5,681 research outputs found
Born-form approximation for e+ e- to W+ W- to 4 fermions(+gamma)
We review the results on representing the differential cross section for
W-pair production, including W decay and hard-photon bremsstrahlung, in terms
of a Born-form approximation of fairly simple analytic form.Comment: 16 pages with 3 figures,(eps files), Latex. Invited talk at the XXII
International School of Theoretical Physics, Ustron '99, Poland, September
199
Mechanical quality factor of a sapphire fiber at cryogenic temperatures
A mechanical quality factor of was obtained for the 199
Hz bending vibrational mode in a monocrystalline sapphire fiber at 6 K.
Consequently, we confirm that pendulum thermal noise of cryogenic mirrors used
for gravitational wave detectors can be reduced by the sapphire fiber
suspension.Comment: To be published to Physiscs Letters A. Number of pages: 10 Number of
figures: 5 Number of tables:
Parametric instabilities in the LCGT arm cavity
We evaluated the parametric instabilities of LCGT (Japanese interferometric
gravitational wave detector project) arm cavity. The number of unstable modes
of LCGT is 10-times smaller than that of Advanced LIGO (U.S.A.). Since the
strength of the instabilities of LCGT depends on the mirror curvature more
weakly than that of Advanced LIGO, the requirement of the mirror curvature
accuracy is easier to be achieved. The difference in the parametric
instabilities between LCGT and Advanced LIGO is because of the thermal noise
reduction methods (LCGT, cooling sapphire mirrors; Advanced LIGO, fused silica
mirrors with larger laser beams), which are the main strategies of the
projects. Elastic Q reduction by the barrel surface (0.2 mm thickness
TaO) coating is effective to suppress instabilities in the LCGT arm
cavity. Therefore, the cryogenic interferometer is a smart solution for the
parametric instabilities in addition to thermal noise and thermal lensing.Comment: 6 pages,3 figures. Amaldi7 proceedings, J. Phys.: Conf. Ser.
(accepted
Second Order Quasi-Normal Mode of the Schwarzschild Black Hole
We formulate and calculate the second order quasi-normal modes (QNMs) of a
Schwarzschild black hole (BH). Gravitational wave (GW) from a distorted BH, so
called ringdown, is well understood as QNMs in general relativity. Since QNMs
from binary BH mergers will be detected with high signal-to-noise ratio by GW
detectors, it is also possible to detect the second perturbative order of QNMs,
generated by nonlinear gravitational interaction near the BH. In the BH
perturbation approach, we derive the master Zerilli equation for the metric
perturbation to second order and explicitly regularize it at the horizon and
spatial infinity. We numerically solve the second order Zerilli equation by
implementing the modified Leaver's continued fraction method. The second order
QNM frequencies are found to be twice the first order ones, and the GW
amplitude is up to that of the first order for the binary BH
mergers. Since the second order QNMs always exist, we can use their detections
(i) to test the nonlinearity of general relativity, in particular the no-hair
theorem, (ii) to remove fake events in the data analysis of QNM GWs and (iii)
to measure the distance to the BH.Comment: 23 pages, no figur
THE STRUCTURE OF 5-AMINO-4-METHYL-1-ISOQUINOLINECARBALDEHYDE THIOSEMICARBAZONE HYDROCHLORIDE, C12H14N5S+.CL-
Mr=295.80 , P21/n , a=8.284(1), b=
13.906 (1), c= 12.040 (2) A, fl= 92.95 (1) °, V=
1385.0 (5) ,/k 3, Z = 4, D m = 1.42, D x = 1.418 Mg m -3,
2(Cu K~t) = 1.54178 A,, g = 3.8134 mm -~, F(000) =
616, R =0.061 for 628 unique significant reflections
measured at 298 K. The structure was compared with
that of other active/inactive thiosemicarbazone
derivatives, in the search for a structure-activity
relationship. It was also compared with the structure of
a related metal complex
On the Interpretation of the Electroweak Precision Data
The recent precision electroweak data on and
are compared with the tree-level and the dominant-fermion-loop as well as the
full one-loop standard-model predictions. While the tree-level predictions are
ruled out, the dominant-fermion-loop predictions, defined by using in the tree-level formulae, as well as the full one-loop
predictions are consistent with the experimental data. Deviations from the
dominant-fermion-loop predictions are quantified in terms of an effective
Lagrangian containing three additional parameters which have a simple meaning
in terms of symmetry violation. The effective Lagrangian yields the
standard one-loop predictions for specific values of these parameters, which
are determined by and .Comment: Preprint BI-TP 93/46 (September 1993), to be published in Phys. Lett.
B, LaTeX, 10 pages, (figures are not included
The total virtual photoabsorption cross section, deeply virtual Compton scattering and vector-meson production
Based on the two-gluon-exchange dynamical mechanism for deeply inelastic
scattering at low x ~= Q^2/W^2 <<1, we stress the intimate connection between
the total virtual photoabsorption cross section, deeply virtual Compton
scattering and vector-meson electroproduction. A simple expression for the
cross section for deeply virtual Compton scattering is derived. Parameter-free
predictions are obtained for deeply-virtual Compton forward scattering and
vector-meson forward production, once the parameters in the total virtual
photoabsorption cross section are determined in a fit to the experimental data
on deeply inelastic scattering. Our predictions are compared with the
experimental data from HERA.Comment: 31 pages Latex, 10 figures and 1 tabl
Ferromagnetic (Ga,Mn)N epilayers versus antiferromagnetic GaMnN clusters
Mn-doped wurtzite GaN epilayers have been grown by nitrogen plasma-assisted
molecular beam epitaxy. Correlated SIMS, structural and magnetic measurements
show that the incorporation of Mn strongly depends on the conditions of the
growth. Hysteresis loops which persist at high temperature do not appear to be
correlated to the presence of Mn. Samples with up to 2% Mn are purely
substitutional GaMnN epilayers, and exhibit paramagnetic
properties. At higher Mn contents, precipitates are formed which are identified
as GaMnN clusters by x-ray diffraction and absorption: this induces a
decrease of the paramagnetic magnetisation. Samples co-doped with enough Mg
exhibit a new feature: a ferromagnetic component is observed up to
K, which cannot be related to superparamagnetism of unresolved magnetic
precipitates.Comment: Revised versio
Force measurements of a superconducting-film actuator for a cryogenic interferometric gravitational-wave detector
We measured forces applied by an actuator with a YBCO film at near 77 K for
the Large-scale Cryogenic Gravitational-wave Telescope (LCGT) project. An
actuator consisting of both a YBCO film of 1.6 micrometers thickness and 0.81
square centimeters area and a solenoid coil exerted a force of up to 0.2 mN on
a test mass. The presented actuator system can be used to displace the mirror
of LCGT for fringe lock of the interferometer.Comment: 9 pages, 3 figure
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