1,356 research outputs found
Translating solitons of mean curvature flow of noncompact spacelike hypersurfaces in Minkowski space
In this paper, we study the existence, uniqueness and asymptotic behavior of
rotationally symmetric translating solitons of the mean curvature flow in
Minkowski space. We also study the asymptotic behavior and the strict convexity
of general solitons of such flows.Comment: 16page
Neutrino flavor instabilities in a time-dependent supernova model
A dense neutrino medium such as that inside a core-collapse supernova can
experience collective flavor conversion or oscillations because of the
neutral-current weak interaction among the neutrinos. This phenomenon has been
studied in a restricted, stationary supernova model which possesses the
(spatial) spherical symmetry about the center of the supernova and the
(directional) axial symmetry around the radial direction. Recently it has been
shown that these spatial and directional symmetries can be broken spontaneously
by collective neutrino oscillations. In this paper we analyze the neutrino
flavor instabilities in a time-dependent supernova model. Our results show that
collective neutrino oscillations start at approximately the same radius in both
the stationary and time-dependent supernova models unless there exist very
rapid variations in local physical conditions on timescales of a few
microseconds or shorter. Our results also suggest that collective neutrino
oscillations can vary rapidly with time in the regimes where they do occur
which need to be studied in time-dependent supernova models.Comment: 5 pages, 2 figures, version to appear in PL
Flavor instabilities in the neutrino line model
A dense neutrino medium can experience collective flavor oscillations through
nonlinear neutrino-neutrino refraction. To make this multi-dimensional flavor
transport problem more tractable, all existing studies have assumed certain
symmetries (e.g., the spatial homogeneity and directional isotropy in the early
universe) to reduce the dimensionality of the problem. In this work we show
that, if both the directional and spatial symmetries are not enforced in the
neutrino line model, collective oscillations can develop in the physical
regimes where the symmetry-preserving oscillation modes are stable. Our results
suggest that collective neutrino oscillations in real astrophysical
environments (such as core-collapse supernovae and black-hole accretion discs)
can be qualitatively different from the predictions based on existing models in
which spatial and directional symmetries are artificially imposed.Comment: 5 pages, 1 figur
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