9,902 research outputs found
Development of displacement- and frequency-noise-free interferometer in 3-D configuration for gravitational wave detection
The displacement- and frequency-noise-free interferometer (DFI) is a multiple
laser interferometer array for gravitational wave detection free from both the
displacement noise of optics and laser frequency noise. So far, partial
experimental demonstrations of DFI have been done in 2-D table top experiments.
In this paper, we report the complete demonstration of a 3-D DFI. The DFI
consists of four Mach-Zehnder interferometers with four mirrors and two
beamsplitters. The displacement noises both of mirrors and beamsplitters were
suppressed by up to 40 dB. The non-vanishing DFI response to a gravitational
wave was successfully confirmed using multiple electro-optic modulators and
computing methods
Vortex-induced topological transition of the bilinear-biquadratic Heisenberg antiferromagnet on the triangular lattice
The ordering of the classical Heisenberg antiferromagnet on the triangular
lattice with the the bilinear-biquadratic interaction is studied by Monte Carlo
simulations. It is shown that the model exhibits a topological phase transition
at a finite-temperature driven by topologically stable vortices, while the spin
correlation length remains finite even at and below the transition point. The
relevant vortices could be of three different types, depending on the value of
the biquadratic coupling. Implications to recent experiments on the triangular
antiferromagnet NiGaS is discussed
On the next-to-next-to-leading order QCD corrections to heavy-quark production in deep-inelastic scattering
The contribution of quarks with masses m >> Lambda_QCD is the only part of
the structure functions in deep-inelastic scattering (DIS) which is not yet
known at the next-to-next-to-leading order (NNLO) of perturbative QCD. We
present improved partial NNLO results for the most important structure function
F_2(x,Q^2) near the partonic threshold, in the high-energy (small-x) limit and
at high scales Q^2 >> m^2; and employ these results to construct approximations
for the gluon and quark coefficient functions which cover the full kinematic
plane. The approximation uncertainties are carefully investigated, and found to
be large only at very small values, x smaller about 10^-3, of the Bjorken
variable.Comment: 62 pages, LaTeX, 13 figures. Erratum for eq.(B.7
Ordering of the Heisenberg spin glass in two dimensions
The spin and the chirality orderings of the Heisenberg spin glass in two
dimensions with the nearest-neighbor Gaussian coupling are investigated by
equilibrium Monte Carlo simulations. Particular attention is paid to the
behavior of the spin and the chirality correlation lengths. In order to observe
the true asymptotic behavior, fairly large system size L\gsim 20 (L the linear
dimension of the system) appears to be necessary. It is found that both the
spin and the chirality order only at zero temperature. At high temperatures,
the chiral correlation length stays shorter than spin correlation length,
whereas at lower temperatures below the crossover temperature T_\times, the
chiral correlation length exceeds the spin correlation length. The spin and the
chirality correlation-length exponents are estimated above T_\times to be
\nu_SG=0.9+-0.2 and \nu_CG=2.1+-0.3, respectively. These values are close to
the previous estimates on the basis of the domain-wall-energy calculation.
Discussion is given about the asymptotic critical behavior realized below
T_\times.Comment: to appear in a special issue of J. Phys.
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Re-Analysis of HFT Data Using the Apollo Lunar Surface Gravimeter Data
Introduction: The Apollo Passive Seismic Experiment (PSE) was carried out on Apollo 12, 14, 15 and 16. Network observations of four seismic stations were performed for five years from 1972 to 1977. The PSE was a successful mission that informed us of the lunar crustal thickness and seismic velocity structure of the Moon from direct observations of the lunar interior (e.g. [1]). However, the paucity of seismic stations and the limited number of usable seismic events have been a major problem of lunar seismology. An additional observation point enables us to expand the network and the observable area will expand accordingly. Using a data set called the Work Tape, Kawamura et al. (2008) [2] showed that the Lunar Surface Gravimeter (LSG) on Apollo 17 functioned as a seismograph.
With this additional seismic station, we tried the first seismic analysis using the LSG data
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The Lunar Surface Gravimeter as a Lunar Seismograph
Introduction: The primary objective for the Lunar Surface Gravimeter (LSG) on Apollo 17 was to search for gravitational waves, but it failed in detecting them [1]. When the instrument was deployed on the Moon, the sensor beam could not be balanced in the proper equilibrium position. Consequently, the LSG was not able to function as originally designed. Lauderdale and Eichelman (1974) [1] concluded that “no provision has been made to supply data from the experiment to the National Space Science Data Center.” However, it was reported in Giganti et al. (1977) [2] that though they had not detected gravitational waves, after a series of reconfigurations the beam was recentered and the LSG gathered useful data. Besides the observation of gravitational waves, the LSG was also designed to observe seismic signals and tidal deformations [3]. According to Giganti et al. (1977) [2] LSG’s sensitivity covered the frequency range from 1~16Hz (Fig.1). There are several types of moonquakes reported, deep moonquakes, meteorite impacts, and high frequency teleseismic (HFT). Each of the moonquakes is known to have a resonant frequency around 1Hz and in addition, HFT has a predominant frequency around 10 Hz [4]. Therefore it is likely that the LSG was detecting the seismic events on the Moon. However, the LSG data have not been analyzed from a seismological point of view
Spin Stiffness of Stacked Triangular Antiferromagnets
We study the spin stiffness of stacked triangular antiferromagnets using both
heat bath and broad histogram Monte Carlo methods. Our results are consistent
with a continuous transition belonging to the chiral universality class first
proposed by Kawamura.Comment: 5 pages, 7 figure
First-Order Transition to Incommensurate Phase with Broken Lattice Rotation Symmetry in Frustrated Heisenberg Model
We study a finite-temperature phase transition in the two-dimensional
classical Heisenberg model on a triangular lattice with a ferromagnetic
nearest-neighbor interaction and an antiferromagnetic
third-nearest-neighbor interaction using a Monte Carlo method. Apart from
a trivial degeneracy corresponding to O(3) spin rotations,the ground state for
has a threefold degeneracy corresponding to 120 degree lattice
rotations. We find that this model exhibits a first-order phase transition with
the breaking of the threefold symmetry when the interaction ratio is
.Comment: 4pages,5figure
Spin and chiral orderings of frustrated quantum spin chains
Ordering of frustrated S=1/2 and 1 XY and Heisenberg spin chains with the
competing nearest- and next-nearest-neighbor antiferromagnetic couplings is
studied by exact diagonalization and density-matrix renormalization-group
methods. It is found that the S=1 XY chain exhibits both gapless and gapped
`chiral' phases characterized by the spontaneous breaking of parity, in which
the long-range order parameter is a chirality, , whereas the spin correlation decays either
algebraically or exponentially. Such chiral phases are not realized in the
S=1/2 XY chain nor in the Heisenberg chains.Comment: 4 pages, 5 EPS-figures, LaTeX(RevTeX),to appear in J.Phys.Soc.Japa
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