Related papers: Dark Radiation Emerging After Big Bang Nucleosynth…
We calculate primordial abundances of light elements produced during big bang nucleosynthesis when the fine structure constant and/or the cosmic expansion rate take non-standard values. We compare them with the recent values of observed D,…
The Cosmic Microwave Background Radiation (CMBR) is the radiation left over from the hot Big Bang. Its blackbody spectrum and small anisotropy provide clues about the origin and early evolution of the Universe. In particular, the spectrum…
These lecture notes comprise an informal but pedagogical introduction to the well established physics and phenomenology of the cosmic microwave background (CMB) between big bang nucleosynthesis and recombination. The dominant properties of…
The abundance and size distribution of quark nuggets (QN), formed a few microseconds after the big bang due to first order QCD phase transition in the early universe, has been estimated. It appears that stable QNs could be a viable…
Using the primordial helium abundance, an upper limit to the magnetic moments for Dirac neutrinos had been provided by imposing restrictions on the number of the additional helicity states. Considering non-thermal photons produced in the…
Preliminary results of a new set of stellar evolution and nucleosynthesis calculations for massive stars are presented. These results were obtained with an extended reaction network up to Bi. The discussion focuses on the importance of…
The astronomical dark matter could be made of weakly interacting and massive particles. If so, these species would be abundant inside the Milky Way, where they would continuously annihilate and produce cosmic rays. Those annihilation…
Big-bang nucleosynthesis is one of the cornerstones of the standard cosmology. For almost thirty years its predictions have been used to test the big-bang model to within a fraction of a second of the bang. The concordance that exists…
Previous studies have examined the holographic principle as a means of producing dark energy. Here we propose instead the possibility of holographic dark matter. In this case, dark matter does not arise in the framework of particle physics…
New measurements of the cosmic microwave background (CMB) by the Planck mission have greatly increased our knowledge about the Universe. Dark radiation, a weakly interacting component of radiation, is one of the important ingredients in our…
Recent cosmological observations indicate the existence of extra light species, i.e., dark radiation. In this paper we show that signatures of the dark radiation are imprinted in the spectrum of inflationary gravitational waves. If the dark…
The Big Bang Nucleosynthesis (BBN) model is a cornerstone for the understanding of the evolution of the early universe, making seminal predictions that are in outstanding agreement with the present observation of light element abundances in…
For the first time the antineutrino spectrum formed as a result of neutron and tritium decays during the epoch of primordial nucleosynthesis is calculated. This spectrum is a non-thermal increase in addition to the standard cosmic neutrino…
I review some of the basic information on the Cosmic Neutrino Background momentum distribution. In particular, I discuss how present data from several cosmological observables such as Big Bang Nucleosynthesis, Cosmic Microwave Background…
We propose a new out-of-equilibrium production mechanism of light dark matter: resonance scanning. If the dark matter mass evolved in the early Universe, resonant production may have occurred for a wide range of light dark matter masses…
The instability of dark matter may produce visible signals in the spectrum of cosmic gamma-rays. We consider this possibility in frameworks with additional spatial dimensions and supersymmetry. Examples of particles include…
Primordial nucleosynthesis, or Big-Bang Nucleosynthesis (BBN), is one of the three evidences for the Big-Bang model, together with the expansion of the Universe and the Cosmic Microwave Background. There is a good global agreement over a…
Recent studies of the cosmic microwave background, large scale structure, and big bang nucleosynthesis (BBN) show trends towards extra radiation. Within the framework of supersymmetric hadronic axion models, we explore two…
Gamma-ray bursts (GRBs) must originate from low baryon load, ultrarelativistic outflows; however, slower, more baryon-rich outflows (BROs) should also arise in connection with GRBs as ``circum-jet winds'' and/or ``failed GRBs''. We study…
In a popular class of models, dark matter comprises an asymmetric population of composite particles with short range interactions arising from a confined nonabelian gauge group. We show that coupling this sector to a well-motivated light…