KLOE measurement of the charged kaon absolute semileptonic BR's

This paper is devoted to the measurement of the fully inclusive absolute branching ratios of the charged kaon semileptonic decays, $K^{\pm}\to\pi^0e^\pm\nu(\gamma)$ and $K^\pm \to \pi^0\mu^\pm\nu(\gamma)$. The measurements have been done using a tag technique, employing the two-body decays, $K^\pm \to \mu^\pm\nu$ and $K^\pm \to \pi^\pm\pi^0$, 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$^\pm_{\mu3}$) = $0.03233 (29)_{Stat} (26)_{Syst}$.Comment: Contributed paper to Lepton Photon 2007, Daegu, Korea, 13-18 August 2007, 5 pages, 2 figure

Recent Results from the KLOE Experiment at DAPHNE

Recent results from the KLOE experiment at the DAPHNE e+e- collider are presented. KLOE has collected about 500 pb^-1 of data in the years from 2000 to 2002. Preliminary results are obtained using wide samples of the full statistics and include: the BR of the Ke3 decay of the K_S and the first measurement of its charge asymmetry, the ratio BR(K_S-->pi+pi-(gamma))/BR(K_S-->pi^0pi^0), the ratio BR(K_L-->gammagamma)/BR(K_L-->3pi^0), a detailed study of the decay phi-->pi+pi-pi^0, the ratio BR(phi-->eta' gamma)/BR(phi-->eta gamma) and the pseudoscalar mixing angle phi_P, the phi-->f_0 gamma and the phi-->a_0 gamma BR's.Comment: 9 pages, 5 figures. To be published in the Proceedings of the XXXVIIIth Rencontres de Moriond - Electroweak Interactions and Unified Theorie

Studies of K0S decays with the KLOE detector at DAFNE

The KLOE detector at DAFNE has collected about 30 pb-1 by the end of year 2000,' allowing, among other things, accurate measurements on several decay channels of the K0S meson. With data acquired in the year 2000 run we have measured the ratio of the branching ratios of the K0S to two charged and neutral pions to 1.5 percent accuracy. The branching ratio of the semileptonic decay of the K0S is also measured to 5 percent accuracy, the best measurement of this BR to date.Comment: Contributed Paper to LP0

KLOE extraction of aμππa_\mu^{\pi\pi} in the mass range [0.35,0.95] GeV^2

The KLOE Experiment at the $\phi$ factory DA$\Phi$NE, has measured the cross section $\sigma(e^+e^-\to\pi^+\pi^-\gamma)$ using two different selection schemes: requiring the photon emission at small polar angle and detecting the photon at large polar angle in the calorimeter. Using a theoretical radiator function we extract the pion form factor and obtain the $\pi\pi$ contribution to the anomalous magnetic moment of the muon. Results presented here come from the analysis of 240 pb^{-1} collected in 2002, with improved systematic uncertainty with respect to the published KLOE analysis. We also include an update of the previous analysis.Comment: Contributed paper to Lepton Photon 200

Measuring the Hadronic Cross Section at KLOE using the Radiative Return

We present a study of the reaction e+e- \to pi+pi-gamma at the phi peak with the KLOE detector at the phi-factory DAPHNE. This reaction allows us to obtain the cross section for \e+e- \to pi+pi- from the e+e- center-of-mass energy W = m_\phi = 1019 MeV down to threshold, i.e. 2m_pi < M_(pipi) < m_phi. This is called radiative return. The status of the analysis and preliminary results on the invariant mass spectrum of the two-pion-state are presented.Comment: Contributed Paper to "Lepton Photon 2001" Conference, Rome, July 23-28 2001; 7 pages, 5 plot

First results from phi -> KL KS decays with the KLOE detector

The KLOE experiment has collected 2.4 1/pb of integrated luminosity during the commissioning of the DAFNE phi-factory in 1999. The performance of the detector has been studied using phi -> KL KS decays collected during this period, yielding also first measurements of relevant K parameters such as masses and lifetimes. A clean Kshort -> pi+ pi- sample is used to select Klong -> 2pi CP-violating decays and Klong -> Kshort regeneration events in the detector material. Results on the regeneration probability in beryllium-alluminum alloy and carbon-fiber plus aluminum composite are presented.Comment: 21 pages, 20 figures, Contributed paper number 294 to XXX ICHEP, Osaka July 200

∣Vus∣|V_{us}| and KSK_S Decays from Kloe

Recent results obtained by the KLOE experiment operating at DA$\Phi$NE, the Frascati $\phi$-factory, are presented. They mainly concern neutral kaon decays including the $K_L$ dominant branching ratios, the $K_L$ lifetime and the extraction of the $CKM$ parameter $V_{us}$ from the $K_L$ semileptonic decays and lifetime. The best world upper limit on K_S \to \pppo channel is also presentedComment: 9 pages, 6 figures. Proceedings of the Moriond EW Conference 200

Preliminary measurement of Gamma(Ke2)/Gamma(Km2) at KLOE

A preliminary measurement of RK = Gamma(Ke2)/Gamma(Km2) at the KLOE experiment is discussed. The result, RK = (2.55+-0.05+-0.05)x 10^-5, is based on 1.7 fb^-1 of luminosity integrated on the phi-meson peak at the Frascati e^+e^- collider DAFNE, corresponding to ~8000 observed Ke2 events. Perspectives on the methods planned to improve both the statistical and the systematic errors are briefly outlined.Comment: 11 pages, 5 figures. Contributed paper for the XXIII International Symposium on Lepton and Photon Interactions at High Energy, Lepton-Photon 2007, Aug 13-18 Daegu, Kore

Study of the radiative decay phi to a0(980) gamma with the KLOE detector

A sample of 1.25x10^9 phi decays, collected with the KLOE detector at the Frascati phi-factory DAFNE at center of mass energy ~ Mphi, has been used to study the radiative decay phi to eta pi0 gamma. This decay is dominated by phi to a0(980) gamma. Two decay chains, corresponding to eta to gamma gamma and eta to pi+ pi- pi0, have been selected. We found respectively: Br(phi to eta pi0 gamma)=(6.92 +/- 0.10 (stat.) +/- 0.20 (syst.))x10^(-5) and (7.19 +/- 0.17 (stat.) +/- 0.24 (syst.))x 10 ^(-5). The eta pi0 invariant mass distributions have been fitted to obtain the relevant a0(980) parameters.Comment: 9 pages, 7 figures, Contributed paper to Lepton Photon 200

Measurement of Gamma(Ks -> pi+pi-gamma)/Gamma(Ks -> pi0pi0)

We have measured the ratio R=Gamma(Ks -> pi+pi-gamma)/Gamma(Ks -> pi0pi0) with the KLOE detector at the DAFNE e+e- collider. This measurement is fully inclusive with respect to the pi+pi-gamma final state. The sample of over 10^6 two-pion decays of tagged Ks mesons allows a statistical error as low as 0.1% to be obtained. The accuracy is limited by systematic uncertainties, which are estimated primarily from data. We find R=2.236 +/- 0.003(stat) +/- 0.015(syst).Comment: 9 pages, 2 Encapsulated Postscript figures. Submitted to Phys. Lett.