1,623 research outputs found
Quark and lepton mass matrices with family symmetry
Realistic quark masses and mixing angles are obtained applying the successful
family symmetry for leptons, motivated by the quark-lepton assignments of
SU(5). The symmetry is suitable to give tri-bimaximal neutrino mixing
matrix which is consistent with current experimental data. We study new
scenario for the quark sector with the symmetry.Comment: 16 pages, 2 figures, Talk given at International Workshop on Neutrino
Masses and Mixings, Shizuoka, Japan, 17-19 December 200
Three-nucleon interactions: dynamics
A discussion is presented of the dynamics underlying three-body nuclear
forces, with emphasis on changes which occurred over several decades.Comment: Talk given at the FM50 symposium, Tokyo, October 200
Post-Newtonian factorized multipolar waveforms for spinning, non-precessing black-hole binaries
We generalize the factorized resummation of multipolar waveforms introduced
by Damour, Iyer and Nagar to spinning black holes. For a nonspinning
test-particle spiraling a Kerr black hole in the equatorial plane, we find that
factorized multipolar amplitudes which replace the residual relativistic
amplitude f_{l m} with its l-th root, \rho_{l m} = f_{l m}^{1/l}, agree quite
well with the numerical amplitudes up to the Kerr-spin value q \leq 0.95 for
orbital velocities v \leq 0.4. The numerical amplitudes are computed solving
the Teukolsky equation with a spectral code. The agreement for prograde orbits
and large spin values of the Kerr black hole can be further improved at high
velocities by properly factoring out the lower-order post-Newtonian
contributions in \rho_{l m}. The resummation procedure results in a better and
systematic agreement between numerical and analytical amplitudes (and energy
fluxes) than standard Taylor-expanded post-Newtonian approximants. This is
particularly true for higher-order modes, such as (2,1), (3,3), (3,2), and
(4,4) for which less spin post-Newtonian terms are known. We also extend the
factorized resummation of multipolar amplitudes to generic mass-ratio,
non-precessing, spinning black holes. Lastly, in our study we employ new,
recently computed, higher-order post-Newtonian terms in several subdominant
modes, and compute explicit expressions for the half and one-and-half
post-Newtonian contributions to the odd-parity (current) and even-parity (odd)
multipoles, respectively. Those results can be used to build more accurate
templates for ground-based and space-based gravitational-wave detectors.Comment: 37 pages, 11 figures; Typos in Sec.IV Eqs.(38-42) fixe
Distance to G14.33-0.64 in the Sagittarius Spiral Arm: H2O Maser Trigonometric Parallax with VERA
We report on trigonometric parallax measurements for the Galactic star
forming region G14.33-0.64 toward the Sagittarius spiral arm. We conducted
multi-epoch phase-referencing observations of an H2O maser source in
G14.33-0.64 with the Japanese VLBI array VERA. We successfully detected a
parallax of 0.893+/-0.101 mas, corresponding to a source distance of
1.12+/-0.13 kpc, which is less than half of the kinematic distance for
G14.33-0.64. Our new distance measurement demonstrates that the Sagittarius arm
lies at a closer distance of ~1 kpc, instead of previously assumed ~2-3 kpc
from kinematic distances. The previously suggested deviation of the Sagittarius
arm toward the Galactic center from the symmetrically fitted model (Taylor &
Cordes 1993) is likely due to large errors of kinematic distances at low
galactic longitudes. G14.33-0.64 most likely traces the near side of the
Sagittarius arm. We attempted fitting the pitch angle of the arm with other
parallax measurements along the arm, which yielded two possible pitch angles of
i=34.7+/-2.7 degrees and i=11.2+/-10.5 degrees. Our proper motion measurements
suggest G14.33-0.64 has no significant peculiar motion relative to the
differential rotation of the Galaxy (assumed to be in a circular orbit),
indicating that the source motion is in good agreement with the Galactic
rotation.Comment: 14 pages, 7 figures, to appear in PASJ Vol. 62, No.
Empirical Abundance Scaling Laws and Implications for the Gamma-Process in Core-Collapse Supernovae
Analyzing the solar system abundances, we have found two empirical abundance
scaling laws concerning the p- and s-nuclei with the same atomic number. The
first scaling is s/p ratios are almost constant over a wide range of the atomic
number, where the p-nculei are lighter than the s-nuclei by two or four
neutrons. The second scaling is p/p ratios are almost constant, where the
second -nuclei are lighter than the first p-nucleus by two neutrons. These
scalings are a piece of evidence that most p-nuclei are dominantly synthesized
by the gamma-process in supernova explosions. The scalings lead to a novel
concept of "universality of gamma-process" that the s/p and p/p ratios of
nuclei produced by individual gamma-processes are almost constant,
respectively. We have calculated the ratios by gamma-process based on
core-collapse supernova explosion models under various astrophysical conditions
and found that the scalings hold for materials produced by individual
gamma-processes independent of the astrophysical conditions assumed. The
universality originates from three mechanisms: the shifts of the gamma-process
layers to keep their peak temperature, the weak s-process in pre-supernovae,
and the independence of the s/p ratios of the nuclear reactions. The results
further suggest an extended universality that the s/p ratios in the
gamma-process layers are not only constant but also centered on a specific
value of 3. With this specific value and the first scaling, we estimate that
the ratios of -process abundance contributions from the AGB stars to the
massive stars are almost 6.7 for the -nuclei of A > 90. We find that large
enhancements of s/p ratios for Ce, Er, and W are a piece of evidence that the
weak s-process actually occurred before SNe.Comment: 35 pages, 15 figure
High density NV sensing surface created via He^(+) ion implantation of (12)^C diamond
We present a promising method for creating high-density ensembles of
nitrogen-vacancy centers with narrow spin-resonances for high-sensitivity
magnetic imaging. Practically, narrow spin-resonance linewidths substantially
reduce the optical and RF power requirements for ensemble-based sensing. The
method combines isotope purified diamond growth, in situ nitrogen doping, and
helium ion implantation to realize a 100 nm-thick sensing surface. The obtained
10^(17) cm^(-3) nitrogen-vacancy density is only a factor of 10 less than the
highest densities reported to date, with an observed spin resonance linewidth
over 10 times more narrow. The 200 kHz linewidth is most likely limited by
dipolar broadening indicating even further reduction of the linewidth is
desirable and possible.Comment: 5 pages including references. 3 figure
Oil palm leaf fibre and its suitability for paper-based products
Due to the shortage of wood as origin materials for paper-based production, agro-residue materials have been explored in the quest of finding the best alternative fibre. Oil palm leaf (OPL) is one of agro-residue that has potential due to its comparable characteristics with wood fibre. Studies on chemical compositions, fibre morphology, and mechanical property of OPL have been carried out aiming to evaluate its potential as a substitute raw material for pulp and paper-based production. The chemical compositions were analysed according to the TAPPI standard, Kurscher-Hoffner and chlorite methods accordingly. The mechanical property (tensile, tearing and bursting strengths) were determined as described in TAPPI test methods. Fibre dimensions were determined using Franklin method and analysed under the optical microscope. The content of cellulose in the OPL is determined to be 43.8%. Although, this result is lower than wood fibre (53%), OPL has higher hemicellulose content (36.4%) than the wood fibre (27.5%). In addition, the lignin content (19.7%) of OPL is in the low range of those in wood resources (18 - 25%). These parameters are important components to produce good quality pulp and will provide high mechanical strength of the paper-based products. The measured fibre length of oil palm leaf (1.13 mm) is shorter than the wood fibre (1.90 mm). Meanwhile, the mechanical property of OPL showed lower indexes than wood resources, however, tear (1.80 mN.m2/g) and burst (0.95 kPa.m2/g) indexes of OPL are higher than other published and successful wood resources (Eucalyptus). Based on the analyses, the oil palm leaf is indeed a suitable alternative of raw material for pulp and paper-based industries
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