1,721,090 research outputs found
Breaking the symmetries in self-induced flavor conversions of neutrino beams from a ring
No full textSelf-induced flavor conversions of supernova neutrinos have been characterized in the spherically symmetric "bulb" model, reducing the neutrino evolution to a one-dimensional problem along a radial direction. We lift this assumption, presenting a two-dimensional toy model where neutrino beams are launched in many different directions from a ring. We find that self-interacting neutrinos spontaneously break the spatial symmetries of this model. As a result the flavor content and the lepton number of the neutrino gas would acquire sizable direction-dependent variations, breaking the coherent behavior found in the symmetric case. This finding would suggest that the previous results of the self-induced flavor evolution obtained in one-dimensional models should be critically reexamined
Multi-azimuthal-angle effects in self-induced supernova neutrino flavor conversions without axial symmetry
No full text
Temporal instability enables neutrino flavor conversions deep inside supernovae
Full text linkWe show that a self-interacting neutrino gas can spontaneously acquire a nonstationary pulsating component in its flavor content, with a frequency that can exactly cancel the "multiangle" refractive effects of dense matter. This can then enable homogeneous and inhomogeneous flavor conversion instabilities to exist even at large neutrino and matter densities, where the system would have been stable if the evolution were strictly stationary. Large flavor conversions, especially close to a supernova core, are possible via this novel mechanism. This may have important consequences for the explosion dynamics, nucleosynthesis, as well as for neutrino observations of supernovae
Damping of self-induced neutrino flavor transitions due to inhomogeneities
No full textSelf-induced neutrino flavor dynamics has been typically characterized assuming that either the time (in the core-collapse supernova environment) or space (in the early universe) homogeneity in the initial conditions is preserved through the evolution. In this talk we show that small deviations from an initial postulated homogeneity can be amplified by the interacting neutrino gas, leading to a new flavor instability. To this end, we consider a simple two flavor isotropic neutrino gas evolving in time, and initially composed by only νe and ν[U+203E]e with equal densities. In the homogeneous case, this system shows a bimodal instability in the inverted mass hierarchy scheme, leading to the well studied flavor pendulum behavior. To break space homogeneity, we introduce small amplitude space-dependent perturbations in the matter potential. We find that even for arbitrarily tiny inhomogeneities, the system evolution runs away from the stable pendulum behavior and the space-averaged ensemble evolves towards flavor equilibrium
Self-induced temporal instability from a neutrino antenna
No full textIt has been recently shown that the flavor composition of a self-interacting
neutrino gas can spontaneously acquire a time-dependent pulsating component
during its flavor evolution. In this work, we perform a more detailed study of
this effect in a model where neutrinos are assumed to be emitted in a
two-dimensional plane from an infinite line that acts as a neutrino antenna. We
consider several examples with varying matter and neutrino densities and find
that temporal instabilities with various frequencies are excited in a cascade.
We compare the numerical calculations of the flavor evolution with the
predictions of linearized stability analysis of the equations of motion. The
results obtained with these two approaches are in good agreement in the linear
regime, while a dramatic speed-up of the flavor conversions occurs in the
non-linear regime due to the interactions among the different pulsating modes.
We show that large flavor conversions can take place if some of the temporal
modes are unstable for long enough, and that this can happen even if the matter
and neutrino densities are changing, as long as they vary slowly
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