Search for neutrinos from transient sources with the ANTARES telescope and optical follow-up observations

The ANTARES telescope has the opportunity to detect transient neutrino sources, such as gamma-ray bursts, core-collapse supernovae, flares of active nuclei... To enhance the sensitivity to these sources, we have developed a new detection method based on the optical follow-up of "golden" neutrino events such as neutrino doublets coincident in time and space or single neutrinos of very high energy. The ANTARES Collaboration has therefore implemented a very fast on-line reconstruction with a good angular resolution. These characteristics allow to trigger an optical telescope network; since February 2009. ANTARES is sending alert trigger one or two times per month to the two 25 cm robotic telescope of TAROT. This follow-up of such special events would not only give access to the nature of the sources but also improves the sensitivity for transient neutrino sources.Comment: 3 pages, 3 figures, Proceedings of the 31st ICRC, Lodz, Polan, July 200

Development of a PbWO4 Detector for Single-Shot Positron Annihilation Lifetime Spectroscopy at the GBAR Experiment

We have developed a PbWO4 (PWO) detector with a large dynamic range to measure the intensity of a positron beam and the absolute density of the ortho-positronium (o-Ps) cloud it creates. A simulation study shows that a setup based on such detectors may be used to determine the angular distribution of the emission and reflection of o-Ps to reduce part of the uncertainties of the measurement. These will allow to improve the precision in the measurement of the cross-section for the (anti)hydrogen formation by (anti)proton-positronium charge exchange and to optimize the yield of antihydrogen ion which is an essential parameter in the GBAR experiment

Iso-singlet Down Quark Mixing And CP Violation Experiments

We confront the new physics models with extra iso-singlet down quarks in the new CP violation experimental era with $\sin{(2\beta)}$ and $\epsilon'/\epsilon$ measurements, $K^+ \to \pi^+ \nu \bar{\nu}$ events, and $x_s$ limits. The closeness of the new experimental results to the standard model theory requires us to include full SM amplitudes in the analysis. In models allowing mixing to a new isosinglet down quark, as in E$_6$, flavor changing neutral currents are induced that allow a $Z^0$ mediated contribution to $B-\bar B$ mixing and which bring in new phases. In $(\rho,\eta)$, $(x_s,\sin{(\gamma)})$, and $(x_s, \sin{(2\phi_s)})$ plots we still find much larger regions in the four down quark model than in the SM, reaching down to $\eta \approx 0$, $0 \leq \sin{(\gamma)} \leq 1$, $-.75 \leq \sin{(2\alpha)} \leq 0.15$, and $\sin{(2\phi_s)}$ down to zero, all at 1$\sigma$. We elucidate the nature of the cancellation in an order $\lambda^5$ four down quark mixing matrix element which satisfies the experiments and reduces the number of independent angles and phases. We also evaluate tests of unitarity for the $3\times3$ CKM submatrix.Comment: 14 pages, 16 figures, REVTeX

Measurement of the branching ratio of the decay Ξ0→Σ+μ−νˉμ\Xi^{0}\rightarrow \Sigma^{+} \mu^{-} \bar{\nu}_{\mu}

From the 2002 data taking with a neutral kaon beam extracted from the CERN-SPS, the NA48/1 experiment observed 97 $\Xi^{0}\rightarrow \Sigma^{+} \mu^{-} \bar{\nu}_{\mu}$ candidates with a background contamination of $30.8 \pm 4.2$ events. From this sample, the BR($\Xi^{0}\rightarrow \Sigma^{+} \mu^{-} \bar{\nu}_{\mu}$) is measured to be $(2.17 \pm 0.32_{\mathrm{stat}}\pm 0.17_{\mathrm{syst}})\times10^{-6}$

Recent NA48/2 and NA62 results

The NA48/2 Collaboration at CERN has accumulated and analysed unprecedented statistics of rare kaon decays in the $K_{e4}$ modes: $K_{e4}(+-)$ ($K^\pm \to \pi^+ \pi^- e^\pm \nu$) and $K_{e4}(00)$ ($K^\pm \to \pi^0 \pi^0 e^\pm \nu$) with nearly one percent background contamination. It leads to the improved measurement of branching fractions and detailed form factor studies. New final results from the analysis of 381 $K^\pm \to \pi^\pm \gamma \gamma$ rare decay candidates collected by the NA48/2 and NA62 experiments at CERN are presented. The results include a decay rate measurement and fits to Chiral Perturbation Theory (ChPT) description.Comment: Prepared for the Proceedings of "Moriond QCD and High Energy Interactions. March 22-29 2014." conferenc

Measurement of K^0_e3 form factors

The semileptonic decay of the neutral K meson, KL -> pi e nu (Ke3), was used to study the strangeness-changing weak interaction of hadrons. A sample of 5.6 million reconstructed events recorded by the NA48 experiment was used to measure the Dalitz plot density. Admitting all possible Lorentz-covariant couplings, the form factors for vector (f_+(q^2)), scalar (f_S) and tensor (f_T) interactions were measured. The linear slope of the vector form factor lambda_+ = 0.0284+-0.0007+-0.0013 and values for the ratios |f_S/f_+(0)| = 0.015^{+0.007}_{-0.010}+-0.012 and |f_T/f_+(0)| = 0.05^{+0.03}_{-0.04}+-0.03 were obtained. The values for f_S and f_T are consistent with zero. Assuming only Vector-Axial vector couplings, lambda_+ = 0.0288+-0.0004+-0.0011 and a good fit consistent with pure V-A couplings were obtained. Alternatively, a fit to a dipole form factor yields a pole mass of M = 859+-18 MeV, consistent with the K^*(892) mass.Comment: 16 pages, 7 figures. submitted to Phys. Lett.

The ANTARES Collaboration: Contributions to ICRC 2017 Part I: Neutrino astronomy (diffuse fluxes and point sources)

Papers on neutrino astronomy (diffuse fluxes and point sources, prepared for the 35th International Cosmic Ray Conference (ICRC 2017, Busan, South Korea) by the ANTARES Collaboratio

The ANTARES Collaboration: Contributions to ICRC 2017 Part II: The multi-messenger program

Papers on the ANTARES multi-messenger program, prepared for the 35th International Cosmic Ray Conference (ICRC 2017, Busan, South Korea) by the ANTARES Collaboratio