9,781 research outputs found
Rotational alignment near N=Z and proton-neutron correlations
The effects of the residual proton-neutron interactions on bandcrossing
features are studied by means of shell model calculations for nucleons in a
high-j intruder orbital. The presence of an odd-nucleon shifts the frequency of
the alignment of two nucleons of the other kind along the axis of rotation. It
is shown that the anomalous delayed crossing observed in nuclei with aligning
neutrons and protons occupying the same intruder subshell can be partly
attributed to these residual interactions.Comment: 14 pages, including 5 eps figures submitted to Phys. Rev.
Symmetry Breaking by Proton-Neutron Pairing
The symmetries of the and pair-fields are different. The
consequences for rotational spectra are discussed. For , the concept of
spontaneous breaking and subsequent restoration of the isospin symmetry turns
out to be important. It permits us to describe the proton-neutron
pair-correlation within the conventional frame of pairing between like
particles. The experimental data are consistent with the presence of a
field at low spin in nuclei. For a substantial field, the
spectra of even-even and odd-odd nuclei become similar. The
possibility of a rotationally induced pair-field at high spin is
considered.Comment: 7 pages 9 figure
On Classification of Geometries with SO(2,2) Symmetry
Motivated by the Extremal Vanishing Horizon (EVH) black holes, their near
horizon geometry and the EVH/CFT proposal, we construct and classify solutions
with (local) SO(2,2) symmetry to four and five dimensional
Einstein-Maxwell-Dilaton (EMD) theory with positive, zero or negative
cosmological constant Lambda, the EMD- theory, and also
gauged supergravity in four dimensions and gauged supergravity in five
dimensions. In four dimensions the geometries are warped product of AdS3 with
an interval or a circle. In five dimensions the geometries are of the form of
warped product of AdS3 and a 2d surface . For the
Einsten-Maxwell- theory we prove that should have a U(1)
isometry, a rigidity theorem in this class of solutions. We also construct all
d dimensional Einstein vacuum solutions with or
isometry.Comment: 26 pages, updated to published versio
Hybrid Coding Technique for Pulse Detection in an Optical Time Domain Reflectometer
The paper introduces a novel hybrid coding technique for improved pulse detection in an optical time domain reflectometer. The hybrid schemes combines Simplex codes with signal averaging to articulate a very sophisticated coding technique that considerably reduces the processing time to extract specified coding gains in comparison to the existing techniques. The paper quantifies the coding gain of the hybrid scheme mathematically and provide simulative results in direct agreement with the theoretical performance. Furthermore, the hybrid scheme has been tested on our self-developed OTDR
Three Theorems on Near Horizon Extremal Vanishing Horizon Geometries
EVH black holes are Extremal black holes with Vanishing Horizon area, where
vanishing of horizon area is a result of having a vanishing one-cycle on the
horizon. We prove three theorems regarding near horizon geometry of EVH black
hole solutions to generic Einstein gravity theories in diverse dimensions.
These generic gravity theories are Einstein-Maxwell-dilaton-Lambda theories,
and gauged or ungauged supergravity theories with U(1) Maxwell fields. Our
three theorems are: (1) The near horizon geometry of any EVH black hole has a
three dimensional maximally symmetric subspace. (2) If the energy momentum
tensor of the theory satisfies strong energy condition either this 3d part is
an AdS3, or the solution is a direct product of a locally 3d flat space and a
d-3 dimensional part. (3) These results extend to the near horizon geometry of
near-EVH black holes, for which the AdS3 part is replaced with BTZ geometry.Comment: 5 page
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