141 research outputs found

    Measurement of the K+→μ+νμγK^+\rightarrow{\mu^+}{\nu_{\mu}}{\gamma} decay form factors in the OKA experiment

    Full text link
    A precise measurement of the vector and axial-vector form factors difference FV−FAF_V-F_A in the K+→μ+νμγK^+\rightarrow{\mu^+}{\nu_{\mu}}{\gamma} decay is presented. About 95K events of K+→μ+νμγK^+\rightarrow{\mu^+}{\nu_{\mu}}{\gamma} are selected in the OKA experiment. The result is FV−FA=0.134±0.021(stat)±0.027(syst)F_V-F_A=0.134\pm0.021(stat)\pm0.027(syst). Both errors are smaller than in the previous FV−FAF_V-F_A measurements.Comment: 9 pages, 8 figure

    Tests of the fundamental symmetries in eta meson decays

    Full text link
    Patterns of chiral symmetry violation and tests of the conservation of the fundamental C, P and CP symmetries are key physics issues in studies of the pi0, eta and eta' meson decays. These tests include searches for rare or forbidden decays and searches for asymmetries among the decay products in the not-so-rare decays. Some examples for the rare decays are eta-->2pi, eta-->4pi0 (CP tests), decays into an odd number of photons (e.g., eta-->3g) and the decay eta-->pi0e+e- (C tests). The experimental studies of the pi0, eta and eta' meson decays are carried out at four European accelerator research facilities: KLOE/KLOE-2 at DAFNE (Frascati), Crystal Ball at MAMI (Mainz), WASA at COSY (J\"ulich), Crystal Barrel at ELSA (Bonn).Comment: 9 pages, 2 figures, proceedings of Symposium on Prospects in the Physics of Discrete Symmetries, DISCRETE 2010, 6 - 11 December, Rome; v2: added reference

    Prospects for K+→π+ννˉK^+ \to \pi^+ \nu \bar{ \nu } at CERN in NA62

    Full text link
    The NA62 experiment will begin taking data in 2015. Its primary purpose is a 10% measurement of the branching ratio of the ultrarare kaon decay K+→π+ννˉK^+ \to \pi^+ \nu \bar{ \nu }, using the decay in flight of kaons in an unseparated beam with momentum 75 GeV/c.The detector and analysis technique are described here.Comment: 8 pages for proceedings of 50 Years of CP

    Searches for the light invisible axion-like particle in K+→π+π0aK^{+}\to\pi^{+}\pi^{0}a decay

    Full text link
    A high statistics data sample of the K+K^{+} decays is recorded by the OKA collaboration. A missing mass analysis is performed to search for a light invisible pseudoscalar axion-like particle (ALP) aa in the decay K+→π+π0aK^{+} \to \pi^{+} \pi^{0} a. No signal is observed, the upper limits for the branching ratio of the decay are calculated. The 90%90\% confidence level upper limit is changing from 2.5⋅10−62.5\cdot10^{-6} to 2⋅10−72\cdot10^{-7} for the ALP mass from 0 to 200 MeV/c2c^{2}, except for the region of π0\pi^{0} mass, where the upper limit is 4.4⋅10−64.4\cdot10^{-6}.Comment: 6 pages, 6 figure

    Study of the decay K+→π+π−π+γK^{+}\to\pi^{+}\pi^{-}\pi^{+}\gamma in the OKA experiment

    Full text link
    A high statistics data sample of the decays of K+K^+ mesons to three charged particles was accumulated by the OKA experiment in 2012 and 2013. This allowed to select a clean sample of about 450 events with K+→π+π−π+γK^{+}\to\pi^{+}\pi^{-}\pi^{+}\gamma decays with the energy of the photon in the kaon rest frame greater than 30 MeV. The measured branching fraction of the K+→π+π−π+γK^{+}\to\pi^{+}\pi^{-}\pi^{+}\gamma, with Eγ∗E_{\gamma}^{*} > 30 MeV is (0.71±0.05)×10−5(0.71 \pm 0.05) \times 10^{-5}. The measured energy spectrum of the decay photon is compared with the prediction of the chiral perturbation theory to O(p4)(p^{4}). A search for an up-down asymmetry of the photon with respect to the hadronic system decay plane is also performed.Comment: 9 pages, 7 figures, 1 tabl

    Externalities and the nucleolus

    Full text link
    In most economic applications, externalities prevail: the worth of a coalition depends on how the other players are organized. We show that there is a unique natural way of extending the nucleolus from (coalitional) games without externalities to games with externalities. This is in contrast to the Shapley value and the core for which many different extensions have been proposed

    Physics with the KLOE-2 experiment at the upgraded DAÏ•\phiNE

    Get PDF
    Investigation at a ϕ\phi--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 eta/eta′^\prime 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−e^+ e^- physics in the continuum with the measurements of (multi)hadronic cross sections and the study of gamma gamma processes.Comment: 60 pages, 41 figures; added affiliation for one of the authors; added reference to section
    • …
    corecore