1,701 research outputs found
Supersymmetric extension of Moyal algebra and its application to the matrix model
We construct operator representation of Moyal algebra in the presence of
fermionic fields. The result is used to describe the matrix model in Moyal
formalism, that treat gauge degrees of freedom and outer degrees of freedom
equally.Comment: to appear in Mod.Phys.Let
Following the Mobile Student: Can We Develop the Capacity for a Comprehensive Database to Assess Student Progression?
Presents a study of state-level databases on postsecondary student retention and completion rates and the feasibility of tracking students across state lines. Outlines challenges and recommendations, including establishing a common reporting standard
Space-time Uncertainty Principle from Breakdown of Topological Symmetry
Starting from topological quantum field theory, we derive space-time
uncertainty relation with respect to the time interval and the spatial length
proposed by Yoneya through breakdown of topological symmetry in the large N
matrix model. This work suggests that the topological symmetry might be an
underlying higher symmetry behind the space-time uncertainty principle of
string theory.Comment: 6 pages, Late
Deformation of Schild String
We attempt to construct new superstring actions with a -plet of Majorana
fermions , where is the dimensional space-time
index and is the two dimensional spinor index, by deforming the Schild
action. As a result, we propose three kinds of actions: the first is invariant
under N=1 (the world-sheet) supersymmetry transformation and the
area-preserving diffeomorphism. The second contains the Yukawa type
interaction. The last possesses some non-locality because of bilinear terms of
. The reasons why completing a Schild type superstring action
with is difficult are finally discussed.Comment: 12 pages, Latex, both title and abstract are changed, discussion of
some relations among our results, Nambu-Goto string and super Yang-Mills
theories, added. Results unchange
On the optical counterpart of NGC300 X-1 and the global Wolf-Rayet content of NGC300
(Conext:) Surveys of Wolf-Rayet (WR) populations in nearby galaxies provide
tests of evolutionary models plus Type Ib/c supernova progenitors. This
spectroscopic study complements the recent imaging survey of the spiral galaxy
NGC 300 by Schild et al. (Aims): Revisions to the known WR content of NGC 300
are presented. We investigate the WR nature of candidate #41 from Schild et al.
which is spatially coincident with the bright X-ray point source NGC 300 X-1;
(Methods:) VLT/FORS2 multi-object spectroscopy of WR candidates in NGC 300 is
obtained; (Results:) We establish an early-type WN nature of #41, i.e. similar
to the optical counterpart of IC 10 X-1, which closely resembles NGC 300 X-1.
We confirm 9 new WR stars, bringing the current WR census of the inner disk to
31, with N(WC)/N(WN)~0.9. (Conclusions:) If #41 is the optical counterpart for
NGC 300 X-1, we estimate a WR mass of 38 Msun based upon ground-based
photometry, from which a black hole mass of > 10 Msun results from the 32.8 hr
period of the system and WR wind velocity of 1250 km/s. We estimate an 95%
completeness among WC stars and 70% among WN stars, such that the total WR
content is ~40, with N(WC)/N(WN)~0.7. From the Halpha-derived star formation
rate of the inner galaxy, we infer N(WR)/N(O)~0.04Comment: 5 pages, 5 figures, accepted for A&A Letter
Observational determination of the time delays in gravitational lens system Q2237+030
We present new brightness monitoring observations of the 4 components of
gravitationally lensed system Q2237+0305, which show detection of an intrinsic
quasar brightness fluctuation at a time of subdued microlensing activity,
between June 27 and October 12, 2003. These data were used to determine the
time delays between the arrivals of the four images. The measured delays are
-6, 35, and 2 hours for images B, C and D relative to A, respectively, so they
confirm that the long history of brightness monitoring has produced significant
detection of microlensing. However the error bars associated with the delays,
of order 2 days, are too large to discriminate between competing macro-imaging
models. Moreover, our simulations show that for the amplitude of this intrinsic
fluctuation and for photometric errors intrinsic to optical monitoring from our
1.5-m telescope or from the OGLE monitoring, a daily sampled brightness record
cannot produce reliable lags for model discrimination. We use our simulations
to devise a strategy for future delay determination with optical data.
Nevertheless, we regard these first estimates to be significant, since they are
the first direct measurements of time delays made for this system from
ground-based observations in the visual wavelengths. Our results provide the
most convincing confirmation of the gravitational-lens nature of Q2237+0305,
and give observational justification to the extensive literature which
attributes the quasar's previously observed brightness fluctuations to
microlensing.Comment: 9 pages, 3 figures, LaTeX, submitted to A&
Hamilton-Jacobi equations and Brane associated Lagrangians
This article seeks to relate a recent proposal for the association of a
covariant Field Theory with a string or brane Lagrangian to the Hamilton-Jacobi
formalism for strings and branes. It turns out that since in this special case,
the Hamiltonian depends only upon the momenta of the Jacobi fields and not the
fields themselves, it is the same as a Lagrangian, subject to a constancy
constraint. We find that the associated Lagrangians for strings or branes have
a covariant description in terms of the square root of the same Lagrangian. If
the Hamilton-Jacobi function is zero, rather than a constant, then it is in in
one dimension lower, reminiscent of the `holographic' idea. In the second part
of the paper, we discuss properties of these Lagrangians, which lead to what we
have called `Universal Field Equations', characteristic of covariant equations
of motion.Comment: 23 pages,LaTeX2e, clarified text, generalised proof in appendi
A multi-epoch spectrophotometric atlas of symbiotic stars
A multi-epoch, absolute-fluxed spectral atlas extending from about 3200 to
9000 Ang is presented for 130 symbiotic stars, including members of the LMC,
SMC and Draco dwarf galaxies. The fluxes are accurate to better than 5% as
shown by comparison with Tycho and ground-based photometric data. The spectra
of 40 reference objects (MKK cool giant standards, Mira and Carbon stars,
planetary nebulae, white dwarfs, hot sub-dwarfs, Wolf-Rayet stars, classical
novae, VV Cep and Herbig Ae/Be objects) are provided to assist the
interpretation of symbiotic star spectra. Astrometric positions and
counterparts in astrometric catalogues are derived for all program symbiotic
stars.Comment: A&A, in press (264 pages, 3 tables, 256 figures). The spectra are
available in electronic form from the authors. Only a sample of the whole
paper is given here. The full text can be downloaded from
http://ulisse.pd.astro.it/symbio-atlas/ where the spectra in electronic form
of the 40 reference objects can be found to
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