We present the current status of the analysis of about 1.7 billion KSKL pair events collected at DAFNE with the KLOE detector to determine the branching ratio of KS -> pi e nu decay and the lepton charge asymmetry. This sample is ~4 times larger in statistics than the one used in a previous KLOE analysis, allowing us to improve the accuracy of the measurement and of the related tests of CPT symmetry and Delta S = Delta Q rule.
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.
In a few months the KLOE-2 detector is expected to start data taking at the upgraded DA$\rmΦ$NE $ϕ$-factory of INFN Laboratori Nazionali di Frascati. It aims to collect 25 fb$^{-1}$ at the $ϕ(1020)$ peak, and about 5 fb$^{-1}$ in the energy region between 1 and 2.5 GeV. We review the status and physics program of the project
Recent KLOE measurements allowing the extraction of the Vus element of the CKM matrix are here briefly described. The status of the resulting value of Vus is summarized. The perspectives for the completion of ongoing analyses are discussed, with particular emphasis on the measurements of scalar form factor slopes from study of KLmu3 and of Vus from the decay width of K+-l3.
The absolute branching ratio of the $K^+ \rightarrow π^+π^-π^+(γ)$ decay, inclusive of final-state radiation, has been measured using $\sim$17 million tagged $K^+$ mesons collected with the KLOE detector at DA$Φ$NE, the Frascati $ϕ$-factory. The result is: \[ BR(K^+ \rightarrow π^+π^-π^+(γ)) = 0.05565 \pm 0.00031_{stat} \pm 0.00025_{syst} \] a factor $\simeq$ 5 more precise with respect to the previous result. This work completes the program of precision measurements of the dominant kaon branching ratios at KLOE.
We present the current status of the analysis of about 1.7 billion K_S K_L pair events collected at DAΦNE with the KLOE detector to determine the branching ratio of K_S -> πeν decay and the lepton charge asymmetry. This sample is ~4 times larger in statistics than the one used in the previous most precise result, from KLOE as well, allowing us to improve the accuracy on the measurement and related tests of CPT symmetry and Delta S = Delta Q rule.
We have searched with the KLOE detector for the P and CP violating decay eta -> pi^+pi^- in a sample of 1.55 x 10^7 eta's from the decay phi -> eta gamma of phi mesons produced in e+e- annihilations at DAFNE. No signal is found. We obtain the upper limit BR(eta -> pi^+pi^-) < 1.3 x 10^-5 at 90% confidence level.
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.
We have searched for the C-violating decay eta to gamma gamma gamma in a sample of ~ 18 million eta mesons produced in phi to eta gamma decays, collected with the KLOE detector at the Frascati phi-factory DAFNE. No signal is observed and we obtain the upper limit BR(eta to gamma gamma gamma) less equal than 1.6x10^(-5) at 90 % C.L.
The KLOE experiment at the Frascati phi-factory DAPHNE, designed to measure $\Re(ε^\prime/ε)$, began preliminary data taking in the Fall of 1999. A large database structure, which logs information coming from the DAPHNE control system and the KLOE slow control and data acquisition systems, has been developed. Data from detector monitoring, online event processing and machine operating conditions are easily accessible for online and offline analysis by means of Web tools and histogramming tools. The system allows powerful real-time data correlations which are necessary for the ongoing program o…
We present a measurement of the branching ratio of the CP violating decay KL->pi+pi- performed by the KLOE experiment at the phi factory DAFNE. We use 328 pb-1 of data collected in 2001 and 2002, corresponding to ~ 150 million tagged KL mesons. We find BR(KL->pi+pi-) = $(1.963 +/- 0.012 +/- 0.017)x 10^-3. This branching ratio measurement is fully inclusive of final-state radiation. Using the above result, we determine the modulus of the amplitude ratio |η_{+-}| to be (2.219 +/- 0.013)x 10^{-3} and |ε| to be (2.216 +/- 0.013)x 10^{-3}.
We have measured the fully inclusive K+ -> mu+nu(gamma) absolute branching ratio with the KLOE experiment at DAFNE, the Frascati Phi-factory. From some 865,283 K+ -> mu+nu(gamma) decays obtained from a sample of about 5.2x10^8 Phi-meson decays, we find BR(K+ -> mu+ nu (gamma)) = 0.6366 +-0.0009(stat.) +-0.0015(syst.), corresponding to an overall fractional error of 0.27%. Using recent lattice results on the decay constants of pseudoscalar mesons one can obtain an estimate for the CKM mixing matrix element |Vus|=0.2223+-0.0026.
A new measurement of the absolute branching ratio BR($K^\pm \to π^\pm π^0 π^0$) with the KLOE detector at the DA$Φ$NE $e^+e^-$ collider is presented, based on a sample of $\sim 3.3\times 10^7$ charged kaons tagged events, produced in the reaction $e^+e^-\toϕ\to K^+K^-$.The value BR($K^\pm \to π^\pm π^0 π^0$) $= (1.781\pm 0.013_{stat}\pm 0.016_{syst})%$ has been obtained.
The major goal of the KLOE experiment is to measure Re(epsilon' /epsilon) in the kkbar system, with a precision of 10^{-4},both via the traditional double ratio method and quantum interferometry. The experiment has started taking data at DAFNE, the phi-factory built at the Frascati National Laboratory (LNF) of INFN in Italy, beginning in April 1999. In the early phase of the commissioning (before KLOE roll-in), DAFNE has achieved multi bunch luminosities of 10^{31} cm^{-2} s^{-1} with 13 bunches and 200 mA. Detailed studies are presently underway to compensate for the large perturbation brough…
The neutral kaon system offers a unique possibility to perform fundamental tests of CPT invariance. In this contribution the KLOE prospects for the measurements of CPT violation in the context of the Standard Model Extension are presented together with a full description of the analysis method needed and with the perspective given by the KLOE-2 data-taking campaign.
Using a sample of over 600 million phi->K+K- decays collected at the Dafne e+e- collider, we have measured with the KLOE detector the absolute branching ratios for the charged kaon semileptonic decays, K+/- -> p0 e nu (gamma) (Ke3) and K+/- -> p0 mu nu (gamma) (Kmu3). The results, BR(Ke3) = 0.04965 +/- 0.00038_{stat} +/- 0.00037_{syst} and BR(Kmu3) = 0.03233 +/- 0.00029_{stat} +/- 0.00026_{syst}, are inclusive of radiation. Accounting for correlations, we derive the ratio Kmu3/Ke3 = 0.6511+/-0.0064. Using the semileptonic form factors measured in the same experiment, we obtain V_{us}f_{+}(0) =…
We have searched for the decay KS->gg in a sample of 2x10^9 phi->KS KL decays collected at DAPHNE with an integrated luminosity of 1.9 fb^{-1}. KS are tagged by the KL interaction in the calorimeter. Two prompt photons must also be detected. Kinematic constraints reduce the initial 6x10^5 events to 2740 candidates, from which a signal of 711\pm 35 events is extracted. By normalizing to the KS->2pi^0 decays counted in the same sample, we measure BR(KS->gg)= (2.26\pm0.12_{stat}\pm0.06_{syst})x10^{-6}, in agreement with O(p^4) Chiral Perturbation Theory predictions.
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.
We have analyzed 1.62 fb$^{-1}$ of $e^{+}e^{-}$ collisions at a center of mass energy $\sim M_ϕ$ collected by the KLOE experiment at DA$Φ$NE. This sample corresponds to a production of $\sim$ 1.7 billion of $\ks$ $\kl$ pairs which allowed us to search for the rare $K_S\to γγ$ decay. $K_S$ are tagged by the $K_L$ interaction in the calorimeter and the signal is searched for by requiring two additional prompt photons. Strong kinematic requirements reduce the initial 0.5$\times 10^6$ events to 2300 candidates from which we extract a signal of 600 $\pm$ 35 events. By normalizing to the $\ks \to 2 …
Among some 400 million KsKl pairs produced in e+e- annihilations at DAFNE, about 6500 each of Ks->pi+e-nubar and Ks->pi-e+nu decays have been observed with the KLOE detector. From these, the ratio G(Ks->pienu)/G(Ks->p+p-(g))=(10.19+-0.13)10-4 is obtained, improving the accuracy on BR(Ks->pienu) by a factor of four and providing the most precise test of the DeltaS=DeltaQ rule. From the partial width Gamma(Ks->pienu), a value for f+(K0)Vus is obtained that is in agreement with unitarity of the quark-mixing matrix. The lepton charge asymmetry AS=(1.5+-9.6stat+-2.9syst)10-3 is compatible with the …
Based on an integrated luminosity of 1.61 fb$^{-1}$ $e^+e^-$ collision data collected with the KLOE detector at DA$Φ$NE, the Frascati $ϕ$-factory, a search for the $P$- and $CP$-violating decay $η\toπ^{+}π^{-}$ has been performed. Radiative $ϕ\toηγ$ decay is exploited to access the $η$ mesons. No signal is observed in the $π^{+}π^{-}$ invariant mass spectrum, and the upper limit on the branching fraction at 90\% confidence level is determined to be ${\mathcal B}(η\toπ^{+}π^{-})<4.9\times10^{-6}$, which is approximately three times smaller than the previous KLOE result. From the combination of …
The status of the R&D on the Cylindrical-GEM (CGEM) detector foreseen as Inner Tracker for KLOE-2, the upgrade of the KLOE experiment at the DAFNE phi-factory, will be presented. The R&D includes several activities: i) the construction and complete characterization of the full-size CGEM prototype, equipped with 650 microns pitch 1-D longitudinal strips; ii) the study of the 2-D readout with XV patterned strips and operation in magnetic field (up to 1.5T), performed with small planar prototypes in a dedicated test at the H4-SPS beam facility; iii) the characterization of the single-mask GEM tec…
We have measured the absolute branching ratio of the K+ -> pi+ pi0 (gamma) decay, using about 20 million tagged K+ mesons collected with the KLOE detector at DAFNE, the Frascati phi-factory. Signal counts are obtained from the fit of the distribution of the momentum of the charged decay particle in the kaon rest frame. The result, inclusive of final-state radiation, is BR(K+ -> pi+ pi0 (gamma))=0.2065+/-0.0005_{stat}+/- 0.0008_{syst}.
We have measured the branching ratio BR(phi --> pi0 pi0 gamma) with the KLOE detector using a sample of ~5x10^7 phi decays. phi mesons are produced at DAFNE, the Frascati phi-factory. We find BR(phi --> pi0 pi0 gamma) = (1.09 +- 0.03 (stat) +- 0.05 (syst))x10^-4. We fit the two--pion mass spectrum to models to disentangle contributions from various sources.
We have studied the eta->pi+pi-e+e-(gamma) decay using about 1.7 fb^-1 collected by the KLOE experiment at the DAFNE phi-factory. This corresponds to about 72 millions eta mesons produced in phi radiative decays. We have measured the branching ratio, inclusive of radiative effects, with 4% accuracy: BR(eta->pi+pi-e+e-(gamma)) = (26.8 +/- 0.9_Stat. +/- 0.7_Syst.) x 10^-5. We have obtained the first measurement of the CP-odd pipi-ee decay planes angular asymmetry, A_phi = (-0.6 +/- 2.5_Stat. +/- 1.8_Syst.) x 10^-2.
The branching fraction for the decay $K_S \to πe ν$ has been measured with a sample of 300 million $K_S$ mesons produced in $ϕ\to K_L K_S$ decays recorded by the KLOE experiment at the DA$Φ$NE $e^+e^-$ collider. Signal decays are selected by a boosted decision tree built with kinematic variables and time-of-flight measurements. Data control samples of $K_L \to πe ν$ decays are used to evaluate signal selection efficiencies. A fit to the reconstructed electron mass distribution finds 49647$\pm$316 signal events. Normalising to the $K_S \to π^+π^-$ decay events the result for the branching fract…
In this paper we discuss the recent finalized analyses by the KLOE experiment at DA$Φ$NE: the CPT and Lorentz invariance test with entangled $K^0 \bar{K}^0$ pairs, and the precision measurement of the branching fraction of the decay ${ K^+} \rightarrow π^+π^-π^+(γ)$. We also present the status of an ongoing analysis aiming to precisely measure the $K^{\pm} $ mass.
The KLOE-2 experiment at the INFN Laboratori Nazionali di Frascati (LNF) is currently taking data at the upgraded $e^{+}e^{-}$ DAFNE collider. Present Run II follows a~development phase to assess the feasibility of a long term acquisition program, Run I, which successfully ended in July 2015 with 1 fb$^{-1}$ integrated luminosity collected in less than eight months. KLOE-2 represents the continuation of the KLOE experiment with a new physics program. The KLOE detector has undergone several upgrades including state-of-the-art cylindrical GEM Inner Tracker, electron-positron taggers for the $γγ$…
The paper presents status of three studies involving the $ω$ meson using data collected by the KLOE detector. The first two projects are feasibility studies performed on simulated data concerning an upper limit measure ment of BR($Φ\to ωγ$) and the form factor measurement in the $ω\toπ^0l^+l^-$ dalitz decay. The third study shows the effect $π^0 - π^0$ interference has in the $ω\toπ^+π^-π^0$ Dalitz plot when $ω$ is produced through the $e^+e^-\toωπ^0$ channel.
The KLOE detector at DAFNE, the Frascati phi-factory, has collected about 30 pb^-1 by the end of 2000, corresponding to about 90 millions of phi(1020) mesons produced. The five photon final state has been exploited to study the rare decays of phi into f0(980) photon and a0(980) photon, with statistical accuracy never reached before. The preliminary results for these branching ratios, from a data sample of 17 pb^-1, are the following: BR(phi-->f0(980) photon)=(23.7 +- 0.6 (stat.) times 10^-5, BR(phi--> a0(980) photon)=(5.8 +- 0.5 (stat.)) times 10^-5. The systematic error is expected to be less…
The $K_S \to 3 π^0$ decay is a pure CP violating process which, assuming CPT invariance, allows one to investigate direct CP violation. This decay has not been observed so far, and the best upper limit on the branching ratio $BR(K_S to 3π^0) < 1.2 \cdot 10^{-7}$ is two orders of magnitude larger than predictions based on the Standard Model: $BR(K_S \to 3π^0) \sim 2 \cdot 10^{-9}$. In this article we present the search for the $K_S \to 3π^0$ decay performed with the KLOE detector operating at the DAFNE Φ-factory at the Frascati Laboratory. We describe the analysis techniques used in the backgro…
Study of semileptonic decays of neutral kaons allows to perform a test of discrete symmetries, as well as basic principles of the Standard Model. In this paper a general review on dependency between charge asymmetry constructed for semileptonic decays of short- and long-lived kaons and CPT symmetry is given. The current status of determination of charge asymmetry for short-lived kaon, obtained by reconstruction of about 10^5 KS -> pen decays collected at DAFNE with the KLOE detector is also reviewed.
We have searched for the decay Ks->3p^0 with the KLOE experiment at DAFNE using data from e^+ e^- collisions at a center of mass energy W= m(phi) for an integrated luminosity L=450 pb^-1. The search has been performed with a pure Ks beam obtained by tagging with Kl interactions in the calorimeter and detecting six photons. We find an upper limit for the branching ratio of 1.2x10^-7 at 90% C.L.
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_ϕ= 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.
We describe the status of the analyses in progress on light meson spectroscopy in the KLOE experiment. We present the analyses of phi decays into f0(980)gamma and a0(980)gamma, the Dalitz plot analysis of the eta to pie+ pie- pie0 decay, the branching ratio measurement of eta to pie0 gamma gamma, the upper limits on Br(eta to 3 gamma) and Br(eta to pie^+ pie^-), the measurement of the ratio Br(phi to eta' gamma)/Br(phi to eta gamma) and phi leptonic width measurements.
Kaon decay studies seeking new-physics (NP) effects in leptonic (K_l2) or semileptonic (K_l3) decays are discussed. A unitarity test of the first row of the CKM mixing matrix is obtained from the KLOE precision measurements of Kl3 widths for K^+-, K_L, and (unique to KLOE) K_S, complemented with the absolute branching ratio for the K_mu2 decay. KLOE results lead to constraints for NP models and can probe possible charged Higgs exchange contribution in SM extensions with two Higgs doublets. The main focus in the present document is set on a new measurement of R_K=Gamma(K_e2)/Gamma(K_mu2) with a…
A short review of two measurements recently published by KLOE/KLOE-2 collaborations is presented. Namely the most stringent limits of the CPT-violating parameters Delta a_mu for neutral kaons, and the absolute branching ratio of K+ --> pi+pi-pi+(gamma) decay. In addition a discussion of starting KLOE-2 project is performed.
We present the measurement of the ratio R = \frac{Γ(\keg;\Estar>30\mev,\qstar>20^\circ)}{Γ(\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.
In the fixed energy environment of the $e^{+}e^{-}$ collider DA$Φ$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 method. At energies below 1 GeV, $e^{+}e^{-} \to ρ\to π^{+}π^{-}$ is the dominating hadronic process. We report here on the status of the analysis of the process $e^{+}e^{-} \to π^{+}π^{-}γ$. Some preliminary results on the invariant mass spectrum of the two pion system, obtained from the analysis of 22.6 pb$^{-1}$, are presented.
We present a measurement of the ratio R = Γ(\keg;\Estar>30\mev,\qstar>20^\circ)$/$Γ(\kegf)$ and a first measurement of the direct emission contribution in KL semileptonic decays. The measurement is done at the DAFNE phi-factory selecting phi->KL KS decays with the KLOE detector. We use 328 pb^{-1}$ of data corresponding to about 3.5 million Ke3(g) events and about 9000 radiative events. Our result is R=(924 +/- 23(stat) +/-16(syst)10^{-5} for the branching ratio and X=-2.3 +/- 1.3(stat) +/- 1.4(syst) for the parameter describing direct emission.
This paper is devoted to the measurement of the fully inclusive absolute branching ratios of the charged kaon semileptonic decays, $K^{\pm}\toπ^0e^\pmν(γ)$ and $K^\pm \to π^0μ^\pmν(γ)$. The measurements have been done using a tag technique, employing the two-body decays, $K^\pm \to μ^\pmν$ and $K^\pm \to π^\pmπ^0$, 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 $ϕ$-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…
We report on the measurement of the hadronic cross section below 1GeV at the electron-positron-collider DAPHNE, using the multiple purpose detector KLOE. The radiative return, which is due to initial state radiation (e+ e- \to gamma + hadrons), allows us to obtain the cross section for variable center-of-mass-energies of the hadronic system from the 2m_pi threshold up to 1.02GeV. This measurement can be performed while DAPHNE is running with a fixed accelerator energy on the phi mass (1.02 GeV). For the exclusive process e+ e- \to pi+ pi- gamma, the status of the analysis and first preliminary…
The most precise determination of Vus comes from semileptonic kaon decays. We have measured with the KLOE detector at DAFNE, the Frascati phi-factory, all the experimental inputs to Vus for both neutral and charged kaons. Using our results we extract the value of Vus with about 0.9% fractional error, which is entirely dominated by the theoretical error on the knowledge of the normalization of the decay form factors, f0. A new determination of the ratio Vus/Vud is also presented, based on our precise measurement of the absolute branching ratio for the decay K+ -> mu+nu, combined with recent lat…
We have measured the ratio R=Gamma(K_L -> gamma gamma)/ Γ(K_L -> 3 pi^0) using the KLOE detector. From a sample of ~ 10^9 phi-mesons produced at DAFNE, the Frascati phi-factory, we select ~ 1.6 10^8 K_L-mesons tagged by observing K_S -> pi^+ pi^- following the reaction e^+ e^- -> phi -> K_L K_S. From this sample we select 27,375 K_L -> gamma gamma events and obtain R = (2.79 \pm 0.02_{stat} \pm 0.02_{syst}) \times 10^{-3}. Using the world average value for BR(K_{L} -> 3 pi^0), we obtain BR(K_{L} -> gamma gamma) = (5.89 \pm 0.07 \pm 0.08) \times 10^{-4} where the second error is due to the unce…
The precision measurement of the $dσ(e^+e^- \rightarrow μ^+μ^- γ)/d\sqrt{s}$ cross section with the photon emitted in the initial state with the KLOE detector has been used to measure the running of the QED coupling constant $α(s)$ in the energy range 0.6 $< \sqrt{s} <$ 0.975 GeV in the time-like region. We were able to achieve a significance of the hadronic contribution to the running of $α(s)$ of more than 5$σ$ with a clear contribution of the $ρ- ω$ resonances to the photon propagator. The real and imaginary part of the shift $Δα$ to the running has been estracted and a fit of the real part…
The most precise determination of Vus comes from semileptonic kaon decays. We have measured with the KLOE detector at DAFNE, the Frascati phi-factory, all the experimental inputs to Vus for both neutral and charged kaons. Using our results we extract the value of Vus with ~0.9% fractional error, which is dominated by the theoretical error on the form factor, f+(0). A new determination of the ratio Vus/Vud is also presented, based on our precise measurement of the absolute branching ratio for the decay K -> mu nu (gamma), combined with lattice results for the ratio f_K/f_pi. New results on CPT …
Based on a sample of 300 million $K_S$ mesons produced in $ϕ\to K_L K_S$ decays recorded by the KLOE experiment at the DA$Φ$NE $e^+e^-$ collider we have measured the branching fraction for the decay $K_S \to πμν$. The $K_S$ mesons are identified by the interaction of $K_L$ mesons in the detector. The $K_S \to πμν$ decays are selected by a boosted decision tree built with kinematic variables and by a time-of-flight measurement. Signal efficiencies are evaluated with data control samples of $K_L \to πμν$ decays. A fit to the reconstructed muon mass distribution finds $7223 \pm 180$ signal events…
The most precise determination of Vus comes from semileptonic kaon decays. The KLOE experiment at DA\PhiNE the Frascati ϕ-factory, has measured all the exeperimental inputs to Vus for both neutral and charged kaons. Preliminary results for BR(K^\pm\toπ^0 e^\pmν) and BR(K^\pm\toπ^0 μ^\pmν), and for τ_\pm are presented, together with measurements of the K_Le3 and K_L\mu3 decay BR, the K_Se3 decay BR and the K_L lifetime τ_L. From our results for the 5 braching ratios and τ_L we find Vus=0.2258\pm0.0022. We have also measured the fully inclusive K^+\mu2(γ) absolute branching ratio for which we ob…
The aim of this work was to determine the KS -> 3pi0 decay branching ratio and a modulus of the eta000 parameter, defined as the ratio of amplitudes for KS -> 3 pi0 to KL -> 3pi0 decays, which characterizes the CP symmetry violation in this decay. The measurement has been carried out with the KLOE detector operating at the phi-factory DAFNE in the Italian National Center for Nuclear Physics in Frascati. The KS mesons were identified with high efficiency via registration of these KL mesons which crossed the drift chamber without decaying and then interacted with the KLOE electromagnetic calorim…
We have studied the e+e- -> omegapi0 cross section in the sqrt(s) interval 1000-1030 MeV using the pi+pi-pi0pi0 and pi0pi0gamma final states with a sample of ~600 pb^-1 collected with the KLOE detector at DAFNE. By fitting the observed interference pattern around M_phi for both final states, we extract the ratio of the decay widths Gamma(omega->pi0gamma)/Gamma(omega->pi+pi-pi0) = 0.0897 +- 0.0016 and derive the branching fractions BR(omega -> pi+pi-pi0)= (90.24 +- 0.19)%, BR(omega -> pi0gamma) = (8.09 +- 0.14)%. The parameters describing the e+e- -> omegapi0 reaction around M_ϕare also used to…
The DAFNE collider, located in the Frascati National Laboratories of INFN, has two main rings, where electrons and positrons are stored to collide at a center of mass energy of 1.02 GeV, the phi resonance mass. KLOE-2 experiment is located at the collider interaction region. The detector is capable to observe and collect data coming from phi decay: charged and neutral kaon pairs, lighter unflavored mesons (eta, eta', f0, a0, omega/rho). In the first half of 2013 the KLOE detector has been upgraded inserting new detector layers in the inner part of the apparatus, around the interaction region i…
We present a new search for the $K_S \to 3π^0$ decay performed with the KLOE detector operating at the DA$Φ$NE $ϕ$--factory. The $K_S$ mesons were tagged via registration of $K_L$ mesons which crossed the drift chamber without decaying and interacted with the KLOE electromagnetic calorimeter. The $K_S \to 3π^0$ decay was then searched requiring six prompt photons. To suppress background, originating from fake $K_S$ tags and $K_S \to 2π^0$ decays with additional two spurious clusters, we have performed a discriminant analysis based on kinematical fit, testing of the signal and background hypoth…
KLOE has measured most decay branching ratios of Ks, Kl and K+/- mesons. It has also measured the Kl and the K+- lifetime and determined the shape of the form factors involved in kaon semileptonic decays. We present in the following a description of the above measurements and a well organized compendium of all of our data, with particular attention to correlations. These data provide the basis for the determination of the CKM parameter Vus and a test of the unitarity of the quark flavor mixing matrix. We also test lepton universality and place bounds on new physics using measurements of Vus fr…
The branching fraction for the decay $K^{-} \to π^{0} e \bar ν$ is measured using in-flight decays detected with {\bf ISTRA+} setup working at the 25 GeV negative secondary beam of the U-70 PS:\linebreak $Br_{K_{e3}}= (5.124 \pm 0.009 (stat) \pm 0.029(norm) \pm 0.030(syst))%$. From this value the $|V_{us}|$ element of the CKM matrix is extracted, using previously measured $f_{+}(t)$ form factor: $|V_{us}|=0.227 \pm 0.002$. The results are in agreement with recent measurements by BNL E865, FNAL KTeV, KLOE.
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.
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.
Using ~600 pb-1 collected with the KLOE detector at DAPhiNE, we have studied the production cross section of pi+ pi- pi0 pi0 and p0p0 gamma final states in e+e- collisions at center of mass energies between 1000 and 1030 MeV. By fitting the observed interference pattern around Mphi for both final states, we extract a measurement (preliminary) for the ratio Gamma(omega -> pi0 gamma)/Gamma(omega -> pi+ pi- pi0) = 0.0934 +- 0.0022. Since these two final states represent the 98% of the omega decay channels, we use unitarity to derive BR(omega -> pi+pi-pi0)= (89.94 +- 0.23)% and BR(omega -> pi0 gam…
The aim of Tau subgroup of the HFAG is to provide average values of the mass and branching fractions of the tau lepton. Using the branching fractions, we present tests of charged current lepton universality and obtain estimates for |Vus|. We also summarize the status of searches for lepton flavor violating decays of the tau lepton.
