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Register a new userVus and lepton universality from kaon decays with the KLOE detector
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KLOE has measured most decay branching ratios of Ks, Kl and K+/- mesons. It has also measured the Kl and the K+- lifetime and determined the shape of the form factors involved in kaon semileptonic decays. We present in the following a description of the above measurements and a well organized compendium of all of our data, with particular attention to correlations. These data provide the basis for the determination of the CKM parameter Vus and a test of the unitarity of the quark flavor mixing matrix. We also test lepton universality and place bounds on new physics using measurements of Vus from Kl2 and Kl3 decays.
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This review presents the analysis of leptonic and semileptonic kaon decays data done by the FlaviaNet Kaon Working group, as described in FlaviaNet Note of October 2008. Data include all recent results by BNL-E865, KLOE, KTeV, ISTRA+, and NA48. Experimental results are critically reviewed and combined, taking into account theoretical (both analytical and numerical) constraints on the semileptonic kaon form factors. We report on a very accurate determination of Vus as well as on many other tests of the SM which can be performed with leptonic and semileptonic kaon decays.
In this paper we discuss the recent finalized analyses by the KLOE experiment at DA$Phi$NE: the CPT and Lorentz invariance test with entangled $K^0 bar{K}^0$ pairs, and the precision measurement of the branching fraction of the decay ${ K^+} rightarrow pi^+pi^-pi^+(gamma)$. We also present the status of an ongoing analysis aiming to precisely measure the $K^{pm} $ mass.
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.
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.
While measuring the ratio R_K = Gamma(K+e2(gamma))/Gamma(K+mu2(gamma)), the KLOE Collaboration has studied the radiative process Ke2gamma. The ratio of the width for the Ke2gamma decay with a positively polarized photon from structure-dependent radiation to the inclusive Kmu2(gamma) width is found to be 1.484(68) 10-5. The observed radiation spectrum agrees with predictions from chiral perturbation theory and is in contrast with predictions based on the light front quark model. This result reduces the contribution to systematic uncertainties on measurements of R_K. In a separate study, KLOE has measured the ratio of the radiative Ke3gamma decay width to the inclusive Ke3(gamma) width to be 924(28) 10-5. The distribution in energy and angle of the radiative photon has been analyzed in an attempt to isolate the signature from interference of the inner-bremsstrahlung and structure-dependent amplitudes.
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