107,365 research outputs found
Crumpling wires in two dimensions
An energy-minimal simulation is proposed to study the patterns and mechanical
properties of elastically crumpled wires in two dimensions. We varied the
bending rigidity and stretching modulus to measure the energy allocation,
size-mass exponent, and the stiffness exponent. The mass exponent is shown to
be universal at value . We also found that the stiffness exponent
is universal, but varies with the plasticity parameters and
. These numerical findings agree excellently with the experimental
results
Probing annihilations and decays of low-mass galactic dark matter in IceCube DeepCore array: Track events
The deployment of DeepCore array significantly lowers IceCube's energy
threshold to about 10 GeV and enhances the sensitivity of detecting neutrinos
from annihilations and decays of light dark matter. To match this experimental
development, we calculate the track event rate in DeepCore array due to
neutrino flux produced by annihilations and decays of galactic dark matter. We
also calculate the background event rate due to atmospheric neutrino flux for
evaluating the sensitivity of DeepCore array to galactic dark matter
signatures. Unlike previous approaches, which set the energy threshold for
track events at around 50 GeV (this choice avoids the necessity of including
oscillation effect in the estimation of atmospheric background event rate), we
have set the energy threshold at 10 GeV to take the full advantage of DeepCore
array. We compare our calculated sensitivity with those obtained by setting the
threshold energy at 50 GeV. We conclude that our proposed threshold energy
significantly improves the sensitivity of DeepCore array to the dark matter
signature for GeV in the annihilation scenario and
GeV in the decay scenario.Comment: 19 pages, 5 figures; match the published versio
Nonuniversal Effects in the Homogeneous Bose Gas
Effective field theory predicts that the leading nonuniversal effects in the
homogeneous Bose gas arise from the effective range for S-wave scattering and
from an effective three-body contact interaction. We calculate the leading
nonuniversal contributions to the energy density and condensate fraction and
compare the predictions with results from diffusion Monte Carlo calculations by
Giorgini, Boronat, and Casulleras. We give a crude determination of the
strength of the three-body contact interaction for various model potentials.
Accurate determinations could be obtained from diffusion Monte Carlo
calculations of the energy density with higher statistics.Comment: 24 pages, RevTex, 5 ps figures, included with epsf.te
Intrinsic Josephson Effects in the Magnetic Superconductor RuSr2GdCu2O8
We have measured interlayer current transport in small sized RuSr2GdCu2O8
single crystals. We find a clear intrinsic Josephson effect showing that the
material acts as a natural
superconductor-insulator-ferromagnet-insulator-superconductor superlattice. So
far, we detected no unconventional behavior due to the magnetism of the RuO2
layers.Comment: 4 pages, 5 figures, to appear in Phys. Rev. Let
Adiabatic self-tuning in a silicon microdisk optical resonator
We demonstrate a method for adiabatically self-tuning a silicon microdisk resonator. This mechanism is not only able to sensitively probe the fast nonlinear cavity dynamics, but also provides various optical functionalities like pulse compression, shaping, and tunable time delay
Spin singlet pairing in the superconducting state of NaxCoO2\cdot1.3H2O: evidence from a ^{59}Co Knight shift in a single crystal
We report a ^{59}Co Knight shift measurement in a single crystal of the
cobalt oxide superconductor Na_{x}CoO_2\cdot1.3H_2O (T_c=4.25 K). We find that
the shift due to the spin susceptibility, K^s, is substantially large and
anisotropic, with the spin shift along the a-axis K^s_a being two times that
along the c-axis K^s_c. The shift decreases with decreasing temperature (T)
down to T\sim100 K, then becomes a constant until superconductivity sets in.
Both K^s_a and K^s_c decrease below T_c. Our results indicate unambiguously
that the electron pairing in the superconducting state is in the spin singlet
form.Comment: 4 pages, 5 figure
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