E. De Lucia

KLOE measurement of the charged kaon absolute semileptonic BR's

The KLOE Collaboration F. Ambrosino, A. Antonelli, M. Antonelli, F. Archilli, C. Bacci, P. Beltrame, G. Bencivenni, S. Bertolucci, C. Bini, C. Bloise, S. Bocchetta, V. Bocci, F. Bossi, P. Branchini, R. Caloi, P. Campana, G. Capon, T. Capussela, F. Ceradini, S. Chi, G. Chiefari, P. Ciambrone, E. De Lucia, A. De Santis, P. De Simone, G. De Zorzi, A. Denig, A. Di Domenico, C. Di Donato, S. Di Falco, B. Di Micco, A. Doria, M. Dreucci, G. Felici, A. Ferrari, M. L. Ferrer, G. Finocchiaro, S. Fiore, C. Forti, P. Franzini, C. Gatti, P. Gauzzi, S. Giovannella, E. Gorini, E. Graziani, M. Incagli, W. Kluge, V. Kulikov, F. Lacava, G. Lanfranchi, J. Lee-Franzini, D. Leone, M. Martini, P. Massarotti, W. Mei, L. Meola, S. Miscetti, M. Moulson, S. Müller, F. Murtas, M. Napolitano, F. Nguyen, M. Palutan, E. Pasqualucci, A. Passeri, V. Patera, F. Perfetto, M. Primavera, P. Santangelo, G. Saracino, B. Sciascia,A. Sciubba, F. Scuri, I. Sfiligoi, A. Sibidanov, T. Spadaro, M. Testa, L. Tortora, P. Valente, B. Valeriani, G. Venanzoni, R. Versaci, G. Xu Correspondig author: B. Sciascia LNF INFN, barbara.sciascia@lnf.infn.it

Light Meson Spectroscopy with KLOE

The KLOE experiment has collected an integrated luminosity of about 2.5 fb−1 at the φ factory DAφNE. φ radiative decays have been used to investigate the properties of the light scalar mesons f0(980)/a0(980), whose structure is still controversial.A direct search of σ(600)→π0π0 decay has been performed with data taken at 1 GeV, where φ decays are suppressed.The whole KLOE data set includes also 100 million η’s produced through the radiative decay φ→ηγ and tagged by means of the monochromatic recoil photon. From this sample we have investigated η decays relevant to test ChPT predictions. We present published and preliminary results achieved from full statistics.

Study of the

The KLOE experiment has concluded its data taking in March 2006, having acquired an integrated luminosity of 2.5 fb_1 of e+e- collisions at the center of mass energy around the o(1020) resonance. The complete data set includes a sample of 100 million ηs produced through the radiative decay o → ηγ and tagged by means of the monochromatic recoil photon. This huge amount of data allows to perform the first test of CP violation in η decays through the study of the rare η → π+π-e+e channel, measuring the asymmetry between the π+π- and the e+e- decay planes in the η rest frame (). Being this process flavor conserving, such an observation will point to unexpected mechanism of CP violation, thus providing an hint of new physics beyond the Standard Model. A study of the η→ π+π-e+e- decay based on a data sample of 1.7 fb_1 will be presented. Electrons and pions are identified using both the time of flight to the calorimeter and the momentum of each track. Cuts on track momenta and on photon conversion on the beam pipe allow to significantly reduce the background, with a final 20% contamination. The analysis efficiency for the signal is 8%, dominated by geometrical acceptance. The final sample of about 1600 signal events, 100 times larger than today best measurement, is used to measure both the η→ π+π-e+e-(γ) branching fraction and the asymmetry .

\eta \to \pi^+ \pi^- e^+ e^-

The KLOE experiment at the electron-positron collider DAΦNE has recently proven the feasibility of using initial state radiation (ISR) in e+e− annihilation for precision measurements of hadronic cross section. This new method, dubbed Radiative Return, allows us to measure hadronic cross sections for energies M2(hadron) < s at particle factories which operate at fixed centre-of-mass energy s. In the recently published KLOE measurement of the pion form factor, events had been collected where the ISR photon is emitted at small polar angles, which reduces the background from final state radiation (FSR) but leads to a suppression of the threshold region M2 ππ < 0.35 GeV2. We present here a complementary analysis using events with ISR photons emitted at large polar angles. Photon tagging is possible in this case (contrary to the small photon polar angle analysis) and the threshold region becomes accessible. Preliminary results are presented, as well as a measurement of the forward-backward asymmetry, which allows a test of the FSR model used for the description of the photon radiation from pions.

decay at KLOE

The KLOE experiment has finished its data taking at the e+e- collider DAΦNE in Frascati. KLOE has collected 2.5 fb-1 at the peak of the ϕ resonance, and 250 pb-1 at

Results with radiative events from KLOE

\sqrt{s}=1~{\rm GeV}

Latest results from KLOE at DAFNE

. The latest experimental results based on a sample of 450 pb-1 are presented in this paper: they mainly concern the neutral and charged kaon decays, and the radiative ϕ decays into scalar and pseudoscalar mesons.