相关论文: Precision Neutrino Counting
One of the primary targets of current and future cosmological observations are light thermal relics of the hot big bang. Within the Standard Model of particle physics, an important thermal relic are cosmic neutrinos, while interesting…
The last parameter of big-bang nucleosynthesis, the baryon density, is being pinned down by measurements of the deuterium abundance in high-redshift hydrogen clouds. When it is determined, it will fix the primeval light-element abundances.…
Massive neutrinos have a detectable effect on cosmological structure formation, in particular on the large-scale distribution of galaxies. Adding Hot Dark Matter to the now-standard Lambda CDM model leads to a worse fit to large-scale…
Primordial or big bang nucleosynthesis (BBN) is one of the three historical strong evidences for the big bang model. Standard BBN is now a parameter free theory, since the baryonic density of the Universe has been deduced with an…
The primordial abundances of deuterium, helium-3, helium-4, and lithium-7 probe the baryon density of the Universe only a few minutes after the Big Bang. Of these relics from the early Universe, deuterium is the baryometer of choice. After…
A new class of neutrino dark energy models is presented. The new models are characterized by the lack of exotic particles or couplings that violate the standard model symmetry. It is shown that these models lead to several concrete…
We revisit several aspects of Standard Model physics at finite temperature that drive the theoretical value of the cosmological parameter $N_{\rm eff}$, the effective number of neutrinos in the early universe, away from 3. Our chief focus…
Neutrinos are amongst the most abundant particles in the universe. The fact that they are massive particles proves that the Standard Model is an incomplete theory and needs to be extended. This thesis focuses on the study of neutrino…
We quantify the extent to which extra relativistic energy density can be concealed by a neutrino asymmetry without conflicting with the baryon asymmetry measured by the Wilkinson Microwave Anisotropy Probe (WMAP). In the presence of a large…
The Hubble expansion of galaxies, the $2.73\dK$ blackbody radiation background and the cosmic abundances of the light elements argue for a hot, dense origin of the universe --- the standard Big Bang cosmology --- and enable its evolution to…
A critical review is given of the current status of cosmological nucleosynthesis. In the framework of the standard model with 3 types of relativistic neutrinos, the baryon-to-photon ratio, \eta, corresponding to the inferred primordial…
We have derived new bounds on the relativistic energy density in the Universe from cosmic microwave background (CMB), large scale structure (LSS), and type Ia supernova (SNI-a) observations. In terms of the effective number of neutrino…
The standard Big Bang cosmology predicts the existence of an, as yet undetected, relic neutrino background, similar to the photons observed in the cosmic microwave background. If neutrinos have mass, then such relic neutrinos are a natural…
The laws of thermodynamics in the expanding universe are formulated within the quasi-metric framework. Since the quasi-metric cosmic expansion does not directly influence momenta of material particles, so that the expansion directly cools…
Big Bang Nucleosynthesis provides us with an observational insight into the very early Universe. Since this mechanism of light element synthesis comes out of the standard model of particle cosmology which follows directly from General…
We calculate the evolution of the early universe through the epochs of weak decoupling, weak freeze-out and big bang nucleosynthesis (BBN) by simultaneously coupling a full strong, electromagnetic, and weak nuclear reaction network with a…
The cosmic neutrino background (CNB) consists of low-energy relic neutrinos which decoupled from the cosmological fluid at a redshift z ~ 10^{10}. Despite being the second-most abundant particles in the universe, direct observation remains…
Primordial magnetic fields and massive neutrinos can leave an interesting signal in the CMB temperature and polarization. We perform a systematic analysis of general perturbations in the radiation-dominated universe, accounting for any…
In the standard hot big bang model, the expansion of the early universe is given by the Friedmann equation with an energy density dominated by relativistic particles. Since in a variety of models this equation is altered, we introduce…
We show that a self-consistent and coupled treatment of the weak decoupling, big bang nucleosynthesis, and photon decoupling epochs can be used to provide new insights and constraints on neutrino sector physics from high-precision…