Related papers: Cosmological abundances of right-handed Dirac neut…
We study the equilibration of the right-helicity states of light Dirac neutrinos in the early universe by solving the momentum dependent Boltzmann equations numerically. We show that the main effect is due to electroweak gauge boson poles,…
We consider the equilibration of the 'wrong--helicity' Dirac neutrino states $\nu_{+}$ and $\overline\nu_{-}$ in the early Universe via weak interactions and calculate carefully the thermally averaged production rate, taking into account…
Relic neutrinos from the Big Bang decoupled from the hot plasma predominantly in helicity eigenstates. Their subsequent propagation through gravitational inhomogeneities of the Universe alters the helicities of both Dirac and Majorana…
We investigate the neutrino helicity-flip process under supernova core conditions, where the left-handed neutrinos being produced can be converted into right-handed neutrinos sterile with respect to the weak interaction due to the…
We consider random primordial magnetic fields and discuss their dissipation, coherence length $L_0$, scaling behaviour and constraints implied by the primoridal nucleosynthesis. Such magnetic fields could excite the right-helicity states of…
We derive new bounds on the Dirac mass of the tau and muonic neutrinos. By solving the kinetic equation for the rate of energy deposition due to helicity flipping processes and imposing the constraint that the number of effective species…
If neutrinos are Dirac particles the existence of light right-handed neutrinos $\nu_{R}$ is implied. Those would contribute to the effective number of relativistic neutrino species $N_{{\rm eff}}$ in the early Universe. With pure standard…
Quantum-mechanical calculations of transitions dynamics between the left- and right-handed helicity states of the atmospheric muon Dirac neutrino,which has a gravitoelectrical dipole moment (GEDM) interacting with the gravitational field of…
A sizable magnetic moment for neutrinos would be evidence of exotic physics. In the early Universe, left-handed neutrinos with a magnetic moment would interact with electromagnetic fields in the primordial plasma, flipping their helicity…
The helicity evolution of a neutrino interacting with randomly moving and polarized matter is studied. We derive the equation for the averaged neutrino helicity. The type of the neutrino interaction with background fermions is not fixed. In…
For Dirac neutrinos with magnetic moment, we compute the production rate for right-handed neutrinos in a hot and dense QED plasma containing an initial population of left-handed neutrinos thermally distributed. The most important mechanisms…
We quantify the effects of light spin-zero particles with pseudoscalar couplings to leptons and scalar couplings to nucleons on the evolution of solar neutrinos. In this scenario the matter potential sourced by the nucleons in the Sun's…
Motivated by the stringent flux limits for UHE neutrinos coming from gamma ray burst or active galactic nuclei, we explore the possibility that the active neutrinos generated in such astrophysical objects could oscillate to sterile right…
The existence of a neutrino magnetic moment implies contributions to the neutrino mass via radiative corrections. We derive model-independent "naturalness" upper bounds on the magnetic moments of Dirac neutrinos, generated by physics above…
We discuss Dirac neutrinos whose right-handed component $\nu_R$ has new interactions that may lead to a measurable contribution to the effective number of relativistic neutrino species $N_{\rm eff}$. We aim at a model-independent and…
A version of the $\mbox{SU(3)}_L\otimes \mbox{U(1)}_N$ electroweak theory in which there are right-handed neutrino currents is reconsidered in detail. We argue that in order to have a result consistent with low-energy one, the right-handed…
If neutrinos are Dirac particles and, as suggested by the so far null LHC results, any new physics lies at energies well above the electroweak scale, the Standard Model effective field theory has to be extended with operators involving the…
The neutrino role in primordial nucleosynthesis is reviewed. The importance of nonequilibrium effects is emphasized both for the standard massless and possibly massive neutrinos. The upper bound on tau neutrino mass is presented. A spatial…
Neutrino with magnetic moment can experience a chirality flip while scattering off charged particles. This effect may lead to important consequences for the dynamics and the neutrino signal of the core-collapse supernova. It is known that…
We improve limits on $Z^\prime$ extensions of the Standard Model (SM) with light right-handed neutrinos. The presence of shared gauge interactions between the light right-handed neutrinos and other SM fermions allows for production of…