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 $t=1$ and $t=0$ pair-fields are different. The consequences for rotational spectra are discussed. For $t=1$, 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 $t=1$ field at low spin in $N\approx Z$ nuclei. For a substantial $t=0$ field, the spectra of even-even and odd-odd $N\approx Z$ nuclei become similar. The possibility of a rotationally induced $J=1$ 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-$\Lambda$ theory, and also $U(1)^4$ gauged supergravity in four dimensions and $U(1)^3$ 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 $\Sigma_2$. For the Einsten-Maxwell-$\Lambda$ theory we prove that $\Sigma_2$ should have a U(1) isometry, a rigidity theorem in this class of solutions. We also construct all d dimensional Einstein vacuum solutions with $SO(2,2) \times U(1)^{d-4}$ or $SO(2,2) \times SO(d-3)$ 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