884,251 research outputs found
Quantum and Braided Linear Algebra
Quantum matrices are known for every matrix obeying the Quantum
Yang-Baxter Equations. It is also known that these act on `vectors' given by
the corresponding Zamalodchikov algebra. We develop this interpretation in
detail, distinguishing between two forms of this algebra, (vectors) and
(covectors). A(R)\to V(R_{21})\tens V^*(R) is an algebra
homomorphism (i.e. quantum matrices are realized by the tensor product of a
quantum vector with a quantum covector), while the inner product of a quantum
covector with a quantum vector transforms as a scaler. We show that if
and are endowed with the necessary braid statistics then their
braided tensor-product V(R)\und\tens V^*(R) is a realization of the braided
matrices introduced previously, while their inner product leads to an
invariant quantum trace. Introducing braid statistics in this way leads to a
fully covariant quantum (braided) linear algebra. The braided groups obtained
from act on themselves by conjugation in a way impossible for the
quantum groups obtained from .Comment: 27 page
The Determination Of Reddening From Intrinsic VR Colors Of RR Lyrae Stars
New R-band observations of 21 local field RR Lyrae variable stars are used to
explore the reliability of minimum light (V-R) colors as a tool for measuring
interstellar reddening. For each star, R-band intensity mean magnitudes and
light amplitudes are presented. Corresponding V-band light curves from the
literature are supplemented with the new photometry, and (V-R) colors at
minimum light are determined for a subset of these stars as well as for other
stars in the literature. Two different definitions of minimum light color are
examined, one which uses a Fourier decomposition to the V and R light curves to
find (V-R) at minimum V-band light, (V-R)_{min}^F, and the other which uses the
average color between the phase interval 0.5-0.8, (V-R)_{min}^{\phi(0.5-0.8)}.
From 31 stars with a wide range of metallicities and pulsation periods, the
mean dereddened RR Lyrae color at minimum light is (V-R)_{min,0}^F = 0.28 pm
0.02 mag and (V-R)_{min,0}^{\phi(0.5-0.8)} = 0.27 pm 0.02 mag. As was found by
Guldenschuh et al. (2005) using (V-I) colors, any dependence of the star's
minimum light color on metallicity or pulsation amplitude is too weak to be
formally detected. We find that the intrinsic (V-R) of Galactic bulge RR Lyrae
stars are similar to those found by their local counterparts and hence that
Bulge RR0 Lyrae stars do not have anomalous colors as compared to the local RR
Lyrae stars.Comment: accepted by A
Lower limit in semiclassical form for the number of bound states in a central potential
We identify a class of potentials for which the semiclassical estimate
of
the number of (S-wave) bound states provides a (rigorous) lower limit:
, where the double braces denote the integer part.
Higher partial waves can be included via the standard replacement of the
potential with the effective -wave potential
. An analogous upper
limit is also provided for a different class of potentials, which is however
quite severely restricted.Comment: 9 page
Energy Extraction and Particle Acceleration Around Rotating Black Hole in Horava-Lifshitz Gravity
Penrose process on rotational energy extraction of the black hole (BH) in the
original non-projectable Ho\v{r}ava-Lifshitz gravity is studied. The strong
dependence of the extracted energy from the special range of parameters of the
Ho\v{r}ava-Lifshitz gravity, such as parameter and specific angular
momentum has been found. Particle acceleration near the rotating BH in
Ho\v{r}ava-Lifshitz gravity has been studied. It is shown that the fundamental
parameter of the Ho\v{r}ava-Lifshitz gravity can impose limitation on the the
energy of the accelerating particles preventing them from the infinite value.Comment: 6 pages, 3 figures, accepted for publication in Physical Review
Klein-Gordon lower bound to the semirelativistic ground-state energy
For the class of attractive potentials V(r) <= 0 which vanish at infinity, we
prove that the ground-state energy E of the semirelativistic Hamiltonian
H = \sqrt{m^2 + p^2} + V(r) is bounded below by the ground-state energy e of
the corresponding Klein--Gordon problem
(p^2 + m^2)\phi = (V(r) -e)^2\phi. Detailed results are presented for the
exponential and Woods--Saxon potentials.Comment: 7 pages, 4 figure
Embedding variables in finite dimensional models
Global problems associated with the transformation from the Arnowitt, Deser
and Misner (ADM) to the Kucha\v{r} variables are studied. Two models are
considered: The Friedmann cosmology with scalar matter and the torus sector of
the 2+1 gravity. For the Friedmann model, the transformations to the Kucha\v{r}
description corresponding to three different popular time coordinates are shown
to exist on the whole ADM phase space, which becomes a proper subset of the
Kucha\v{r} phase spaces. The 2+1 gravity model is shown to admit a description
by embedding variables everywhere, even at the points with additional symmetry.
The transformation from the Kucha\v{r} to the ADM description is, however,
many-to-one there, and so the two descriptions are inequivalent for this model,
too. The most interesting result is that the new constraint surface is free
from the conical singularity and the new dynamical equations are linearization
stable. However, some residual pathology persists in the Kucha\v{r}
description.Comment: Latex 2e, 29 pages, no figure
Quasinormal modes of a black hole in the deformed Ho\v{r}ava-Lifshitz gravity
We study the quasinormal modes of the massless scalar perturbation in the
background of a deformed black hole in the Ho\v{r}ava-Lifshitz gravity with
coupling constant . Our results show that the quasinormal
frequencies depend on the parameter in the Ho\v{r}ava-Lifshitz gravity and the
behavior of the quasinormal modes is different from those in the
Reissner-Norstr\"{om} and Einstein-Born-Infeld black hole spacetimes. The
absolute value of imaginary parts is smaller and the scalar perturbations decay
more slowly in the deformed Ho\v{r}ava-Lifshitz black hole spacetime. This
information can help us understand more about the Ho\v{r}ava-Lifshitz gravity.Comment: 9 pages, 3 figures and 4 table
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