2,771 research outputs found
The Experimental plan of the 4m Resonant Sideband Extraction Prototype for The LCGT
The 4m Resonant Sideband Extraction (RSE) interferometer is a planned prototype of the LCGT interferometer. The aim of the experiment is to operate a powerrecycled Broadband RSE interferometer with suspended optics and to achieve diagonalization of length signals of the central part of the interferometer directly through the optical setup. Details of the 4m RSE interferometer control method as well as the design of the experimental setup will be presented
Development of a control scheme of homodyne detection for extracting ponderomotive squeezing from a Michelson interferometer
We developed a control scheme of homodyne detection. To operate the homodyne detector as easy as possible, a simple Michelson interferometer is used. Here a motivation that the control scheme of the homodyne detection is developed is for our future experiment of extracting the ponderomotively squeezed vacuum fluctuations. To obtain the best signalto- noise ratio using the homodyne detection, the homodyne phase should be optimized. The optimization of the homodyne phase is performed by changing a phase of a local oscillator for the homodyne detection from a point at which a signal is maximized. In fact, in this experiment, using the developed control scheme, we locked the Michelson interferometer with the homodyne detector and changed the phase of the local oscillator for the homodyne detection. Then, we measured signals quantity changed by changing the phase of the local oscillator for the homodyne detection. Here we used the output from the homodyne detection as the signal
Downselect of the signal extraction scheme for LCGT
Large Cryogenic Gravitational wave Telescope (LCGT) is the future Japanese gravitational-wave detector. It will employ the broadband resonant sideband extraction (RSE) as its optical configuration. We compared four signal extraction schemes that have been proposed so as to downselect one of them as the scheme for LCGT. The selected scheme uses the phase and amplitude modulation sidebands: the phase modulation sidebands transmitting to the antisymmetric port (AP) and the amplitude modulation sidebands reffected to the symmetric port (SP) by the functions of the Michelson asymmetry. Using these sidebands, a new technique called 'delocation' is applicable. One advantage is that the control signals of the undesired signals do not appear at the AP, where the differential signals appear
Ultra-stable performance of an underground-based laser interferometer observatory for gravitational waves
In order to detect the rare astrophysical events that generate gravitational
wave (GW) radiation, sufficient stability is required for GW antennas to allow
long-term observation. In practice, seismic excitation is one of the most
common disturbances effecting stable operation of suspended-mirror laser
interferometers. A straightforward means to allow more stable operation is
therefore to locate the antenna, the ``observatory'', at a ``quiet'' site. A
laser interferometer gravitational wave antenna with a baseline length of 20m
(LISM) was developed at a site 1000m underground, near Kamioka, Japan. This
project was a unique demonstration of a prototype laser interferometer for
gravitational wave observation located underground. The extremely stable
environment is the prime motivation for going underground. In this paper, the
demonstrated ultra-stable operation of the interferometer and a well-maintained
antenna sensitivity are reported.Comment: 8 pages, to appear on PR
Unifying flipped SU(5) in five dimensions
It is shown that embedding a four-dimensional flipped SU(5) model in a
five-dimensional SO(10) model, preserves the best features of both flipped
SU(5) and SO(10). The missing partner mechanism, which naturally achieves both
doublet-triplet splitting and suppression of d=5 proton decay operators, is
realized as in flipped SU(5), while the gauge couplings are unified as in
SO(10). The masses of down quarks and charged leptons, which are independent in
flipped SU(5), are related by the SO(10). Distinctive patterns of quark and
lepton masses can result. The gaugino mass M_1 is independent of M_3 and M_2,
which are predicted to be equal.Comment: revised version-to appear in PRD, 23 pages, 3 figures, ReVTeX
Sfermion Mass Degeneracy, Superconformal Dynamics and Supersymmetric Grand Unified Theories
We discuss issues in a scenario that hierarchical Yukawa couplings are
generated through strong dynamics of superconformal field theories (SCFTs).
Independently of mediation mechanism of supersymmetry breaking, infrared
convergence property of SCFTs can provide an interesting solution to
supersymmetric flavor problem; sfermion masses are suppressed around the
decoupling scale of SCFTs and eventually become degenerate to some degree,
thanks to family-independent radiative corrections governed by the SM gaugino
masses. We discuss under what conditions the degeneracy of sfermion mass can be
estimated in a simple manner. We also discuss the constraints from lepton
flavor violations. We then study explicitly sfermion mass degeneracy within the
framework of grand unified theories coupled to SCFTs. It is found that the
degeneracy for right-handed sleptons becomes worse in the conventional SU(5)
model than in the MSSM. On the other hand, in the flipped SU(5) \times U(1)
model, each right-handed lepton is still an SU(5)-singlet, whereas the bino
mass M_1 is determined by two independent gaugino masses of SU(5) \times U(1).
These two properties enable us to have an improved degeneracy for the
right-handed sleptons. We also speculate how further improvement can be
obtained in the SCFT approach.Comment: 24 pages, latex, 4 figure
Cosmological perturbations of self-accelerating universe in nonlinear massive gravity
We study cosmological perturbations of self-accelerating universe solutions
in the recently proposed nonlinear theory of massive gravity, with general
matter content. While the broken diffeomorphism invariance implies that there
generically are 2 tensor, 2 vector and 2 scalar degrees of freedom in the
gravity sector, we find that the scalar and vector degrees have vanishing
kinetic terms and nonzero mass terms. Depending on their nonlinear behavior,
this indicates either nondynamical nature of these degrees or strong couplings.
Assuming the former, we integrate out the 2 vector and 2 scalar degrees of
freedom. We then find that in the scalar and vector sectors, gauge-invariant
variables constructed from metric and matter perturbations have exactly the
same quadratic action as in general relativity. The difference from general
relativity arises only in the tensor sector, where the graviton mass modifies
the dispersion relation of gravitational waves, with a time-dependent effective
mass. This may lead to modification of stochastic gravitational wave spectrum.Comment: 32 pages, 1 figure; v2: minor update to match the published versio
Lifting a Realistic SO(10) Grand Unified Model to Five Dimensions
It has been shown recently that the problem of rapid proton decay induced by
dimension five operators arising from the exchange of colored Higgsinos can be
simply avoided in grand unified models where a fifth spatial dimension is
compactified on an orbifold. Here we demonstrate that this idea can be used to
solve the Higgsino-mediated proton decay problem in any realistic SO(10) model
by lifting that model to five dimensions. A particular SO(10) model that has
been proposed to explain the pattern of quark and lepton masses and mixings is
used as an example. The idea is to break the SO(10) down to the Pati-Salam
symmetry by the orbifold boundary conditions. The entire four-dimensional
SO(10) model is placed on the physical SO(10) brane except for the gauge
fields, the 45 and a single 10 of Higgs fields, which are placed in the
five-dimensional bulk. The structure of the Higgs superpotential can be
somewhat simplified in doing so, while the Yukawa superpotential and mass
matrices derived from it remain essentially unaltered.Comment: 17 pages, version to be published in Phys. Rev. D with expanded
discussion of the suppression of dim-5 proton decay operator
Possible Candidates for SUSY SO(10) Model with an Intermediate Scale
We study the possibility of an intermediate scale existing in supersymmetric
SO(10) grand unified theories: The intermediate scale is demanded to be around
10^{12} GeV so that neutrinos can obtain masses suitable for explaining the
experimental data on the deficit of solar neutrino with
Mikheev-Smirnov-Wolfenstein solution and the existence of hot dark matter. We
show that any Pati-Salam type intermediate symmetries are excluded by requiring
reasonable conditions and only is likely to be realized as an intermediate symmetry.Comment: LaTeX, 8 pages + 1 uuencoded eps figure (Error corrected
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