Recent Results in Rare and Semileptonic Kaon Decays from NA48

Recent results are presented on rare neutral kaon decays from the NA48/1 collaboration, and on semileptonic charged kaon decays from the NA48/2 collaboration.Using data taken on 2002, NA48/1 has measured the CP conserving component of the decay K0→π0π+π−. For the λ parameter describing this decay the values Re(λ)=0.038±0.008stat±0.006syst and Im(λ)=−0.013±0.005stat±0.004syst have been obtained. This is consistent with previous measurements and with chiral perturbation theory predictions. NA48/1 has also measured the BR(Ks→π±e∓ν)=(6.8±0.2stat±0.2syst)10−4, consistent with ΔS=ΔQ.Using data collected during eight hours minimum bias run on 2003, the NA48/2 collaboration has measured BR(K±→π0e±ν)=(5.14±0.02stat±0.06syst)10−2, where the channel K±→π0π± has been used as normalization. From the same data sample, the ratio of K±→π0μ±ν to K±→π0e±ν has been obtained. This results on BR(K±→π0μ±ν)=(3.462±0.018stat±0.006syst±0.011λ+,λ0±0.068norm). From semileptonic decays the value of the CKM matrix element Vus can be extracted. The values of Vus|f+(0)| obtained by NA48/2 from electron and muon channels are compatible.The result on K0→π0π+π− is final, and all the other results presented here are preliminary.