1,886 research outputs found
Precision test of the SM with Kl2 and Kl3 decays at KLOE
Kaon decay studies seeking new-physics (NP) effects in leptonic (K_l2) or
semileptonic (K_l3) decays are discussed.
A unitarity test of the first row of the CKM mixing matrix is obtained from
the KLOE precision measurements of Kl3 widths for K^+-, K_L, and (unique to
KLOE) K_S, complemented with the absolute branching ratio for the K_mu2 decay.
KLOE results lead to constraints for NP models and can probe possible charged
Higgs exchange contribution in SM extensions with two Higgs doublets.
The main focus in the present document is set on a new measurement of
R_K=Gamma(K_e2)/Gamma(K_mu2) with an accuracy at the % level, aiming at finding
evidence of deviations from the SM prediction induced by lepton-flavor
violation NP effects.Comment: Contributed to Rencontres de Moriond EW 2009, La Thuile, Italy, 7-14
March 200
Interleukin-13 (IL-13)in autoimmune rheumatic diseases: relationship with autoantibody profile
Objective: Several cytokines play a role in the production of autoantibodies such as RF and ANA by B-lymphocytes; the role of IL- 13 in this process has not been previously studied. We investigated the relationship between the serum concentration of this cytokine and circulating autoantibodies. Methods: IL-13 serum levels, as well as RF and ANA, were evaluated in 282 patients with autoimmune rheumatic diseases including RA (n=84), SLE (n = 114), SS (n = 52) and Scl (n =32). Results: Serum levels of IL-13 (pg/ml) were significantly higher in patients with RA (p < 0.00003), SLE (p < 0.03), SS (p < 0.0007), or Scl (p < 0.025) compared to controls. IL-13 serian levels correlated with those of RF in RA (p < 0.00001), SLE (p < 0.003) and Scl (p < 0.03). IL- 13 levels were higher in RA (p<0.0003), SLE (p<0.005) and Scl (p<0.05) patients with RF than in patients,without RE SS patients with anti-SSA/Ro antibodies had significantly higher IL-13 levels than SS patients without this autoantibody (p < 0.04). No statistically significant correlation was found between IL-13 levels and any other antinuclear autoantibody, total immunoglobulin levels or the main clinical features of each disease. Conclusion: The evidence of higher IL- 13 levels in our RA, SLE, SS and Scl patients confirms that this cytokine is involved in the pathogenesis of autoimmune rheumatic diseases. The relationship of this cytokine with RF in RA, SLE and Scl, as well as with antiSSA/ Ro antibody in SS, strengthens the hypothesis that it plays a role in autoantibody production. However the different autoantibody synthesis by Bcells recognises different pathways depending on the underlying autoimmune disease
A prototype large-angle photon veto detector for the P326 experiment at CERN
The P326 experiment at the CERN SPS has been proposed with the purpose of
measuring the branching ratio for the decay K^+ \to \pi^+ \nu \bar{\nu} to
within 10%. The photon veto system must provide a rejection factor of 10^8 for
\pi^0 decays. We have explored two designs for the large-angle veto detectors,
one based on scintillating tiles and the other using scintillating fibers. We
have constructed a prototype module based on the fiber solution and evaluated
its performance using low-energy electron beams from the Frascati Beam-Test
Facility. For comparison, we have also tested a tile prototype constructed for
the CKM experiment, as well as lead-glass modules from the OPAL electromagnetic
barrel calorimeter. We present results on the linearity, energy resolution, and
time resolution obtained with the fiber prototype, and compare the detection
efficiency for electrons obtained with all three instruments.Comment: 8 pages, 9 figures, 2 tables. Presented at the 2007 IEEE Nuclear
Science Symposium, Honolulu HI, USA, 28 October - 3 November 200
Effects of solar irradiation on thermally driven CO2 methanation using Ni/CeO2-based catalyst
Utilization of the renewable energy sources is one of the main challenges in the state-of-the-art technologies for CO2 recycling. Here we have taken advantage of the solar light harvesting in the thermocatalytic approach to carbon dioxide methanation. The large-surface-area Ni/CeO2 catalyst produced by a scalable low-cost method was characterized and tested in the dark and under solar light irradiation conditions. Light-assisted CO2 con-version experiments as well as in-situ DRIFT spectrometry, performed at different illumination intensities, have revealed a dual effect of the incident photons on the catalytic properties of the two-component Ni/CeO2 catalyst. On the one hand, absorbed photons induce a localized surface plasmon resonance in the Ni nanoparticles fol-lowed by dissipation of the heat to the oxide matrix. On the other hand, the illumination activates the photo-catalytic properties of the CeO2 support, which leads to an increase in the concentration of the intermediates being precursor for methane production. Analysis of the methane production at different temperatures and illumination conditions has shown that the methanation reaction in our case is controlled by a photothermally- activated process. The used approach has allowed us to increase the reaction rate up to 2.4 times and conse-quently to decrease the power consumption by 20 % under solar illumination, thus replacing the conventional thermal activation of the reaction with a green energy source
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