We derive for the first time an effective neutrino evolution Hamiltonian accounting for neutrino interactions with external magnetic field due to neutrino charge radii and anapole moment. The results are interesting for possible applications in astrophysics.
In our previous studies (see [1] and references therein) we developed a new theoretical framework that enabled one to consider a new mechanism of neutrino quantum decoherence engendered by the neutrino radiative decay. In parallel, another framework was developed (see [2] and references therein) for the description of the neutrino quantum decoherence due to the non-forward neutrino scattering processes. Both mechanisms are described by the master equations in the Lindblad form. We study the influence of the neutrino quantum decoherence on collective neutrino oscillations. In the present studies we are are not interested in a specific mechanism of neutrino quantum decoherence. Therefore, we use the general Lindblad master equation for the description of the neutrino quantum decoherence and do not fix an analytical expressions for the decoherence and relaxation parameters.
We study distances of propagation and the group velocities of the muon neutrinos in the presence of mixing and oscillations assuming that Lorentz invariance holds. Oscillations lead to distortion of the $ u_mu$ wave packet which, in turn, changes the group velocity and the distance $ u_mu$ travels. We find that the change of the distance, $d_{osc}$, is proportional to the length of the wave packet, $sigma_x$, and the oscillation phase, $phi_p$, acquired by neutrinos in the $pi-$ and $K-$ meson decay tunnel where neutrino wave packet is formed: $d_{osc} propto sigma phi_p$. Although the distance $d_{osc}$ may effectively correspond to the superluminal motion, the effect is too tiny ($sim 10^{- 5}$ cm) to be reconciled with the OPERA result. We analyze various possibilities to increase $d_{osc}$ and discuss experimental setups in which $d_{osc}$ (corresponding to the superluminal motion) can reach an observable value $sim 1$ m.
In the last decades, a very important breakthrough has been brought in the elementary particle physics by the discovery of the phenomenon of the neutrino oscillations, which has shown neutrino properties beyond the Standard Model. But a full understanding of the various aspects of the neutrino oscillations is far to be achieved. In this paper the theoretical background of the neutrino oscillation phenomenon is described, referring in particular to the paradigmatic models. Then the various techniques and detectors which studied neutrinos from different sources are discussed, starting from the pioneering ones up to the detectors still in operation and to those in preparation. The physics results are finally presented adopting the same research path which has crossed this long saga. The problems not yet fixed in this field are discussed, together with the perspectives of their solutions in the near future.
This letter proposes an alternative quantum mechanical picture for the observed phenomena of neutrino oscillations. It is assumed in the following that neutrinos interact via diabatic (or localised) interactions with a new particle field, which changes their flavor. Furthermore, it is assumed that each neutrino flavor state can only have a single associated mass thereby making them fundamental particles of nature. The effective masses associated with matter interactions replace the concept of neutrino mixing angles. Preliminary evidence that left-handed neutrinos and right-handed antineutrinos oscillate differently is presented, implying charge-parity violation. Given the apparent anomalous observations of some neutrino oscillation experiments, which have led to speculations about the existence of a fourth (sterile) neutrino, it is worth examining the oscillation behavior predicted by alternative mechanisms to determine if they more naturally explain the available data.