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A bstract The quantum interference between the decays of entangled neutral kaons is studied in the process ϕ → K S K L → π + 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 DAΦNE, the Frascati ϕ -factory, and corresponds to an integrated luminosity of about 1.7 fb − 1 , i.e. to about 1 . 7 × 10 9 ϕ → K S K L decays produced. From the fit of the observed ∆ t distribution, being ∆ t 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.

A bstract The ratio R = Γ( K S → πeν ) / Γ( K S → π + π − ) has been measured with a sample of 300 million K S mesons produced in ϕ → K L K S decays recorded by the KLOE experiment at the DAΦNE e + e − collider. K S → πeν events are selected by a boosted decision tree built with kinematic variables and time-of-flight measurements. Data control samples of K L → πeν decays are used to evaluate signal selection efficiencies. With 49647 ± 316 signal events we measure R = (1 . 0421 ± 0 . 0066 stat ± 0 . 0075 syst ) × 10 − 3 . The combination with our previous measurement gives R = (1 . 0338 ± 0 . 0054 stat ± 0 . 0064 syst ) × 10 − 3 . From this value we derive the branching fraction B ( K S → πeν ) = (7 . 153 ± 0 . 037 stat ± 0 . 044 syst ) × 10 − 4 and f + (0) |V us | = 0 . 2170 ± 0 . 009.

A bstract Using 1.63 fb −1 of integrated luminosity collected by the KLOE experiment about 7 × 10 4 K S → π ± e ∓ ν decays have been reconstructed. The measured value of the charge asymmetry for this decay is A S = (−4.9 ± 5.7 stat ± 2.6 syst ) × 10 −3 , which is almost twice more precise than the previous KLOE result. The combination of these two measurements gives A S = (−3.8 ± 5.0 stat ± 2.6 syst ) × 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.

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 η / η ′ 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 γ γ processes.

We present a measurement of the doubly radiative decay η → π0γγ based ona sample of 82 million η mesons produced in the e+e− → ϕ → ηγ process at the Frascatiϕ-factory DAΦNE. From the data analysis, 1246 ± 133 signal events were observed. Bynormalising the signal to the well-known η → 3π0 decay the branching fraction B(η → π0γγ) ismeasured to be (0.98 ± 0.11stat ± 0.14syst) × 10−4. This result agrees with a preliminary KLOEmeasurement, but is a factor of two smaller than the current world average. Results for dΓ(η →π0γγ)/dM 2(γγ) are also presented and compared with the latest theoretical predictions.

A bstract We present a measurement of the doubly radiative decay η → π 0 γγ based on a sample of 82 million η mesons produced in the e + e − → ϕ → ηγ process at the Frascati ϕ -factory DAΦNE. From the data analysis, 1246 ± 133 signal events were observed. By normalising the signal to the well-known η → 3 π 0 decay the branching fraction is measured to be (0 . 98 ± 0 . 11 stat ± 0 . 14 syst ) × 10 − 4 . This result agrees with a preliminary KLOE measurement, but is a factor of two smaller than the current world average. Results for d Γ( η → π 0 γγ ) /dM 2 ( γγ ) are also presented and compared with the latest theoretical predictions.

The Italian institute for nuclear physics (INFN) has financed the SIMP project (2019–2021) in order to strengthen its skills and technologies in the field of meV detectors with the ultimate aim of developing a single microwave photon detector. This goal will be pursued by improving the sensitivity and the dark-count rate of two types of photodetectors: current-biased Josephson junction (CBJJ) for the frequency range 10–50 GHz and transition-edge sensor (TES) for the frequency range 30–100 GHz. Preliminary results on materials and devices characterization are presented.

A bstract Based on an integrated luminosity of 1.61 fb − 1 e + e − collision data collected with the KLOE detector at DAΦNE, the Frascati ϕ -factory, a search for the P - and CP -violating decay η → π + π − has been performed. Radiative ϕ → ηγ 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 ℬ( η → π + π − ) < 4 . 9 × 10 − 6 , which is approximately three times smaller than the previous KLOE result. From the combination of these two measurements we get ℬ( η → π + π − ) < 4 . 4 × 10 − 6 at 90% confidence level.

Josephson junctions, in appropriate configurations, can be excellent candidates for detection of single photons in the microwave frequency band. Such possibility has been recently addressed in the framework of galactic axion detection. Here are reported recent developments in the modelling and simulation of dynamic behaviour of a Josephson junction single microwave photon detector. For a Josephson junction to be enough sensitive, small critical currents and operating temperatures of the order of ten of mK are necessary. Thermal and quantum tunnelling out of the zero-voltage state can also mask the detection process. Axion detection would require dark count rates in the order of 0.001 Hz. It is, therefore, is of paramount importance to identify proper device fabrication parameters and junction operation point.