189,333 research outputs found
Mass of Rotating Black Holes in Gauged Supergravities
The masses of several recently-constructed rotating black holes in gauged
supergravities, including the general such solution in minimal gauged
supergravity in five dimensions, have until now been calculated only by
integrating the first law of thermodynamics. In some respects it is more
satisfactory to have a calculation of the mass that is based directly upon the
integration of a conserved quantity derived from a symmetry principal. In this
paper, we evaluate the masses for the newly-discovered rotating black holes
using the conformal definition of Ashtekar, Magnon and Das (AMD), and show that
the results agree with the earlier thermodynamic calculations. We also consider
the Abbott-Deser (AD) approach, and show that this yields an identical answer
for the mass of the general rotating black hole in five-dimensional minimal
gauged supergravity. In other cases we encounter discrepancies when applying
the AD procedure. We attribute these to ambiguities or pathologies of the
chosen decomposition into background AdS metric plus deviations when scalar
fields are present. The AMD approach, involving no decomposition into
background plus deviation, is not subject to such complications. Finally, we
also calculate the Euclidean action for the five-dimensional solution in
minimal gauged supergravity, showing that it is consistent with the quantum
statistical relation.Comment: Typos corrected and references update
Separability in Cohomogeneity-2 Kerr-NUT-AdS Metrics
The remarkable and unexpected separability of the Hamilton-Jacobi and
Klein-Gordon equations in the background of a rotating four-dimensional black
hole played an important role in the construction of generalisations of the
Kerr metric, and in the uncovering of hidden symmetries associated with the
existence of Killing tensors. In this paper, we show that the Hamilton-Jacobi
and Klein-Gordon equations are separable in Kerr-AdS backgrounds in all
dimensions, if one specialises the rotation parameters so that the metrics have
cohomogeneity 2. Furthermore, we show that this property of separability
extends to the NUT generalisations of these cohomogeneity-2 black holes that we
obtained in a recent paper. In all these cases, we also construct the
associated irreducible rank-2 Killing tensor whose existence reflects the
hidden symmetry that leads to the separability. We also consider some
cohomogeneity-1 specialisations of the new Kerr-NUT-AdS metrics, showing how
they relate to previous results in the literature.Comment: Latex, 15 pages, minor typos correcte
Behavior of the collective rotor in wobbling motion
The behavior of the collective rotor in wobbling motion is investigated
within the particle-rotor model for the nucleus Pr by transforming the
wave functions from the -representation to the -representation. After
reproducing the experimental energy spectra and wobbling frequencies, the
evolution of the wobbling mode in Pr, from transverse at low spins to
longitudinal at high spins, is illustrated by the distributions of the total
angular momentum in the intrinsic reference frame (azimuthal plot). Finally,
the coupling schemes of the angular momenta of the rotor and the high-
particle for transverse and longitudinal wobbling are obtained from the
analysis of the probability distributions of the rotor angular momentum
(-plots) and their projections onto the three principal axes (-plots).Comment: 21 pages, 9 page
Effective field theory for triaxially deformed nuclei
Effective field theory (EFT) is generalized to investigate the rotational
motion of triaxially deformed even-even nuclei. A Hamiltonian, called the
triaxial rotor model (TRM), is obtained up to next-to-leading order (NLO)
within the EFT formalism. Its applicability is examined by comparing with a
five-dimensional collective Hamiltonian (5DCH) for the description of the
energy spectra of the ground state and band in Ru isotopes. It is
found that by taking into account the NLO corrections, the ground state band in
the whole spin region and the band in the low spin region are well
described. The results presented here indicate that it should be possible to
further generalize the EFT to triaxial nuclei with odd mass number.Comment: 21 pages, 9 figure
Behavior of the collective rotor in nuclear chiral motion
The behavior of the collective rotor in the chiral motion of triaxially
deformed nuclei is investigated using the particle rotor model by transforming
the wave functions from the -representation to the -representation. After
examining the energy spectra of the doublet bands and their energy differences
as functions of the triaxial deformation, the angular momentum components of
the rotor, proton, neutron, and the total system are investigated. Moreover,
the probability distributions of the rotor angular momentum (-plots) and
their projections onto the three principal axes (-plots) are analyzed. The
evolution of the chiral mode from a chiral vibration at the low spins to a
chiral rotation at high spins is illustrated at triaxial deformations
and .Comment: 21 pages, 6 figure
Dirac-Brueckner-Hartree-Fock versus chiral effective field theory
We compare nuclear and neutron matter predictions based on two different ab
initio approaches to nuclear forces and the nuclear many-body problem. The
first consists of a realistic meson-theoretic nucleon-nucleon potential
together with the relativistic counterpart of the Brueckner-Hartree-Fock theory
of nuclear matter. The second is based on chiral effective field theory, with
density-dependent interactions derived from leading order chiral three-nucleon
forces. We find the results to be very close and conclude that both approaches
contain important features governing the physics of nuclear and neutron matter.Comment: PDFLATEX, 6 figures. arXiv admin note: substantial text overlap with
arXiv:1107.3339, arXiv:1111.0695, arXiv:1002.014
A Killing tensor for higher dimensional Kerr-AdS black holes with NUT charge
In this paper, we study the recently discovered family of higher dimensional
Kerr-AdS black holes with an extra NUT-like parameter. We show that the inverse
metric is additively separable after multiplication by a simple function. This
allows us to separate the Hamilton-Jacobi equation, showing that geodesic
motion is integrable on this background. The separation of the Hamilton-Jacobi
equation is intimately linked to the existence of an irreducible Killing
tensor, which provides an extra constant of motion. We also demonstrate that
the Klein-Gordon equation for this background is separable.Comment: LaTeX, 14 pages. v2: Typo corrected and equation added. v3: Reference
added, introduction expanded, published versio
Local spin polarisation of electrons in Rashba semiconductor nanowires: effects of the bound state
The local spin polarisation (LSP) of electrons in two typical semiconductor
nanowires under the modulation of Rashba spin-orbit interaction (SOI) is
investigated theoretically. The influence of both the SOI- and
structure-induced bound states on the LSP is taken into account via the
spin-resolved lattice Green function method. It is discovered that high
spin-density islands with alternative signs of polarisation are formed inside
the nanowires due to the interaction between the bound states and the Rashba
effective magnetic field. Further study shows that the spin-density islands
caused by the structure-induced bound state exhibit a strong robustness against
disorder. These findings may provide an efficient way to create local magnetic
moments and store information in semiconductors.Comment: 8 pages, 3 figure
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