34,508 research outputs found
Noncommutativity and Duality through the Symplectic Embedding Formalism
This work is devoted to review the gauge embedding of either commutative and
noncommutative (NC) theories using the symplectic formalism framework. To sum
up the main features of the method, during the process of embedding, the
infinitesimal gauge generators of the gauge embedded theory are easily and
directly chosen. Among other advantages, this enables a greater control over
the final Lagrangian and brings some light on the so-called "arbitrariness
problem". This alternative embedding formalism also presents a way to obtain a
set of dynamically dual equivalent embedded Lagrangian densities which is
obtained after a finite number of steps in the iterative symplectic process,
oppositely to the result proposed using the BFFT formalism. On the other hand,
we will see precisely that the symplectic embedding formalism can be seen as an
alternative and an efficient procedure to the standard introduction of the
Moyal product in order to produce in a natural way a NC theory. In order to
construct a pedagogical explanation of the method to the nonspecialist we
exemplify the formalism showing that the massive NC U(1) theory is embedded in
a gauge theory using this alternative systematic path based on the symplectic
framework. Further, as other applications of the method, we describe exactly
how to obtain a Lagrangian description for the NC version of some systems
reproducing well known theories. Naming some of them, we use the procedure in
the Proca model, the irrotational fluid model and the noncommutative self-dual
model in order to obtain dual equivalent actions for these theories. To
illustrate the process of noncommutativity introduction we use the chiral
oscillator and the nondegenerate mechanics
Propfan noise propagation
The unconventional supersonic tip speed of advanced propellers has led to uncertainties about Propfan's noise acceptability and compliance with Federal Aviation Noise Regulation (FAR 36). Overhead flight testing of the Propfan with an SR-7L blade during 1989's Propfan Test Assessment (PTA) Program have shown unexpectedly high far-field sound pressure levels. This study here attempts to provide insights into the acoustics of a single-rotating propeller (SRP) with supersonic tip speed. At the same time, the role of the atmosphere in shaping the far-field noise characteristics is investigated
Tsallis and Kaniadakis statistics from a point of view of the holographic equipartition law
In this work, we have illustrated the difference between both Tsallis and
Kaniadakis entropies through cosmological models obtained from the formalism
proposed by Padmanabhan, which is called holographic equipartition law.
Similarly to the formalism proposed by Komatsu, we have obtained an extra
driving constant term in the Friedmann equation if we deform the Tsallis
entropy by Kaniadakis' formalism. We have considered initially Tsallis entropy
as the Black Hole (BH) area entropy. This constant term may lead the universe
to be in an accelerated mode. On the other hand, if we start with the
Kaniadakis entropy as the BH area entropy and then by modifying the Kappa
expression by Tsallis' formalism, the same constant, which shows that the
universe have an acceleration is obtained. In an opposite limit, no driving
inflation term of the early universe was derived from both deformations.Comment: 8 pages, preprint format. Final version to appear in Europhysics
Letter
(1RS,2SR,7RS,8RS)-N-Benzoyltricyclo[6.2.2.0²,⁷]dodeca-9,11-diene-1,10-dicarboximide
The title 1,4-photoadduct, C₂₁H₁₉NO₃, was formed on irradiation of N-benzoylphthalimide in dichloromethane containing cyclohexene. The bond lengths and angles are generally within the normal ranges. A notable feature of the molecule is the presence within it of four contiguous chiral centres
4',5',6',7'-Tetrachlorospiro[cyclohex-2-ene-1,2'-indan]-1',3'-dione
The title compound, C₁₄H₈Cl₄O₂, has been isolated following irradiation of a dichloromethane solution of N-acetyltetrachlorophthalimide and cyclohexene. The structure refinement is slightly compromised by the disorder over two positions of equal occupancy of a methylene groupβ to the spiro C atom
The Noncommutative Doplicher-Fredenhagen-Roberts-Amorim Space
This work is an effort in order to compose a pedestrian review of the
recently elaborated Doplicher, Fredenhagen, Roberts and Amorim (DFRA)
noncommutative (NC) space which is a minimal extension of the DFR space. In
this DRFA space, the object of noncommutativity () is a
variable of the NC system and has a canonical conjugate momentum. The DFRA
formalism is constructed in an extended space-time with independent degrees of
freedom associated with the object of noncommutativity . A
consistent algebra involving the enlarged set of canonical operators is
described, which permits one to construct theories that are dynamically
invariant under the action of the rotation group. A consistent classical
mechanics formulation is analyzed in such a way that, under quantization, it
furnishes a NC quantum theory with interesting results. The Dirac formalism for
constrained Hamiltonian systems is considered and the object of
noncommutativity plays a fundamental role as an independent
quantity. It is also explained about the generalized Dirac equation issue, that
the fermionic field depends not only on the ordinary coordinates but on
as well. The dynamical symmetry content of such fermionic
theory is discussed, and we show that its action is invariant under . In the last part of this work we analyze the complex scalar fields using
this new framework. As said above, in a first quantized formalism,
and its canonical momentum are seen as
operators living in some Hilbert space. In a second quantized formalism
perspective, we show an explicit form for the extended Poincar\'e generators
and the same algebra is generated via generalized Heisenberg relations. We also
consider a source term and construct the general solution for the complex
scalar fields using the Green function technique
Benzylammonium 2,4-bis(dicyanomethylene)-2,3-dihydroisoindolide
The cation and anion of the title salt, C⁷H₁₀N⁺.C₁₄H₄N₅-, are both bisected by a crystallographic mirror plane. Extensive hydrogen bonding, with the R₆⁶(28) graph-set motif, connects the ions into layers
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