Related papers: Two approaches to the cosmic ray "knee" problem an…
In this paper we review the main features of the observed Cosmic Rays spectrum in the energy range $10^{17} {\rm eV}~\div~10^{20} {\rm eV}$. We present a theoretical model that explains the main observed features of the spectrum, namely the…
We consider the propagation of galactic cosmic rays in the fractal interstellar medium. Steady state solution of the fractional diffusion equation, describing cosmic ray propagation, is found. We show that the exponent of the steady state…
This article presents a description of a cosmic rays diffusive propagationmodel of a close point-like flash lamp like source and an approximation ofexperimentally observed spectral irregularity with this model. We show thatthis spectral…
Energetic particles, traditionally called Cosmic Rays, were discovered nearly a hundred years ago, and their origin is still uncertain. Their main constituents are the normal nuclei as in the standard cosmic abundances of matter, with some…
The search for the origin of cosmic rays is as active as ever, mainly driven by new insights provided by recent pieces of observation. Much effort is being channelled in putting the so called supernova paradigm for the origin of galactic…
A calculation based on flat spacetime symmetries shows how there can be two quantum phases. For one, extreme phase change determines a conventional classical trajectory and four-momentum, i.e. mass times four-velocity. The other phase…
Primary energy spectral models are tested in the energy range of 1-200 PeV using standardized extensive air shower responses from BASJE-MAS, Tibet, GAMMA and KASCADE scintillation shower arrays. Results point towards the two-component…
A composition analysis of KASCADE air shower data is performed by means of unfolding the two-dimensional frequency spectrum of electron and muon numbers. Aim of the analysis is the determination of energy spectra for elemental groups…
The origin of the cosmic-ray (CR) knee remains one of the central open questions in particle astrophysics. Recent measurements by the Large High Altitude Air Shower Observatory revealed a pronounced feature in the proton spectrum at…
Our purpose is to evaluate the rate of the maximum energy and the acceleration rate that cosmic rays acquire in the non-relativistic diffusive shock acceleration as it could apply during their lifetime in various astrophysical sites, where…
Various contributions to the cosmological constant are discussed and confronted with its recent measurement. We briefly review different scenarious -- and their difficulties -- for a solution of the cosmological constant problem.
The wealth of data collected in the last few years thanks to the Pierre Auger Observatory and recently to the Telescope Array made the problem of the origin of ultra high energy cosmic rays a genuinely experimental/observational one. The…
It is shown that the fine stucture of the cosmic ray energy spectrum in the knee region, if explained by the Single Source Model (SSM), can, in principle, be clearly revealed and magnified in the size spectrum of extensive air showers (EAS)…
One of the most striking astrophysical phenomena today is the existence of cosmic ray particles with energies in excess of 10^20 eV. While their presence has been confirmed by a number of experiments, it is not clear where and how these…
The propagation of high-energy cosmic rays in the Galaxy is investigated. Solutions of a diffusion model are combined with numerically calculated trajectories of particles. The resulting escape path length and interaction path length are…
We show that the second knee in the cosmic ray spectrum (i.e. the steepening occurring at $E\simeq 4\times 10^{17}$ eV) could be related to drift effects affecting the heaviest nuclear component, the iron group nuclei, in a scenario in…
The cosmological two brane model is discussed in detail. An elegant method for deriving the generalised non-linear equations for the interbrane distance is presented. These equations are used to identify equilibrium positions of the radion,…
New physics beyond the electroweak scale may increase weak interaction cross sections beyond the Standard Model predictions. Such cross sections can be expected within theories that solve the hierarchy problem of known interactions with a…
The last two decades have brought spectacular advances in astrophysics of cosmic rays (CRs) and space- and ground-based astronomy. Launches of missions that employ forefront detector technologies enabled measurements with large effective…
Although the cosmic concordance cosmology is quite successful in fitting data, fine tuning and coincidence problems apparently weaken it. We review several possibilities to ease its problems, by considering various kinds of dynamical Dark…