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 KLOE Collaboration completed the full data taking on March 2006, acquiring 2.5 fb ^ -1 at the peak of the ϕand other 240 pb ^ -1 off-peak. A new Collaboration is working on a new project, called KLOE-2, to refine and extend the KLOE physics program. We present here some preliminary and published results from the KLOE Collaboration on the pseudoscalar ηmeson and the study of γγprocesses, that are among the main points of the KLOE-2 physics program.
We describe the KLOE detector at DAFNE, and its physics program. The impact of our results on flavor and hadron physics to date, as well as an outlook for further improvement in the near future, are discussed.
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.
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…
Kaon physics can test new-physics effects in leptonic or semileptonic decays. A unitarity test of the first row of the CKM mixing matrix is obtained from the precision measurements of Kl3 widths for K{\pm}, KL, and (unique to KLOE) KS. The KLOE measurement of RK = Γ(Ke2)/Γ(Kμ2) with an accuracy at the % level, aims at finding evidence of deviations from the SM prediction induced by lepton-flavor violation new-physics effects.
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…
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-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 $γγ$…
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.
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 results on the measurement of the transition form factors of the eta and pi0 mesons in phi Dalitz decays are presented, and the determination of the Gamma(eta->gamma gamma) in gamma gamma processes is also reported. The prospects for gamma gamma physics of the new data-taking, started in November 2014 with the upgraded detector, are reviewed.
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…
All relevant inputs for the extraction of the CKM matrix element \vus from \kl, \ks and \kpm decays have been measured at KLOE. From a global fit using only KLOE results, but \ks lifetime, a value of $|\vus|\fzero = 0.2157 \pm 0.0006$ is obtained, where \fzero is the form factor parametrizing the hadronic matrix element evaluated at zero momentum transfer. Comparison of the values of \fVus for $K_{e3}$ and $K_{\mu3}$ modes provides a test of lepton universality at 0.8% level of accuracy. The value $\vus/\vud=0.2323(15)$ has been obtained from the ratio $Γ(K\toμν)/Γ(π\toμν)$ using KLOE measurem…
Physics at DAFNE, the new Frascati e+e- machine, is reviewed, as well as the esperiments: DEAR - search for KN exotic atoms, FINUDA - spectroscopy and decays of hypernuclei, and KLOE - a multipurpose detector designed for measuring direct CP violation in the K system.
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.
The KLOE detector at DAFNE, the Frascati Phi-factory, has collected about 8 millions phi decays in 1999. Measurements of Phi decays into pi0, eta, eta', f0(980), a0(980) and pi+pi-pi0 have been performed with statistical accuracy better than previously in a single detector, as well as new decay modes. Phi radiative decays can clarify the nature of f0 and a0 (are they 4 quark states?) and measure the eta-eta' mixing angle. Analysis of Phi->pi+pi-pi0 allows us to extract the possible existence of direct decay in addition to the dominant rho-pi mode and to obtain a precise measurement of the rho …
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.
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…
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 at the Frascati $ϕ$-factory DA$Φ$NE has collected about 0.5 fb$^{-1}$ of data till the end of the year 2002. These data allow to perform a wide physics program, ranging from the physics of charged and neutral kaons to radiative $ϕ$-decays. Results are presented for the $K_L$ lifetime and the semileptonic processes $K_{S,L} \to πe ν$. From the light meson spectroscopy program, results on the decays $ϕ\to f_0(980)γ, a_0(980)γ$ as well as $ϕ\to ηγ, η' γ$ are presented.
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…
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…
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…
One of the basic motivations of the KLOE and KLOE-2 collaborations is the test of fundamental symmetries and the search for phenomena beyond the Standard Model via the hadronic and leptonic decays of ground-state mesons and via their production in the fusion of virtual gamma quanta exchanged between colliding electrons and positrons. This contribution includes brief description of results of recent analysis of the KLOE data aimed at (i) the search for the dark matter boson, (ii) determination of the hadronic and light-by-light contributions to the g-2 muon anomaly and (iii) tests of QCD anomal…
Here we present KLOE results on the phi meson decays in pi0 pi0 gamma, pi+ pi- gamma and eta pi0 gamma, the measurement of the ratio Br(phi to eta' gamma)/Br(phi to eta gamma) with the estimate of the eta' gluonium content and the measurement of the eta mass.
The processes $e^+e^-\to e^+e^-X$, with $X$ being either the $η$ meson or $π^0π^0$, are studied at DA$Φ$NE, with $e^+e^-$ beams colliding at $\sqrt{s}\simeq1$ GeV, below the $ϕ$ resonance peak. The data sample is from an integrated luminosity of 240 pb$^{-1}$, collected by the KLOE experiment without tagging of the outgoing $e^+e^-$. Preliminary results are presented on the observation of the $γγ\toη$ process, with both $η\toπ^+π^-π^0$ and $η\toπ^0π^0π^0$ channels, and the evidence for $γγ\toπ^0π^0$ production at low $π^0π^0$ invariant mass.
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 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 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 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 pseudos…
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…
I review some of the highlights of results from non-hadron collider flavor experiments shown at the EPS conference in the summer of 2009. These include highlights of the latest results from the BaBar and Belle B-factories, CLEO-c, BES-III, NA48, KTeV, KLOE, NA62, MEG, and mu to e conversion experiments.
In order to fully reconstruct to the reaction e+e- to e+e- gamma-gamma in the energy region of the phi meson production, new detectors along the DAFNE beam line have to be installed in order to detect the scattered e+e-. The High Energy Tagger (HET) detector measures the deviation of leptons from their main orbit by determining their position and timing so to tag gamma-gamma physics events and disentangle them from background. The HET detectors are placed at the exit of the DAFNE dipole magnets, 11 m away from the IP, both on positron and electron lines. The HET sensitive area is made up of a …
The 4.2$σ$ discrepancy between the standard model prediction for the muon anomalous magnetic moment $a_μ$ and the experimental result is accompanied by other anomalies. A crucial input for the prediction is the hadronic vacuum polarization $a_μ^{\rm HVP}$ inferred from $σ_{\rm had} =σ(e^+e^- \to\,$hadrons) data. However, the two most accurate determinations of $σ_{\rm had}$ from KLOE and BaBar disagree by almost 3$\,σ$. Additionally, the combined data-driven result disagrees with the most precise lattice determination of $a_μ^{\rm HVP}$ by $2.1\,σ$. We show that all these discrepancies could b…
Investigation at a $ϕ$--factory can shed light on several debated issues in particle physics. We discuss: i) recent theoretical development and experimental progress in kaon physics relevant for the Standard Model tests in the flavor sector, ii) the sensitivity we can reach in probing CPT and Quantum Mechanics from time evolution of entangled kaon states, iii) the interest for improving on the present measurements of non-leptonic and radiative decays of kaons and eta/eta$^\prime$ mesons, iv) the contribution to understand the nature of light scalar mesons, and v) the opportunity to search for …
Time to Digital Converters (TDCs) are very common devices in particles physics experiments. A lot of "off-the-shelf" TDCs can be employed but the necessity of a custom DAta acQuisition (DAQ) system makes the TDCs implemented on the Field-Programmable Gate Arrays (FPGAs) desirable. Most of the architectures developed so far are based on the tapped delay lines with precision down to 10 ps, obtained with high FPGA resources usage and non-linearity issues to be managed. Often such precision is not necessary; in this case TDC architectures with low resources occupancy are preferable allowing the im…
The original plan of a vigorous program of frontier physics at LNF, based on the phi-factory DAFNE with the KLOE detector, has not yet reached its major aim in the study of discrete symmetries in the neutral kaon system. It has however led to the education of a new generation of particle and accelerator physicists. With such invaluable human resources it seems appropriate to consider a renewed effort in achieving much improved collider performance. It will be argued in the following that it is still possible to envision a program of superior quality physics, requiring several years and broad e…
Recent measurements of kaon decays provide new information about CKM unitarity, lepton universality, and discrete symmetries. KLOE-2, the proposed extension of the kaon physics program at Frascati, will extend the world data set on kaon decays and conduct interference measurements with neutral kaons. Meanwhile, the decays K \to πν\barν can be directly related to the CKM matrix elements with minimal theoretical uncertainty, and are the focus of a series of experiments. Several events of K+ \to π+ν\barν have been observed to date; the goal of the NA62 experiment at CERN is to perform an O(100)-e…
This document reviews the physics program of the KLOE-2 detector at DA$Φ$NE upgraded in energy and provides a simple solution to run the collider above the $ϕ$-peak (up to 2, possibly 2.5 GeV). It is shown how a precise measurement of the multihadronic cross section in the energy region up to 2 (possibly 2.5) GeV would have a major impact on the tests of the Standard Model through a precise determination of the anomalous magnetic moment of the muon and the effective fine-structure constant at the $M_Z$ scale. With a luminosity of about $10^{32}$cm$^{-2}$s$^{-1}$, DA$Φ$NE upgraded in energy can…
An overview of selected topics in DO B-Physics is presented, covering relevant detector characteristics, and with emphasis on the most recent results in the Bs, FCNC and rare decay programs.
Selected results from tau analyses performed using the BaBar detector at the SLAC National Accelerator Laboratory are presented. A precise measurement of the tau mass and the tau{+} tau{-} mass difference is undertaken using the hadronic decay mode tau- --> pi+ pi- pi- nu. In addition an investigation into the strange decay modes tau- --> K0S pi- pi0 nu and tau- --> K0S pi- nu is also presented, including a fit to the tau- --> K0S pi-nu invariant mass spectrum. Precise values for the Mass and Width of the K*(892) are obtained.
We report studies in polarization in B decay into two vector mesons with data equivalent to $253 {\rm fb^{-1}}$ on $Υ(4S)$ resonance at KEKB. In $B^0 \to ϕK^{*0}$, $B^+ \to ϕK^{*+}$ and $B^+ \to ρ^+ K^{*0}$ decays, we determine $f_L = 0.45 \pm 0.05({\rm stat.}) \pm 0.02({\rm syst.})$, $f_L = 0.52 \pm 0.08({\rm stat.}) \pm 0.03({\rm syst.})$ and $f_L = 0.43 \pm 0.11({\rm stat.}) ^{+ 0.05}_{-0.02}({\rm syst.})$ respectively, where $f_L$ is a ratio between longitudinal and transverse polarization, and a naïve theoretical estimation assumes $f_L \sim 1$. The discrepancy from 1 in $f_L$ may suggest…
Ultra-peripheral collisions of relativistic heavy ions involve long-ranged electromagnetic interactions at impact parameters too large for hadronic interactions to occur. The nuclear charges are large; with the coherent enhancement, the cross sections are also large. Many types of photonuclear and purely electromagnetic interactions are possible. We present here an introduction to ultra-peripheral collisions, and present four of the most compelling physics topics. This note developed from a discussion at a workshop on ``Electromagnetic Probes of Fundamental Physics,'' in Erice, Italy, Oct. 16-…
This report summarizes the findings of the AF5 Topical Subgroup to Snowmass 2021, which investigated accelerators for rare processes and physics beyond colliders. The report focuses primarily on opportunities for dark sector searches and the need for coordinated development of the Fermilab experimental program for PIP-II and beyond. In addition, a number of other physics opportunities are cataloged and suggestions for synergistic R & D opportunities with various areas of technological development are discussed.
The B Factories have generated a large amount of new results on the tau lepton. The present status of some selected topics on tau physics is presented: charged-current universality tests, bounds on lepton-flavour violation, the determination of alpha_s from the inclusive tau hadronic width, and the measurement of |V_{us}| through the Cabibbo-suppressed decays of the tau lepton.
After an introduction on the peculiarities of flavor-physics measurements at a hadron collider, and on the upgraded Collider Detector at Fermilab (CDF II), I show recent results on two-body B0 and B0s decays into charged, pseudo-scalar, charmless mesons or into muons, to illustrate how the flavor physics program at CDF is competitive with (in B0 decays) and complementary (in B0s decays) to B-factories. Results shown include the new measurement of the CP-violating asymmetry in B0-->K+pi- decays, the first measurement of the time-evolution of B0s-->K+K- decays, and the world best limits on the d…
These lecture notes review the theoretical background to the Higgs boson, provide an introduction to its phenomenology, and describe the experimental tests that lead us to think that "beyond any reasonable doubt, it is a Higgs boson". Motivations for expecting new physics beyond the Standard Model are recalled, and the Standard Model effective field theory is advocated as a tool to help search for it. The phenomenology of $N = 1$ and $N = 2$ supersymmetric Higgs bosons is reviewed, and the prospects for possible future Higgs factories are previewed.
We review the status of flavour physics in spring 2014. The numerous accurate new measurements of flavour experiments have enabled us to test our theoretical understanding of flavour processes with an unprecedented precision. At first sight the dominant amount of measurements seems to be standard model like. Having a closer look one finds, however, that in most of the observables there is still some considerable space for new effects. In addition many discrepancies are still not settled yet. For further investigations and definite conclusions an improvement of the theoretical precision as well…
We have just entered a new round in the testing of the flavour sector of the Standard Model through high-precision measurements of B-meson decays. A particularly exciting aspect is the exploration of the B_s-meson system at LHCb. We focus on two particularly promising probes of new physics which may give us first solid evidence for New Physics at the LHC: the strongly suppressed rare decay B_s^0 -> mu^+mu^- and CP-violating effects in the B_s^0 -> J/psi phi channel. We discuss recent theoretical developments related to these measurements and shall also sketch other highlights of the B-physics …
These lectures concern two topics that are becoming increasingly important in the analysis of High Energy Physics (HEP) data: Bayesian statistics and multivariate methods. In the Bayesian approach we extend the interpretation of probability to cover not only the frequency of repeatable outcomes but also to include a degree of belief. In this way we are able to associate probability with a hypothesis and thus to answer directly questions that cannot be addressed easily with traditional frequentist methods. In multivariate analysis we try to exploit as much information as possible from the chara…
This is the proceedings article for the concluding lecture of the 1999 High Energy Physics Conference of the European Physical Society. In this article, I review a number of topics that were highlighted at the meeting and have more general importance in high energy physics. The major topics discussed include: (1) precision electroweak physics, (2) CP violation, (3) new directions in QCD, (4) supersymmetry spectroscopy, (5) the experimental physics of extra dimensions.
