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Preliminary result on the charged kaon lifetime, obtained by the KLOE experiment operating at DA$Phi$NE, the Frascati $phi$-factory, is presented
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We have measured the charged kaon lifetime using a sample of 15 times 10^6 tagged kaon decays. Charged kaons were produced in pairs at the DAPhiNE phi-factory, e^+e^- to phi to K^+ K^-. The decay of a K^+ was tagged by the production of a K^- and viceversa. The lifetime was obtained, for both charges, from independent measurements of the decay time and decay lenght distributions. From fits to the four distributions we find tau = (12.347pm0.030) ns.
This paper is devoted to the measurement of the fully inclusive absolute branching ratios of the charged kaon semileptonic decays, $K^{pm}topi^0e^pm u(gamma)$ and $K^pm to pi^0mu^pm u(gamma)$. The measurements have been done using a tag technique, employing the two-body decays, $K^pm to mu^pm u$ and $K^pm to pi^pmpi^0$, and using a sample of about 410 pb$^{-1}$ collected during the 2001 and 2002 data taking of the KLOE experiment at Daphne, the Frascati $phi$-factory. The results obtained are BR(K$^pm_{e3}$) = $0.04965 (38)_{Stat} (37)_{Syst}$ and BR(K$^pm_{mu3}$) = $0.03233 (29)_{Stat} (26)_{Syst}$.
Neutral kaons produced in correlated pairs at a phi-factory offer unique possibilities to perform fundamental tests of CPT invariance, as well as of the basic principles of quantum mechanics. The analysis of the data collected by the KLOE experiment at DAFNE is still ongoing with the aim of improving previous results and limits on several parameters describing CPT violation and decoherence. Ancillary measurements like the regeneration cross section on the beam pipe materials are also in progress and will be very useful to reduce the systematic uncertainties. Prospects on improvements at the KLOE-2 experiment, aiming at an increase of the integrated luminosity of about a factor of ten with an upgraded detector, will be also discussed.
All relevant inputs for the extraction of the CKM matrix element vus from kl, ks and kpm decays have been measured at KLOE. From a global fit using only KLOE results, but ks lifetime, a value of $|vus|fzero = 0.2157 pm 0.0006$ is obtained, where fzero is the form factor parametrizing the hadronic matrix element evaluated at zero momentum transfer. Comparison of the values of fVus for $K_{e3}$ and $K_{mu3}$ modes provides a test of lepton universality at 0.8% level of accuracy. The value $vus/vud=0.2323(15)$ has been obtained from the ratio $Gamma(Ktomu u)/Gamma(pitomu u)$ using KLOE measurement of $BR(kpm to mudue)$ and lattice calculation of the ratio of decay constants $f_K/f_{pi}$. These results, together with $vud = 0.97418(26)$, are compatible at 0.6$sigma$ level with CKM matrix unitarity. The universality of lepton and quark weak couplings can be tested and constraints on new physics extensions of the Standard Model can be set using these very precise measurements from kaon decays.
Kaon physics can test new-physics effects in leptonic or semileptonic decays. A unitarity test of the first row of the CKM mixing matrix is obtained from the precision measurements of Kl3 widths for K{pm}, KL, and (unique to KLOE) KS. The KLOE measurement of RK = {Gamma}(Ke2)/{Gamma}(K{mu}2) with an accuracy at the % level, aims at finding evidence of deviations from the SM prediction induced by lepton-flavor violation new-physics effects.
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