The measurement of the absolute branching ratio of the K+ to pi+ pi0 (gamma) decay at KLOE

The preliminary result on the absolute branching ratio of the decay K+ to pi+ pi0 (gamma), obtained by the KLOE experiment operating at the DAPHNE Frascati Phi-Factory, is presented.Comment: Contributed paper to Lepton-Photon 200

CP and CPT tests with the KLOE detector

Neutral kaons provide one of the most sensitive system to CP and CPT violation. Tests on CP, CPT and quantum mechanics have been performed at KLOE operating at the DAFNE e+e- collider. Results on the quantum interference in the channel phi-> KSKL ->pi+pi-pi+pi-, the measurement of the BR(KL ->pi+pi-) and the related CP violating parameter epsilon are presented. Using the Bell-Steinberger relation, CPT violating parameters have been also obtaine

Search for phi to K0 K0bar gamma decay with KLOE

The KLOE collaboration has searched for the phi to K0 K0bar gamma decay using a sample of 1.4 fb-1 of e+e- collisions at W ~ M(phi) collected with the KLOE experiment at the Frascati e+e- collider DAFNE. No previous search exists for this decay, while many theory models predict a BR of 10-8 for this channel. We set a preliminary value of the U.L. on this BR to 1.8x10-8 at 90% C.L.. This limit rules out most of the existing theory predictions.Comment: Contributed paper to Lepton Photon 200

Test of lepton flavor violation with Ke2 decay at KLOE

We present a precise measurement of the ratio R_K = \Gamma(Ke2(\gamma))/\Gamma(K\mu2(\gamma)) performed with the KLOE detector. The results are based on data collected at the Frascati e^+e^- collider DAFNE for an integrated luminosity of 2.2 fb^{-1}. We find R_K = (2.493\pm0.025_{stat}\pm0.019_{syst})\times 10^{-5}, in agreement with the Standard Model expectation. This result is used to improve constraints on parameters of the Minimal Supersymmetric Standard Model with lepton flavor violation.Comment: 6 pages, prepared for KAON09 Conference, Tsukuba 9-12 June 200

KLOE Results on Rare K0 Decays

This paper describes the current neutral Kaon dataset and physics measurements of KLOE at DAFNE. A brief discussion on the prospects for detector upgrades and analysis of other K0 rare decays is also included.Comment: Invited talk at the Workshop on e+e- in the 1-2 GeV range, Alghero, Italy, September 2003 (eConf C0309101). 4 pages, 8 figures, all source .tex/.aux/.log/.dvi/.ps/.eps/.pdf file

KLOE results on f0(980), a0(980) scalars and eta decays

The KLOE experiment running at the phi-factory DAPHNE has collected ~ 450 pb^(-1) in the 2001--2002 data taking. We report preliminary results on light meson spectroscopy based on this data sample; particles are all produced through phi radiative decays. The nature of f0(980) and a0(980) is investigated by studying the shape of the resulting mass spectra, which is sensitive to their structure. A detailed study of the eta --> pi pi pi dynamics through a Dalitz plot analysis gives the possibility to extract information on the quark mass difference. Finally, the branching ratio for the eta --> pi0 gamma gamma decay is compared with previous measurements and with the expectations from Chiral Perturbation Theory.Comment: 4 pages, 2 figures, proceedings of "Rencontres de Moriond 2005 - QCD and hadronic interactions

Measurements of the form-factors slopes of KL -> pi mu nu decay with the KLOE Detector

We present a measurement of the K-$\pi$ form-factor parameters for the decay \klpmn. We use 328 pb^{-1} of data collected in 2001 and 2002, corresponding to $\sim$ 1.8 million \semil events. Measurements of semileptonic form factors provide information about the dynamics of the strong interaction and are necessary for evaluation of the phase-space integral $I^\mu_K$ needed to measure the CKM matrix element $|V_{us}|$ for \klpmn decays and to test lepton universality in kaon decays. Using a new parameterization for the vector and scalar form factors we find $\lambda_+$=\pt(25.6\pm 0.4_{\rm{stat.}}\pm 0.3_{\rm{syst.}}),-3, and $\lambda_0$=\pt(14.3\pm 1.7_{\rm{stat.}}\pm 1.1_{\rm{stat.}}),-3,. In the more usual quadratic expansion of the form factor the above result is corresponds to $\lambda'_+=\lambda_+$, $\lambda''_+=2\lambda^2_+$, $\lambda'_0=\lambda_0$ and $\lambda''_0=(\lambda^2_0+0.000416)/2$. Our results, together with recent lattice calculations of $f_\pi$, $f_K$ and $f(0)$, satisfy the Callan-Trieman relation.Comment: 15 pages, 6 figures, Contributed paper to Lepton Photon 200

Recent results from KLOE

In this report I will present the recent results on K mesons from the KLOE experiment at the DAFNE e+e- collider working at the center of mass energy ~1GeV ~m_{phi}. They include V_{us} determinations, the test on the unitarity of the first row of the CKM matrix and the related experimental measurements. Tests of lepton universality from leptonic and semileptonic decays will be also discussed. Then I will present tests of quantum coherence, CPT and Lorentz symmetry performed by studying the time evolution of the neutral kaon system.Comment: To appear in the proceedings of 43nd Rencontres de Moriond on Electroweak Interactions and Unified Theories, La Thuile, Italy, 1-8 Mar 200

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

A Study of the Radiative KL->pi nu e (g) Decay and Possible Osservation of Direct Photon Emission with the KLOE Detector

We present the measurement of the ratio R = \frac{\Gamma(\keg;\Estar>30\mev,\qstar>20^\circ)}{\Gamma(\kegf)} and a first measurement of the direct emission contribution for the same process. We use 328 pb^{-1} of data collected at \kloe in 2001 and 2002, corresponding to about 3 million of \kegf events and about 9 thousand \keg radiative events. Our result is R= (924 \pm 23_{stat} \pm 16_{syst})10^{-5} for the branching ratio and X =-2.3\pm 1.3_{stat}\pm 1.4_{syst} for the parameter describing direct emission.Comment: 13 pages + 9 figures Contribute to Leptono Photon 200