Related papers: Are cosmological neutrinos free-streaming?
We study the neutrino distributions that arise in a simulation of a neutron star merger that uses a Monte Carlo (MC) neutrino transport scheme. In a snapshot taken 1 ms after merger, we calculate relevant observables to test when neutrinos…
We discuss several pairing-related phenomena in nuclear systems, ranging from superfluidity in neutron stars to the gradual breaking of pairs in finite nuclei. We describe recent experimental evidence that points to a relation between…
Assuming that neutrinos are spacelike (tachyonic) fermions, we calculate width for the kinematically allowed, lepton number conserving, three-body decay $\nu_{\alpha}\rightarrow \nu_{\alpha} \; \nu_{\beta} \bar{\nu}_{\beta}$ in the Standard…
The cold dark matter may be in a meta-stable state and decays to other particles with a very long lifetime. If the decaying products of the dark matter are weakly interacting, e.g. neutrinos, then it would have little impact on…
A massive particle decaying into neutrinos in the early Universe is known to be less constrained than if it was decaying into other standard model particles. However, even if the decay proceeds into neutrinos, the latter still inevitably…
The existence of two sterile neutrinos $\nu_s$ and $\nu'_s$ (blind to all Standard-Model interactions) is shown to be implied by a model of fermion "texture" that we develop since some time. They may mix nearly maximally with two of three…
Cosmic reionization is expected to be complex, extended and very inhomogeneous. Existing constraints at z~6 on the volume-averaged neutral hydrogen fraction, <x_HI>, are highly model-dependent and controversial. Constraints at z<6,…
We review the distortions of spectra of relic neutrinos due to the interactions with electrons, positrons, and neutrinos in the early universe. We solve integro-differential kinetic equations for the neutrino density matrix, including…
Sterile neutrinos can be produced through mixing with active neutrinos in the hot, dense core of a core-collapse supernova (SN). The standard bounds on the active-sterile mixing ($\sin^2 \theta$) from SN arise from SN1987A energy-loss,…
Decaying topological defects, in particular cosmic strings, can produce a significant flux of high energy neutrinos, photons and cosmic rays. According to the prevailing understanding of cosmic string dynamics in an expanding Universe, the…
A search for extremely high energy cosmic neutrinos has been carried out with the IceCube Neutrino Observatory. The main signals in the search are neutrino-induced energetic charged leptons and their rate depends on the neutrino-nucleon…
We show that there is no one-loop enhancement of the rate for a light neutrino to decay into a lighter neutrino plus a majoron, contrary to a recent claim. Thus the light neutrinos must satisfy the cosmological bound of having masses less…
Cosmological implications of neutrinos are reviewed. The subjects considered involve: (a) bounds on neutrino mass from the observational limits on the universe age and the Hubble constant both in cosmology with and without cosmological…
Sterile neutrinos arise naturally in extensions of the Standard Model and can affect cosmological evolution even with subdominant abundance. Their impact is often described by a constant shift in the effective number of relativistic…
The observation of astrophysical neutrinos requires a detailed understanding of the atmospheric neutrino background. Since neutrinos are produced in meson decays together with a charged lepton, important constraints on this background can…
We investigate the possibility that neutrinos form superfluid-type condensates in background cosmological densities. Such condensates could give rise to small neutrino masses and splittings, as well as an important contribution, perhaps, to…
We reanalyze the cosmological constraints on the existence of a net universal lepton asymmetry and neutrino degeneracy. We show that neutrinos can begin to decouple at higher temperatures than previous estimates due to several corrections…
We discuss the phenomenological implications of the neutron (n) oscillation into the mirror neutron (n'), a hypothetical particle exactly degenerate in mass with the neutron but sterile to normal matter. We show that the present…
The most stringent bounds on the absolute neutrino mass scale come from cosmological data. These bounds are made possible because massive relic neutrinos affect the expansion history of the universe and lead to a suppression of matter…
We derive general constraints on the relic abundances of a long-lived particle which mainly decays into a neutrino (and something else) at cosmological time scales. Such an exotic particle may show up in various particle-physics models…