5,360 research outputs found
Interplanetary magnetic fields as a cause of comet tails
Interplanetary magnetic fields as cause of comet tail
The Importance of Parity-Dependence of the Nuclear Level Density in the Prediction of Astrophysical Reaction Rates
A simple description for obtaining the parity distribution of nuclear levels
in the pf + g9/2 shell as a function of excitation energy was recently derived.
We implement this in a global nuclear level density model. In the framework of
the statistical model, cross sections and astrophysical reaction rates are
calculated in the Fe region and compared to rates obtained with the common
assumption of an equal distribution of parities. We find considerable
differences, especially for reactions involving particles in the exit channel.Comment: 4 pages, to appear in the proceedings of CGS11 (Prague), World
Scientifi
A Test of CPT Symmetry in K^0 vs \bar{K}^0 to \pi^+\pi^-\pi^0 Decays
I show that the CP-violating asymmetry in K^0 vs \bar{K}^0 \to
\pi^+\pi^-\pi^0 decays differs from that in K_L \to \pi^+\pi^-, K_L \to
\pi^0\pi^0 or the semileptonic K_L transitions, if there exists CPT violation
in K^0-\bar{K}^0 mixing. A delicate measurement of this difference at a super
flavor factory (e.g., the \phi factory) will provide us with a robust test of
CPT symmetry in the neutral kaon system.Comment: 4 pages, 1 figure. To appear in the Proceedings of the International
PHIPSI09 Workshop, October 2009, Beijing, Chin
Binomial level densities
It is shown that nuclear level densities in a finite space are described by a
continuous binomial function, determined by the first three moments of the
Hamiltonian, and the dimensionality of the underlying vector space.
Experimental values for Mn, Fe, and Ni are very well
reproduced by the binomial form, which turns out to be almost perfectly
approximated by Bethe's formula with backshift. A proof is given that binomial
densities reproduce the low moments of Hamiltonians of any rank: A strong form
of the famous central limit result of Mon and French. Conditions under which
the proof may be extended to the full spectrum are examined.Comment: 4 pages 2 figures Second version (previous not totally superseeded
Natural extensions and entropy of -continued fractions
We construct a natural extension for each of Nakada's -continued
fractions and show the continuity as a function of of both the entropy
and the measure of the natural extension domain with respect to the density
function . In particular, we show that, for all , the product of the entropy with the measure of the domain equals .
As a key step, we give the explicit relationship between the -expansion
of and of
AKARI Near- to Mid-Infrared Imaging and Spectroscopic Observations of the Small Magellanic Cloud. I. Bright Point Source List
We carried out a near- to mid-infrared imaging and spectroscopic observations
of the patchy areas in the Small Magellanic Cloud using the Infrared Camera on
board AKARI. Two 100 arcmin2 areas were imaged in 3.2, 4.1, 7, 11, 15, and 24
um and also spectroscopically observed in the wavelength range continuously
from 2.5 to 13.4 um. The spectral resolving power (lambda/Delta lambda) is
about 20, 50, and 50 at 3.5, 6.6 and 10.6 um, respectively. Other than the two
100 arcmin2 areas, some patchy areas were imaged and/or spectroscopically
observed as well. In this paper, we overview the observations and present a
list of near- to mid-infrared photometric results, which lists ~ 12,000
near-infrared and ~ 1,800 mid-infrared bright point sources detected in the
observed areas. The 10 sigma limits are 16.50, 16.12, 13.28, 11.26, 9.62, and
8.76 in Vega magnitudes at 3.2, 4.1, 7, 11, 15, and 24 um bands, respectively.Comment: 16 pages, 7 figures, accepted for publication in PASJ. Full
resolution version is available at
http://www-irc.mtk.nao.ac.jp/%7Eyita/smc20100112.pd
Quantum number projection at finite temperature via thermofield dynamics
Applying the thermo field dynamics, we reformulate exact quantum number
projection in the finite-temperature Hartree-Fock-Bogoliubov theory. Explicit
formulae are derived for the simultaneous projection of particle number and
angular momentum, in parallel to the zero-temperature case. We also propose a
practical method for the variation-after-projection calculation, by
approximating entropy without conflict with the Peierls inequality. The quantum
number projection in the finite-temperature mean-field theory will be useful to
study effects of quantum fluctuations associated with the conservation laws on
thermal properties of nuclei.Comment: 27 pages, using revtex4, to be published in PR
Total and Parity-Projected Level Densities of Iron-Region Nuclei in the Auxiliary Fields Monte Carlo Shell Model
We use the auxiliary-fields Monte Carlo method for the shell model in the
complete -shell to calculate level densities. We introduce
parity projection techniques which enable us to calculate the parity dependence
of the level density. Results are presented for Fe, where the calculated
total level density is found to be in remarkable agreement with the
experimental level density. The parity-projected densities are well described
by a backshifted Bethe formula, but with significant dependence of the
single-particle level-density and backshift parameters on parity. We compare
our exact results with those of the thermal Hartree-Fock approximation.Comment: 14 pages, 3 Postscript figures included, RevTe
Theoretical Study on Transport Properties of Normal Metal - Zigzag Graphene Nanoribbon - Normal Metal Junctions
We investigate transport properties of the junctions in which the graphene
nanoribbon with the zigzag shaped edges consisting of the legs is
sandwiched by the two normal metals by means of recursive Green's function
method. The conductance and the transmission probabilities are found to have
the remarkable properties depending on the parity of . The singular
behaviors close to E=0 with being the Fermi energy are demonstrated. The
channel filtering is shown to occur in the case with even.Comment: 4 pages, 5 figure
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