021(corr-stat)+/- 0.0050(syst), which is in good agreement with the previously published result based on the KLOE data sample from the year 2000. The average of the KLOE results is R-S(pi) = 2.2549 +/- 0.0054, reducing the total error by a factor of three, to 0.25%.