Spherical harmonic moments are well-suited for capturing anisotropy at any scale in the flux of cosmic rays. An unambiguous measurement of the full set of spherical harmonic coefficients requires full-sky coverage. This can be achieved by combining data from observatories located in both the northern and southern hemispheres. To this end, a joint analysis using data recorded at the Telescope Array and the Pierre Auger Observatory above 10 19 eV is presented in this work. The resulting multipolar expansion of the flux of cosmic rays allows us to perform a series of anisotropy searches, and in particular to report on the angular power spectrum of cosmic rays above 10 19 eV. No significant deviation from isotropic expectations is found throughout the analyses performed. Upper limits on the amplitudes of the dipole and quadrupole moments are derived as a function of the direction in the sky, varying between 7% and 13% for the dipole and between 7% and 10% for a symmetric quadrupole.
We adopt a non-perturbative relativistic constituent-quark model for the π-meson electromagnetic form factor, which have successfully predicted experimental results, and supplement it with the effective momentum-dependent quark mass to study quantitatively the transition to the perturbative QCD asymptotics. The required asymptotical behaviour (including both the Q −2 fall-off and the correct coefficient) settles down automatically when the quark mass is switched off; however, the present experimental data on the form factor suggest that this cannot happen at the values of the momentum transfer below ∼ 10 GeV 2 . The effective constituent-quark mass below this scale acquires substantial non-perturbative contributions.PACS numbers: 13.
The existence of astrophysical neutrinos with energies of tens of TeV and higher has been firmly established by the IceCube experiment; the first confirmations of this discovery were obtained by the ANTARES and Baikal-GVD installations. At the same time, observational results do not fully agree with those expected before the start of these experiments. The origin of the neutrino has not yet been determined, while simple theoretical models, popular for decades, cannot explain the entire ensemble of observational data. In the present review, a summary of experimental results is given with a particular emphasis on those most relevant for constraining theoretical models; features of various scenarios of the origin of high-energy neutrinos are discussed; and particular classes of their potential astrophysical sources are briefly listed. It is shown that observational data may be explained if the astrophysical neutrino flux includes both a contribution of extragalactic sources, dominant at high energies, and a Galactic component, essential only at neutrino energies ≲ 100 TeV. Other possible scenarios are also discussed.
Starting from a successful model of the π -meson electromagnetic form factor, we calculate a similar form factor, F K (Q 2 ), of the charged K meson for a wide range of the momentum transfer squared, Q 2 . The only remaining free parameter is to be determined from the measurements of the K -meson charge radius, r K . We fit this single parameter to the published data of the NA-7 experiment which measured F K (Q 2 ) at Q 2 → 0 and determine our preferred range of r K , which happens to be close to recent lattice results. Still, the accuracy in the determination of r K is poor. However, future measurements of the K -meson electromagnetic form factor at Q 2 5.5 GeV 2 , scheduled in Jefferson Laboratory for 2017, will test our approach and will reduce the uncertainty in r K significantly.
Joint analysis of the energy spectrum of ultra-high-energy cosmic rays measured at the Pierre Auger Observatory and the Telescope Array Yoshiki Tsunesada , * on behalf of the Pierre Auger and the Telescope Array Collaboration
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