相关论文: A Cosmological Three Level Neutrino Laser
In the early universe, neutrinos decouple from equilibrium with the electromagnetic plasma at a temperature which is only slightly higher than the temperature where electrons and positrons annihilate. Therefore neutrinos to some extent…
We consider the consequences for the relic neutrino abundance if extra neutrino interactions are allowed, e.g., the coupling of neutrinos to a light (compared to $m_\nu$) boson. For a wide range of couplings not excluded by other…
Neutrino mass generation may affect the basic structure of the electroweak symmetry breaking sector. We consider a broad class of elementary particle theories where neutrinos get mass at a low mass scale. We show how these can be made…
Superradiance emerges from collective spontaneous emission in optically pumped gases, and is characterized by photon emission enhancements of up to $\frac{1}{4}N^{2}$ in an $N$ atom system. The gain mechanism derives from correlations…
We re-investigate the evolution of the strongly degenerate neutrinos in the early universe. With the larger degeneracy, the neutrino number freezes at higher temperatures because the neutrino annihilation rate decreases. We consider very…
Neutrinos are perhaps the most elusive known particles in the universe. We know they have some nonzero mass, but unlike all other particles, the absolute scale remains unknown. In addition, their fundamental nature is uncertain; they can…
Considering neutrinos as time-like leptons one may estimate the three-body decay probability of muon neutrinos in long base-line accelerator experiments. In the extreme assumption of time-space symmetry the absolute value of the…
At present, the strongest upper limit on $\sum m_{\nu}$, the sum of neutrino masses, is from cosmological measurements. However, this bound assumes that the neutrinos are stable on cosmological timescales, and is not valid if the neutrino…
Neutrinos can play an important role in the evolution of the Universe, modifying some of the cosmological observables. In this contribution we summarize the main aspects of cosmological relic neutrinos and we describe how the precision of…
We have examined the consequences of assuming the existence of a light scalar boson, weakly coupled to neutrinos, and not coupled to any other light fermions. For a range of parameters, we find that this hypothesis leads to the development…
We investigate the potential of short-baseline experiments in order to measure the dispersion relation of the (muon) neutrino, with a prospect of eventually measuring the neutrino mass. As a byproduct, the experiment would help to constrain…
Precision measurements of the acoustic peaks of the cosmic microwave background indicate that neutrinos must be freely streaming at the photon decoupling epoch when T ~ 0.3 eV. This requirement implies restrictive limits on ``secret…
In a new measurement on neutrino oscillation $\nu_{\mu}\to\nu_e$, the MiniBooNE Collaboration observes an excess of electron-like events at low energy and the phenomenon may demand an explanation which obviously is beyond the oscillation…
Future cosmological data may be sensitive to the effects of a finite sum of neutrino masses even as small as ~0.06 eV, the lower limit guaranteed by neutrino oscillation experiments. We show that a cosmological detection of neutrino mass at…
The observed excess of high-energy cosmic rays from the Galactic plane in the energy range \sim 10^18 eV may be naturally explained by neutron primaries generated in the photo-dissociation of heavy nuclei. In this scenario, neutrons with…
In this paper, we examine the possibility that massive neutrinos are unstable due to their invisible decays $\nu^{}_i \to \nu^{}_j + \phi$, where $\nu^{}_i$ and $\nu^{}_j$ (for $i, j = 1, 2, 3$) are any two of neutrino mass eigenstates with…
The case for small neutrino mass differences from atmospheric and solar neutrino oscillation experiments has become compelling, but leaves the overall neutrino mass scale m_nu undetermined. The most restrictive limit of m_nu < 0.8 eV arises…
Future direct observations of the Cosmic Neutrino Background (C$\nu$B) have the potential to explore a neutrino lifetime, especially in the region of the age of the universe, $t_0=4.35\times 10^{17}\ {\rm s}$. We forecast constraints on…
We investigate decays of hypothetical unstable new physics particles into metastable species such as muons, pions, or kaons in the Early Universe, when temperatures are in the MeV range, and study how they affect cosmic neutrinos. We…
Dark matter (DM), in spite of being stable or long-lived on cosmological scales, can decay in the early Universe due to finite-temperature effects. In particular, a first order phase transition (FOPT) in the early Universe can provide a…