We present recent results obtained by the KLOE-2 Collaboration at the DAPHNE e+e- collider. The first class of results concerns search for dark forces at the scale of 1 GeV in associated production of gamma and the U boson, in search for the Higgsstrahlung and in possible decays of phi into eta and U. The second is in neutral kaon physics, on testing the CPT and Lorentz invariance, and on search for quantum decoherence effects in entangled pairs of kaons. The third class of results concerns precision measurements in hadronic physics at low energy where transition form factors of phi to pseudoscalar mesons pi0 and eta are determined.
The KLOE experiment at DAPHNE has collected ~ 450 pb-1 of e+e- collisions at center of mass energy W~1.02 GeV. Preliminary results are presented for the most recent measurements: limit on the BR(Ks->3pi0), BR of the Ke3 decay of the Ks and determination of the hadronic cross section.
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 have measured the cross section sigma(e+e- \to pi+pi-gamma) as a function of the pi+pi- invariant mass, M_pipi, with the KLOE detector at DAPHNE (W=m_phi=1.02GeV). The photon in the above process is due to Initial State Radiation. Dividing by a theoretical radiator function we obtain the cross section sigma(e+e- \to pi+pi-) for the mass range 0.37<M_pipi^2<0.93GeV^2. We extract the pion form factor and the hadronic contribution to the muon anomaly, a_mu.
Recent results from the KLOE experiment at the DAPHNE e+e- collider are presented. KLOE has collected about 500 pb^-1 of data in the years from 2000 to 2002. Preliminary results are obtained using wide samples of the full statistics and include: the BR of the Ke3 decay of the K_S and the first measurement of its charge asymmetry, the ratio BR(K_S-->pi+pi-(gamma))/BR(K_S-->pi^0pi^0), the ratio BR(K_L-->gammagamma)/BR(K_L-->3pi^0), a detailed study of the decay phi-->pi+pi-pi^0, the ratio BR(phi-->eta' gamma)/BR(phi-->eta gamma) and the pseudoscalar mixing angle phi_P, the phi-->f_0 gamma and th…
The phi-factory DAPHNE offers a possibility to select pure kaon beams, charged and neutral ones. In particular, neutral kaons from phi->KS KL are produced in pairs and the detection of a KS (KL) tags the presence of a KL (KS). This allows to perform precise measurements of kaon properties by means of KLOE detector. Another advantage of a phi-factory consists in fact that the neutral kaon pairs are produced in a pure quantum state (J^(PC) = 1^(--)), which allowsto investigate CP and CPT symmetries via quantum interference effects, as well as the basic principles of quantum mechanics.A review of…
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…
Interferometry with neutral kaons at KLOE is reviewed. The preliminary results on phi->KS KL->pi+pi- pi+pi- and decoherence parameter are presented. The impact of C-even background and regenerators is shortly discussed and updated. Finally KLOE perspectives on interferometry at DAPHNE and expectations at a new higher luminosity phi-factory are briefly illustrated.
This paper is devoted to the first analyses based on the complete data sample collected by the KLOE detector at DAPHNE, the Frascati ϕ-factory. The result for the BR(K_S -> γγ) and the search for the decay K_S->e+e- are presented. Particular emphasis is put on the measurement of the ratio of Ke2 and Kmu2 BR's.
The existence of a light dark force mediator has been tested with the KLOE detector at DAPHNE. This particle, called U, is searched for using the decay chain phi-->etaU, eta-->pi+pi-pi0, U-->e+e-. No evidence is found in 1.5 fb-1 of data. The resulting exclusion plot covers the mass range 5<M_U<470 MeV, setting an upper limit on the ratio between the U boson coupling constant and the fine structure constant, alpha'/alpha, of <= 2x10^-5 at 90% C.L. for 50<M_U<420 MeV.
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.
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. 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 for the $e^{+}e^{-} \to \ppg$ channel, which allows to obtain a preliminary measurement of the pion form factor using an integrated luminosity of $\sim73 pb^{-1}$.
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 --> pi…
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 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.
At the Frascati phi-factory DAPHNE the pion formfactor is measured by means of the 'radiative return', i.e. by using events in which one of the collider electrons (positrons) has radiated an initial state radiation photon, lowering in such a way the invariant mass M_pipi of the two-pion-system. In a recent publication of the KLOE collaboration the initial state radiation photon had been required to be at small polar angles with respect to the beam axis. We are presenting results from a new and complementary analysis in which the photon is tagged at large polar angles. Only like this the thresh…
We have studied the vector to pseudoscalar conversion decay phi -> eta e+e-, with eta -> pi0pi0pi0, with the KLOE detector at DAPHNE. The data set of 1.7 fb-1 of e+e- collisions at sqrt(s)~Mphi contains a clear conversion decay signal of ~31,000 events from which we measured a value of BR(phi -> eta e+e-)=(1.075+-0.007+-0.038)x10-4. The same sample is used to determine the transition form factor by a fit to the e+e- invariant mass spectrum, obtaining b(phi eta) =(1.17 +- 0.10 + 0.07) GeV-2, that improves by a factor of five the precision of the previous measurement and is in good agreement wit…
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 new limit on the production of a light dark-force mediator with the KLOE detector at DAPHNE. This boson, called U, has been searched for in the decay phi --> eta U, U --> e+ e-, analyzing the decay eta --> pi0 pi0 pi0 in a data sample of 1.7 fb-1. No structures are observed in the e+e- invariant mass distribution over the background. This search is combined with a previous result obtained from the decay eta --> pi+ pi- pi0, increasing the sensitivity. We set an upper limit at 90% C.L. on the ratio between the U boson coupling constant and the fine structure constant of alpha'/alph…
Prospective presentation is given for the experimental program of the KLOE-2 Collaboration, to be performed using the DA$Φ$NE $e^+e^-$ collider upgraded in luminosity. Data with the total luminosity of 25 fb$^{-1}$ are aimed to be collected in 3 years. Major modifications of the accelerator and the spectrometer are described. The KLOE-2 physics program contains: CKM unitarity and lepton universality tests, $γγ$ physics, search for quantum decoherence and testing CPT conservation, low-energy QCD, rare kaon decays, physics of $η$ and $η^\prime$, structure of low-mass scalars, contribution of vac…
A possibility of KLOE-2 experiment to measure the width Gamma(pi0 to gamma gamma) and the (pi0 gamma gamma*) form factor F(Q^2) at low invariant masses of the virtual photon in the space-like region is considered. This measurement is an important test of the strong interaction dynamics at low energies. The feasibility is estimated on the basis of a Monte-Carlo simulation. The expected accuracy for Gamma(pi0 to gamma gamma) is at a per cent level, which is better than the current experimental world average and theory. The form factor will be measured for the first time at Q^2 less or equal 0.1 …
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 $γγ$…
Precise measurements of semileptonic kaon decay rates at KLOE provide the measurement of the CKM mixing matrix element \vus\ and information about lepton universality. Leptonic kaon decays provide an independent measurement of $\abs{\vus}^2/\abs{\vud}^2$, through the ratio $Γ(K\toμν)/Γ(π\toμν)$. These measurements, together with the result of $|\vud|$ from nuclear $β$ transitions, provide the most precise test of CKM unitarity, allowing the universality of lepton and quark weak couplings to be tested. After the completion of the KLOE data taking, the proposal of a new run with an upgraded KLOE…
Working at a $ϕ$-factory, KLOE/KLOE-2 has collected a very large and clean sample of $η$ decays, which allow to perform a variety of precision measurements. This report presents the recent results on the $η$-meson decays from KLOE/KLOE-2 experiments, including the search of the $C$-violating decay $η\rightarrowγγγ$, the determination of the $CP$ asymmetry in $η\rightarrowπ^+π^-e^+e^-$, the precision measurement of the $η\rightarrowπ^+π^-π^0$ Dalitz plot distribution, the search for the $CP$-violating decay $η\rightarrowπ^+π^-$ and the precision measurement of ${\cal O}(p^6)$ dominated decay $η…
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.
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.
KLOE, a new state of the art detector recently commissioned for physics operation at DAFNE, has many innovative interesting features, especially in the DAQ and Trigger areas. Custom electronics assert a trigger in a 2 microseconds decision time and distributes it to the FEE with a 50 ps time resolution. Data are read out using 10 front-end data acquisition chains and sent to a farm of online servers through a FDDI Gigaswitch. This design of the KLOE DAQ system allows us to manage an input data rate as high as 50 Mbyte/s, and is completely scalable by extending the number of computers connected…
The goal of the KLOE-2 experiment operating at the upgraded DAΦNE e+e-collider is to collect an integrated luminosity of about 20 fb-1 during 3-4 years of running. Measurements using the KLOE-2 apparatus equipped with the inner tracker, new scintillation calorimeters and tagging detectors for gamma-gamma physics will allow to refine and extend the KLOE program on kaon physics and tests of fundamental symmetries as well as the quantum interferometry. Here the latest results from KLOE data analysis and perspectives at KLOE-2 are presented.
The basic motivation of the KLOE-2 experiment is the test of fundamental symmetries and Quantum Mechanics coherence of the neutral kaon system, and the search for phenomena beyond the Standard Model in the hadronic and leptonic decays of ground-state mesons. Perspectives for experimentation by means of the KLOE-2 apparatus equipped with the inner tracker, new scintillation calorimeters, and the gamma-gamma taggers at the DA\$Phi$NE electron-positron collider upgraded in luminosity and energy are presented.
In this contribution we describe KNEDLE - the new event display for the KLOE-2 experiment. The basic objectives and software requirements are presented. The current status of the development is given along with a short discussion of the future plans.
This paper is a simple, quick guide to KLOE, the flagship experiment of INFN's Φfactory DAFNE at Frascati. KLOE's design principles, properties, its physics accomplishments and its impact on "flavor physics", are described in terms comprehensible to non specialists.
The KLOE-2 experiment at the INFN Laboratori Nazionali di Frascati (LNF) completed its data-taking at the $e^+ e^-$ DA$Φ$NE collider, which implements an innovative collision scheme based on a crab-waist configuration, and achieved the integrated luminosity of more than 5 fb$^-1$. KLOE-2 represents the continuation of KLOE with an upgraded detector and an extended physics program which includes, among the main topics, neutral kaon interferometry and test of discrete symmetries . Entangled neutral kaon pairs produced at DA$Φ$NE are a unique tool to test discrete symmetries and quantum coherence…
The KLOE experiment at DA$Φ$NE collected about 450 pb$^-1$ of data in 2001--2002. Much of this data set has been analyzed and has yielded definitive results on $K_S$ and radiative $ϕ$ decays, as well as studies concerning a wide range of topics in kaon and hadronic physics.
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.
The KLOE detector at the DA$Φ$NE $ϕ$-factory has been operating in two periods from 2001 to 2006 and from 2014 to 2018 collecting a large sample of $ϕ$-meson decays. This allowed to perform precision measurements and studies of fundamental symmetries, and searches of New Physics phenomena. In this overview, the results of KLOE and KLOE-2 Collaborations are presented. The most recent results from the KLOE experiment are discussed, covering: the measurement of the running fine-structure constant $α_{em}$, the Dalitz plot measurement of $η\rightarrow π^+π^-π^0$, the search of a U boson, tests of …
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 KLOE experiment operating at the $ϕ$--factory DA$Φ$NE has collected an integrated luminosity of about 2.5 fb$^{-1}$ and 250 pb$^{-1}$, on and off the $ϕ$ meson peak respectively. Recent results achieved from studying properties of pseudoscalar and scalar mesons are presented.
The most recent results from the KLOE experiment are presented, covering: the measurement of the running fine-structure constant alpha_em,the Dalitz plot measurement of eta to pi+pi-pi0, the search of a U boson, tests of discrete symmetries and quantum coherence. The KLOE-2 Collaboration will take data until mid 2018 aiming to collect 5 inversed fb increasing the data set, in order to produce new precision measurements and continue studies of fundamental symmetries and New Physics.
The KLOE experiment has been running since April 1999 at the DAFNE e+e- collider at a center of mass energy centered around the phi meson mass. The luminosity integrated up to September 2002 is about 500 pb-1 . Here we present the perspectives on the measurement of the V_{us} CKM-matrix element with the KLOE detector, using both charged and neutral kaon semileptonic decays.
The KLOE-2 detector records decays of quantum-entangled pairs of neutral kaons produced in decays of phi mesons provided by the DAFNE accelerator at the Laboratori Nazionali di Frascati, Italy. This system allows for a broad range of studies of fundamental discrete symmetries including tests which are only feasible with entangled neutral mesons. This work reports on the Lorentz non-invariance and CPT violation searches with the KSKL->pi+pi-pi+pi- process in the framework of the Standard Model Extension. Moreover, status and results of quantum coherence tests with the same process are discussed…
The broad physics program of the KLOE experiment is based on the high event rate at the Frascati phi factory, and calls for an up-to-date system for data acquisition and processing. In this review of the KLOE offline environment, the architecture of the data-processing system and the programs developed for data reconstruction and Monte Carlo simulation are described, as well as the various procedures used for data handling and transfer between the different components of the system.
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.
Recent results obtained by the KLOE experiment operating at DA$Φ$NE, the Frascati $ϕ$-factory, are presented. They mainly concern neutral kaon decays including the $K_L$ dominant branching ratios, the $K_L$ lifetime and the extraction of the $CKM$ parameter $V_{us}$ from the $K_L$ semileptonic decays and lifetime. The best world upper limit on $K_S \to \pppo$ channel is also presented
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.
Since april 1999, the KLOE experiment at DAFNE has collected about 200 inverse pb of data, produced in electron-positron collision at the c.m. energy of 1020 MeV, the mass of the phi meson. These data have been used for detailed studies on the phi radiative decays, as well as on rare K short decays. The first results, based on the 20 inverse pb collected in year 2000 are presented here
The KLOE experiment at the DA$Φ$NE $ϕ$-factory has performed a new precise measurement of the pion form factor using Initial State Radiation events. Results based on an integrated luminosity of 240 pb$^{-1}$ and extraction of the $ππ$ contribution to $a_μ$ in the mass range $0.35< M^2_{ππ}<0.95$ GeV$^2$ are presented. The new value of $a^{ππ}_μ$ has smaller statistical and systematic error and is consistent with the KLOE published value (confirming the current disagreement between the Standard Model prediction for $a_μ$ and the measured value).
DAFNE, the Frascati phi factory, has been in operation since 1999. At the center of the physics program is the KLOE experiment, a multipurpose detector with optimizations for tagged and interferometry-based measurements of the neutral kaon system. KLOE has been taking data since 2000 and has helped to explore a wide array of topics in kaon and hadronic physics, including a comprehensive set of measurements to determine the CKM matrix element |Vus|, and a measurement of the e+e- --> pi+pi- cross section for the determination of the hadronic contribution to the muon anomaly. In addition, the DEA…
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 experiment at the DA$Φ$NE $ϕ$-factory performed precise studies of charged and neutral kaon physics, low energy QCD, as well as tests of CP and CPT invariance. For the new run the KLOE has been upgraded by adding new tagger systems for the $γγ$ physics, the inner tracking chamber and two calorimeters in the final focusing region. We are also improving on kaon identification techniques, in particular algorithms for the $K_S$ meson tagging. In this article we discuss the impact of the improved tagging procedure on studies of the $K_S$ decays.
The KLOE Experiment at the $ϕ$ factory DA$Φ$NE, has measured the cross section $σ(e^+e^-\toπ^+π^-γ)$ using two different selection schemes: requiring the photon emission at small polar angle and detecting the photon at large polar angle in the calorimeter. Using a theoretical radiator function we extract the pion form factor and obtain the $ππ$ contribution to the anomalous magnetic moment of the muon. Results presented here come from the analysis of 240 pb^{-1} collected in 2002, with improved systematic uncertainty with respect to the published KLOE analysis. We also include an update of the…
The KLOE experiment at the upgraded DAFNE e+e- collider in Frascati (KLOE-2) is going to start a new data taking at the beginning of 2010 with its detector upgraded with a tagging system for the identification of gamma-gamma interactions. The tagging stations for low-energy e+e- will consist in two calorimeters The calorimeter used to detect low-energy e+e- will be placed between the beam-pipe outer support structure and the inner wall of the KLOE drift chamber. This calorimeter will be made of LYSO crystals readout by Silicon Photomultipliers, to achieve an energy resolution better than 8% at…
In order to fully reconstruct the gamma gamma processes (e+e- -> e+e- gamma gamma) in the energy region of the phi meson production, new detectors along the DAFNE beam line have been installed in order to detect the scattered e+e-.
A preliminary measurement of RK = Gamma(Ke2)/Gamma(Km2) at the KLOE experiment is discussed. The result, RK = (2.55+-0.05+-0.05)x 10^-5, is based on 1.7 fb^-1 of luminosity integrated on the phi-meson peak at the Frascati e^+e^- collider DAFNE, corresponding to ~8000 observed Ke2 events. Perspectives on the methods planned to improve both the statistical and the systematic errors are briefly outlined.
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.
Three new sub-detectors have been installed on May 2013 in the KLOE apparatus of Laboratori Nazionali di Frascati of INFN. Photon detection is improved by means of a small crystal calorimeter, named CCALT, in the very forward direction and of a tungsten-scintillating tile sampling device, named QCALT, instrumenting the low-beta quadrupoles of the accelerator. During the first DA$ϕ$NE operations, some preliminary runs, both with and without collisions, have been acquired allowing the commissioning of new subdetectors. In this paper, we report a brief description of QCALT and CCALT and a summary…
The KLOE experiment at the DA$Φ$NE $ϕ$-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 $ππ$ contribution to $a_μ$ in the mass range [0.35,0.95] GeV$^2$ are presented, the systematic uncertainty is reduced with respect to the published KLOE result.
In order to reconstruct gamma-gamma physics events tagged with High Energy Tagger (HET) in the KLOE-2 (K LOng Experiment 2), we need to measure the Time Of Flight (TOF) of the electrons and positrons from the KLOE-2 Interaction Point (IP) to our tagging stations (11 m apart). The required resolution must be better than the bunch spacing (2.7 ns). We have developed and implemented on a Xilinx Virtex-5 FPGA a Time to Digital Converter (TDC) with 625 ps resolution (LSB) along with an embedded data acquisition system and the interface to the online FARM of KLOE-2. We will describe briefly the arch…
The KLOE experiment has collected 2.4 1/pb of integrated luminosity during the commissioning of the DAFNE phi-factory in 1999. The performance of the detector has been studied using phi -> KL KS decays collected during this period, yielding also first measurements of relevant K parameters such as masses and lifetimes. A clean Kshort -> pi+ pi- sample is used to select Klong -> 2pi CP-violating decays and Klong -> Kshort regeneration events in the detector material. Results on the regeneration probability in beryllium-alluminum alloy and carbon-fiber plus aluminum composite are presented.
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.
The KLOE experiment at the DA$Φ$NE $ϕ$-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 $ππ$ contribution to $a_μ$ in the mass range $0.35< M^2_{ππ}<0.95$ GeV$^2$ are presented. The new value of $a^{ππ}_μ$ 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 $a_μ$ and the measured value).
