8,487 research outputs found
Analytic Solutions to the RG Equations of the Neutrino Physical Parameters
In the case of two generation neutrinos, the energy-scale dependence of the
lepton-flavor mixing matrix with Majorana phase can be governed by only one
parameter r, which is the ratio between the diagonal elements of neutrino mass
matrix. By using this parameter r, we derive the analytic solutions to the
renormalization group equations of the physical parameters, which are the
mixing angle, Majorana phase, and the ratio of the mass-squared difference to
the mass squared of the heaviest neutrino. The energy-scale dependence of the
Majorana phase is clarified by using these analytic solutions. The instability
of the Majorana phase causes in the same parameter region in which the mixing
angle is unstable against quantum corrections.Comment: LaTeX2e, 9 pages, 6 figure
The effects of Majorana phases in three-generation neutrinos
Neutrino-oscillation solutions for the atmospheric neutrino anomaly and the
solar neutrino deficit can determine the texture of the neutrino mass matrix
according to three types of neutrino mass hierarchies as Type A: ,
Type B: , and Type C: , where is the -th generation neutrino absolute mass. The
relative sign assignments of neutrino masses in each type of mass hierarchies
play the crucial roles for the stability against quantum corrections. Actually,
two physical Majorana phases in the lepton flavor mixing matrix connect among
the relative sign assignments of neutrino masses. Therefore, in this paper we
analyze the stability of mixing angles against quantum corrections according to
three types of neutrino mass hierarchies (Type A, B, C) and two Majorana
phases. Two phases play the crucial roles for the stability of the mixing
angles against the quantum corrections.Comment: LaTeX2e, 15 pages, 8 figure
Are lepton flavor mixings in the democratic mass matrix stable against quantum corrections?
We investigate whether the lepton flavor mixing angles in the so-called
democratic type of mass matrix are stable against quantum corrections or not in
the minimal supersymmetric standard model with dimension five operator which
induces neutrino mass matrix. By taking simple breaking patterns of or flavor symmetries and the scale where
democratic textures are induced as GeV, we find that the stability
of the lepton flavor mixing angles in the democratic type of mass matrix
against quantum corrections depends on the solar neutrino solutions. The
maximal flavor mixing of the vacuum oscillation solution is spoiled by the
quantum corrections in the experimental allowed region of . The
large angle MSW solution is spoiled by the quantum corrections in the region of
. The condition of is needed in order to
obtain the suitable mass squared difference of the small angle MSW solution.
These strong constraints must be regarded for the model building of the
democratic type of mass matrixComment: 12pages,LaTe
The effect of Majorana phase in degenerate neutrinos
There are physical Majorana phases in the lepton flavor mixing matrix when
neutrinos are Majorana fermions. In the case of two degenerate neutrinos, the
physical Majorana phase plays the crucial role for the stability of the maximal
flavor mixing between the second and the third generations against quantum
corrections. The physical Majorana phase of guarantees the maximal mixing
to be stable against quantum corrections, while the Majorana phase of zero lets
the maximal mixing be spoiled by quantum corrections when neutrino masses are
of O(eV). The continuous change of the Majorana phase from to 0 makes the
maximal mixing be spoiled by quantum corrections with O(eV) degenerate neutrino
masses. On the other hand, when there is the large mass hierarchy between
neutrinos, the maximal flavor mixing is not spoiled by quantum corrections
independently of the Majorana phase.Comment: 7 pages, 1 figures, LaTe
Energy-Scale Dependence of the Lepton-Flavor-Mixing Matrix
We study an energy-scale dependence of the lepton-flavor-mixing matrix in the
minimal supersymmetric standard model with the effective dimension-five
operators which give the masses of neutrinos. We analyze the renormalization
group equations of kappa_{ij}s which are coefficients of these effective
operators under the approximation to neglect the corrections of O(\kappa^2). As
a consequence, we find that all phases in do not depend on the
energy-scale, and that only n_g-1 (n_g: generation number) real independent
parameters in the lepton-flavor-mixing matrix depend on the energy-scale.Comment: 6 pages, no figur
Si/Ge hole-tunneling double-barrier resonant tunneling diodes formed on sputtered flat Ge layers
We have demonstrated Si/Ge hole-tunneling double-barrier resonant tunneling diodes (RTDs) formed on flat Ge layers with a relaxation rate of 89% by our proposed method; in this method, the flat Ge layers can be directly formed on highly B-doped Si(001) substrates using our proposed sputter epitaxy method. The RTDs exhibit clear negative differential resistance effects in the static current–voltage (I–V) curves at room temperature. The quantized energy level estimation suggests that resonance peaks that appeared in the I–V curves are attributed to hole tunneling through the first heavy- and light-hole energy levels
Spectroscopic Observation on the Combustion Characteristics of Japanese Traditional Oil Lamp
In this research, spectroscopic measurement has been made to investigate the combustion characteristics of a Japanese traditional oil lamp, called toumyou, that has been used since ancient periods until present. Combustion characteristics, i.e. flame stability and temperature, were analyzed by using a temperature video camera. Spectral emission intensity of hydroxyl (OH) radical (band head of 310 nm) was measured by using a UV-visible spectrometer and visualized by a CCD camera while the brightness was measured using a lux meter. The experimental result showed that the flames of vegetable oils burned were stable and temperatures ranged over about 1000-2500ºC. In addition, the emission intensity of OH radical was successfully detected by the UV-visible spectrometry and visualized by the CCD Camera. The emission intensities of OH radical from flames of coconut oil and palm oil were higher than those of other tested vegetable oils. From measurement using a lux meter, it was obtained that coconut oil gives the brightest flame
Void-induced cross slip of screw dislocations in fcc copper
Pinning interaction between a screw dislocation and a void in fcc copper is
investigated by means of molecular dynamics simulation. A screw dislocation
bows out to undergo depinning on the original glide plane at low temperatures,
where the behavior of the depinning stress is consistent with that obtained by
a continuum model. If the temperature is higher than 300 K, the motion of a
screw dislocation is no longer restricted to a single glide plane due to cross
slip on the void surface. Several depinning mechanisms that involve multiple
glide planes are found. In particular, a depinning mechanism that produces an
intrinsic prismatic loop is found. We show that these complex depinning
mechanisms significantly increase the depinning stress
Seasonal variation of the transport of black carbon aerosol from the Asian continent to the Arctic during the ARCTAS aircraft campaign
Extensive measurements of black carbon (BC) aerosol were conducted in and near the North American Arctic during the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) aircraft campaign in April and June-July 2008. We identify the pathways and mechanisms of transport of BC to the Arctic from the Asian continent using these data. The concentration, transport efficiency, and measured altitude of BC over the North American Arctic were highly dependent on season and origin of air parcels, e.g., biomass burning (BB) in Russia (Russian BB) and anthropogenic (AN) in East Asia (Asian AN). Russian BB air was mainly measured in the middle troposphere and caused maximum BC concentrations at this altitude in spring. The median BC concentration and transport efficiency of the Russian BB air were 270 ng m -3 (at STP) and 80% in spring and 20 ng m-3 and 4% in summer, respectively. Asian AN air was measured most frequently in the upper troposphere, with median values of 20 ng m-3 and 13% in spring and 5 ng m-3 and 0.8% in summer. These distinct differences are explained by differences in the transport mechanisms and accumulated precipitation along trajectories (APT), which is a measure of wet removal processes during transport. The transport of Russian BB air to the Arctic was nearly isentropic with slow ascent (low APT), while Asian AN air underwent strong uplift associated with warm conveyor belts (high APT). The APT values in summer were much larger than those in spring due to the increase in humidity in summer. These results show that the impact of BC emitted from AN sources in East Asia on the Arctic was very limited in both spring and summer. The BB emissions in Russia in spring are demonstrated to be the most important sources of BC transported to the North American Arctic. Copyright 2011 by the American Geophysical Union
- …
