8,407 research outputs found
Electron Mass Enhancement due to Anharmonic Local Phonons
In order to understand how electron effective mass is enhanced by anharmonic
local oscillation of an atom in a cage composed of other atoms, i.e., {\it
rattling}, we analyze anharmonic Holstein model by using a Green's function
method. Due to the evaluation of an electron mass enhancement factor , we
find that becomes maximum when zero-point energy is comparable with
potential height at which the amplitude of oscillation is rapidly enlarged.
Cooperation of such quantum and rattling effects is considered to be a key
issue to explain the electron mass enhancement in electron-rattling systems.Comment: 3 pages, 3 figures, to appear in J. Phys. Soc. Jpn. Suppl.
(Proceedings for International Conference on Heavy Electrons
Flavor changing neutrino interactions and CP violation in neutrino oscillations
We investigate the interference effects of non-standard neutrino-matter
interactions (NSNI) with the mass-induced neutrino oscillations. The NSNI is
composed of flavor-changing neutrino interactions (FCNI) and flavor-diagonal
neutrino interactions (FDNI). Both of the interactions are introduced in the
\nu_\mu -\nu_\tau sector and the \nu_e -\nu_\mu sector in order to study their
effects in \nu_\mu\to\nu_\tau and \nu_\mu\to\nu_e oscillations, respectively.
The FCNI effect proves to possibly dominate the CP violating effect and
significantly survive as a fake CP violating effct in the neutrino energy
region where the pure CP violating effect, ordinary matter effect and FDNI
effect fall, for example, above 4 GeV at the baseline of L=730 km in the
\nu_\mu\to\nu_\tau oscillation for the maximum parameter values of FCNI and
FDNI allowed by the atmospheric neutrino oscillation data. The FCNI and FDNI
effects on CP violation in the oscillation are negligibly
small due to the stringent constraints on FCNI from the bounds on lepton flavor
violating processes and on FDNI from the limits on lepton universality
violation.Comment: 18 pages in LaTeX2e, 12 ps figures. The discussion of detectability
of the CP violation is delete
A possible route to spontaneous reduction of the heat conductivity by a temperature gradient driven instability in electron-ion plasmas
We have shown that there exists low-frequency growing modes driven by a
global temperature gradient in electron and ion plasmas, by linear perturbation
analysis within the frame work of plasma Kinetic theory. The driving force of
the instability is the local deviation of the distribution function from the
Maxwell-Boltzmann due to global temperature gradient. Application to the
intracluster medium shows that scattering of the particles due to waves excited
by the instability is possible to reduce mean free paths of electron and ion
down to five to seven order of magnitude than the mean free paths due to
Coulomb collisions. This may provide a hint to explain why hot and cool gas can
co-exist in the intracluster medium in spite of the very short evaporation time
scale due to thermal conduction if the conductivity is the classical Spitzer
value. Our results suggest that the realization of the global thermal
equilibrium is postponed by the local instability which is induced for quicker
realization of local thermal equilibrium state in plasmas. The instability
provides a new possibility to create and grow cosmic magnetic fields without
any seed magnetic field.Comment: Accepted for publication in ApJ: 16 pages, 1figur
Diversity and altitudinal niche width characteristics for 35 taxa of the Papua New Guinea Frullania flora with consideration of sibling pairs
The Frullania taxa on Mount Albert Edward, Papua New Guinea, form many associations that suggest a high degree of niche similarity, but at different altitudes, different associations form. The species diversity of the genus is greatest at the middle altitudes and least in the dry lowlands. This altitudinal separation is apparent in the niche widths of the taxa. The members of the four sibling taxa pairs examined exhibit distinct altitudinal niches, suggesting that the sibling taxa are distinct, with different niche optima
Transition density of diffusion on Sierpinski gasket and extension of Flory's formula
Some problems related to the transition density u(t,x) of the diffusion on
the Sierpinski gasket are considerd, based on recent rigorous results and
detailed numerical calculations. The main contents are an extension of Flory's
formula for the end-to-end distance exponent of self-avoiding walks on the
fractal spaces, and an evidence of the oscillatory behavior of u(t,x) on the
Sierpinski gasket.Comment: 11 pages, REVTEX, 2 postscript figure
Gas, Iron and Gravitational Mass in Galaxy Clusters: The General Lack of Cluster Evolution at z < 1.0
We have analyzed the ASCA data of 29 nearby clusters of galaxies
systematically, and obtained temperatures, iron abundances, and X-ray
luminosities of their intracluster medium (ICM). We also estimate ICM mass
using the beta model, and then evaluate iron mass contained in the ICM and
derive the total gravitating mass. This gives the largest and most homogeneous
information about the ICM derived only by the ASCA data. We compare these
values with those of distant clusters whose temperatures, abundances, and
luminosities were also measured with ASCA, and find no clear evidence of
evolution for the clusters at z<1.0. Only the most distant cluster at z=1.0,
AXJ2019.3+1127, has anomalously high iron abundance, but its iron mass in the
ICM may be among normal values for the other clusters, because the ICM mass may
be smaller than the other clusters. This may suggest a hint of evolution of
clusters at z ~ 1.0.Comment: 23 pages including 5 figures. Using PASJ2.sty, and PASJ95.sty.
Accepted by PAS
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