2,695 research outputs found
Nonrelativistic Limit of the Scalar Chern-Simons Theory and the Aharonov-Bohm Scattering
We study the nonrelativistic limit of the quantum theory of a Chern-Simons
field minimally coupled to a scalar field with quartic self-interaction. The
renormalization of the relativistic model, in the Coulomb gauge, is discussed.
We employ a procedure to calculate scattering amplitudes for low momenta that
generates their expansion and separates the contributions coming from
high and low energy intermediary states. The two body scattering amplitude is
calculated up to order . It is shown that the existence of a critical
value of the self-interaction parameter for which the 2-particle scattering
amplitude reduces to the Aharonov-Bohm one is a strictly nonrelativistic
feature. The subdominant terms correspond to relativistic corrections to the
Aharonov-Bohm scattering. A nonrelativistic reduction scheme and an effective
nonrelativistic Lagrangian to account for the relativistic corrections are
proposed.Comment: 22 pages, 8 figures, revtex, to be published in Int. J. Mod. Phys.
High-temperature liquid-mercury cathodes for ion thrusters Quarterly progress report, 1 Dec. 1966 - 28 Feb. 1967
High temperature liquid mercury cathodes for ion thrusters - thermal design analysi
The Stellar Content of the Polar Rings in the Galaxies NGC 2685 and NGC 4650A
We present the results of stellar photometry of polar-ring galaxies NGC 2685
and NGC 4650A, using the archival data obtained with the Hubble Space
Telescope's Wide Field Planetary Camera 2. Polar rings of these galaxies were
resolved into ~800 and ~430 stellar objects in the B, V and Ic bands,
considerable part of which are blue supergiants located in the young stellar
complexes. The stellar features in the CM-diagrams are best represented by
isochrones with metallicity Z = 0.008. The process of star formation in the
polar rings of both galaxies was continuous and the age of the youngest
detected stars is about 9 Myr for NGC 2685 and 6.5 Myr for NGC 4650A.Comment: 21 pages, 9 figures, AJ 2004 February, accepte
Liquid mercury cathode electron bombardment ion thrusters Summary report, 1 Aug. 1964 - 31 Oct. 1966
Life tests of liquid mercury cathodes for electron bombardment ion thruster
A Generalized Gauge Invariant Regularization of the Schwinger Model
The Schwinger model is studied with a new one - parameter class of gauge
invariant regularizations that generalizes the usual point - splitting or
Fujikawa schemes. The spectrum is found to be qualitatively unchanged, except
for a limiting value of the regularizing parameter, where free fermions appear
in the spectrum.Comment: 16 pages, SINP/TNP/93-1
Color Variability of the Blazar AO 0235+16
Multicolor (UBVRIJHK) observations of the blazar AO 0235+16 are analyzed. The
light curves were compiled at the Turin Observatory from literature data and
the results of observations obtained in the framework of the WEBT program
(http://www.to.astro/blazars/webt/). The color variability of the blazar was
studied in eight time intervals with a sufficient number of multicolor optical
observations; JHK data are available for only one of these. The spectral energy
distribution (SED) of the variable component remained constant within each
interval, but varied strongly from one interval to another. After correction
for dust absorption, the SED can be represented by a power law in all cases,
providing evidence for a synchrotron nature of the variable component. We show
that the variability at both optical and IR wavelengths is associated with the
same variable source.Comment: 11 pages, 9 figures, 4 tables, accepted for publication in Astronomy
Report
HS 1857+5144 : a hot and young pre-cataclysmic variable
Aims. We report the discovery of a new white dwarf/M dwarf binary, HS 1857+5144, identified in the Hamburg Quasar Survey (HQS).
Methods. Time-resolved optical spectroscopy and photometry were carried out to determine the properties of this new cataclysmic variable progenitor (pre-CV).
Results. The light curves of HS 1857+5144 display a sinusoidal variation with a period of Porb = 383.52 min and peak-to-peak amplitudes of 0.7 mag and 1.1mag in the B-band and R-band, respectively. The large amplitude of the brightness variation results from a reflection effect on the heated inner hemisphere of the companion star, suggesting a very high temperature of the white
dwarf. Our radial velocity study confirms the photometric period as the orbital period of the system. A model atmosphere fit to the spectrum of the white dwarf obtained at minimum light provides limits to its mass and temperature of Mwd 0.6−1.0 M and Twd 70 000−100 000 K, respectively. The detection of He II λ4686 absorption classifies the primary star of HS 1857+5144 as a
DAO white dwarf. Combining the results from our spectroscopy and photometry, we estimate the mass of the companion star and the binary inclination to be Msec 0.15−0.30 M and i 45◦−55◦, respectively.
Conclusions. We classify HS 1857+5144 as one of the youngest pre-CV known to date. The cooling age of the white dwarf suggests that the present system has just emerged from a common envelope phase ∼105 yr ago. HS 1857+5144 will start mass transfer within or below the 2–3 h period gap
Covariance systems
We introduce new definitions of states and of representations of covariance
systems. The GNS-construction is generalized to this context. It associates a
representation with each state of the covariance system. Next, states are
extended to states of an appropriate covariance algebra. Two applications are
given. We describe a nonrelativistic quantum particle, and we give a simple
description of the quantum spacetime model introduced by Doplicher et al.Comment: latex with ams-latex, 23 page
Operator Ordering Problem of the Nonrelativistic Chern-Simons Theory
The operator ordering problem due to the quantization or regularization
ambiguity in the Chern-Simons theory exists. However, we show that this can be
avoided if we require Galilei covariance of the nonrelativistic Abelian
Chern-Simons theory even at the quantum level for the extended sources. The
covariance can be recovered only by choosing some particular operator orderings
for the generators of the Galilei group depending on the quantization
ambiguities of the commutation relation. We show that the
desired ordering for the unusual prescription is not the same as the well-known
normal ordering but still satisfies all the necessary conditions. Furthermore,
we show that the equations of motion can be expressed in a similar form
regardless of the regularization ambiguity. This suggests that the different
regularization prescriptions do not change the physics. On the other hand, for
the case of point sources the regularization prescription is uniquely
determined, and only the orderings, which are equivalent to the usual one, are
allowed.Comment: 18 page
Superfield Formulation for Non-Relativistic Chern-Simons-Matter Theory
We construct a superfield formulation for non-relativistic
Chern-Simons-Matter theories with manifest dynamical supersymmetry. By
eliminating all the auxiliary fields, we show that the simple action reduces to
the one obtained by taking non-relativistic limit from the relativistic
Chern-Simons-Matter theory proposed in the literature. As a further
application, we give a manifestly supersymmetric derivation of the
non-relativistic ABJM theory.Comment: 18 page
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