Study of the a_0(980) meson via the radiative decay phi->eta pi^0 gamma with the KLOE detector

We have studied the phi->a_0(980) gamma process with the KLOE detector at the Frascati phi-factory DAPhNE by detecting the phi->eta pi^0 gamma decays in the final states with eta->gamma gamma and eta->pi^+ pi^- pi^0. We have measured the branching ratios for both final states: Br(phi->eta pi^0 gamma)=(7.01 +/- 0.10 +/- 0.20)x10^-5 and (7.12 +/- 0.13 +/- 0.22)x10^-5 respectively. We have also extracted the a_0(980) mass and its couplings to eta pi^0, K^+ K^-, and to the phi meson from the fit of the eta pi^0 invariant mass distributions using different phenomenological models.Comment: 17 pages, 6 figures, submitted to Physics Letters B. Corrected typos in eq.

Particle acoustic detection in gravitational wave aluminum resonant antennas

The results on cosmic rays detected by the gravitational antenna NAUTILUS have motivated an experiment (RAP) based on a suspended cylindrical bar, which is made of the same aluminum alloy as NAUTILUS and is exposed to a high energy electron beam. Mechanical vibrations originate from the local thermal expansion caused by warming up due to the energy lost by particles crossing the material. The aim of the experiment is to measure the amplitude of the fundamental longitudinal vibration at different temperatures. We report on the results obtained down to a temperature of about 4 K, which agree at the level of about 10% with the predictions of the model describing the underlying physical process.Comment: RAP experiment, 16 pages, 7 figure

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.

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

Determination of η→π+π−π0\eta\to\pi^+\pi^-\pi^0 Dalitz plot slopes and asymmetries with the KLOE detector

We have studied, with the KLOE detector at the DA$\Phi$NE $\Phi$-Factory, the dynamics of the decay $\eta\to\pi^+\pi^-\pi^0$ using $\eta$ mesons from the decay $\phi\to\eta\gamma$ for an integrated luminosity ${\mathcal L}$ = 450 pb$^{-1}$. From a fit to the Dalitz plot density distribution we obtain a precise measurement of the slope parameters. An alternative parametrization relates the $\pi^+\pi^-\pi^0$ slopes to that for $\eta\to 3\pi^0$ showing the consistency of KLOE results for both channels. We also obtain the best confirmation of the $C$-invariance in the $\eta\to\pi^+\pi^-\pi^0$ decay.Comment: 15 pages, 7 figure

Measurement of hadronic cross section and preliminary results on the pion form factor using the radiative return at DAPHNE

In the fixed energy environment of the $e^{+}e^{-}$ collider DA$\Phi$NE, KLOE can measure the cross section of the process $e^{+}e^{-} \to$ hadrons as a function of the hadronic system energy using the radiative return. At energies below 1 GeV, $e^{+}e^{-} \to \rho \to \pi^{+}\pi^{-}$ is the dominating hadronic process. We report here on the status of the analysis for the e^{+}e^{-} \to \ppg channel, which allows to obtain a preliminary measurement of the pion form factor using an integrated luminosity of $\sim73 pb^{-1}$.Comment: Invited talk at the Seventh International Workshop on Tau Lepton Physics (TAU02-WE07), Santa Cruz, Ca, USA, Sept 2002, 9 pages, LaTeX, 9 eps figure

Measurement of Gamma(phi -> eta' gamma)/Gamma(phi -> eta gamma) and the pseudoscalar mixing angle

We have measured the radiative decays phi -> eta gamma, phi ->etaprime gamma selecting pi+ pi- gamma gamma gamma final state in a sample of about 5 times 10^7 phi mesons produced at the Frascati phi factory DAFNE. We obtain Gamma(phi -> etaprime gamma)/Gamma(phi -> eta gamma)=(4.70 +- 0.47 +- 0.31) times 10^-3. From this result we derive new accurate values for the branching ratio BR(phi ->etaprime gamma) = (6.10 +- 0.61 +- 0.43) times 10^-5, and the mixing angle of pseudoscalar mesons in the flavour basis phi_P=(41.8 +1.9 -1.6) degrees.Comment: Submitted to Phys. Lett.

Measuring the hadronic cross section via radiative return

Recently it has been demonstrated that particle factories, such as DAPHNE and PEP-II, operating at fixed center-of-mass energies, are able to measure hadronic cross sections as a function of the hadronic system energy using the raditive return. This paper is an experimental overview of the progress in this aera. Preliminary results from KLOE for the process e+e- -> \rho \gamma -> \pi+\pi-\gamma and a fit to the pion form factor are presented. Some first results from the BABAR collaboration are also shown.Comment: Invited talk presented at RADCOR/Loops and Legs 2002, Kloster Banz/Germany, September 8-13 2002, 6 pages, 2 Figures; v1: references added, typos correcte