A precise new KLOE measurement of ∣Fπ∣2|F_\pi|^2 with ISR events and determination of ππ\pi\pi contribution to aμa_\mu for 0.592<Mππ<0.9750.592 < M_{\pi\pi} < 0.975 GeV

The KLOE experiment at the DA$\Phi$NE $\phi$-factory has performed a new precise measurement of the pion form factor using Initial State Radiation events, with photons emitted at small polar angle. Results based on an integrated luminosity of 240 pb$^{-1}$ and extraction of the $\pi\pi$ contribution to $a_\mu$ in the mass range $0.35< M^2_{\pi\pi}<0.95$ GeV$^2$ are presented. The new value of $a^{\pi\pi}_\mu$ has smaller (30%) statistical and systematic error and is consistent with the KLOE published value (confirming the current disagreement between the standard model prediction for $a_\mu$ and the measured value).Comment: 5 pages, proceedings for the CIPANP 2009 conferenc

Incoherent pion photoproduction on the deuteron in the first resonance region

Incoherent pion photoproduction on the deuteron is studied in the first resonance region. The unpolarized cross section, the beam asymmetry, and the vector and tensor target asymmetries are calculated in the framework of a diagrammatic approach. Pole diagrams and one-loop diagrams with $NN$ scattering in the final state are taken into account. An elementary operator for pion photoproduction on the nucleon is taken in various on-shell forms and calculated using the SAID and MAID multipole analyses. Model dependence of the obtained results is discussed in some detail. A comparison with predictions of other works is given. Although a reasonable description of many available experimental data on the unpolarized total and differential cross sections and photon asymmetry has been achieved, in some cases a significant disagreement between the theory and experiment has been found. Invoking known information on the reactions $\gamma d\to\pi^0 d$ and $\gamma d\to np$ we predict the total photoabsorption cross section for deuterium. We find that our values strongly overestimate experimental data in the vicinity of the $\Delta$ peak.Comment: 22 pages, 23 figure

Quasifree pion photoproduction on the deuteron in the Δ\Delta region

Photo production of pions on the deuteron is studied in the spectator nucleon model. The Born terms of the elementary production amplitude are determined in pseudovector $\pi$N coupling and supplied with a form factor. The $\Delta$ resonance is considered both in the $s$ and the $u$ channel. The parameters of the $\Delta$ resonance and the cutoff of the form factors are fixed on the leading photoproduction multipoles. Results for total and differential cross sections are compared with experimental data. Particular attention is paid to the role of Pauli correlations of the final state nucleons in the quasifree case. The results are compared with those for pion photoproduction on the nucleon.Comment: 17 pages LateX2e including 5 postscript figure

Determination of CP and CPT violation parameters in the neutral kaon system using the Bell-Steinberger relation and data from the KLOE experiment

We present an improved determination of the CP and CPT violation parameters Re(epsilon) and Im(delta) based on the unitarity condition (Bell-Steinberger relation) and on recent results from the KLOE experiment. We find Re(epsilon) = (159.6 \pm 1.3)10^-5 and Im(delta) = (0.4 \pm 2.1)10^-5, consistent with no CPT violation.Comment: Submitted to JHE

Measurements of the Absolute Branching Ratios for the Dominant KL Decays, the KL Lifetime, and Vus with the KLOE Detector

From a sample of about 10^9 Phi mesons produced at DAFNE, we have selected KL mesons tagged by observing KS->pi+pi- decays. We present results on the major KL branching ratios, including those of the semileptonic decays needed for the determination of Vus. These branching ratio measurements are fully inclusive with respect to final-state radiation. The KL lifetime has also been measured.Comment: Submitted to Phys. Lett.

Charged kaon lifetime at KLOE

Preliminary result on the charged kaon lifetime, obtained by the KLOE experiment operating at DA$\Phi$NE, the Frascati $\phi$-factory, is presentedComment: 3 pages, 3 figures, to appear in the proceedings of 42nd Rencontres de Moriond on Electroweak Interactions and Unified Theories, La Thuile, Aosta Valley, Italy, 10-17 Mar 200

Measurement of the branching fraction for the decay KS --> pi e nu

We present a measurement of the branching ratio BR(KS --> pi e nu) performed using the KLOE detector. KS mesons are produced in the reaction e+ e- --> phi --> KS KL at the DAFNE collider. In a sample of about 5 million KS-tagged events we find 624 +- 30 semileptonic KS decays. Normalizing to the KS --> pi+ pi- count in the same data sample, we obtain BR(KS --> pi e nu) = (6.91 +- 0.37) 10^-4, in agreement with the Standard Model expectation.Comment: 9 pages, 5 Encapsulated Postscript figures. Submitted to Phys. Lett.