16,913 research outputs found
New optimized Schwarz algorithms for one dimensional Schr\"odinger equation with general potential
The aim of this paper is to develop new optimized Schwarz algorithms for the
one dimensional Schr{\"o}dinger equation with linear or nonlinear potential.
After presenting the classical algorithm which is an iterative process, we
propose a new algorithm for the Schr{\"o}dinger equation with time-independent
linear potential. Thanks to two main ingredients (constructing explicitly the
interface problem and using a direct method on the interface problem), the new
algorithm turns to be a direct process. Thus, it is free to choose the
transmission condition. Concerning the case of time-dependent linear potential
or nonlinear potential, we propose to use a pre-processed linear operator as
preconditioner which leads to a preconditioned algorithm. Numerically , the
convergence is also independent of the transmission condition. In addition,
both of these new algorithms implemented in parallel cluster are robust,
scalable up to 256 sub domains (MPI process) and take much less computation
time than the classical one, especially for the nonlinear case
Captures of Hot and Warm Sterile Antineutrino Dark Matter on EC-decaying Ho-163 Nuclei
Capturing low-energy electron antineutrinos on radioactive Ho-163 nuclei,
which decay into Dy-163 via electron capture (EC), is a noteworthy opportunity
to detect relic sterile antineutrinos. Such hypothetical particles are more or
less implied by current experimental and cosmological data, and they might be a
part of hot dark matter or a candidate for warm dark matter in the Universe.
Using the isotope Ho-163 as a target and assuming reasonable active-sterile
antineutrino mixing angles, we calculate the capture rate of relic electron
antineutrinos against the corresponding EC-decay background in the presence of
sterile antineutrinos at the sub-eV or keV mass scale. We show that the
signature of hot or warm sterile antineutrino dark matter should in principle
be observable, provided the target is big enough and the energy resolution is
good enough.Comment: 16 pages, 6 figures, more discussions and references added. To appear
in JCA
Periodic vortex shedding in the supersonic wake of a planar plate
Vortex sheets in the wake have been mainly studied in incompressible flows and in the transonic region. Heinemann et al. (1976) have shown that for the subsonic region the Strouhal number is nearly independent of the Mach number. Motallebi and Norbury (1981) have observed an increase in the Strouhal number in transonic supersonic flow at Mach numbers up to 1.25. The present investigation is concerned with an extension of the studies of vortex shedding to higher supersonic Mach numbers, taking into account questions regarding the possibility of a generation of stable von Karman vortex paths in the considered Mach number range. It is found that the vortex sheet observed in a supersonic wake behind a rough plate is only stable and reproducible in cases involving a certain surface roughness and certain aspects of trailing edge geometry
The parity of specular Andreev reflection under mirror operation in zigzag graphene ribbon
It is known that the parity of reflection amplitude can either be even or odd
under the mirror operation. Up to now, all the parities of reflection amplitude
in the one-mode energy region are even under the mirror operation. In this
paper, we give an example of odd parity for Andreev reflection (AR) in a
three-terminal graphene-supercondutor hybrid systems. We found that the parity
is even for the Andreev retroreflection (ARR) and odd for specular Andreev
reflection (SAR). We attribute this remarkable phenomenon to the distinct
topology of the band structure of graphene and the specular Andreev reflection
involving two energy bands with different parity symmetry. As a result of odd
parity of SAR, the SAR probability of a four-terminal system with two
superconducting leads (two reflection interfaces) can be zero even when the
system is asymmetric due to the quantum interference of two ARs.Comment: 11 pages, 3 figure
The Majorana Neutrino Mass Matrix with One Texture Zero and One Vanishing Eigenvalue
Possible patterns of the Majorana neutrino mass matrix with one texture
zero and one vanishing eigenvalue are classified and discussed. We find that
three one-zero textures of with and four one-zero textures of
with are compatible with current neutrino oscillation data. The
implications of these phenomenological anstze on the neutrino mass
spectrum and the neutrinoless double beta decay are also explored in some
detail.Comment: RevTex 10 pages (with 2 PS figues). More discussions and references
adde
Vanishing Effective Mass of the Neutrinoless Double Beta Decay?
We stress that massive neutrinos may be Majorana particles even if the
effective mass of the neutrinoless double beta decay m_ee vanishes. We show
that current neutrino oscillation data do allow m_ee = 0 to hold, if the
Majorana CP-violating phases lie in two specific regions. Strong constraints on
three neutrino masses can then be obtained. We find that the neutrino mass
spectrum performs a normal hierarchy: m_1 < m_2 < m_3. A possible texture of
the neutrino mass matrix is also illustrated under the m_ee = 0 condition.Comment: RevTex 9 pages (2 PS figures included). More discussions and
references added. Results partly changed. To appear in Phys. Rev.
Can the Lepton Flavor Mixing Matrix Be Symmetric?
Current neutrino oscillation data indicate that the 3x3 lepton flavor mixing
matrix V is likely to be symmetric about its V_{e3}-V_{\mu 2}-V_{\tau 1} axis.
This off-diagonal symmetry corresponds to three pairs of {\it congruent}
unitarity triangles in the complex plane. Terrestrial matter effects can
substantially modify the genuine CP-violating parameter and off-diagonal
asymmetries of V in realistic long-baseline experiments of neutrino
oscillations.Comment: RexTex 14 pages (4 PS figures). More discussions adde
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