Related papers: Two approaches to the cosmic ray "knee" problem an…
The cosmological constant problem and brane universes are reviewed briefly. We discuss how the cosmological constant problem manifests itself in various scenarios for brane universes. We review attempts - and their difficulties - that aim…
Cosmic ray story begins at the beginning of XX century. More then 100 years later, most of the main issues are still open questions, as sources, acceleration mechanism, propagation and composition. There is a continuing fascination with the…
Several dark energy models on the brane are investigated. They are compared with corresponding theories in the frame of 4d Friedmann-Robertson-Walker cosmology. To constrain the parameters of the models considered, recent observational…
We deal with the analysis of on-off measurements designed for the confirmation of a weak source of events whose presence is hypothesized, based on former observations. The problem of a small number of source events that are masked by an…
We review the current observational status of string cosmology when confronted with experimental datasets. We begin by defining common observational parameters and discuss how they are determined for a given model. Then we review the…
A novel type of Extensive Air Shower (EAS) array is proposed and described. It is shown that only new approaches to the so called "knee problem" could solve this complicated and old problem.
The differential energy spectrum of cosmic rays exhibits a change of slope, called "knee" of the spectrum, around the nominal energy of 3 x 10^15 eV, and individual "knees" for single ions, at different energies. The present work reports a…
The Cosmic Defect theory has been confronted with four observational constraints: primordial nuclear species abundances emerging from the big bang nucleosynthesis; large scale structure formation in the universe; cosmic microwave background…
The status of the solar neutrino problem is reviewed. Attempts to explain the observed deficit and spectral distortion, both by astrophysical and particle physics methods, are described. It is argued that the comparison of all experiments…
Research in cosmic rays is now nearly a century old, but most of the fundamental questions in this field remain unanswered, on the other hand the perspectives of future studies in the next decade are very bright. New detectors will provide…
In this work we study the presence of kinks in models described by two real scalar fields in bi-dimensional space-time. We generate new two-field models, constructed from distinct but important one-field models, and we solve them with…
A numerical likelihood approach to the determination of cosmic ray anisotropies is presented which offers many advantages over other approaches. It allows a wide range of statistically meaningful hypotheses to be compared even when full sky…
We investigate the physically accepted solutions of general Braneworld scenarios, scanning uniformly the associated parameter space. Without making any further assumptions we find that solutions which give "small" Hubble parameters on the…
The energy spectrum of cosmic rays between 10**16 eV and 10**18 eV, derived from measurements of the shower size (total number of charged particles) and the total muon number of extensive air showers by the KASCADE-Grande experiment, is…
The standard Bayesian model formalism comparison cannot be applied to most cosmological models as they lack well-motivated parameter priors. However, if the data-set being used is separable then it is possible to use some of the data to…
In models with extra dimensions the fundamental scale of gravity M_D could be of order TeV. In that case the interaction cross section between a cosmic proton of energy E and a dark matter particle \chi will grow fast with E for center of…
Recent observations of cosmic ray protons in the energy range $10^2$--$10^5$~GeV have revealed that the spectrum cannot be described by a simple power law. A hardening of the spectrum around an energy of order few hundred~GeV, first…
A generalized version of the Randall-Sundrum model-2 with different cosmological constants on each side of a brane has been discussed. A possibility of replacing the singular brane by a configuration of a scalar field has been also…
Our fundamental lack of understanding of the acceleration of the Universe suggests that we consider a kinematic description. The simplest formalism involves the third derivative of the scale factor through a jerk parameter. A new approach…
We analyze $pp$ total cross section data from accelerator to cosmic-ray energies and show that the experimental information presently available indicate two different scenarios at the highest energies. One of them accommodates the…