相关论文: The GZK Bound and Strong Neutrino-Nucleon Interact…
Cosmic ray events above $10^{20}$ eV are on the verge of confronting fundamental particle physics. The neutrino is the only candidate primary among established particles capable of crossing 100 Mpc intergalactic distances unimpeded. The…
Scattering processes in the cosmic microwave background limit the propagation of ultra high energy charged particles in our Universe. For extragalactic proton sources resonant photopion production results in the famous…
The spectrum of extra-galactic cosmic rays (CRs) is expected to follow the Greisen-Zatsepin-Kuzmin (GZK) cutoff at about 5x10^10 GeV which results from energy losses of charged nuclei in the cosmic microwave background. So far the…
The origin and nature of ultrahigh-energy cosmic ray events, above the Greisen-Zatsepin-Kuzmin (GZK) cutoff energy, constitute a long-standing, unsolved mistery. Neutrinos are proposed candidates but their standard interactions with matter…
Resonant photopion production with the cosmic microwave background predicts a suppression of extragalactic protons above the famous Greisen-Zatsepin-Kuzmin cutoff at about E_{GZK} ~ 5 x 10^10 GeV. Current cosmic ray data measured by the…
A search for extremely high energy cosmic neutrinos has been carried out with the IceCube Neutrino Observatory. The main signals in the search are neutrino-induced energetic charged leptons and their rate depends on the neutrino-nucleon…
Neutrino interactions with nuclei have been the subject of intense interest over the last 15 years. Current and future measurements of neutrino oscillation and exotic physics use order 0.1--10 GeV neutrinos on a range of nuclear targets…
If there are large extra dimensions and the fundamental Planck scale is at the TeV scale, then the question arises of whether ultra-high energy cosmic rays might probe them. We study the neutrino-nucleon cross section in these models. The…
The origin and chemical composition of ultra high energy cosmic rays is still an open question in astroparticle physics. The observed large-scale isotropy and also direct composition measurements can be interpreted as an extragalactic…
Cosmic rays of energies larger than the Greisen-Zatsepin-Kuzmin (GZK) cutoff may be neutrinos if they acquire strong interactions due to a ``precocious unification'' of forces. A scenario for this to happen is outlined. There is no…
After a short review of the ultrahigh energy cosmic ray puzzle - the apparent observation of cosmic rays originating from cosmological distances with energies above the expected Greisen-Zatsepin-Kuzmin cutoff 4x10^{19} eV - we consider…
Cross sections for the interactions of ultrahigh-energy neutrinos with nucleons are evaluated in light of new information about nucleon structure functions. For $10^{20}$--eV neutrinos, the cross section is about 2.4 times previous…
The observed interaction energy of cosmic rays with atmospheric nuclei reaches up to a PeV in the center of mass. We compute nucleon-nucleon and nucleon-neutrino cross sections for various generic parton cross sections appearing in string…
Physics beyond the standard model might imply the cosmological production of particles with grand unification scale energies. Nucleons and gamma-rays from such processes are candidates for the cosmic rays observed beyond 100 EeV [10**(20)…
The observation of cosmic--ray events above the Greisen-Kuzmin-Zatsepin (GZK) cutoff of $\sim 5\times 10^{19}$ eV challenges orthodox modeling. We discuss a possible solution which uses standard hot Big Bang cosmology and Standard Model…
Recent experimental results and developments in the theoretical treatment of neutrino-nucleus interactions in the energy range of 1-10 GeV are discussed. Difficulties in extracting neutrino-nucleon cross sections from neutrino-nucleus…
The cosmic ray spectrum has been shown to extend well beyond 10^20 eV. With nearly 20 events observed in the last 40 years, it is now established that particles are accelerated or produced in the universe with energy near 10^21 eV. In all…
Ultra high energy cosmic rays (UHECR) pose a problem either for particle physics or for astrophysics (or for both) by the unexpectedly high number of cosmic ray showers observed with energy above about 5x10^{19}eV, the…
The present uncertainties in the knowledge of the neutrino cross sections for E_nu \sim 1 GeV, that is in the energy range most important for atmospheric and long baseline accelerator neutrinos, are large. These uncertainties do not play a…
Neutrino astronomy offers the possibility to perform extra-galactic observations well beyond the photon absorption cutoff above 50 TeV. Based on observations of cosmic rays, we already know that astrophysical sources produce particles with…