NA48/2 studies of rare decays

The first observation of about 2000 candidates, with a background contamination below 3%, of the rare decay $K^{\pm} \to \pi^{\pm}\pi^{0}e^+e^-$ is reported by the NA48/2 experiment. The preliminary branching ratio in the full kinematic region is obtained to be: ${\cal B}(K^{\pm} \to \pi^{\pm}\pi^{0}e^+e^-)=(4.06\pm0.17)\cdot10^{-6}$ by analyzing the data collected in 2003. A sample of $4.687\times 10^6$ $K^\pm\to\pi^\pm\pi^0_D$, decay candidates with a negligible background contamination collected in 2003-04 is analyzed to search for the dark photon ($A'$) via the decay chain $K^\pm\to\pi^\pm\pi^0$, $\pi^0\to\gamma A'$, $A'\to e^+e^-$. No signal is observed, and preliminary limits in the plane dark photon mixing parameter $\varepsilon^2$ versus its mass $m_{A'}$ are reported.Comment: To be published in La Thuile 2015 proceedings. arXiv admin note: text overlap with arXiv:1412.805

Study of the performance of the NA62 Small-Angle Calorimeter at the DAΦ\PhiNE Linac

The measurement of $BR(K^+\to\pi^+\nu\bar{\nu})$ with 10% precision by the NA62 experiment requires extreme background suppression. The Small Angle Calorimeter aims to provide an efficient veto for photons flying at angles down to zero with respect to the kaon flight direction. The initial prototype was upgraded and tested at the Beam Test Facility of the DA$\Phi$NE Linac at Frascati. The energy resolution and the efficiency were measured and are presented.Comment: 5 pages, 7 figure

Innovation adoption and farm profitability: What role for research and information sources?

The paper analyses the determinants of farmers\u2019 adoption of innovations and studies the effect of the source of information and the connection with agricultural research on the contribution of innovation to farm performance. The paper uses primary data collected ad hoc in the Province of Bologna (Emilia-Romagna, Italy) and analyses it through an econometric analysis. The results indicate that structural factors and farm specialisation still play a relevant role in innovation adoption. Connection to scientific research triggers significant improvements in terms of value-added and qual-ity of production but does not affect other profitability-related parameters. The results confirm the need for policy to better consider the role of intermediate actors between research and the farmer as well as to better clarify the final performance strategy in order to set the policy instruments right. The paper also highlights the need for fur-ther research about farms\u2019 proactivity in searching for and selecting information dur-ing the process of innovation adoption and competitive advantages in terms of profitability components

Time over threshold in the presence of noise

The time over threshold is a widely used quantity to describe signals from various detectors in particle physics. Its electronics implementation is straightforward and in this paper we present the studies of its behavior in the presence of noise. A unique comb-like structure was identified in the data for a first time and was explained and modeled successfully. The effects of that structure on the efficiency and resolution are also discussed.Comment: 6 pages, 8 figure

Cooperative Management of Ecosystem Services: Coalition Formation, Landscape Structure and Policies

A growing body of literature shows that full-cooperation among farmers to manage productive ecosystem services would yield gains with respect to uncoordinated approaches. The public good feature of these ecosystem services may, however, hinder the emergence of a cooperative solution at the landscape scale. In this paper, we introduce in a coalition formation game a spatially-explicit bioeconomic model of fruit pollination, where pollinaton depends on the distance to the choosen location of natural habitats. We analyse: (i) which coalitions are stable; (ii) what benefits they provide; (iii) how cooperation depends on the initial landscape structure; and (iv) how policy instruments affect cooperation. The theoretical model presents the rationality of cooperation but, due to the detailed heterogeneity and complex spatial interactions among farms, we use a numerical example to determine the stable coalitions. We find that only small coalitions are stable and that the benefits of cooperation decrease when the spatial autocorrelation of fruit tree covers increase. Policy instruments can increase the interest for cooperation but per-hectare payments and minimum participation rules may reduce the habitat area at the margin (by decreasing the stability of coalitions). Price premium for the coalition members increase the habitat area but its budget-effectiveness decreases as the spatial autocorrelation of fruit tree covers increase

Evidence that muscle cells do not express the histidine-rich glycoprotein associated with AMP deaminase but can internalise the plasma protein

Histidine-rich glycoprotein (HRG) is synthesized by liver and is present at relatively high concentration in the plasma of vertebrates. We have previously described the association of a HRG-like molecule to purified rabbit skeletal muscle AMP deaminase (AMPD). We also provided the first evidence for the presence of a HRG-like protein in human skeletal muscle where a positive correlation between HRG content and total determined AMPD activity has been shown. In the present paper we investigate the origin of skeletal muscle HRG. The screening of a human skeletal muscle cDNA expression library using an anti-HRG antibody failed to reveal any positive clone. The RT-PCR analysis, performed on human skeletal muscle RNA as well as on RNA from the rhabdomyosarcoma (RD) cell line, failed to show any mRNA specific for the plasma HRG or for the putative muscle variant. When the RD cells were incubated with human plasma HRG, a time-dependent increase of the HRG immunoreactivity was detected both at the plasma membrane level and intracellularly. The internalisation of HRG was inhibited by the addition of heparin. The above data strongly suggest that skeletal muscle cells do not synthesize the muscle variant of HRG but instead can actively internalise it from plasma

Probing the dark sector with PADME

Among the theoretical models addressing the dark matter problem, the category based on a secluded sector is attracting increasing interest. The PADME experiment, at the Laboratori Nazionali di Frascati (LNF) of INFN, is designed to be sensitive to the production of a low mass gauge boson A' of a new U(1) symmetry holding for dark particles. The “dark photon” is weakly coupled to the photon of the Standard Model, and it provides an experimental signature for one of the simplest implementation of the dark sector paradigm. The DAΦNE Beam-Test Facility of LNF will provide a high intensity, mono-energetic positron beam impacting on a low Z target. The PADME detector will measure with high precision the momentum of the photon, produced along with A' boson in e+e− annihilation in the target, thus allowing to measure the A' mass as the missing mass in the final state. This technique, particularly useful in case of invisible decays of the A' boson, will be exploited for the first time in a fixed target experiment. Simulation studies predict a sensitivity on the interaction strength (l2 parameter) down to 10−6, in the mass region 1MeV<MA' < 23.7MeV, for one year of data taking with a 550MeV beam. In 2018 the first run will take place, and early data will give the opportunity to compare the detector performance with the design requirements

GEANT4-based full simulation of the PADME experiment at the DAΦNE BTF

A possible solution to the dark matter problem postulates that dark particles can interact with Standard Model particles only through a new force mediated by a “portal”. If the new force has a U(1) gauge structure, the “portal” is a massive photon-like vector particle, called dark photon or A′. The PADME experiment at the DAΦNE Beam-Test Facility (BTF) in Frascati is designed to detect dark photons produced in positron on fixed target annihilations decaying to dark matter (e+e-→γA′) by measuring the final state missing mass. The experiment will be composed of a thin active diamond target where a 550 MeV positron beam will impinge to produce e+e- annihilation events. The surviving beam will be deflected with a magnet while the photons produced in the annihilation will be measured by a calorimeter composed of BGO crystals. To reject the background from Bremsstrahlung gamma production, a set of segmented plastic scintillator vetoes will be used to detect positrons exiting the target with an energy lower than that of the beam, while a fast small angle calorimeter will be used to reject the e+e-→γγ(γ) background. To optimize the experimental layout in terms of signal acceptance and background rejection, the full layout of the experiment was modelled with the GEANT4 simulation package. In this paper we will describe the details of the simulation and report on the results obtained with the software