Related papers: Loop Quantum Gravity and Ultra High Energy Cosmic …
We investigate the proposal that primary cosmic rays of energy above the Greisen-Zatsepin-Kuzmin cutoff are exotic massive strongly interacting particles (uhecrons). We study the properties of air showers produced by uhecrons and find that…
We review the basic ideas on the origin of cosmic rays with energy in excess of $\sim 10^{19}$ eV, in the light of the most recent observational findings. The limited statistics of events detected by the two largest experiments currently…
Although cosmic rays were discovered over 100 years ago their origin remains uncertain. They have an energy spectrum that extends from 1 GeV to beyond 1020 eV, where the rate is less than 1 particle per km2 per century. Shortly after the…
In this letter, we present an update of a method for analysing arrival directions of ultra-high-energy cosmic rays (UHECRs) above the Greisen--Zatsepin--Kuz'min cut-off with a deep convolutional neural network developed originally in…
Although cosmic rays were discovered 90 years ago, we do not know how and where they are accelerated. There is compelling evidence that the highest energy cosmic rays are extra-galactic -- they cannot be contained by our galaxy's magnetic…
The energy spectrum of primary cosmic rays with ultra high energies based on the Yakutsk EAS Array data is presented. For the largest events values of S600 and axis coordinates have been obtained using revised lateral distribution function.…
From the analysis of AGASA data above $4 \times 10^{19}$ eV, we show that the ultra-high energy cosmic rays flux is neither purely isotropic, nor reflects the expected anisotropy from a pure source distribution that maps large scale…
High energy cosmic rays allow probing phenomena that are inacessible to accelerators. Observation of cosmic rays, presumebly protons, with energies beyond $4 \times 10^{19} eV$, the so-called Greisen-Zatsepin-Kuzmin (GZK) cut-off, give…
We investigate the injection spectrum of ultra-high-energy (>10^{15} eV) cosmic rays under the hypotheses that (1) these cosmic rays are protons and (2) the sources of these cosmic rays are extra-galactic and are homogeneously distributed…
The status of the Greisen-Zatsepin-Kuzmin (GZK) cutoff and pair-production dip in Ultra High Energy Cosmic Rays (UHECR) is discussed.They are the features in the spectrum of protons propagating through CMB radiation in extragalactic space,…
Some models for quantum gravity (QG) violate Lorentz invariance and predict an energy dependence of the speed of light, leading to a dispersion of high-energy gamma-ray signals that travel over cosmological distances. Limits on the…
We develop the statistical methods for comparing two sets of arrival directions of cosmic rays in which the two-dimensional distribution of arrival directions is reduced to the one-dimensional distributions so that the standard…
Explanations of the origin of ultra-high energy cosmic rays are severely constrained by the Greisen-Zatsepin-Kuz'min effect, which limits their propagation over cosmological distances. We argue that possible departures from strict Lorentz…
The High Resolution Fly's Eye (HiRes) experiment has observed the GZK cutoff. HiRes' measurement of the flux of cosmic rays shows a sharp suppression at an energy of 6 x 10^{19} eV, exactly the expected cutoff energy. We observe the…
Multidimensional modification of gravity with a smaller mass scale of the gravitational interaction is considered. Stable by assumption dark matter particles could decay via interactions with virtual black holes. The decay rates of such…
HiRes has made the first statistically significant observation of the Griessen-Zatsepin-Kuzmin suppression, by fitting the ultra high energy cosmic ray spectrum observed in monocular mode by the two HiRes detectors to a broken power law…
In this report we review the important progress made in recent years towards understanding the experimental data on ultra-high-energy ($E \gtrsim 10^9$ GeV) cosmic rays. We begin with a general survey of the available data, including a…
The nature of the unknown sources of ultra-high energy cosmic rays can be revealed through the detection of the GZK feature in the cosmic ray spectrum. The only two experiments that have probed this energy range, AGASA and HiRes, have…
We report the detection of a 51-joule (320 +/- 90 EeV) cosmic ray by the Fly's Eye air shower detector in Utah. This is substantially greater than the energy of any previously reported cosmic ray. A Greisen-Zatsepin-Kuz'min cutoff of the…
Ultra-high-energy (UHE) cosmic rays (CRs) interact with cosmic background radiation through hadronic processes, and the Universe would become `opaque' to UHE CRs of energies $\sim$($10^{18}$- $10^{20}$) eV over about several tens of Mpc,…