3,187 research outputs found
Penetration depth, multiband superconductivity, and absence of muon-induced perturbation in superconducting PrOsSb
Transverse-field muon spin rotation (SR) experiments in the
heavy-fermion superconductor PrOsSb ( K) suggest that
the superconducting penetration depth is temperature-independent
at low temperatures, consistent with a gapped quasiparticle excitation
spectrum. In contrast, radiofrequency (rf) inductive measurements yield a
stronger temperature dependence of , indicative of point nodes in
the gap. This discrepancy appears to be related to the multiband structure of
PrOsSb. Muon Knight shift measurements in PrOsSb
suggest that the perturbing effect of the muon charge on the neighboring
Pr crystalline electric field is negligibly small, and therefore is
unlikely to cause the difference between the SR and rf results.Comment: 10 pages, 7 figure
Standard model plethystics
We study the vacuum geometry prescribed by the gauge invariant operators of the minimal supersymmetric standard model via the plethystic program. This is achieved by using several tricks to perform the highly computationally challenging Molien-Weyl integral, from which we extract the Hilbert series, encoding the invariants of the geometry at all degrees. The fully refined Hilbert series is presented as the explicit sum of 1422 rational functions. We found a good choice of weights to unrefine the Hilbert series into a rational function of a single variable, from which we can read off the dimension and the degree of the vacuum moduli space of the minimal supersymmetric standard model gauge invariants. All data in Mathematica format are also presented
Euler characteristic of coherent sheaves on simplicial torics via the Stanley-Reisner ring
We combine work of Cox on the total coordinate ring of a toric variety and
results of Eisenbud-Mustata-Stillman and Mustata on cohomology of toric and
monomial ideals to obtain a formula for computing the Euler characteristic of a
Weil divisor D on a complete simplicial toric variety in terms of graded pieces
of the Cox ring and Stanley-Reisner ring. The main point is to use Alexander
duality to pass from the toric irrelevant ideal, which appears in the
computation of the Euler characteristic of D, to the Stanley-Reisner ideal of
the fan, which is used in defining the Chow ring. The formula also follows from
work of Maclagan-Smith.Comment: 9 pages 1 figur
Correlates of Northern Bobwhite Distribution and Abundance with Land-Use Characteristics in Kansas
County-level agricultural statistics were correlated with Rural Mail Carrier Survey reports and Breeding Bird Survey data for northern bobwhite (Colinus virginianus) in Kansas. Results indicate statewide analysis is feasible when temporally congruent data exist for both agricultural land-use characteristics and bobwhite distribution and abundance. Interpretations of these results can be useful in state or regional analysis and in the development of habitat management strategies for bobwhite. The Multiple Response Permutation Procedure identified 16 land-use variables, 3 soil variables, and 1 spatial variable that were significantly different in counties where bobwhite were present from counties where they were absent. Sixteen land-use variables, 5 soil variables, and 3 spatial variables distinguished between counties where bobwhite abundance was classified as high or low. Spearman\u27s rank correlation identified 8 soil variables, 14 land-use variables, and 3 spatial variables that were significantly correlated with bobwhite abundance. Least absolute deviation regression analysis revealed 4 land-use variables that were significantly correlated (Agreement= 0.48, P = 0.0001) with bobwhite abundance
Delocalization of slowly damped eigenmodes on Anosov manifolds
We look at the properties of high frequency eigenmodes for the damped wave
equation on a compact manifold with an Anosov geodesic flow. We study
eigenmodes with spectral parameters which are asymptotically close enough to
the real axis. We prove that such modes cannot be completely localized on
subsets satisfying a condition of negative topological pressure. As an
application, one can deduce the existence of a "strip" of logarithmic size
without eigenvalues below the real axis under this dynamical assumption on the
set of undamped trajectories.Comment: 28 pages; compared with version 1, minor modifications, add two
reference
Hole doping dependences of the magnetic penetration depth and vortex core size in YBa2Cu3Oy: Evidence for stripe correlations near 1/8 hole doping
We report on muon spin rotation measurements of the internal magnetic field
distribution n(B) in the vortex solid phase of YBa2Cu3Oy (YBCO) single
crystals, from which we have simultaneously determined the hole doping
dependences of the in-plane Ginzburg-Landau (GL) length scales in the
underdoped regime. We find that Tc has a sublinear dependence on
1/lambda_{ab}^2, where lambda_{ab} is the in-plane magnetic penetration depth
in the extrapolated limits T -> 0 and H -> 0. The power coefficient of the
sublinear dependence is close to that determined in severely underdoped YBCO
thin films, indicating that the same relationship between Tc and the superfluid
density is maintained throughout the underdoped regime. The in-plane GL
coherence length (vortex core size) is found to increase with decreasing hole
doping concentration, and exhibit a field dependence that is explained by
proximity-induced superconductivity on the CuO chains. Both the magnetic
penetration depth and the vortex core size are enhanced near 1/8 hole doping,
supporting the belief by some that stripe correlations are a universal property
of high-Tc cuprates.Comment: 12 pages, 13 figure
- …