6,776 research outputs found
Comment: Struggles with Survey Weighting and Regression Modeling
Comment: Struggles with Survey Weighting and Regression Modeling
[arXiv:0710.5005]Comment: Published in at http://dx.doi.org/10.1214/088342307000000177 the
Statistical Science (http://www.imstat.org/sts/) by the Institute of
Mathematical Statistics (http://www.imstat.org
Maximal entanglement of two spinor Bose-Einstein condensates
Starting with two weakly-coupled anti-ferromagnetic spinor condensates, we
show that by changing the sign of the coefficient of the spin interaction,
, via an optically-induced Feshbach resonance one can create an
entangled state consisting of two anti-correlated ferromagnetic condensates.
This state is maximally entangled and a generalization of the Bell state from
two anti-correlated spin-1/2 particles to two anti-correlated spin atomic
samples, where is the total number of atoms.Comment: 5 pages, 3 figures, accepted for publication in PR
Continued Analysis on Multiscale Aspects of Tropical Cyclone Formation, Structure Change and Predictability in the Western North Pacific Region as Part of the TCS08 DRI
2012 ANNUAL REPORT FOR ONR SPONSORED RESEARCHLONG-TERM GOALS AND OBJECTIVES: The overarching objectives of this research project are to obtain an improved understanding of the formation, intensification, predictability and structure change of tropical cyclones in the Western Pacific region. These new insights will ultimately improve forecast guidance for U.S. Naval operations in this region.ONRN0001411WX2009
Calibration of the CH and CN Variations Among Main Sequence Stars in M71 and in M13
An analysis of the CN and CH band strengths measured in a large sample of M71
and M13 main sequence stars by Cohen (1999a,b) is undertaken using synthetic
spectra to quantify the underlying C and N abundances. In the case of M71 it is
found that the observed CN and CH band strengths are best matched by the
{\it{identical}} C/N/O abundances which fit the bright giants, implying: 1)
little if any mixing is taking place during red giant branch ascent in M71, and
2) a substantial component of the C and N abundance inhomogeneities is in place
before the main sequence turn-off. The unlikelihood of mixing while on the main
sequence requires an explanation for the abundance variations which lies
outside the present stars (primordial inhomogeneities or intra-cluster self
enrichment). For M13 it is shown that the 3883\AA CN bands are too weak to be
measured in the spectra for any reasonable set of expected compositions. A
similar situation exists for CH as well. However, two of the more luminous
program stars do appear to have C abundances considerably greater than those
found among the bright giants thereby suggesting deep mixing has taken place on
the M13 red giant branch.Comment: 14 pages, 4 figures, accepted for publication by A
Covariant Helicity-Coupling Amplitudes: A New Formulation
We have worked out covariant amplitudes for any two-body decay of a resonance
with an arbitrary non-zero mass, which involves arbitrary integer spins in the
initial and the final states. One key new ingredient for this work is the
application of the total intrinsic spin operator which is given
directly in terms of the generators of the Poincar\'e group.
Using the results of this study, we show how to explore the Lorentz factors
which appear naturally, if the momentum-space wave functions are used to form
the covariant decay amplitudes. We have devised a method of constructing our
covariant decay amplitudes, such that they lead to the Zemach amplitudes when
the Lorentz factors are set one
Unitarisation of EFT Amplitudes for Dark Matter Searches at the LHC
We propose a new approach to the LHC dark matter search analysis within the
effective field theory (EFT) framework by utilising the K-matrix unitarisation
formalism. This approach provides a reasonable estimate of the dark matter
production cross section at high energies, and hence allows reliable bounds to
be placed on the cut-off scale of relevant operators without running into the
problem of perturbative unitarity violation. We exemplify this procedure for
the effective operator D5 in monojet dark matter searches in the collinear
approximation. We compare our bounds to those obtained using the truncation
method and identify a parameter region where the unitarisation prescription
leads to more stringent bounds.Comment: 20 pages, 7 figures. References added and minor corrections made to
match published versio
CN Bimodality at Low Metallicity: The Globular Cluster M53
We present low resolution UV-blue spectroscopic observations of red giant
stars in the globular cluster M53 ([Fe/H]=-1.84), obtained to study primordial
abundance variations and deep mixing via the CN and CH absorption bands. The
metallicity of M53 makes it an attractive target: a bimodal distribution of
3883 angstrom CN bandstrength is common in moderate- and high-metallicity
globular clusters ([Fe/H] > -1.6) but unusual in those of lower metallicity
([Fe/H] < -2.0). We find that M53 is an intermediate case, and has a broad but
not strongly bimodal distribution of CN bandstrength, with CN and CH
bandstrengths anticorrelated in the less-evolved stars. Like many other
globular clusters, M53 also exhibits a general decline in CH bandstrength and
[C/Fe] abundance with rising luminosity on the red giant branch.Comment: 8 pages including 11 figures and 1 table, accepted by PAS
An axisymmetric view of concentric eyewall evolution in Hurricane Rita (2005)
J. Atmos. Sci., 69 2414-2432The article of record as published may be located at http://dx.doi.org/10.1175/JAS-D-11-0167.
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