Showing 1–50 of 70 results for author: Bossi, F

Search for a new 17 MeV resonance via $e^+e^-$ annihilation with the PADME Experiment

Authors: F. Bossi, R. De Sangro, C. Di Giulio, E. Di Meco, D. Domenici, G. Finocchiaro, L. G. Foggetta, M. Garattini, P. Gianotti, M. Mancini, I. Sarra, T. Spadaro, C. Taruggi, E. Vilucchi, K. Dimitrova, S. Ivanov, Sv. Ivanov, K. Kostova, V. Kozhuharov, R. Simeonov, F. Ferrarotto, E. Leonardi, P. Valente, E. Long, G. C. Organtini , et al. (2 additional authors not shown)

Abstract: The PADME Experiment at the Frascati DA$Φ$NE LINAC has searched for a hypothetical particle with mass around 17 MeV, commonly referred to as the X17, using a positron beam incident on a fixed target. The beam energy was varied between 262 and 296 MeV, corresponding to center-of-mass energies $\sqrt{s}$ between 16.4 and 17.4 MeV. The X17 should be produced resonantly via $e^+e^-$ annihilation when… ▽ More The PADME Experiment at the Frascati DA$Φ$NE LINAC has searched for a hypothetical particle with mass around 17 MeV, commonly referred to as the X17, using a positron beam incident on a fixed target. The beam energy was varied between 262 and 296 MeV, corresponding to center-of-mass energies $\sqrt{s}$ between 16.4 and 17.4 MeV. The X17 should be produced resonantly via $e^+e^-$ annihilation when $\sqrt{s}$ approaches its mass, inducing an excess of events with a two-body final state over the background expectation. The beam energy spacing was fixed to less than half the expected width of the resonance's line shape. Uncertainties below 1% per $\sqrt{s}$ point were achieved. A blind analysis has been performed. The data are consistent with the expected background in most of the explored energy range, and limits are set in previously unexplored regions of the available parameter space. The most significant deviation is found for $\sqrt{s} \approx 16.90$ MeV, corresponding to a global significance of approximately 2 standard deviations over the null hypothesis expectation. △ Less

Submitted 24 February, 2026; v1 submitted 30 May, 2025; originally announced May 2025.

Comments: 31 pages, 24 figures

Journal ref: JHEP 11 (2025) 007

Measurement of $η\toπ^{0}γγ$ branching fraction with the KLOE detector

Authors: D. Babusci, P. Beltrame, M. Berlowski, C. Bloise, F. Bossi, P. Branchini, B. Cao, F. Ceradini, P. Ciambrone, L. Cotrozzi, F. Curciarello, E. Czerwiński, G. D'Agostini, R. D'Amico, E. Danè, V. De Leo, E. De Lucia, A. De Santis, P. De Simone, A. Di Domenico, E. Diociaiuti, D. Domenici, A. D'Uffizi, G. Fantini, S. Fiore , et al. (28 additional authors not shown)

Abstract: We present a measurement of the radiative decay $η\toπ^0γγ$ using 82 million $η$ mesons produced in $e^+e^-\toφ\toηγ$ process at the Frascati $φ$-factory DA$Φ$NE. From the data analysis $1246\pm133$ signal events are observed. By normalising the signal to the well-known $η\to3π^0$ decay the branching fraction ${\cal B}(η\toπ^0γγ)$ is measured to be… ▽ More We present a measurement of the radiative decay $η\toπ^0γγ$ using 82 million $η$ mesons produced in $e^+e^-\toφ\toηγ$ process at the Frascati $φ$-factory DA$Φ$NE. From the data analysis $1246\pm133$ signal events are observed. By normalising the signal to the well-known $η\to3π^0$ decay the branching fraction ${\cal B}(η\toπ^0γγ)$ is measured to be $(0.98\pm 0.11_\text{stat}\pm 0.14_\text{syst})\times10^{-4}$. This result agrees with a preliminary KLOE measurement, but is twice smaller than the present world average. Results for $dΓ(η\toπ^0γγ)/dM^2(γγ)$ are also presented and compared with latest theory predictions. △ Less

Submitted 16 May, 2025; v1 submitted 14 May, 2025; originally announced May 2025.

Comments: 16 pages, 9 figures, prepared for submission to JHEP. Small changes in affiliation and acknowledgments

Blind unblinding procedure for the PADME X17 data sample

Authors: Susanna Bertelli, Fabio Bossi, Riccardo De Sangro, Claudio Di Giulio, Elisa Di Meco, Danilo Domenici, Giuseppe Finocchiaro, Luca Gennaro Foggetta, Marco Garattini, Paola Gianotti, Marco Mancini, Ivano Sarra, Tommaso Spadaro, Eleuterio Spiriti, Elisabetta Vilucchi, Venelin Kozhuharov, Kalina Dimitrova, Simeon Ivanov, Svetoslav Ivanov, Radoslav Simeonov, Fabio Ferrarotto, Emanuele Leonardi, Paolo Valente, Alessandro Variola, Elizabeth Long , et al. (7 additional authors not shown)

Abstract: The PADME experiment at the Frascati DA$Φ$NE LINAC has performed a search for the hypothetical X17 particle, with a mass of around 17 MeV, by scanning the energy of a positron beam striking a fixed target. The X17 should be produced from the resulting $e^+e^-$ annihilation. Since the expected mass of this particle is only roughly known, data sidebands cannot be clearly defined. Furthermore, the ne… ▽ More The PADME experiment at the Frascati DA$Φ$NE LINAC has performed a search for the hypothetical X17 particle, with a mass of around 17 MeV, by scanning the energy of a positron beam striking a fixed target. The X17 should be produced from the resulting $e^+e^-$ annihilation. Since the expected mass of this particle is only roughly known, data sidebands cannot be clearly defined. Furthermore, the need to keep the analysis blind to potentially sizable signal contributions prevents a clear assessment even of the quality of the data sample in this search. In light of these challenges, this paper presents an innovative strategy adopted by the PADME Collaboration to perform data quality checks without disclosing the X17 sample. Moreover, the procedure designed to eventually unblind the data is described, together with the statistical approach adopted to extract the limits on the coupling between the X17 and the Standard Model. △ Less

Submitted 7 March, 2025; originally announced March 2025.

Comments: 14 pages, 13 figures

Characterization of the PADME positron beam for the X17 measurement

Authors: S. Bertelli, F. Bossi, B. Buonomo, R. De Sangro, C. Di Giulio, E. Di Meco, K. Dimitrova, D. Domenici, F. Ferrarotto, G. Finocchiaro, L. G. Foggetta, A. Frankenthal, M. Garattini, G. Georgiev, P. Gianotti, S. Ivanov, Sv. Ivanov, V. Kozhuharov, E. Leonardi, E. Long, M. Mancini, G. C. Organtini, M. Raggi, I. Sarra, R. Simeonov , et al. (5 additional authors not shown)

Abstract: This paper presents a detailed characterization of the positron beam delivered by the Beam Test Facility at Laboratori Nazionali of Frascati to the PADME experiment during Run III, which took place from October to December 2022. It showcases the methodology used to measure the main beam parameters such as the position in space, the absolute momentum scale, the beam energy spread, and its intensity… ▽ More This paper presents a detailed characterization of the positron beam delivered by the Beam Test Facility at Laboratori Nazionali of Frascati to the PADME experiment during Run III, which took place from October to December 2022. It showcases the methodology used to measure the main beam parameters such as the position in space, the absolute momentum scale, the beam energy spread, and its intensity through a combination of data analysis and Monte Carlo simulations. The results achieved include an absolute precision in the momentum of the beam to within $\sim$ 1-2 MeV$/c$, a relative beam energy spread below 0.25\%, and an absolute precision in the intensity of the beam at the level of 2\% percent. △ Less

Submitted 12 May, 2024; originally announced May 2024.

The future search for low-frequency axions and new physics with the FLASH resonant cavity experiment at Frascati National Laboratories

Authors: David Alesini, Danilo Babusci, Paolo Beltrame, Fabio Bossi, Paolo Ciambrone, Alessandro D'Elia, Daniele Di Gioacchino, Giampiero Di Pirro, Babette Döbrich, Paolo Falferi, Claudio Gatti, Maurizio Giannotti, Paola Gianotti, Gianluca Lamanna, Carlo Ligi, Giovanni Maccarrone, Giovanni Mazzitelli, Alessandro Mirizzi, Michael Mueck, Enrico Nardi, Federico Nguyen, Alessio Rettaroli, Javad Rezvani, Francesco Enrico Teofilo, Simone Tocci , et al. (3 additional authors not shown)

Abstract: We present a proposal for a new experiment, the FINUDA magnet for Light Axion SearcH (FLASH), a large resonant-cavity haloscope in a high static magnetic field which is planned to probe new physics in the form of dark matter (DM) axions, scalar fields, chameleons, hidden photons, as well as high frequency gravitational waves (GWs). Concerning the QCD axion, FLASH will search for these particles as… ▽ More We present a proposal for a new experiment, the FINUDA magnet for Light Axion SearcH (FLASH), a large resonant-cavity haloscope in a high static magnetic field which is planned to probe new physics in the form of dark matter (DM) axions, scalar fields, chameleons, hidden photons, as well as high frequency gravitational waves (GWs). Concerning the QCD axion, FLASH will search for these particles as the DM in the mass range (0.49-1.49) ueV, thus filling the mass gap between the ranges covered by other planned searches. A dedicated Microstrip SQUID operating at ultra-cryogenic temperatures will amplify the signal. The frequency range accessible overlaps with the Very High Frequency (VHF) range of the radio wave spectrum and allows for a search in GWs in the frequency range (100-300) MHz. The experiment will make use of the cryogenic plant and magnet of the FINUDA experiment at INFN Frascati National Laboratories near Rome (Italy); the operations needed to restore the functionalities of the apparatus are currently underway. We present the setup of the experiment and the sensitivity forecasts for the detection of axions, scalar fields, chameleons, hidden photons, and GWs. △ Less

Submitted 1 September, 2023; originally announced September 2023.

Report number: CA21106; CA21136

Journal ref: Phys.Dark Univ. 42 (2023) 101370

Status and Prospects of PADME

Authors: Susanna Bertelli, Fabio Bossi, Riccardo De Sangro, Claudio Di Giulio, Elisa Di Meco, Danilo Domenici, Giuseppe Finocchiaro, Luca Gennaro Foggetta, Marco Garattini, Andrea Ghigo, Paola Gianotti, Marco Mancini, Ivano Sarra, Tommaso Spadaro, Eleuterio Spiriti, Clara Taruggi, Elisabetta Vilucchi, Venelin Kozhuharov, Kalina Dimitrova, Simeon Ivanov, Svetoslav Ivanov, Radoslav Simeonov, Georgi Georgiev, Fabio Ferrarotto, Emanuele Leonardi , et al. (6 additional authors not shown)

Abstract: The Positron Annihilation to Dark Matter Experiment (PADME) was designed and constructed to search for dark photons ($A'$) in the process $e^+e^-\rightarrowγA'$, using the positron beam at the Beam Test Facility (BTF) at the National Laboratories of Frascati (LNF). Since the observation of an anomalous spectra in internal pair creation decays of nuclei seen by the collaboration at the ATOMKI insti… ▽ More The Positron Annihilation to Dark Matter Experiment (PADME) was designed and constructed to search for dark photons ($A'$) in the process $e^+e^-\rightarrowγA'$, using the positron beam at the Beam Test Facility (BTF) at the National Laboratories of Frascati (LNF). Since the observation of an anomalous spectra in internal pair creation decays of nuclei seen by the collaboration at the ATOMKI institute, the PADME detector has been modified and a new data-taking run has been undertaken to probe the existance of the so-called ``X17" particle △ Less

Submitted 15 May, 2023; originally announced May 2023.

Comments: 6 pages, 12 figures, proceedings from Moriond EW 2023

Direct tests of T, CP, CPT symmetries in transitions of neutral K mesons with the KLOE experiment

Authors: D. Babusci, M. Berłowski, C. Bloise, F. Bossi, P. Branchini, B. Cao, F. Ceradini, P. Ciambrone, F. Curciarello, E. Czerwiński, G. D'Agostini, R. D'Amico, E. Danè, V. De Leo, E. De Lucia, A. De Santis, P. De Simone, A. Di Domenico, E. Diociaiuti, D. Domenici, A. D'Uffizi, G. Fantini, A. Gajos, S. Gamrat, P. Gauzzi , et al. (18 additional authors not shown)

Abstract: Tests of the T, CP and CPT symmetries in the neutral kaon system are performed by the direct comparison of the probabilities of a kaon transition process to its symmetry-conjugate. The exchange of in and out states required for a genuine test involving an anti-unitary transformation implied by time-reversal is implemented exploiting the entanglement of $K^0\bar{K}{}^0$ pairs produced at a $φ$-fact… ▽ More Tests of the T, CP and CPT symmetries in the neutral kaon system are performed by the direct comparison of the probabilities of a kaon transition process to its symmetry-conjugate. The exchange of in and out states required for a genuine test involving an anti-unitary transformation implied by time-reversal is implemented exploiting the entanglement of $K^0\bar{K}{}^0$ pairs produced at a $φ$-factory. A data sample collected by the KLOE experiment at DA$Φ$NE corresponding to an integrated luminosity of about 1.7 fb$^{-1}$ is analysed to study the $Δ$t distributions of the $φ\to K_{S}K_{L}\to π^+π^- \: π^{\pm}e^{\mp}ν$ and $φ\to K_{S}K_{L}\to π^{\pm}e^{\mp}ν\: 3π^0$ processes, with $Δ$t the difference of the kaon decay times. A comparison of the measured $Δ$t distributions in the asymptotic region $Δt \gg τ_{S}$ allows to test for the first time T and CPT symmetries in kaon transitions with a precision of few percent, and to observe CP violation with this novel method. △ Less

Submitted 19 December, 2022; v1 submitted 22 November, 2022; originally announced November 2022.

Comments: 26 pages, 10 figures. Minor style corrections applied before journal submission. Sumbmitted to Physics Letters B

Cross-section measurement of two-photon annihilation in-flight of positrons at $\sqrt{s}=20$ MeV with the PADME detector

Authors: F. Bossi, P. Branchini, B. Buonomo, V. Capirossi, A. P. Caricato, G. Chiodini, R. De Sangro, C. Di Giulio, D. Domenici, F. Ferrarotto, G. Finocchiaro, L. G Foggetta, A. Frankenthal, M. Garattini, G. Georgiev, F. Giacchino, P. Gianotti, S. Ivanov, Sv. Ivanov, V. Kozhuharov, E. Leonardi, E. Long, M. Martino, I. Oceano, F. Oliva , et al. (13 additional authors not shown)

Abstract: The inclusive cross-section of annihilation in flight $e^+e^-\rightarrowγγ$ of 430 MeV positrons with atomic electrons of a thin diamond target has been measured with the PADME detector at the Laboratori Nazionali di Frascati. The two photons produced in the process were detected by an electromagnetic calorimeter made of BGO crystals. This measurement is the first one based on the direct detection… ▽ More The inclusive cross-section of annihilation in flight $e^+e^-\rightarrowγγ$ of 430 MeV positrons with atomic electrons of a thin diamond target has been measured with the PADME detector at the Laboratori Nazionali di Frascati. The two photons produced in the process were detected by an electromagnetic calorimeter made of BGO crystals. This measurement is the first one based on the direct detection of the photon pair and one of the most precise for positron energies below 1 GeV. This measurement represents a necessary step to search for dark sector particles and mediators weakly coupled to photons and/or electrons with masses ranging from 1 MeV to 20 MeV with PADME. The measurement agrees with the Next to Leading Order QED prediction within the overall 6% uncertainty. △ Less

Submitted 7 November, 2022; v1 submitted 26 October, 2022; originally announced October 2022.

Comments: Submitted to PRD

Dark sector studies with the PADME experiment

Authors: Anna Paola Caricato, Maurizio Martino, Isabella Oceano, Federica Oliva, Stefania Spagnolo, Gabriele Chiodini, Fabio Bossi, Riccardo De Sangro, Claudio Di Giulio, Danilo Domenici, Giuseppe Finocchiaro, Luca Gennaro Foggetta, Marco Garattini, Andrea Ghigo, Federica Giacchino, Paola Gianotti, Tommaso Spadaro, Eletuerio Spiriti, Clara Taruggi, Elisabetta Vilucchi, Venelin Kozhuharov, Simeon Ivanov, Svetoslav Ivanov, Radoslav Simeonov, Georgi Georgiev , et al. (13 additional authors not shown)

Abstract: The Positron Annihilation to Dark Matter Experiment (PADME) uses the positron beam of the DA$Φ$NE Beam-Test Facility, at the Laboratori Nazionali di Frascati (LNF) to search for a Dark Photon $A'$. The search technique studies the missing mass spectrum of single-photon final states in $e^+e^-\rightarrow A'γ$ annihilation in a positron-on-thin-target experiment. This approach facilitates searches f… ▽ More The Positron Annihilation to Dark Matter Experiment (PADME) uses the positron beam of the DA$Φ$NE Beam-Test Facility, at the Laboratori Nazionali di Frascati (LNF) to search for a Dark Photon $A'$. The search technique studies the missing mass spectrum of single-photon final states in $e^+e^-\rightarrow A'γ$ annihilation in a positron-on-thin-target experiment. This approach facilitates searches for new particles such as long lived Axion-Like-Particles, protophobic X bosons and Dark Higgs. This talk illustrated the scientific program of the experiment and its first physics results. In particular, the measurement of the cross-section of the SM process $e^+e^-\rightarrow γγ$ at $\sqrt{s}$=21 MeV was shown. △ Less

Submitted 1 May, 2023; v1 submitted 29 September, 2022; originally announced September 2022.

Comments: Fixed typos and updated gamma gamma results from preliminary ones to published ones. 6 pages, 6 figures, conference proceedings to be published in SciPost

Measurement of the $K_S \to πe ν$ branching fraction with the KLOE experiment

Authors: D. Babusci, M. Berlowski, C. Bloise, F. Bossi, P. Branchini, B. Cao, F. Ceradini, P. Ciambrone, F. Curciarello, E. Czerwiński, G. D'Agostini, R. D'Amico, E. Danè, V. De Leo, E. De Lucia, A. De Santis, P. De Simone, A. Di Cicco, A. Di Domenico, E. Diociaiuti, D. Domenici, A. D'Uffizi, G. Fantini, A. Gajos, S. Gamrat , et al. (18 additional authors not shown)

Abstract: 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 sig… ▽ More 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 fraction is $\mathcal{B}(K_S \to πe ν) = (7.211 \pm 0.046_{\rm stat} \pm 0.052_{\rm syst}) \times10^{-4}$. The combination with our previous measurement gives $\mathcal{B}(K_S \to πe ν) = (7.153 \pm 0.037_{\rm stat} \pm 0.043_{\rm syst}) \times10^{-4}$. From this value we derive $f_+(0)|V_{us}| = 0.2170 \pm 0.009$. △ Less

Submitted 24 January, 2023; v1 submitted 9 August, 2022; originally announced August 2022.

Comments: arXiv admin note: substantial text overlap with arXiv:1912.05990

Commissioning of the PADME experiment with a positron beam

Authors: P. Albicocco, R. Assiro, F. Bossi, P. Branchini, B. Buonomo, V. Capirossi, E. Capitolo, C. Capoccia, A. P. Caricato, S. Ceravolo, G. Chiodini, G. Corradi, R. De Sangro, C. Di Giulio, D. Domenici, F. Ferrarotto, S. Fiore, G. Finocchiaro, L. G Foggetta, A. Frankenthal, M. Garattini, G. Georgiev, F. Giacchino, A. Ghigo, P. Gianotti , et al. (31 additional authors not shown)

Abstract: The PADME experiment is designed to search for a hypothetical dark photon $A^{\prime}$ produced in positron-electron annihilation using a bunched positron beam at the Beam Test Facility of the INFN Laboratori Nazionali di Frascati. The expected sensitivity to the $A^{\prime}$-photon mixing parameter $ε$ is 10$^{-3}$, for $A^{\prime}$ mass $\le$ 23.5 MeV/$c^{2}$ after collecting $\sim 10^{13}$ posi… ▽ More The PADME experiment is designed to search for a hypothetical dark photon $A^{\prime}$ produced in positron-electron annihilation using a bunched positron beam at the Beam Test Facility of the INFN Laboratori Nazionali di Frascati. The expected sensitivity to the $A^{\prime}$-photon mixing parameter $ε$ is 10$^{-3}$, for $A^{\prime}$ mass $\le$ 23.5 MeV/$c^{2}$ after collecting $\sim 10^{13}$ positrons-on-target. This paper presents the PADME detector status after commissioning in July 2019. In addition, the software algorithms employed to reconstruct physics objects, such as photons and charged particles, and the calibration procedures adopted are illustrated in detail. The results show that the experimental apparatus reaches the design performance, and is able to identify and measure standard electromagnetic processes, such as positron Bremsstrahlung, electron-positron annihilation into two photons. △ Less

Submitted 20 July, 2022; v1 submitted 6 May, 2022; originally announced May 2022.

Comments: submitted to JINST

The PADME beam line Monte Carlo simulation

Authors: F. Bossi, P. Branchini, B. Buonomo, V. Capirossi, A. P. Caricato, G. Chiodini, R. De Sangro, C. Di Giulio, D. Domenici, F. Ferrarotto, S. Fiore, G. Finocchiaro, L. G Foggetta, A. Frankenthal, M. Garattini, G. Georgiev, A. Ghigo, P. Gianotti, F. Iazzi, S. Ivanov, Sv. Ivanov, V. Kozhuharov, E. Leonardi, E. Long, M. Martino , et al. (16 additional authors not shown)

Abstract: The PADME experiment at the DA$Φ$NE Beam-Test Facility (BTF) of the INFN Laboratory of Frascati is designed to search for invisible decays of dark sector particles produced in electron-positron annihilation events with a positron beam and a thin fixed target, by measuring the missing mass of single-photon final states. The presence of backgrounds originating from beam halo particles can significan… ▽ More The PADME experiment at the DA$Φ$NE Beam-Test Facility (BTF) of the INFN Laboratory of Frascati is designed to search for invisible decays of dark sector particles produced in electron-positron annihilation events with a positron beam and a thin fixed target, by measuring the missing mass of single-photon final states. The presence of backgrounds originating from beam halo particles can significantly reduce the sensitivity of the experiment. To thoroughly understand the origin of the beam background contribution, a detailed Geant4-based Monte Carlo simulation has been developed, containing a full description of the detector together with the beam line and its optical elements. This simulation allows the full interactions of each particle to be described, both during beam line transport and during detection, a possibility which represents an innovative way to obtain reliable background predictions △ Less

Submitted 12 April, 2022; originally announced April 2022.

Comments: 14 pages 10 figures

European Strategy for Particle Physics -- Accelerator R&D Roadmap

Authors: C. Adolphsen, D. Angal-Kalinin, T. Arndt, M. Arnold, R. Assmann, B. Auchmann, K. Aulenbacher, A. Ballarino, B. Baudouy, P. Baudrenghien, M. Benedikt, S. Bentvelsen, A. Blondel, A. Bogacz, F. Bossi, L. Bottura, S. Bousson, O. Brüning, R. Brinkmann, M. Bruker, O. Brunner, P. N. Burrows, G. Burt, S. Calatroni, K. Cassou , et al. (111 additional authors not shown)

Abstract: The 2020 update of the European Strategy for Particle Physics emphasised the importance of an intensified and well-coordinated programme of accelerator R&D, supporting the design and delivery of future particle accelerators in a timely, affordable and sustainable way. This report sets out a roadmap for European accelerator R&D for the next five to ten years, covering five topical areas identified… ▽ More The 2020 update of the European Strategy for Particle Physics emphasised the importance of an intensified and well-coordinated programme of accelerator R&D, supporting the design and delivery of future particle accelerators in a timely, affordable and sustainable way. This report sets out a roadmap for European accelerator R&D for the next five to ten years, covering five topical areas identified in the Strategy update. The R&D objectives include: improvement of the performance and cost-performance of magnet and radio-frequency acceleration systems; investigations of the potential of laser / plasma acceleration and energy-recovery linac techniques; and development of new concepts for muon beams and muon colliders. The goal of the roadmap is to document the collective view of the field on the next steps for the R&D programme, and to provide the evidence base to support subsequent decisions on prioritisation, resourcing and implementation. △ Less

Submitted 30 March, 2022; v1 submitted 19 January, 2022; originally announced January 2022.

Comments: 270 pages, 58 figures. Editor: N. Mounet. LDG chair: D. Newbold. Panel chairs: P. Védrine (HFM), S. Bousson (RF), R. Assmann (plasma), D. Schulte (muon), M. Klein (ERL). Panel editors: B. Baudouy (HFM), L. Bottura (HFM), S. Bousson (RF), G. Burt (RF), R. Assmann (plasma), E. Gschwendtner (plasma), R. Ischebeck (plasma), C. Rogers (muon), D. Schulte (muon), M. Klein (ERL)

Report number: CERN-2022-001

Journal ref: European Strategy for Particle Physics - Accelerator R&D Roadmap, N. Mounet (ed.), CERN Yellow Reports: Monographs, CERN-2022-001 (CERN, Geneva, 2022)

Precision tests of Quantum Mechanics and CPT symmetry with entangled neutral kaons at KLOE

Authors: D. Babusci, M. Berlowski, C. Bloise, F. Bossi, P. Branchini, A. Budano, B. Cao, F. Ceradini, P. Ciambrone, F. Curciarello, E. Czerwiński, G. D'Agostini, R. D'Amico, E. Danè, V. De Leo, E. De Lucia, A. De Santis, P. De Simone, A. Di Cicco, A. Di Domenico, E. Diociaiuti, D. Domenici, A. D'Uffizi, A. Fantini, G. Fantini , et al. (33 additional authors not shown)

Abstract: The quantum interference between the decays of entangled neutral kaons is studied in the process $φ\rightarrow K_S K_L \rightarrowπ^+π^-π^+π^-$, which exhibits the characteristic Einstein--Podolsky--Rosen correlations that prevent both kaons to decay into $π^+π^-$ at the same time. This constitutes a very powerful tool for testing at the utmost precision the quantum coherence of the entangled kaon… ▽ More The quantum interference between the decays of entangled neutral kaons is studied in the process $φ\rightarrow K_S K_L \rightarrowπ^+π^-π^+π^-$, which exhibits the characteristic Einstein--Podolsky--Rosen correlations that prevent both kaons to decay into $π^+π^-$ at the same time. This constitutes a very powerful tool for testing at the utmost precision the quantum coherence of the entangled kaon pair state, and to search for tiny decoherence and CPT violation effects, which may be justified in a quantum gravity framework. The analysed data sample was collected with the KLOE detector at DA$Φ$NE, the Frascati $φ$-factory, and corresponds to an integrated luminosity of about 1.7 fb$^{-1}$, i.e. to about $1.7 \times 10^9$ $φ\rightarrow K_S K_L$ decays produced. From the fit of the observed $Δt$ distribution, being $Δt$ the difference of the kaon decay times, the decoherence and CPT violation parameters of various phenomenological models are measured with a largely improved accuracy with respect to previous analyses. The results are consistent with no deviation from quantum mechanics and CPT symmetry, while for some parameters the precision reaches the interesting level at which -- in the most optimistic scenarios -- quantum gravity effects might show up. They provide the most stringent limits up to date on the considered models. △ Less

Submitted 6 April, 2022; v1 submitted 8 November, 2021; originally announced November 2021.

Comments: 17 pages 6 figures

Characterisation and performance of the PADME electromagnetic calorimeter

Authors: P. Albicocco, J. Alexander, F. Bossi, P. Branchini, B. Buonomo, C. Capoccia, E. Capitolo, G. Chiodini, A. P. Caricato, R. de Sangro, C. Di Giulio, D. Domenici, F. Ferrarotto, G. Finocchiaro, S. Fiore, L. G. Foggetta, A. Frankenthal, G. Georgiev, A. Ghigo, F. Giacchino, P. Gianotti, S. Ivanov, V. Kozhuharov, E. Leonardi, B. Liberti , et al. (20 additional authors not shown)

Abstract: The PADME experiment at the LNF Beam Test Facility searches for dark photons produced in the annihilation of positrons with the electrons of a fix target. The strategy is to look for the reaction $e^{+}+e^{-}\rightarrow γ+A'$, where $A'$ is the dark photon, which cannot be observed directly or via its decay products. The electromagnetic calorimeter plays a key role in the experiment by measuring t… ▽ More The PADME experiment at the LNF Beam Test Facility searches for dark photons produced in the annihilation of positrons with the electrons of a fix target. The strategy is to look for the reaction $e^{+}+e^{-}\rightarrow γ+A'$, where $A'$ is the dark photon, which cannot be observed directly or via its decay products. The electromagnetic calorimeter plays a key role in the experiment by measuring the energy and position of the final-state $γ$. The missing four-momentum carried away by the $A'$ can be evaluated from this information and the particle mass inferred. This paper presents the design, construction, and calibration of the PADME's electromagnetic calorimeter. The results achieved in terms of equalisation, detection efficiency and energy resolution during the first phase of the experiment demonstrate the effectiveness of the various tools used to improve the calorimeter performance with respect to earlier prototypes. △ Less

Submitted 21 October, 2020; v1 submitted 28 July, 2020; originally announced July 2020.

Comments: 15 pages, 15 figures

Upper limit on the $η\toπ^{+}π^{-}$ branching fraction with the KLOE experiment

Authors: D. Babusci, M. Berlowski, C. Bloise, F. Bossi, P. Branchini, A. Budano, B. Cao, F. Ceradini, P. Ciambrone, F. Curciarello, E. Czerwiński, G. D'Agostini, E. Danè, V. De Leo, E. De Lucia, A. De Santis, P. De Simone, A. Di Cicco, A. Di Domenico, D. Domenici, A. D'Uffizi, A. Fantini, P. Fermani, S. Fiore, A. Gajos , et al. (31 additional authors not shown)

Abstract: 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 f… ▽ More 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 these two measurements we get ${\mathcal B}(η\toπ^{+}π^{-}) < 4.4\times10^{-6}$ at 90\% confidence level. △ Less

Submitted 28 February, 2021; v1 submitted 25 June, 2020; originally announced June 2020.

Comments: 11 pages, 3 figures

Journal ref: J. High Energ. Phys. 2020, 47 (2020)

Lepton Flavor Violation at muon-electron colliders

Authors: Fabio Bossi, Paolo Ciafaloni

Abstract: Lepton Flavor Violating (LFV) processes are clear signals of physics beyond the Standard Model. We investigate the possibility of measuring this kind of processes at present and foreseeable future muon-electron colliders, taking into account present day bounds from existing experiments. As a model of new physics we consider a Z' boson with a $U'(1)$ gauge symmetry and generic couplings. Processes… ▽ More Lepton Flavor Violating (LFV) processes are clear signals of physics beyond the Standard Model. We investigate the possibility of measuring this kind of processes at present and foreseeable future muon-electron colliders, taking into account present day bounds from existing experiments. As a model of new physics we consider a Z' boson with a $U'(1)$ gauge symmetry and generic couplings. Processes that violate lepton flavor by two units seem to be particularly promising. △ Less

Submitted 12 December, 2020; v1 submitted 9 March, 2020; originally announced March 2020.

Comments: 9 pages, 4 figures. Final version published on JHEP

Measurement of the branching fraction for the decay $K_S \to πμν$ with the KLOE detector

Authors: D. Babusci, M. Berlowski, C. Bloise, F. Bossi, P. Branchini, A. Budano, B. Cao, F. Ceradini, P. Ciambrone, F. Curciarello, E. Czerwisnski, G. D'Agostini, E. Danè, V. De Leo, E. De Lucia, A. De Santis, P. De Simone, A. Di Cicco, A. Di Domenico, D. Domenici, A. D'Uffizi, A. Fantini, P. Fermani, S. Fiore, A. Gajos , et al. (31 additional authors not shown)

Abstract: 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… ▽ More 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. Normalising to the $K_S \to π^+ π^-$ decay events the result for the branching fraction is $\mathcal{B}(K_S \to πμν) = (4.56 \pm 0.11_{\rm stat} \pm 0.17_{\rm syst})\times10^{-4}$. △ Less

Submitted 19 March, 2020; v1 submitted 12 December, 2019; originally announced December 2019.

Comments: 16 pages, 12 figures, Accepted in PLB

KLASH Conceptual Design Report

Authors: D. Alesini, D. Babusci, P. Beltrame S. J., F. Björkeroth, F. Bossi, P. Ciambrone, G. Delle Monache, D. Di Gioacchino, P. Falferi, A. Gallo, C. Gatti, A. Ghigo, M. Giannotti, G. Lamanna, C. Ligi, G. Maccarrone, A. Mirizzi, D. Montanino, D. Moricciani, A. Mostacci, M. Mück, E. Nardi, F. Nguyen, L. Pellegrino, A. Rettaroli , et al. (4 additional authors not shown)

Abstract: The last decade witnessed an increasing interest in axions and axion-like particles with many theoretical works published and many new experimental proposals that started a real race towards their discovery. This paper is the Conceptual Design Report of the KLASH (KLoe magnet for Axion SearcH) experiment at the Laboratori Nazionali di Frascati (LNF). The idea of this experiment has been stimulated… ▽ More The last decade witnessed an increasing interest in axions and axion-like particles with many theoretical works published and many new experimental proposals that started a real race towards their discovery. This paper is the Conceptual Design Report of the KLASH (KLoe magnet for Axion SearcH) experiment at the Laboratori Nazionali di Frascati (LNF). The idea of this experiment has been stimulated by the availability of the large volume superconducting magnet, with a moderate magnetic field of 0.6 T, used in the KLOE detector at the DAFNE collider. The main conclusion we draw from this report is the possibility to build and put in operation at LNF in 2-3 years a large haloscope with the sensitivity to KSVZ axions in the low mass range between 0.2 and 1 $μ$eV, complementary to that of other experiments. Timeline and cost are competitive with respect to other proposals in the same mass region thanks to the availability of most of the infrastructure, in particular the superconducting magnet and the cryogenics plant. △ Less

Submitted 6 November, 2019; originally announced November 2019.

Report number: INFN-19-18/LNF

Combined limit on the production of a light gauge boson decaying into $μ^+μ^-$ and $π^+π^-$

Authors: KLOE-2 Collaboration, :, A. Anastasi, D. Babusci, M. Berlowski, C. Bloise, F. Bossi, P. Branchini, A. Budano, B. Cao, F. Ceradini, P. Ciambrone, F. Curciarello, E. Czerwiński, G. D'Agostinio, E. Dané, V. De Leo, E. De Lucia, A. De Santis, P. De Simone, A. Di Cicco, A. Di Domenico, D. Domenici, A. D'Uffizi, A. Fantini , et al. (35 additional authors not shown)

Abstract: We searched for the $μ^+μ^-$ decay of a light vector gauge boson, also known as dark photon, in the $e^+ e^- \to μ^+ μ^- γ_{\rm ISR}$ process by means of the Initial State Radiation (ISR) method. We used 1.93~fb$^{-1}$ of data collected by the KLOE experiment at the DA$Φ$NE $φ$-factory. No structures have been observed over the irreducible $μ^+ μ^-$ background. A 90\% CL limit on the ratio… ▽ More We searched for the $μ^+μ^-$ decay of a light vector gauge boson, also known as dark photon, in the $e^+ e^- \to μ^+ μ^- γ_{\rm ISR}$ process by means of the Initial State Radiation (ISR) method. We used 1.93~fb$^{-1}$ of data collected by the KLOE experiment at the DA$Φ$NE $φ$-factory. No structures have been observed over the irreducible $μ^+ μ^-$ background. A 90\% CL limit on the ratio $\varepsilon^2=α^{\prime}/α$ between the dark coupling constant and the fine structure constant of $ 3\times 10^{-6}-2\times 10^{-7}$ has been set in the dark photon mass region between 519 MeV and 973 MeV. This new limit has been combined with the published result obtained investigating the hypothesis of the dark photon decaying into hadrons in $e^+ e^- \to π^+ π^- γ_{\rm ISR}$ events. The combined 90\% CL limit increases the sensitivity especially in the $ρ-ω$ interference region and excludes $\varepsilon^2$ greater than $(13-2)\times 10^{-7}$. For dark photon masses greater than 600 MeV the combined limit is lower than 8~$\times\, 10^{-7}$ resulting more stringent than present constraints from other experiments. △ Less

Submitted 9 August, 2018; v1 submitted 7 July, 2018; originally announced July 2018.

Comments: 7 pages, 9 figures, 1 table, accepted for publication in Physics Letters B

Journal ref: Physics Letters B 784 (2018), 336

Measurement of the charge asymmetry for the $K_S \rightarrow πe ν$ decay and test of CPT symmetry with the KLOE detector

Authors: A. Anastasi, D. Babusci, M. Berłowski, C. Bloise, F. Bossi, P. Branchini, A. Budano, B. Cao, G. Capon, F. Ceradini, P. Ciambrone, F. Curciarello, E. Czerwiński, G. D'Agostini, E. Danè, V. De Leo, E. De Lucia, A. De Santis, P. De Simone, A. Di Cicco, A. Di Domenico, D. Domenici, A. D'Uffizi, A. Fantini, G. Fantini , et al. (35 additional authors not shown)

Abstract: Using 1.63 fb$^{-1}$ of integrated luminosity collected by the KLOE experiment about $7\times 10^4$ $K_S \rightarrow π^{\pm}e^{\mp}ν$ decays have been reconstructed. The measured value of the charge asymmetry for this decay is $A_S = (-4.9 \pm 5.7_{stat} \pm 2.6_{syst}) \times 10^{-3}$, which is almost twice more precise than the previous KLOE result. The combination of these two measurements give… ▽ More Using 1.63 fb$^{-1}$ of integrated luminosity collected by the KLOE experiment about $7\times 10^4$ $K_S \rightarrow π^{\pm}e^{\mp}ν$ decays have been reconstructed. The measured value of the charge asymmetry for this decay is $A_S = (-4.9 \pm 5.7_{stat} \pm 2.6_{syst}) \times 10^{-3}$, which is almost twice more precise than the previous KLOE result. The combination of these two measurements gives $A_S = (-3.8 \pm 5.0_{stat} \pm 2.6_{syst}) \times 10^{-3}$ and, together with the asymmetry of the $K_L$ semileptonic decay, provides significant tests of the CPT symmetry. The obtained results are in agreement with CPT invariance. △ Less

Submitted 11 August, 2018; v1 submitted 22 June, 2018; originally announced June 2018.

Comments: submitted to JHEP

Combination of KLOE $σ\big(e^+e^-\rightarrowπ^+π^-γ(γ)\big)$ measurements and determination of $a_μ^{π^+π^-}$ in the energy range $0.10 < s < 0.95$ GeV$^2$

Authors: The KLOE-2 Collaboration, :, A. Anastasi, D. Babusci, M. Berlowski, C. Bloise, F. Bossi, P. Branchini, A. Budano, L. Caldeira Balkeståhl, B. Cao, F. Ceradini, P. Ciambrone, F. Curciarello, E. Czerwiński, G. D'Agostini, E. Danè, V. De Leo, E. De Lucia, A. De Santis, P. De Simone, A. Di Cicco, A. Di Domenico, D. Domenici, A. D'Uffizi , et al. (41 additional authors not shown)

Abstract: The three precision measurements of the cross section $σ\big(e^+e^-\rightarrowπ^+π^-γ(γ)\big)$ using initial state radiation by the KLOE collaboration provide an important input for the prediction of the hadronic contribution to the anomalous magnetic moment of the muon. These measurements are correlated for both statistical and systematic uncertainties and, therefore, the simultaneous use of thes… ▽ More The three precision measurements of the cross section $σ\big(e^+e^-\rightarrowπ^+π^-γ(γ)\big)$ using initial state radiation by the KLOE collaboration provide an important input for the prediction of the hadronic contribution to the anomalous magnetic moment of the muon. These measurements are correlated for both statistical and systematic uncertainties and, therefore, the simultaneous use of these measurements requires covariance matrices that fully describe the correlations. We present the construction of these covariance matrices and use them to determine a combined KLOE measurement for $σ\big(e^+e^-\rightarrowπ^+π^-γ(γ)\big)$. We find, from this combination, a two-pion contribution to the muon magnetic anomaly in the energy range $0.10 < s < 0.95$ GeV$^2$ of $a_μ^{π^+π^-} = (489.8 \pm 1.7_{\rm stat} \pm 4.8_{\rm sys} ) \times 10^{-10}$. △ Less

Submitted 8 June, 2018; v1 submitted 8 November, 2017; originally announced November 2017.

Comments: 20 pages, 8 figures. Version as published in JHEP 1803 (2018) 173

Measurement of the running of the fine structure constant below 1 GeV with the KLOE Detector

Authors: The KLOE-2 Collaboration, :, A. Anastasi, D. Babusci, G. Bencivenni, M. Berlowski, C. Bloise, F. Bossi, P. Branchini, A. Budano, L. Caldeira Balkeståhl, B. Cao, F. Ceradini, P. Ciambrone, F. Curciarello, E. Czerwiński, G. D'Agostini, E. Dané, V. De Leo, E. De Lucia, A. De Santis, P. De Simone, A. Di Cicco, A. Di Domenico, R. Di Salvo , et al. (42 additional authors not shown)

Abstract: We have measured the running of the effective QED coupling constant $α(s)$ in the time-like region $0.6<\sqrt s< 0.975$ GeV with the KLOE detector at DA$Φ$NE using the Initial State Radiation process $e^+e^-\toμ^+ μ^-γ$. It represents the first measurement of the running of $α(s)$ in this energy region. Our results show a more than 5$σ$ significance of the hadronic contribution to the running of… ▽ More We have measured the running of the effective QED coupling constant $α(s)$ in the time-like region $0.6<\sqrt s< 0.975$ GeV with the KLOE detector at DA$Φ$NE using the Initial State Radiation process $e^+e^-\toμ^+ μ^-γ$. It represents the first measurement of the running of $α(s)$ in this energy region. Our results show a more than 5$σ$ significance of the hadronic contribution to the running of $α(s)$, which is the strongest direct evidence both in time- and space-like regions achieved in a single measurement. By using the $e^+e^-\toπ^+π^-$ cross section measured by KLOE, the real and imaginary part of the shift $Δα(s)$ has been extracted. By a fit of the real part of $Δα(s)$ and assuming the lepton universality the branching ratio $BR(ω\toμ^+μ^-) = (6.6\pm1.4_{stat}\pm1.7_{syst})\cdot 10^{-5} $ has been determined. △ Less

Submitted 10 April, 2017; v1 submitted 21 September, 2016; originally announced September 2016.

Comments: 19 pages, 8 figures, version accepted for publication in Phys. Lett. B

Dark Sectors 2016 Workshop: Community Report

Authors: Jim Alexander, Marco Battaglieri, Bertrand Echenard, Rouven Essig, Matthew Graham, Eder Izaguirre, John Jaros, Gordan Krnjaic, Jeremy Mardon, David Morrissey, Tim Nelson, Maxim Perelstein, Matt Pyle, Adam Ritz, Philip Schuster, Brian Shuve, Natalia Toro, Richard G Van De Water, Daniel Akerib, Haipeng An, Konrad Aniol, Isaac J. Arnquist, David M. Asner, Henning O. Back, Keith Baker , et al. (179 additional authors not shown)

Abstract: This report, based on the Dark Sectors workshop at SLAC in April 2016, summarizes the scientific importance of searches for dark sector dark matter and forces at masses beneath the weak-scale, the status of this broad international field, the important milestones motivating future exploration, and promising experimental opportunities to reach these milestones over the next 5-10 years. This report, based on the Dark Sectors workshop at SLAC in April 2016, summarizes the scientific importance of searches for dark sector dark matter and forces at masses beneath the weak-scale, the status of this broad international field, the important milestones motivating future exploration, and promising experimental opportunities to reach these milestones over the next 5-10 years. △ Less

Submitted 30 August, 2016; originally announced August 2016.

Comments: 66 pages, 15 figures, 3 tables. Workshop website and agenda: http://www-conf.slac.stanford.edu/darksectors2016/ https://indico.cern.ch/event/507783/ Editors: J. Alexander, M. Battaglieri, B. Echenard, R. Essig, M. Graham, E. Izaguirre, J. Jaros, G. Krnjaic, J. Mardon, D. Morrissey, T. Nelson, M. Perelstein, M. Pyle, A. Ritz, P. Schuster, B. Shuve, N. Toro, R. Van De Water

Limit on the production of a new vector boson in $\mathrm{e^+ e^-}\rightarrow {\rm U}γ$, U$\rightarrow π^+π^-$ with the KLOE experiment

Authors: KLOE-2 Collaboration, :, A. Anastasi, D. Babusci, G. Bencivenni, M. Berlowski, C. Bloise, F. Bossi, P. Branchini, A. Budano, L. Caldeira Balkeståhl, B. Cao, F. Ceradini, P. Ciambrone, F. Curciarello, E. Czerwinski, G. D'Agostini, E. Danè, V. De Leo, E. De Lucia, A. De Santis, P. De Simone, A. Di Cicco, A. Di Domenico, R. Di Salvo , et al. (41 additional authors not shown)

Abstract: The recent interest in a light gauge boson in the framework of an extra U(1) symmetry motivates searches in the mass range below 1 GeV. We present a search for such a particle, the dark photon, in ${\rm e^+ e^-}\rightarrow {\rm U}γ$, U$\rightarrow π^+π^-$ based on 28 million $\mathrm{e^+ e^-} \rightarrow π^+ π^-γ$ events collected at DA$Φ$NE by the KLOE experiment. The $π^+ π^-$ production by in… ▽ More The recent interest in a light gauge boson in the framework of an extra U(1) symmetry motivates searches in the mass range below 1 GeV. We present a search for such a particle, the dark photon, in ${\rm e^+ e^-}\rightarrow {\rm U}γ$, U$\rightarrow π^+π^-$ based on 28 million $\mathrm{e^+ e^-} \rightarrow π^+ π^-γ$ events collected at DA$Φ$NE by the KLOE experiment. The $π^+ π^-$ production by initial-state radiation compensates for a loss of sensitivity of previous KLOE ${\rm U} \rightarrow \mathrm{e^+ e^-}$, $μ^+μ^-$ searches due to the small branching ratios in the $ρ-ω$ resonance region. We found no evidence for a signal and set a limit at 90\% CL on the mixing strength between the photon and the dark photon, $\varepsilon^2$, in the U mass range between $527$ and $987$~MeV. Above 700 MeV this new limit is more stringent than previous ones. △ Less

Submitted 19 March, 2016; originally announced March 2016.

Comments: 6 pages, 9 figures, 1 table, submitted to Phys. Lett. B

Journal ref: Physics Letters B 757 (2016) pp. 356-361

Precision measurement of the $η\toπ^+π^-π^0$ Dalitz plot distribution with the KLOE detector

Authors: KLOE-2 Collaboration, :, A. Anastasi, D. Babusci, G. Bencivenni, M. Berlowski, C. Bloise, F. Bossi, P. Branchini, A. Budano, L. Caldeira Balkeståhl, B. Cao, F. Ceradini, P. Ciambrone, F. Curciarello, E. Czerwiński, G. D'Agostini, E. Dané, V. De Leo, E. De Lucia, A. De Santis, P. De Simone, A. Di Cicco, A. Di Domenico, R. Di Salvo , et al. (40 additional authors not shown)

Abstract: Using $1.6$ fb$^{-1}$ of $e^+ e^-\toφ\toηγ$ data collected with the KLOE detector at DA$Φ$NE, the Dalitz plot distribution for the $η\to π^+ π^- π^0$ decay is studied with the world's largest sample of $\sim 4.7 \cdot 10^6$ events. The Dalitz plot density is parametrized as a polynomial expansion up to cubic terms in the normalized dimensionless variables $X$ and $Y$. The experiment is sensitive t… ▽ More Using $1.6$ fb$^{-1}$ of $e^+ e^-\toφ\toηγ$ data collected with the KLOE detector at DA$Φ$NE, the Dalitz plot distribution for the $η\to π^+ π^- π^0$ decay is studied with the world's largest sample of $\sim 4.7 \cdot 10^6$ events. The Dalitz plot density is parametrized as a polynomial expansion up to cubic terms in the normalized dimensionless variables $X$ and $Y$. The experiment is sensitive to all charge conjugation conserving terms of the expansion, including a $gX^2Y$ term. The statistical uncertainty of all parameters is improved by a factor two with respect to earlier measurements. △ Less

Submitted 26 January, 2016; originally announced January 2016.

Comments: 11 pages, 9 figures, supplement: an ascii table

Measurement of the $φ\to π^0 e^+e^-$ transition form factor with the KLOE detector

Authors: KLOE-2 Collaboration, :, A. Anastasi, D. Babusci, G. Bencivenni, M. Berlowski, C. Bloise, F. Bossi, P. Branchini, A. Budano, L. Caldeira Balkeståhl, B. Cao, F. Ceradini, P. Ciambrone, F. Curciarello, E. Czerwiński, G. D'Agostini, E. Danè, V. De Leo, E. De Lucia, A. De Santis, P. De Simone, A. Di Cicco, A. Di Domenico, R. Di Salvo , et al. (40 additional authors not shown)

Abstract: A measurement of the vector to pseudoscalar conversion decay $φ\to π^0 e^+e^-$ with the KLOE experiment is presented. A sample of $\sim 9500$ signal events was selected from a data set of 1.7 fb$^{-1}$ of $e^+e^-$ collisions at $\sqrt{s} \sim m_φ$ collected at the DA$Φ$NE $e^+e^-$ collider. These events were used to obtain the first measurement of the transition form factor $| F_{φπ^0}(q^2) |$ and… ▽ More A measurement of the vector to pseudoscalar conversion decay $φ\to π^0 e^+e^-$ with the KLOE experiment is presented. A sample of $\sim 9500$ signal events was selected from a data set of 1.7 fb$^{-1}$ of $e^+e^-$ collisions at $\sqrt{s} \sim m_φ$ collected at the DA$Φ$NE $e^+e^-$ collider. These events were used to obtain the first measurement of the transition form factor $| F_{φπ^0}(q^2) |$ and a new measurement of the branching ratio of the decay: $\rm{BR}\,(φ\to π^0 e^+e^-) = (\,1.35 \pm 0.05^{\,\,+0.05}_{\,\,-0.10}\,) \times 10 ^{-5}$. The result improves significantly on previous measurements and is in agreement with theoretical predictions. △ Less

Submitted 3 June, 2016; v1 submitted 25 January, 2016; originally announced January 2016.

Comments: 13 pages, 4 figures; matches published version

Journal ref: Phys. Lett. B 757 (2016) 362

Limit on the production of a low-mass vector boson in $\mathrm{e}^{+}\mathrm{e}^{-} \to \mathrm{U}γ$, $\mathrm{U} \to \mathrm{e}^{+}\mathrm{e}^{-}$ with the KLOE experiment

Authors: A. Anastasi, D. Babusci, G. Bencivenni, M. Berlowski, C. Bloise, F. Bossi, P. Branchini, A. Budano, L. Caldeira Balkeståhl, B. Cao, F. Ceradini, P. Ciambrone, F. Curciarello, E. Czerwiński, G. D'Agostini, E. Danè, V. De Leo, E. De Lucia, A. De Santis, P. De Simone, A. Di Cicco, A. Di Domenico, R. Di Salvo, D. Domenici, A. D'Uffizi , et al. (39 additional authors not shown)

Abstract: The existence of a new force beyond the Standard Model is compelling because it could explain several striking astrophysical observations which fail standard interpretations. We searched for the light vector mediator of this dark force, the $\mathrm{U}$ boson, with the KLOE detector at the DA$Φ$NE $\mathrm{e}^{+}\mathrm{e}^{-}$ collider. Using an integrated luminosity of 1.54 fb$^{-1}$, we studied… ▽ More The existence of a new force beyond the Standard Model is compelling because it could explain several striking astrophysical observations which fail standard interpretations. We searched for the light vector mediator of this dark force, the $\mathrm{U}$ boson, with the KLOE detector at the DA$Φ$NE $\mathrm{e}^{+}\mathrm{e}^{-}$ collider. Using an integrated luminosity of 1.54 fb$^{-1}$, we studied the process $\mathrm{e}^{+}\mathrm{e}^{-} \to \mathrm{U}γ$, with $\mathrm{U} \to \mathrm{e}^{+}\mathrm{e}^{-}$, using radiative-return to search for a resonant peak in the dielectron invariant-mass distribution. We did not find evidence for a signal, and set a 90\%~CL upper limit on the mixing strength between the Standard Model photon and the dark photon, $\varepsilon^2$, at $10^{-6}$--$10^{-4}$ in the 5--520~MeV/c$^2$ mass range. △ Less

Submitted 19 October, 2015; v1 submitted 2 September, 2015; originally announced September 2015.

Search for dark Higgsstrahlung in e+ e- -> mu+ mu- and missing energy events with the KLOE experiment

Authors: KLOE-2 Collaboration, :, D. Babusci, G. Bencivenni, C. Bloise, F. Bossi, P. Branchini, A. Budano, L. Caldeira Balkestahl, F. Ceradini, P. Ciambrone, F. Curciarello, E. Czerwinski, E. Dane', V. De Leo, E. De Lucia, A. De Santis, P. De Simone, A. Di Cicco, A. Di Domenico, R. Di Salvo, D. Domenici, A. Fantini, G. Felici, S. Fiore , et al. (34 additional authors not shown)

Abstract: We searched for evidence of a Higgsstrahlung process in a secluded sector, leading to a final state with a dark photon U and a dark Higgs boson h', with the KLOE detector at DAFNE. We investigated the case of h' lighter than U, with U decaying into a muon pair and h' producing a missing energy signature. We found no evidence of the process and set upper limits to its parameters in the range 2m_mu<… ▽ More We searched for evidence of a Higgsstrahlung process in a secluded sector, leading to a final state with a dark photon U and a dark Higgs boson h', with the KLOE detector at DAFNE. We investigated the case of h' lighter than U, with U decaying into a muon pair and h' producing a missing energy signature. We found no evidence of the process and set upper limits to its parameters in the range 2m_mu<m_U<1000 MeV, m_h'<m_U. △ Less

Submitted 27 January, 2015; originally announced January 2015.

Comments: 16 pages, 7 figures, submitted to Physics Letters B

Study of Dalitz decay phi -> eta e+e- with KLOE detector

Authors: D. Babusci, I. Balwierz-Pytko, G. Bencivenni, C. Bloise, F. Bossi, P. Branchini, A. Budano, L. Caldeira Balkestahl, F. Ceradini, P. Ciambrone, F. Curciarello, E. Czerwinski, E. Dane', V. De Leo, E. De Lucia, G. De Robertis, A. De Santis, P. De Simone, A. Di Cicco, A. Di Domenico, R. Di Salvo, D. Domenici, O. Erriquez, G. Fanizzi, A. Fantini , et al. (40 additional authors not shown)

Abstract: 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 b… ▽ More 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 with VMD expectations. △ Less

Submitted 16 September, 2014; originally announced September 2014.

Comments: 13 pages, 6 figures, submitted to PLB

Search for light vector boson production in $e^+e^- \rightarrow μ^+ μ^- γ$ interactions with the KLOE experiment

Authors: D. Babusci, I. Balwierz-Pytko, G. Bencivenni, C. Bloise, F. Bossi, P. Branchini, A. Budano, L. Caldeira Balkeståhl, F. Ceradini, P. Ciambrone, F. Curciarello, E. Czerwinski, E. Danè, V. De Leo, E. De Lucia, G. De Robertis, A. De Santis, P. De Simone, A. Di Cicco, A. Di Domenico, R. Di Salvo, D. Domenici, O. Erriquez, G. Fanizzi, A. Fantini , et al. (44 additional authors not shown)

Abstract: We have searched for a light vector boson $U$, the possible carrier of a "dark force", with the KLOE detector at the DA$Φ$NE \epm\ collider, motivated by astrophysical evidence for the presence of dark matter in the universe. Using \epm\ collisions collected with an integrated luminosity of $239.3$~pb$^{-1}$, we look for a dimuon mass peak in the reaction \epm\to$μ^+ μ^-$\gam, corresponding to the… ▽ More We have searched for a light vector boson $U$, the possible carrier of a "dark force", with the KLOE detector at the DA$Φ$NE \epm\ collider, motivated by astrophysical evidence for the presence of dark matter in the universe. Using \epm\ collisions collected with an integrated luminosity of $239.3$~pb$^{-1}$, we look for a dimuon mass peak in the reaction \epm\to$μ^+ μ^-$\gam, corresponding to the decay $U\toμ^+μ^-$. We find no evidence for a $U$ vector boson signal. We set a 90\% CL upper limit for the mixing parameter squared between the photon and the $U$ boson of 1.6$\times$10$^{-5}$ to 8.6$\times$10$^{-7}$ for the mass region $520<m_{\rm U}<980$ MeV. △ Less

Submitted 9 August, 2014; v1 submitted 30 April, 2014; originally announced April 2014.

Comments: 12 pages, 7 figures, version accepted for publication in Physics Letters B

Journal ref: Physics Letters B 736, 459 (2014)

Test of CPT and Lorentz symmetry in entangled neutral kaons with the KLOE experiment

Authors: KLOE-2 Collaboration, :, D. Babusci, I. Balwierz-Pytko, G. Bencivenni, C. Bloise, F. Bossi, P. Branchini, A. Budano, L. Caldeira Balkestahl, G. Capon, F. Ceradini, P. Ciambrone, F. Curciarello, E. Czerwinski, E. Danè, V. De Leo, E. De Lucia, G. De Robertis, A. De Santis, P. De Simone, A. Di Cicco, A. Di Domenico, C. Di Donato, R. Di Salvo , et al. (49 additional authors not shown)

Abstract: Neutral kaon pairs produced in phi decays in anti-symmetric entangled state can be exploited to search for violation of CPT symmetry and Lorentz invariance. We present an analysis of the CP-violating process phi->K_S K_L->pi+pi-pi+pi- based on 1.7 fb-1 of data collected by the KLOE experiment at the Frascati phi-factory DAFNE. The data are used to perform a measurement of the CPT-violating paramet… ▽ More Neutral kaon pairs produced in phi decays in anti-symmetric entangled state can be exploited to search for violation of CPT symmetry and Lorentz invariance. We present an analysis of the CP-violating process phi->K_S K_L->pi+pi-pi+pi- based on 1.7 fb-1 of data collected by the KLOE experiment at the Frascati phi-factory DAFNE. The data are used to perform a measurement of the CPT-violating parameters Delta_amu for neutral kaons in the contest of the Standard Model Extension framework. The parameters measured in the reference frame of the fixed stars are: Delta_ao = (-6.0 +- 7.7_{stat} +- 3.1_{syst}) x 10^{-18} GeV Delta_ax = ( 0.9 +- 1.5_{stat} +- 0.6_{syst}) x 10^{-18} GeV Delta_ay = (-2.0 +- 1.5_{stat} +- 0.5_{syst}) x 10^{-18} GeV Delta_az = ( 3.1 +- 1.7_{stat} +- 0.5_{syst}) x 10^{-18} GeV These are presently the most precise measurements in the quark sector of the Standard Model Extension. △ Less

Submitted 12 March, 2014; v1 submitted 24 December, 2013; originally announced December 2013.

Comments: 16 pages, 6 figures, added few typo corrections

Journal ref: Phys. Lett. B 730 (2014) 89-94

Dark Sectors and New, Light, Weakly-Coupled Particles

Authors: R. Essig, J. A. Jaros, W. Wester, P. Hansson Adrian, S. Andreas, T. Averett, O. Baker, B. Batell, M. Battaglieri, J. Beacham, T. Beranek, J. D. Bjorken, F. Bossi, J. R. Boyce, G. D. Cates, A. Celentano, A. S. Chou, R. Cowan, F. Curciarello, H. Davoudiasl, P. deNiverville, R. De Vita, A. Denig, R. Dharmapalan, B. Dongwi , et al. (64 additional authors not shown)

Abstract: Dark sectors, consisting of new, light, weakly-coupled particles that do not interact with the known strong, weak, or electromagnetic forces, are a particularly compelling possibility for new physics. Nature may contain numerous dark sectors, each with their own beautiful structure, distinct particles, and forces. This review summarizes the physics motivation for dark sectors and the exciting oppo… ▽ More Dark sectors, consisting of new, light, weakly-coupled particles that do not interact with the known strong, weak, or electromagnetic forces, are a particularly compelling possibility for new physics. Nature may contain numerous dark sectors, each with their own beautiful structure, distinct particles, and forces. This review summarizes the physics motivation for dark sectors and the exciting opportunities for experimental exploration. It is the summary of the Intensity Frontier subgroup "New, Light, Weakly-coupled Particles" of the Community Summer Study 2013 (Snowmass). We discuss axions, which solve the strong CP problem and are an excellent dark matter candidate, and their generalization to axion-like particles. We also review dark photons and other dark-sector particles, including sub-GeV dark matter, which are theoretically natural, provide for dark matter candidates or new dark matter interactions, and could resolve outstanding puzzles in particle and astro-particle physics. In many cases, the exploration of dark sectors can proceed with existing facilities and comparatively modest experiments. A rich, diverse, and low-cost experimental program has been identified that has the potential for one or more game-changing discoveries. These physics opportunities should be vigorously pursued in the US and elsewhere. △ Less

Submitted 31 October, 2013; originally announced November 2013.

Comments: Report of the Community Summer Study 2013 (Snowmass) Intensity Frontier New, Light, Weakly-Coupled Particles subgroup

Dark photon searches using displaced vertices at low energy e+e- colliders

Authors: Fabio Bossi

Abstract: The existence of a new, photon-like, massive particle, the gamma' or dark photon, is postulated in several extensions of the Standard Model. These models are often advocated to explain some recent puzzling astrophysical observations, as well as to solve the unsofar unexplained deviation between the measured and calculated values of the muon anomaly. Dark photons can be produced at e+e- colliders b… ▽ More The existence of a new, photon-like, massive particle, the gamma' or dark photon, is postulated in several extensions of the Standard Model. These models are often advocated to explain some recent puzzling astrophysical observations, as well as to solve the unsofar unexplained deviation between the measured and calculated values of the muon anomaly. Dark photons can be produced at e+e- colliders both in continuum events and in vector meson transitions and can eventually decay into an electron-positron pair. For a proper choice of the parameters of the theory, a $γ'$ can have a relatively long lifetime and can therefore be observed as an e+e- vertex well separated by the primary interaction point. This case is discussed in reference to very high luminosity e+e- colliders either in construction or under study in several laboratories in the world. It is shown that a search strategy based on the detection of displaced vertices can be in principle very effective in covering a rather wide and to date unexplored region of the theoretical parameters space. △ Less

Submitted 31 January, 2014; v1 submitted 30 October, 2013; originally announced October 2013.

Comments: Version 2 accepted for publication by Hindawi

IRIDE White Book, An Interdisciplinary Research Infrastructure based on Dual Electron linacs&lasers

Authors: D. Alesini, M. Alessandroni, M. P. Anania, S. Andreas, M. Angelone, A. Arcovito, F. Arnesano, M. Artioli, L. Avaldi, D. Babusci, A. Bacci, A. Balerna, S. Bartalucci, R. Bedogni, M. Bellaveglia, F. Bencivenga, M. Benfatto, S. Biedron, V. Bocci, M. Bolognesi, P. Bolognesi, R. Boni, R. Bonifacio, M. Boscolo, F. Boscherini , et al. (189 additional authors not shown)

Abstract: This report describes the scientific aims and potentials as well as the preliminary technical design of IRIDE, an innovative tool for multi-disciplinary investigations in a wide field of scientific, technological and industrial applications. IRIDE will be a high intensity 'particle factory', based on a combination of a high duty cycle radio-frequency superconducting electron linac and of high ener… ▽ More This report describes the scientific aims and potentials as well as the preliminary technical design of IRIDE, an innovative tool for multi-disciplinary investigations in a wide field of scientific, technological and industrial applications. IRIDE will be a high intensity 'particle factory', based on a combination of a high duty cycle radio-frequency superconducting electron linac and of high energy lasers. Conceived to provide unique research possibilities for particle physics, for condensed matter physics, chemistry and material science, for structural biology and industrial applications, IRIDE will open completely new research possibilities and advance our knowledge in many branches of science and technology. IRIDE will contribute to open new avenues of discoveries and to address most important riddles: What does matter consist of? What is the structure of proteins that have a fundamental role in life processes? What can we learn from protein structure to improve the treatment of diseases and to design more efficient drugs? But also how does an electronic chip behave under the effect of radiations? How can the heat flow in a large heat exchanger be optimized? The scientific potential of IRIDE is far reaching and justifies the construction of such a large facility in Italy in synergy with the national research institutes and companies and in the framework of the European and international research. It will impact also on R&D work for ILC, FEL, and will be complementarity to other large scale accelerator projects. IRIDE is also intended to be realized in subsequent stages of development depending on the assigned priorities. △ Less

Submitted 30 July, 2013; originally announced July 2013.

Comments: 270 pages

Recent results on hadron physics at KLOE

Authors: D. Babusci, D. Badoni, I. Balwierz-Pytko, G. Bencivenni, C. Bini, C. Bloise, F. Bossi, P. Branchini, A. Budano, L. Caldeira Balkest, G. Capon, F. Ceradini, P. Ciambrone, F. Curciarello, E. Czerwinski, E. Dane, V. De Leo, E. De Lucia, G. De Robertis, A. De Santis, A. Di Domenico, C. Di Donato, R. Di Salvo, D. Domenici, O. Erriquez , et al. (49 additional authors not shown)

Abstract: 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 recen… ▽ More 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 anomalies. △ Less

Submitted 23 June, 2013; originally announced June 2013.

Comments: 4 pages, Proceedings of the 48th Rencontres de Moriond "QCD and High Energy Interactions", La Thuile, Italy, March 9-16, 2013

A new limit on the CP violating decay KS -> 3pi0 with the KLOE experiment

Authors: D. Babusci, D. Badoni, I. Balwierz-Pytko, G. Bencivenni, C. Bini, C. Bloise, F. Bossi, P. Branchini, A. Budano, L. Caldeira Balkestahl, G. Capon, F. Ceradini, P. Ciambrone, F. Curciarello, E. Czerwinski, E. Dane, V. De Leo, E. De Lucia, G. De Robertis, A. De Santis, A. Di Domenico, C. Di Donato, R. Di Salvo, D. Domenici, O. Erriquez , et al. (48 additional authors not shown)

Abstract: We have carried out a new direct search for the CP violating decay KS -> 3pi0 with 1.7 fb^-1 of e+e- collisions collected by the KLOE detector at the phi-factory DAFNE. We have searched for this decay in a sample of about 5.9 x 10^8 KS KL events tagging the KS by means of the KL interaction in the calorimeter and requiring six prompt photons. With respect to our previous search, the analysis has b… ▽ More We have carried out a new direct search for the CP violating decay KS -> 3pi0 with 1.7 fb^-1 of e+e- collisions collected by the KLOE detector at the phi-factory DAFNE. We have searched for this decay in a sample of about 5.9 x 10^8 KS KL events tagging the KS by means of the KL interaction in the calorimeter and requiring six prompt photons. With respect to our previous search, the analysis has been improved by increasing of a factor four the tagged sample and by a more effective background rejection of fake KS tags and spurious clusters. We find no candidates in data and simulated background samples, while we expect 0.12 standard model events. Normalizing to the number of KS -> 2pi0 events in the same sample, we set the upper limit on BR(KS -> 3pi0 < 2.6 x 10^-8 at 90% C.L., five times lower than the previous limit. We also set the upper limit on the eta_000 parameter, |eta_000 | < 0.0088 at 90% C.L., improving by a factor two the latest direct measurement. △ Less

Submitted 19 May, 2013; v1 submitted 31 January, 2013; originally announced January 2013.

Comments: Accepted for publication in Physics Letters B (15 pages, 13 figures)

Journal ref: Physics Letters B 723 (2013), pp. 54-60

Precision measurement of $σ(e^+e^-\rightarrowπ^+π^-γ)/σ(e^+e^-\rightarrow μ^+μ^-γ)$ and determination of the $π^+π^-$ contribution to the muon anomaly with the KLOE detector

Authors: KLOE, KLOE-2 Collaborations, :, D. Babusci, D. Badoni, I. Balwierz-Pytko, G. Bencivenni, C. Bini, C. Bloise, F. Bossi, P. Branchini, A. Budano, L. Caldeira Balkestahl, G. Capon, F. Ceradini, P. Ciambrone, F. Curciarello, E. Czerwinski, E. Dane', V. De Leo, E. De Lucia, G. De Robertis, A. De Santis, P. De Simone, A. Di Domenico , et al. (52 additional authors not shown)

Abstract: We have measured the ratio $σ(e^+e^-\rightarrowπ^+π^-γ)/σ(e^+e^-\rightarrow μ^+μ^-γ)$, with the KLOE detector at DA$Φ$NE for a total integrated luminosity of $\sim$ 240 pb$^{-1}$. From this ratio we obtain the cross section $σ(e^+e^-\rightarrowπ^+π^-)$. From the cross section we determine the pion form factor $|F_π|^2$ and the two-pion contribution to the muon anomaly $a_μ$ for… ▽ More We have measured the ratio $σ(e^+e^-\rightarrowπ^+π^-γ)/σ(e^+e^-\rightarrow μ^+μ^-γ)$, with the KLOE detector at DA$Φ$NE for a total integrated luminosity of $\sim$ 240 pb$^{-1}$. From this ratio we obtain the cross section $σ(e^+e^-\rightarrowπ^+π^-)$. From the cross section we determine the pion form factor $|F_π|^2$ and the two-pion contribution to the muon anomaly $a_μ$ for $0.592<M_{ππ}<0.975$ GeV, $Δ^{ππ} a_μ$= $({\rm 385.1\pm1.1_{stat}\pm2.7_{sys+theo}})\times10^{-10}$. This result confirms the current discrepancy between the Standard Model calculation and the experimental measurement of the muon anomaly. △ Less

Submitted 23 February, 2013; v1 submitted 18 December, 2012; originally announced December 2012.

Comments: 18 pages, 8 figures, minor text corrections, one table added, version to appear on Physics Letters B

Measurement of η meson production in γγ interactions and Γ(η-->γγ) with the KLOE detector

Authors: KLOE-2 Collaboration, :, D. Babusci, D. Badoni, I. Balwierz-Pytko, G. Bencivenni, C. Bini, C. Bloise, F. Bossi, P. Branchini, A. Budano, L. Caldeira Balkestaahl, G. Capon, F. Ceradini, P. Ciambrone, E. Czerwinski, E. Dane, E. De Lucia, G. De Robertis, A. De Santis, A. Di Domenico, C. Di Donato, R. Di Salvo, D. Domenici, O. Erriquez , et al. (47 additional authors not shown)

Abstract: We present a measurement of η meson production in photon-photon interactions produced by electron-positron beams colliding with \sqrt{s}=1 GeV. The measurement is done with the KLOE detector at the φ-factory DAΦNE with an integrated luminosity of 0.24 fb^{-1}. The e^+e^- --> e^+e^-η cross section is measured without detecting the outgoing electron and positron, selecting the decays η-->π^+π^-π^0 a… ▽ More We present a measurement of η meson production in photon-photon interactions produced by electron-positron beams colliding with \sqrt{s}=1 GeV. The measurement is done with the KLOE detector at the φ-factory DAΦNE with an integrated luminosity of 0.24 fb^{-1}. The e^+e^- --> e^+e^-η cross section is measured without detecting the outgoing electron and positron, selecting the decays η-->π^+π^-π^0 and η-->π^0π^0π^0. The most relevant background is due to e^+e^- --> ηγ when the monochromatic photon escapes detection. The cross section for this process is measured as σ(e^+e^- -->ηγ) = (856 \pm 8_{stat} \pm 16_{syst}) pb. The combined result for the e^+e^- -->e^+e^-η cross section is σ(e^+e^- -->e^+e^-η) = (32.72 \pm 1.27_{stat} \pm 0.70_{syst}) pb. From this we derive the partial width Γ(η-->γγ) = (520 \pm 20_{stat} \pm 13_{syst}) eV. This is in agreement with the world average and is the most precise measurement to date. △ Less

Submitted 12 December, 2012; v1 submitted 8 November, 2012; originally announced November 2012.

Comments: Version accepted by JHEP

Limit on the production of a light vector gauge boson in phi meson decays with the KLOE detector

Authors: KLOE-2 Collaboration, :, D. Babusci, D. Badoni, I. Balwierz-Pytko, G. Bencivenni, C. Bini, C. Bloise, F. Bossi, P. Branchini, A. Budano, L. Caldeira Balkestaahl, G. Capon, F. Ceradini, P. Ciambrone, E. Czerwinski, E. Dane, E. De Lucia, G. De Robertis, A. De Santis, A. Di Domenico, C. Di Donato, R. Di Salvo, D. Domenici, O. Erriquez , et al. (47 additional authors not shown)

Abstract: 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 obta… ▽ More 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'/alpha < 1.7x10^-5 for 30<M_U<400 MeV and alpha'/alpha < 8x10^-6 for the sub-region 50<M_U<210 MeV. This result assumes the Vector Meson Dominance expectations for the phietagamma^* transition form factor. The dependence of this limit on the transition form factor has also been studied. △ Less

Submitted 31 January, 2013; v1 submitted 15 October, 2012; originally announced October 2012.

Comments: 12 pages, 7 figures, updated PLB version

Measurement of Γ(η-> π^+π^-γ)/Γ(η-> π^+π^-π^0) with the KLOE Detector

Authors: D. Babusci, D. Badoni, I. Balwierz-Pytko, G. Bencivenni, C. Bini, C. Bloise, V. Bocci, F. Bossi, P. Branchini, A. Budano, L. Caldeira Balkest, G. Capon, F. Ceradini, P. Ciambrone, E. Czerwinski, E. Dane, E. De Lucia, G. De Robertis, A. De Santis, P. De Simone, A. Di Domenico, C. Di Donato, B. Di Micco, R. Di Salvo, D. Domenici , et al. (49 additional authors not shown)

Abstract: The ratio R_η=Γ(η-> π^+π^-γ)/Γ(η-> π^+π^-π^0) has been measured by analyzing 22 million φ\to ηγdecays collected by the KLOE experiment at DA\PhiNE, corresponding to an integrated luminosity of 558 pb^{-1}. The η\to π^+π^-γproceeds both via the ρresonant contribution, and possibly a non-resonant direct term, connected to the box anomaly. Our result, R_η= 0.1856\pm 0.0005_{stat} \pm 0.0028_{syst}, p… ▽ More The ratio R_η=Γ(η-> π^+π^-γ)/Γ(η-> π^+π^-π^0) has been measured by analyzing 22 million φ\to ηγdecays collected by the KLOE experiment at DA\PhiNE, corresponding to an integrated luminosity of 558 pb^{-1}. The η\to π^+π^-γproceeds both via the ρresonant contribution, and possibly a non-resonant direct term, connected to the box anomaly. Our result, R_η= 0.1856\pm 0.0005_{stat} \pm 0.0028_{syst}, points out a sizable contribution of the direct term to the total width. The di-pion invariant mass for the η-> π^+π^-γdecay could be described in a model-independent approach in terms of a single free parameter, α. The determined value of the parameter αis α= (1.32 \pm 0.08_{stat} +0.10/-0.09_{syst}\pm 0.02_{theo}) GeV^{-2} △ Less

Submitted 16 November, 2012; v1 submitted 20 September, 2012; originally announced September 2012.

Comments: Paper in press, accepted by PLB

Fundamental Physics at the Intensity Frontier

Authors: J. L. Hewett, H. Weerts, R. Brock, J. N. Butler, B. C. K. Casey, J. Collar, A. de Gouvea, R. Essig, Y. Grossman, W. Haxton, J. A. Jaros, C. K. Jung, Z. T. Lu, K. Pitts, Z. Ligeti, J. R. Patterson, M. Ramsey-Musolf, J. L. Ritchie, A. Roodman, K. Scholberg, C. E. M. Wagner, G. P. Zeller, S. Aefsky, A. Afanasev, K. Agashe , et al. (443 additional authors not shown)

Abstract: The Proceedings of the 2011 workshop on Fundamental Physics at the Intensity Frontier. Science opportunities at the intensity frontier are identified and described in the areas of heavy quarks, charged leptons, neutrinos, proton decay, new light weakly-coupled particles, and nucleons, nuclei, and atoms. The Proceedings of the 2011 workshop on Fundamental Physics at the Intensity Frontier. Science opportunities at the intensity frontier are identified and described in the areas of heavy quarks, charged leptons, neutrinos, proton decay, new light weakly-coupled particles, and nucleons, nuclei, and atoms. △ Less

Submitted 11 May, 2012; originally announced May 2012.

Comments: 229 pages

Report number: ANL-HEP-TR-12-25, SLAC-R-991

Measurement of $Γ(η\to π^+π^-γ)/Γ(η\to π^+π^-π^0)$ with KLOE experiment

Authors: The KLOE Collaboration, F. Ambrosino, A. Antonelli, M. Antonelli, F. Archilli, I. Balwierz, G. Bencivenni, C. Bini, C. Bloise, S. Bocchetta, F. Bossi, P. Branchini, G. Capon, T. Capussela, F. Ceradini, P. Ciambrone, E. Czerwiski, E. De Lucia, A. De Santis, P. De Simone, G. De Zorzi, A. Denig, A. Di Domenico, C. Di Donato, B. Di Micco , et al. (65 additional authors not shown)

Abstract: We report the measurement of the ratio $Γ(η\to π^+π^-γ)/Γ(η\to π^+π^-π^0)$ analyzing a large sample of $φ\to ηγ$ decays recorded with the KLOE experiment at the DA$Φ$NE $e^+ e^-$ collider, corresponding to an integrated luminosity of 558 pb$^{-1}$. The $η\to π^+π^-γ$ process is supposed to proceed both via a resonant contribution, mediated by the $ρ$ meson, and a non resonant direct term, connecte… ▽ More We report the measurement of the ratio $Γ(η\to π^+π^-γ)/Γ(η\to π^+π^-π^0)$ analyzing a large sample of $φ\to ηγ$ decays recorded with the KLOE experiment at the DA$Φ$NE $e^+ e^-$ collider, corresponding to an integrated luminosity of 558 pb$^{-1}$. The $η\to π^+π^-γ$ process is supposed to proceed both via a resonant contribution, mediated by the $ρ$ meson, and a non resonant direct term, connected to the box anomaly. The presence of the direct term affects the partial width value. Our result $R_η=Γ(η\to π^+ π^- γ)/Γ(η\to π^+ π^- π^0)= 0.1838\pm 0.0005_{stat} \pm 0.0030_{syst}$ is in agreement with a recent CLEO measurement, which differs by more 3 $σ$ from the average of previous results. △ Less

Submitted 28 July, 2011; originally announced July 2011.

$γγ$ physics with the KLOE experiment

Authors: The KLOE-2 Collaboration, F. Archilli, D. Babusci, D. Badoni, I. Balwierz, G. Bencivenni, C. Bini, C. Bloise, V. Bocci, F. Bossi, P. Branchini, A. Budano, S. A. Bulychjev, P. Campana, G. Capon, F. Ceradini, P. Ciambrone, E. Czerwinski, E. Dane, E. De Lucia, G. De Robertis, A. De Santis, G. De Zorzi, A. Di Domenico, C. Di Donato , et al. (45 additional authors not shown)

Abstract: 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… ▽ More 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. △ Less

Submitted 19 July, 2011; originally announced July 2011.

Comments: Contributed paper to the Lepton-Photon 2011 Conference

U boson searches at KLOE

Authors: F. Archilli, D. Babusci, D. Badoni, I. Balwierz, G. Bencivenni, C. Bini, C. Bloise, V. Bocci, F. Bossi, P. Branchini, A. Budano, S. A. Bulychjev, P. Campana, G. Capon, F. Ceradini, P. Ciambrone, E. Czerwinski, E. Dane', E. De Lucia, G. De Robertis, A. De Santis, G. De Zorzi, A. Di Domenico, C. Di Donato, D. Domenici , et al. (44 additional authors not shown)

Abstract: The existence of a secluded gauge sector could explain several puzzling astrophysical observations. This hypothesis can be tested at low energy e+e- colliders such as DAPHNE. Preliminary results obtained with KLOE data and perpectives for the KLOE-2 run, where a larger data sample is expected, are discussed. The existence of a secluded gauge sector could explain several puzzling astrophysical observations. This hypothesis can be tested at low energy e+e- colliders such as DAPHNE. Preliminary results obtained with KLOE data and perpectives for the KLOE-2 run, where a larger data sample is expected, are discussed. △ Less

Submitted 13 July, 2011; originally announced July 2011.

Comments: 8 pages, 5 figures

Observation of the rare eta->e+e-e+e- decay with the KLOE experiment

Authors: The KLOE Collaboration, F. Ambrosino, A. Antonelli, M. Antonelli, F. Archilli, I. Balwierz, G. Bencivenni, C. Bini, C. Bloise, S. Bocchetta, F. Bossi, P. Branchini, G. Capon, T. Capussela, F. Ceradini, P. Ciambrone, E. Czerwinski, E. DeLucia, A. DeSantis, P. DeSimone, G. DeZorzi, A. Denig, A. DiDomenico, C. DiDonato, B. DiMicco , et al. (65 additional authors not shown)

Abstract: We report the first observation of the rare eta->e+e-e+e- decay based on 1.7 fb^{-1} collected by the KLOE experiment at the DAFNE phi-factory. The selection of the e+e-e+e- final state is fully inclusive of radiation. We have identified 362 +- 29 events resulting in a branching ratio of (2.4 +- 0.2_stat+bckg +- 0.1_syst) x 10^{-5}. We report the first observation of the rare eta->e+e-e+e- decay based on 1.7 fb^{-1} collected by the KLOE experiment at the DAFNE phi-factory. The selection of the e+e-e+e- final state is fully inclusive of radiation. We have identified 362 +- 29 events resulting in a branching ratio of (2.4 +- 0.2_stat+bckg +- 0.1_syst) x 10^{-5}. △ Less

Submitted 21 October, 2011; v1 submitted 30 May, 2011; originally announced May 2011.

Comments: 12 pages, 3 figures, to be published on PLB

Journal ref: Phys.Lett. B702 (2011) 324-328

Proposal for taking data with the KLOE-2 detector at the DA$Φ$NE collider upgraded in energy

Authors: D. Babusci, C. Bini, F. Bossi, G. Isidori, D. Moricciani, F. Nguyen, P. Raimondi, G. Venanzoni, D. Alesini, F. Archilli, D. Badoni, R. Baldini-Ferroli, M. Bellaveglia, G. Bencivenni, M. Bertani, M. Biagini, C. Biscari, C. Bloise, V. Bocci, R. Boni, M. Boscolo, P. Branchini, A. Budano, S. A. Bulychjev, B. Buonomo , et al. (97 additional authors not shown)

Abstract: 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 determ… ▽ More 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 perform a scan in the region from 1 to 2.5 GeV in one year by collecting an integrated luminosity of 20 pb$^{-1}$ (corresponding to a few days of data taking) for single point, assuming an energy step of 25 MeV. A few years of data taking in this region would provide important tests of QCD and effective theories by $γγ$ physics with open thresholds for pseudo-scalar (like the $η'$), scalar ($f_0,f'_0$, etc...) and axial-vector ($a_1$, etc...) mesons; vector-mesons spectroscopy and baryon form factors; tests of CVC and searches for exotics. In the final part of the document a technical solution for the energy upgrade of DA$Φ$NE is proposed. △ Less

Submitted 29 July, 2010; originally announced July 2010.

Comments: 19 pages, 8 figures

Report number: LNF-10/17(P)

Measurement of sigma(e+ e- -> pi+ pi-) from threshold to 0.85 GeV^2 using Initial State Radiation with the KLOE detector

Authors: KLOE Collaboration, F. Ambrosino, F. Archilli, P. Beltrame, G. Bencivenni, C. Bini, C. Bloise, S. Bocchetta, F. Bossi, P. Branchini, G. Capon, T. Capussela, F. Ceradini, P. Ciambrone, E. De Lucia, A. De Santis, P. De Simone, G. De Zorzi, A. Denig, A. Di Domenico, C. Di Donato, B. Di Micco, M. Dreucci, G. Felici, S. Fiore , et al. (23 additional authors not shown)

Abstract: We have measured the cross section of the radiative process e+e- -> pi+pi-gamma with the KLOE detector at the Frascati phi-factory DAPHNE, from events taken at a CM energy W=1 GeV. Initial state radiation allows us to obtain the cross section for e+e- -> pi+pi-, the pion form factor |F_pi|^2 and the dipion contribution to the muon magnetic moment anomaly, Delta a_mu^{pipi} = (478.5+-2.0_{stat}+-5.… ▽ More We have measured the cross section of the radiative process e+e- -> pi+pi-gamma with the KLOE detector at the Frascati phi-factory DAPHNE, from events taken at a CM energy W=1 GeV. Initial state radiation allows us to obtain the cross section for e+e- -> pi+pi-, the pion form factor |F_pi|^2 and the dipion contribution to the muon magnetic moment anomaly, Delta a_mu^{pipi} = (478.5+-2.0_{stat}+-5.0_{syst}+-4.5_{th}) x 10^{-10} in the range 0.1 < M_{pipi}^2 < 0.85 GeV^2, where the theoretical error includes a SU(3) ChPT estimate of the uncertainty on photon radiation from the final pions. The discrepancy between the Standard Model evaluation of a_mu and the value measured by the Muon g-2 collaboration at BNL is confirmed. △ Less

Submitted 21 May, 2011; v1 submitted 28 June, 2010; originally announced June 2010.

Comments: 17 pages, 11 figures, revised treatment of FSR uncertainty, version to appear on Physics Letters B

Journal ref: Phys.Lett.B700:102-110,2011

Measurement of the $η\to 3π^{0}$ slope parameter $α$ with the KLOE detector

Authors: F. Ambrosino, A. Antonelli, M. Antonelli, F. Archilli, P. Beltrame, G. Bencivenni, C. Bini, C. Bloise, S. Bocchetta, F. Bossi, P. Branchini, P. Campana, G. Capon, T. Capussela, F. Ceradini, P. Ciambrone, E. De Lucia, A. De Santis, P. De Simone, G. De Zorzi, A. Denig, A. Di Domenico, C. Di Donato, B. Di Micco, M. Dreucci , et al. (34 additional authors not shown)

Abstract: We present a measurement of the slope parameter $α$ for the $η\to 3π^{0}$ decay, with the KLOE experiment at the DA$Φ$NE $φ$-factory, based on a background free sample of $\sim$ 17 millions $η$ mesons produced in $φ$ radiative decays. By fitting the event density in the Dalitz plot we determine $α= -0.0301 \pm 0.0035\,stat\;_{-0.0035}^{+0.0022}\,syst\,$. The result is in agreement with recent meas… ▽ More We present a measurement of the slope parameter $α$ for the $η\to 3π^{0}$ decay, with the KLOE experiment at the DA$Φ$NE $φ$-factory, based on a background free sample of $\sim$ 17 millions $η$ mesons produced in $φ$ radiative decays. By fitting the event density in the Dalitz plot we determine $α= -0.0301 \pm 0.0035\,stat\;_{-0.0035}^{+0.0022}\,syst\,$. The result is in agreement with recent measurements from hadro- and photo-production experiments. △ Less

Submitted 8 April, 2010; originally announced April 2010.

Comments: 14 pages, 11 figures

Journal ref: Phys.Lett.B694:16-21,2010

Physics with the KLOE-2 experiment at the upgraded DA$φ$NE

Authors: G. Amelino-Camelia, F. Archilli, D. Babusci, D. Badoni, G. Bencivenni, J. Bernabeu, R. A. Bertlmann, D. R. Boito, C. Bini, C. Bloise, V. Bocci, F. Bossi, P. Branchini, A. Budano, S. A. Bulychjev, P. Campana, G. Capon, F. Ceradini, P. Ciambrone, E. Czerwinski, H. Czyz, G. D'Ambrosio, E. Dané, E. De Lucia, G. De Robertis , et al. (73 additional authors not shown)

Abstract: 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 pre… ▽ More 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 narrow di-lepton resonances suggested by recent models proposing a hidden dark-matter sector. We also report on the $e^+ e^-$ physics in the continuum with the measurements of (multi)hadronic cross sections and the study of gamma gamma processes. △ Less

Submitted 26 May, 2010; v1 submitted 19 March, 2010; originally announced March 2010.

Comments: 60 pages, 41 figures; added affiliation for one of the authors; added reference to section 6

Report number: CAFPE-141/10, UG-FT-271/10

Journal ref: Eur.Phys.J.C68:619-681,2010