13,671 research outputs found
BRS Cohomology of Zero Curvature Systems II. The Noncomplete Ladder Case
The Yang-Mills type theories and their BRS cohomology are analysed within the
zero curvature formalism.Comment: 14 pages, latex, no figures, latex improve
Chiral thermodynamics of dense hadronic matter
We discuss phases of hot and dense hadronic matter using chiral Lagrangians.
A two-flavored parity doublet model constrained by the nuclear matter ground
state predicts chiral symmetry restoration. The model thermodynamics is shown
within the mean field approximation. A field-theoretical constraint on possible
phases from the anomaly matching is also discussed.Comment: 8 pages, 2 figures, to appear in the proceedings of 6th International
Workshop on Critical Point and Onset of Deconfinement (CPOD), 23-29 August
2010 at Joint Institute for Nuclear Research, Dubna, Russi
Algebraic Characterization of Vector Supersymmetry in Topological Field Theories
An algebraic cohomological characterization of a class of linearly broken
Ward identities is provided. The examples of the topological vector
supersymmetry and of the Landau ghost equation are discussed in detail. The
existence of such a linearly broken Ward identities turns out to be related to
BRST exact antifield dependent cocycles with negative ghost number.Comment: 30 pages, latex2e file, subm. to Journ. of Math. Phy
Binary optical communication in single-mode and entangled quantum noisy channels
We address binary optical communication in single-mode and entangled quantum
noisy channels. For single-mode we present a systematic comparison between
direct photodetection and homodyne detection in realistic conditions, i.e.
taking into account the noise that occurs both during the propagation and the
detection of the signals. We then consider entangled channels based on
twin-beam state of radiation, and show that with realistic heterodyne detection
the error probability at fixed channel energy is reduced in comparison to the
single-mode cases for a large range of values of quantum efficiency and noise
parameters
Large-Scale Bulk Motions Complicate the Hubble Diagram
We investigate the extent to which correlated distortions of the luminosity
distance-redshift relation due to large-scale bulk flows limit the precision
with which cosmological parameters can be measured. In particular, peculiar
velocities of type 1a supernovae at low redshifts may prevent a sufficient
calibration of the Hubble diagram necessary to measure the dark energy equation
of state to better than 10%, and diminish the resolution of the equation of
state time-derivative projected for planned surveys. We consider similar
distortions of the angular-diameter distance, as well as the Hubble constant.
We show that the measurement of correlations in the large-scale bulk flow at
low redshifts using these distance indicators may be possible with a cumulative
signal-to-noise ratio of order 7 in a survey of 300 type 1a supernovae spread
over 20,000 square degrees.Comment: 6 pages; 4 figure
Non-extensive entropy from incomplete knowledge of Shannon entropy?
In this paper we give an interpretation of Tsallis' nonextensive statistical
mechanics based upon the information-theoretic point of view of Luzzi et al.
[cond-mat/0306217; cond-mat/0306247; cond-mat/0307325], suggesting Tsallis'
entropy to be not a fundamental concept but rather a derived one, stemming from
an incomplete knowledge of the system, not taking properly into account its
interaction with the environment. This interpretation seems to avoid some
problems occurring with the original interpretation of Tsallis statistics.Comment: v.4. 11 pages. Title changed. Content substantially changed: added
discussion of several points raised by various referees and readers; Also
reference made to work by Luzzi, Vasconcellos, Galvao Ramos. Physica Scripta,
to appea
Exceptional Askey-Wilson type polynomials through Darboux-Crum transformations
An alternative derivation is presented of the infinitely many exceptional
Wilson and Askey-Wilson polynomials, which were introduced by the present
authors in 2009. Darboux-Crum transformations intertwining the discrete quantum
mechanical systems of the original and the exceptional polynomials play an
important role. Infinitely many continuous Hahn polynomials are derived in the
same manner. The present method provides a simple proof of the shape invariance
of these systems as in the corresponding cases of the exceptional Laguerre and
Jacobi polynomials.Comment: 24 pages. Comments and references added. To appear in J.Phys.
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