6,959 research outputs found
Nodeless superconductivity and preserved time-reversal symmetry in the noncentrosymmetric Mo3P superconductor
We report a comprehensive study of the noncentrosymmetric superconductor
MoP. Its bulk superconductivity, with K, was characterized via
electrical resistivity, magnetization, and heat-capacity measurements, while
its microscopic electronic properties were investigated by means of muon-spin
rotation/relaxation (SR) and nuclear magnetic resonance (NMR) techniques.
In the normal state, NMR relaxation data indicate an almost ideal metallic
behavior, confirmed by band-structure calculations, which suggest a relatively
high electron density of states, dominated by the Mo -orbitals. The
low-temperature superfluid density, determined via transverse-field SR and
electronic specific heat, suggest a fully-gapped superconducting state in
MoP, with meV, the same as the BCS gap value in the
weak-coupling case, and a zero-temperature magnetic penetration depth
nm. The absence of spontaneous magnetic fields below the
onset of superconductivity, as determined from zero-field SR measurements,
indicates a preserved time-reversal symmetry in the superconducting state of
MoP and, hence, spin-singlet pairing.Comment: 13 pages, 16 figures, accepted by Phys. Rev.
Towards a New Standard Model for Black Hole Accretion
We briefly review recent developments in black hole accretion disk theory,
emphasizing the vital role played by magnetohydrodynamic (MHD) stresses in
transporting angular momentum. The apparent universality of accretion-related
outflow phenomena is a strong indicator that large-scale MHD torques facilitate
vertical transport of angular momentum. This leads to an enhanced overall rate
of angular momentum transport and allows accretion of matter to proceed at an
interesting rate. Furthermore, we argue that when vertical transport is
important, the radial structure of the accretion disk is modified at small
radii and this affects the disk emission spectrum. We present a simple model
demonstrating how energetic, magnetically-driven outflows modify the emergent
disk emission spectrum with respect to that predicted by standard accretion
disk theory. A comparison of the predicted spectra against observations of
quasar spectral energy distributions suggests that mass accretion rates
inferred using the standard disk model may severely underestimate their true
values.Comment: To appear in the Fifth Stromlo Symposium Proceedings special issue of
ApS
1/m_Q Corrections to the Heavy-to-Light-Vector Transitions in the HQET
Within the HQET, the heavy to light vector meson transitions are
systematically analyzed to the order of 1/m_Q. Besides the four universal
functions at the leading order, there are twenty-two independent universal form
factors at the order of 1/m_Q. Both the semileptonic decay B->\rho which is
relevant to the |V_{ub}| extraction, and the penguin induced decay B -> K^*
which is important to new physics discovering, depend on these form factors.
Phenomenological implications are discussed.Comment: RevTeX, 9 pages, no figure
An Intrinsic Description of the Nonlinear Aeroelasticity of Very Flexible Wings
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90662/1/AIAA-2011-1917-972.pd
Quadratic Volume Preserving Maps
We study quadratic, volume preserving diffeomorphisms whose inverse is also
quadratic. Such maps generalize the Henon area preserving map and the family of
symplectic quadratic maps studied by Moser. In particular, we investigate a
family of quadratic volume preserving maps in three space for which we find a
normal form and study invariant sets. We also give an alternative proof of a
theorem by Moser classifying quadratic symplectic maps.Comment: Ams LaTeX file with 4 figures (figure 2 is gif, the others are ps
The PLATO Dome A Site-Testing Observatory : instrumentation and first results
The PLATeau Observatory (PLATO) is an automated self-powered astrophysical observatory that was deployed to Dome A, the highest point on the Antarctic plateau, in 2008 January. PLATO consists of a suite of site-testing instruments designed to quantify the benefits of the Dome A site for astronomy, and science instruments designed to take advantage of the unique observing conditions. Instruments include CSTAR, an array of optical telescopes for transient astronomy; Gattini, an instrument to measure the optical sky brightness and cloud cover statistics; DASLE, an experiment to measure the statistics of the meteorological conditions within the near-surface layer; Pre-HEAT, a submillimeter tipping radiometer measuring the atmospheric transmission and water vapor content and performing spectral line imaging of the Galactic plane; and Snodar, an acoustic radar designed to measure turbulence within the near-surface layer. PLATO has run completely unattended and collected data throughout the winter 2008 season. Here we present a detailed description of the PLATO instrument suite and preliminary results obtained from the first season of operation
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