31,455 research outputs found
A new weak lensing shear analysis method using ellipticity defined by 0th order moments
We developed a new method that uses ellipticity defined by 0th order moments
(0th-ellipticity) for weak gravitational lensing shear analysis. Although there
is a strong correlation between the ellipticity calculated using this approach
and the usual ellipticity defined by the 2nd order moment, the ellipticity
calculated here has a higher signal-to-noise ratio because it is weighted to
the central region of the image. These results were confirmed using data for
Abell 1689 from the Subaru telescope. For shear analysis, we adopted the
ellipticity of re-smeared artificial image (ERA) method for point spread
function (PSF) correction, and we tested the precision of this 0th-ellipticity
with simple simulation, then we obtained the same level of precision with the
results of ellipticity defined by quadrupole moments. Thus, we can expect that
weak lensing analysis using 0 shear will be improved in proportion to the
statistical error.Comment: 25pages, 8figures; published by A&A 201
Faithful actions from hyperplane arrangements
We show that if X is a smooth quasiprojective 3–fold admitting a flopping contraction, then the fundamental group of an associated simplicial hyperplane arrangement acts faithfully on the derived category of X. The main technical advance is to use torsion pairs as an efficient mechanism to track various objects under iterations of the flop functor (or mutation functor). This allows us to relate compositions of the flop functor (or mutation functor) to the theory of Deligne normal form, and to give a criterion for when a finite composition of 3–fold flops can be understood as a tilt at a single torsion pair. We also use this technique to give a simplified proof of a result of Brav and Thomas (Math. Ann. 351 (2011) 1005–1017) for Kleinian singularities
Realization of odd-frequency p-wave spin-singlet superconductivity coexisting with antiferromagnetic order near quantum critical point
A possibility of the realization of the p-wave spin-singlet superconductivity
(SS), whose gap function is odd both in momentum and in frequency, is
investigated by solving the gap equation with the phenomenological interaction
mediated by the antiferromagnetic spin fluctuation. The SS is realized
prevailing over the d-wave singlet superconductivity (SS) in the vicinity of
antiferromagnetic quantum critical pint (QCP) both on the paramagnetic and on
the antiferromagnetic sides. Off the QCP in the paramagnetic phase, however,
the SS with line-nodes is realized as \textit{conventional} anisotropic
superconductivity. For the present SS state, there is no gap in the
quasiparticle spectrum everywhere on the Fermi surface due to its odd
frequency. These features can give a qualitative understanding of the anomalous
behaviors of NQR relaxation rate on CeCuSi or CeRhIn where the
antiferromagnetism and superconductivity coexist on a microscopic level.Comment: 20 pages with 12 figures. To appear in J. Phys. Soc. Jpn. Vol. 72,
No. 1
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