Related papers: The Physics of Light Relics
Cosmological measurements of the radiation density in the early universe can be used as a sensitive probe of physics beyond the standard model. Observations of primordial light element abundances have long been used to place non-trivial…
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 hot dense environment of the early universe is known to have produced large numbers of baryons, photons, and neutrinos. These extreme conditions may have also produced other long-lived species, including new light particles (such as…
The light relic density affects the thermal and expansion history of the early Universe leaving a number of observable imprints. We focus on the primordial abundances of light elements produced during the process of Big Bang nucleosynthesis…
Many scenarios of physics beyond the standard model predict new light, weakly coupled degrees of freedom, populated in the early universe and remaining as cosmic relics today. Due to their high abundances, these relics can significantly…
The existence of big bang relic neutrinos - exact analogues of the big bang relic photons comprising the cosmic microwave background radiation - is a basic prediction of standard cosmology. At present, the observational evidence for their…
Cosmological data provide a powerful tool in the search for physics beyond the Standard Model (SM). An interesting target are light relics, new degrees of freedom which decoupled from the SM while relativistic. Nearly massless relics…
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 relic abundance and the scalar cross-section off nucleon for light neutralinos (of mass below about 45 GeV) are evaluated in an effective MSSM model without GUT-inspired relations among gaugino masses. It is shown that these neutralinos…
Future CMB experiments have the potential to probe the density of relativistic species at the sub-percent level. Sensitivity at this level allows light thermal relics to be detected up to arbitrarily high decoupling temperatures.…
The Standard Cosmological Model predicts the existence of relic neutrinos, which are indirectly probed through the effective number of relativistic species in the early Universe. In addition, from neutrino flavour oscillations we know that…
Light thermal relics of the hot big bang, often quantified by the parameter $N_\mathrm{eff}$, are one of the primary targets of cosmological measurements. At present, the energy density in such relics is constrained to be less than ten…
We use here a family of scaling transformations, that scale key rates in the evolution equations, to analytically understand constraints on light relics from cosmic microwave background (CMB) maps, given cosmological models of varying…
The combination of detections of anisotropy in the Cosmic Microwave Background radiation and observations of the large-scale distribution of galaxies probes the primordial density fluctuations of the universe on spatial scales varying by…
The presence of additional relativistic particles at the time of recombination can be inferred through their contribution to $\Delta N_{\rm eff}$. If these species have a finite but low mass (Light Massive Relics - LiMRs), they act as a hot…
A brief sketch is made of the present observational status of neutrino physics, with emphasis on the hints that follow from solar and atmospheric neutrino observations, as well as cosmological data on the amplitude of primordial density…
Neutrino oscillations present the only robust example of experimentally detected physics beyond the standard model. This review discusses the established and several hypothetical beyond standard models neutrino characteristics and their…
Extragalactic and galactic cosmic rays scatter with the cosmic neutrino background during propagation to Earth, yielding a flux of relic neutrinos boosted to larger energies. If an overdensity of relic neutrinos is present in galaxies, and…
The existence of a cosmic neutrino background -- the analogue of the cosmic microwave background -- is a fundamental prediction of standard big bang cosmology. Up to now, the observational evidence for its existence is rather indirect and…
Astrophysics and cosmology can be used to test the standard model of particle physics under conditions and over distance and time scales not accessible to laboratory experiments. Most of the astrophysical observations are in good agreement…