New Measurement of the Charged Kaon Semileptonic $K^\pm \to \pi^ \pi^- E^\pm\nu$ ($K_E4$) Decay Branching Ratio and Hadronic Form Factors

title: Monte Carlo comparison of mid-size telescope designs for the Cherenkov Telescope Array
abstract: The Cherenkov Telescope Array (CTA) is a future very high energy gamma-ray observatory. CTA will be comprised of small-, medium-and large-size telescopes covering an energy range from tens of GeV to hundreds of TeV and will surpass existing telescopes in sensitivity by an order of magnitude. The aim of our study is to find the optimal design for the medium-size telescopes (MSTs), which will determine the sensitivity in the key energy range between a few hundred GeV to about ten TeV. To study the effect of the telescope design parameters on the array performance, we simulated arrays of 61 MSTs with 120 m spacing and a variety of telescope configurations. We investigated the influence of the primary telescope characteristics including optical resolution, pixel size, and light collection area on the total array performance with a particular emphasis on telescope configurations with imaging performance similar to the proposed Davis-Cotton (DC) and Schwarzschild-Couder (SC) MST designs. We compare the performa...

title: High precision study of CP-violating charge asymmetry in K+- ---> 3pi+- decays by the NA-48/2 experiment at CERN

title: RECENT NA48/2 AND NA62 RESULTS
abstract: 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.

title: Radiative tau production and decay.
abstract: A study of the muon decay channel of the τ lepton with the presence of a photon has been carried out to verify theoretical predictions for the production rate of e + e - → τ + τ - γ and for the branching ratio of τ - → ν τ µ - ν µ γ. Included in this study is the first direct measurement of radiative tau decay.  The ratio of measured-to-predicted number of events from radiative T production, e + e - → τ + τ - γ, where one of the τ's decay to μνν is found to be 0.91 ± 0.20. We have not seen an indication of anomalous behavior in radiative tau events.

title: Charged multiplicity of hadronic events containing heavy-quark jets.
abstract: The charged-particle multiplicities of hadronic events deriving from produced bottom or charm quarks have been measured in the Mark II detector at PEP in e+e- annihilation at 29 GeV. For events containing one semileptonic and one hadronic weak decay, we find multiplicities of 15.20.50.7 for bottom and 13.00.50.8 for charm. The corresponding multiplicities of charged particles accompanying the pair of heavy hadrons are 5.20.50.9 for bottom, and 8.10.50.9 for charm.

title: Search for a nearly degenerate lepton doublet (L-,L0).
abstract: We have searched for a heavy charged lepton with an associated neutrino of nearly the same mass in {ital e}{sup +}{ital e}{sup {minus}} annihilation data taken with the Mark II detector at a center-of-mass energy of 29 GeV. In order to suppress contamination from conventional two-photon reactions, this analysis uses a novel, radiative-tagging technique. Requiring the presence of an isolated, energetic photon allows a search for lepton doublets with mass splittings smaller than that previously accessible to experiment. No evidence for such a new lepton doublet has been found, enabling limits to be placed on allowed mass combinations. Mass splittings as low as 250--400 MeV/{ital c}{sup 2} are excluded for charged-lepton masses between 500 MeV/{ital c}{sup 2} and 10 GeV/{ital c}{sup 2}.