5,993 research outputs found
Lorentz transformation and vector field flows
The parameter changes resulting from a combination of Lorentz transformation
are shown to form vector field flows. The exact, finite Thomas rotation angle
is determined and interpreted intuitively. Using phase portraits, the
parameters evolution can be clearly visualized. In addition to identifying the
fixed points, we obtain an analytic invariant, which correlates the evolution
of parameters.Comment: 11 pages, 3 figures. Section IV revised and title change
Real Forms of the Oscillator Quantum Algebra and its Representations
We consider the conditions under which the -oscillator algebra becomes a
Hopf -algebra. In particular, we show that there are at least two real forms
associated with the algebra. Furthermore, through the representations, it is
shown that they are related to with different
conjugations.Comment: 10 pages, Ams-Tex, To be published in Letters in Mathematical physic
The OmegaWhite Survey for Short-Period Variable Stars IV: Discovery of the warm DQ white dwarf OW J175358.85-310728.9
We present the discovery and follow-up observations of the second known
variable warm DQ white dwarf OW J175358.85-310728.9 (OW J1753-3107). OW
J1753-3107 is the brightest of any of the currently known warm or hot DQ and
was discovered in the OmegaWhite Survey as exhibiting optical variations on a
period of 35.5452 (2) mins, with no evidence for other periods in its light
curves. This period has remained constant over the last two years and a
single-period sinusoidal model provides a good fit for all follow-up light
curves. The spectrum consists of a very blue continuum with strong absorption
lines of neutral and ionised carbon, a broad He I 4471 A line, and possibly
weaker hydrogen lines. The C I lines are Zeeman split, and indicate the
presence of a strong magnetic field. Using spectral Paschen-Back model
descriptions, we determine that OW J1753-3107 exhibits the following physical
parameters: T_eff = 15430 K, log(g) = 9.0, log(N(C)/N(He)) = -1.2, and the mean
magnetic field strength is B_z =2.1 MG. This relatively low temperature and
carbon abundance (compared to the expected properties of hot DQs) is similar to
that seen in the other warm DQ SDSS J1036+6522. Although OW J1753-3107 appears
to be a twin of SDSS J1036+6522, it exhibits a modulation on a period slightly
longer than the dominant period in SDSS J1036+6522 and has a higher carbon
abundance. The source of variations is uncertain, but they are believed to
originate from the rotation of the magnetic white dwarf.Comment: 11 pages, 8 figures, 7 tables. Accepted for publication by MNRA
Hopf algebraic structure of the parabosonic and parafermionic algebras and paraparticle generalization of the Jordan Schwinger map
The aim of this paper is to show that there is a Hopf structure of the
parabosonic and parafermionic algebras and this Hopf structure can generate the
well known Hopf algebraic structure of the Lie algebras, through a realization
of Lie algebras using the parabosonic (and parafermionic) extension of the
Jordan Schwinger map. The differences between the Hopf algebraic and the graded
Hopf superalgebraic structure on the parabosonic algebra are discussed.Comment: 11 pages, LaTex2e fil
Algebraic structure of the Green's ansatz and its q-deformed analogue
The algebraic structure of the Green's ansatz is analyzed in such a way that
its generalization to the case of q-deformed para-Bose and para-Fermi operators
is becoming evident. To this end the underlying Lie (super)algebraic properties
of the parastatistics are essentially used.Comment: plain TeX, Preprint INRNE-TH-94/4, 13
High Resolution X-ray Spectra of the Brightest OB Stars in the Cygnus OB2 Association
The Cygnus OB2 Association contains some of the most luminous OB stars in our
Galaxy, the brightest of which are also among the most luminous in X-rays. We
have obtained a Chandra High Energy Transmission Grating Spectrometer (HETGS)
observation centered on Cyg OB2 No. 8a, the most luminous X-ray source in the
Association. Although our analysis will focus on the X-ray properties of Cyg
OB2 No. 8a, we also present limited analyses of three other OB stars (Cyg OB2
Nos. 5, 9, and 12). Applying standard diagnostic techniques as used in previous
studies of early-type stars, we find that the X-ray properties of Cyg OB2 No.
8a are very similar to those of other OB stars that have been observed using
high-resolution X-ray spectroscopy. From analyses of the He-like ion "fir"
emission lines, we derive radial distances of the He-like line emission sources
and find these fir-inferred radii are consistent with their corresponding X-ray
continuum optical depth unity radii. Contrary to other O-star results, the
emission lines of Cyg OB2 No. 8a show a large range in line centroid shifts
(roughly -800 to +250 km/s). We discuss the implications of our results in
light of the fact that Cyg OB2 No. 8a is a member of a rather tight stellar
cluster, and shocks could arise at interfaces with the winds of these other
stars.Comment: 36 pages (including 4 tables and 12 figures). LaTeX. Submitted to Ap
Unitarizable Representations of the Deformed Para-Bose Superalgebra Uq[osp(1/2)] at Roots of 1
The unitarizable irreps of the deformed para-Bose superalgebra , which
is isomorphic to , are classified at being root of 1. New
finite-dimensional irreps of are found. Explicit expressions
for the matrix elements are written down.Comment: 19 pages, PlainTe
Generalized q-Oscillators and their Hopf Structures
We study the relationships among the various forms of the oscillator
algebra and consider the conditions under which it supports a Hopf structure.
We also present a generalization of this algebra together with its
corresponding Hopf structure. Its multimode extensions are also considered.Comment: 14 page
Hyperfine Fields in an Ag/Fe Multilayer Film Investigated with 8Li beta-Detected Nuclear Magnetic Resonance
Low energy -detected nuclear magnetic resonance (-NMR) was used
to investigate the spatial dependence of the hyperfine magnetic fields induced
by Fe in the nonmagnetic Ag of an Au(40 \AA)/Ag(200 \AA)/Fe(140 \AA) (001)
magnetic multilayer (MML) grown on GaAs. The resonance lineshape in the Ag
layer shows dramatic broadening compared to intrinsic Ag. This broadening is
attributed to large induced magnetic fields in this layer by the magnetic Fe
layer. We find that the induced hyperfine field in the Ag follows a power law
decay away from the Ag/Fe interface with power , and a field
extrapolated to T at the interface.Comment: 5 pages, 4 figure. To be published in Phys. Rev.
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