Papers by Camilla Di Donato
AIP Conference Proceedings, 2010
The KLOE Collaboration completed the full data taking on March 2006, acquiring 2.5 f b −1 at the ... more The KLOE Collaboration completed the full data taking on March 2006, acquiring 2.5 f b −1 at the peak of the φ and other 240 pb −1 off-peak. A new Collaboration is working on a new project, called KLOE-2, to refine and extend the KLOE physics program. We present here some preliminary and published results from the KLOE Collaboration on the pseudoscalar η meson and the study of γγ processes, that are among the main points of the KLOE-2 physics program.
This document reviews the physics program of the KLOE-2 detector at DAFNE upgraded in energy and ... more This document reviews the physics program of the KLOE-2 detector at DAFNE 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 will 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 MZ scale. With a luminosity of about 10^32 cm^-2 s^-1, DAFNE 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...) an...
The technical design report of the Inner Tracker for the KLOE-2 experiment is presented
One of the basic motivations of the KLOE and KLOE-2 collaborations is the test of fundamental sym... 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.
Journal of High Energy Physics, 2014
Several models of physics beyond the Standard Model predict neutral particles that decay into fin... more Several models of physics beyond the Standard Model predict neutral particles that decay into final states consisting of collimated jets of light leptons and hadrons (socalled "lepton jets"). These particles can also be long-lived with decay length comparable to, or even larger than, the LHC detectors' linear dimensions. This paper presents the results of a search for lepton jets in proton-proton collisions at the centre-of-mass energy of √ s = 8 TeV in a sample of 20.3 fb −1 collected during 2012 with the ATLAS detector at the LHC. Limits on models predicting Higgs boson decays to neutral long-lived lepton jets are derived as a function of the particle's proper decay length.
Journal of High Energy Physics, 2006
We present an improved determination of the CP and CP T violation parameters Re(ǫ) and Im(δ) base... more We present an improved determination of the CP and CP T violation parameters Re(ǫ) and Im(δ) based on the unitarity condition (Bell-Steinberger relation) and on recent results from the KLOE experiment. We find Re(ǫ) = (159.6 ± 1.3) × 10 −5 and Im(δ) = (0.4 ± 2.1) × 10 −5 , consistent with no CP T violation.
Journal of High Energy Physics, 2013
We present a measurement of η meson production in photon-photon interactions produced by electron... 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 out-going electron and positron, selecting the decays η → π + π − π 0 and η → π 0 π 0 π 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 ± 8stat ± 16syst) pb. The combined result for the e + e − → e + e − η cross section is σ(e + e − → e + e − η) = (32.72 ± 1.27stat ± 0.70syst) pb. From this we derive the partial width Γ(η → γγ) = (520 ± 20stat ± 13syst) eV. This is in agreement with the world average and is the most precise measurement to date.
Physics Letters B, 2003
We have measured the ratio R = Γ(K L → γγ)/Γ(K L → π 0 π 0 π 0) using the KLOE detector. From a s... more We have measured the ratio R = Γ(K L → γγ)/Γ(K L → π 0 π 0 π 0) using the KLOE detector. From a sample of ∼ 10 9 φ-mesons produced at DAΦNE, the Frascati φ−factory, we select ∼ 1.6 10 8 K L-mesons tagged by observing K S → π + π − following the reaction e + e − → φ → K L K S. From this sample we select 27,375 K L → γγ events and obtain R = (2.79 ± 0.02 stat ± 0.02 syst) × 10 −3. Using the world average value for BR(K L → π 0 π 0 π 0), we obtain BR(K L → γγ) = (5.89±0.07±0.08)×10 −4 where the second error is due to the uncertainty on the π 0 π 0 π 0 branching fraction.
Physics Letters B, 2005
We have searched for the decay K S → 3π 0 with the KLOE experiment at DAΦNE using data from e + e... more We have searched for the decay K S → 3π 0 with the KLOE experiment at DAΦNE using data from e + e -collisions at a center of mass energy W ∼ m φ for an integrated luminosity L = 450 pb -1 . The search has been performed with a pure K S beam obtained by tagging with K L interactions in the calorimeter and detecting six photons. We find an upper limit for the branching ratio of 1.2 × 10 -7 at 90% C.L.
Physics Letters B, 2006
From a sample of about 10 9 φ mesons produced at DAΦNE, we have selected K L mesons tagged by obs... more From a sample of about 10 9 φ mesons produced at DAΦNE, we have selected K L mesons tagged by observing K S → π + π − decays. We present results on the major K L branching ratios, including those of the semileptonic decays needed for the determination of |V us |. These branching ratio measurements are fully inclusive with respect to final-state radiation. The K L lifetime has also been measured.
Physics Letters B, 2005
We present a measurement of the K L lifetime using the KLOE detector. From a sample of ∼ 4 × 10 8... more We present a measurement of the K L lifetime using the KLOE detector. From a sample of ∼ 4 × 10 8 K S K L pairs following the reaction e + e − → φ → K S K L we select ∼ 15 × 10 6 K L → π 0 π 0 π 0 decays tagged by K S → π + π − events. From a fit of the proper time distribution we find τ L = (50.92 ± 0.17 stat ± 0.25 syst) ns. This is the most precise measurement of the K L lifetime performed to date.
Physics Letters B, 2003
We have measured the branching ratio BR(φ → π 0 π 0 γ) with the KLOE detector using a sample of ∼... more We have measured the branching ratio BR(φ → π 0 π 0 γ) with the KLOE detector using a sample of ∼5 × 10 7 φ decays. φ mesons are produced at DAΦNE, the Frascati φ-factory. We find BR(φ→π 0 π 0 γ)= (1.09 ± 0.03 stat ± 0.05 syst) × 10 −4. We fit the two-pion mass spectrum to models to disentangle contributions from various sources.
Physics Letters B, 2005
We have searched with the KLOE detector for the P and CP violating decay η → π + π -in a sample o... more We have searched with the KLOE detector for the P and CP violating decay η → π + π -in a sample of 1.55 × 10 7 η's from the decay φ → ηγ of φ-mesons produced in e + e -annihilations at DAΦNE. No signal is found. We obtain the upper limit BR(η → π + π -)< 1.3×10 -5 at 90% confidence level.
Physics Letters B, 2006
We have measured the fully inclusive K + → µ + ν(γ) absolute branching ratio with the KLOE experi... more We have measured the fully inclusive K + → µ + ν(γ) absolute branching ratio with the KLOE experiment at DAΦNE, the Frascati φ-factory. From some 865,283 K + → µ + ν(γ) decays obtained from a sample of ∼5.2 × 10 8 φ-meson decays, we find BR(K + → µ + ν µ (γ))=0.6366±0.0009 stat. ±0.0015 syst. , corresponding to an overall fractional error of 0.27%. Using recent lattice results on the decay constants of pseudoscalar mesons one can obtain an estimate for the CKM mixing matrix element |V us |=0.2223±0.0026.
Physics Letters B, 2006
We present the first observation of quantum interference in the process φ→K S K L →π + π − π + π ... more We present the first observation of quantum interference in the process φ→K S K L →π + π − π + π − , using the KLOE detector at the Frascati e + e − collider DAΦNE. From about 5 × 10 4 neutral kaon pairs both decaying to π + π − pairs we obtain the distribution of ∆t, the difference between the two kaon decay times, which allows testing the validity of quantum mechanics and CP T invariance: no violation of either is observed. New or improved limits on coherence loss and CP T violation are presented.
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Papers by Camilla Di Donato