13,794 research outputs found
Beak deformation in an Antarctic Cormorant Phalacrocorax [atriceps] bransfieldensis chick
Fil: Casaux, Ricardo Jorge. Ministerio de Relaciones Exteriores, Comercio Interno y Culto. DirecciĂłn Nacional del AntĂĄrtico. Instituto AntĂĄrtico Argentino; Argentina. Universidad Nacional de la Patagonia; Argentin
Chern-Simons Supergravities with Off-Shell Local Superalgebras
A new family of supergravity theories in odd dimensions is presented. The
Lagrangian densities are Chern-Simons forms for the connection of a
supersymmetric extension of the anti-de Sitter algebra. The superalgebras are
the supersymmetric extensions of the AdS algebra for each dimension, thus
completing the analysis of van Holten and Van Proeyen, which was valid for N=1
and for D=2,3,4,mod 8. The Chern-Simons form of the Lagrangian ensures
invariance under the gauge supergroup by construction and, in particular, under
local supersymmetry. Thus, unlike standard supergravity, the local
supersymmetry algebra closes off-shell and without requiring auxiliary fields.
The Lagrangian is explicitly given for D=5, 7 and 11. In all cases the
dynamical field content includes the vielbein, the spin connection, N
gravitini, and some extra bosonic ``matter'' fields which vary from one
dimension to another. The superalgebras fall into three families: osp(m|N) for
D=2,3,4, mod 8, osp(N|m) for D=6,7,8, mod 8, and su(m-2,2|N) for D=5 mod 4,
with m=2^{[D/2]}. The possible connection between the D=11 case and M-Theory is
also discussed.Comment: 13pages, RevTeX, no figures, two column
Free Surface RANSE Analisys Around Fixed Fully Appended
This paper presents results of Free Surface RANSE (Reynolds Average Navier Stokes Equations) simulations of the flow around a MedCup TP52. Appendages forces calculations are important to know their hydrodynamic characteristics when they work jointly. In the ETSIN towing tank, some tests had begun to measure hydrodynamics forces in each appendage that allowed evaluate the forces distribution in different conditions. StarCCM+ has been used to compute drag, lift and wave elevation. It is shown how the CFD analysis has been prepared and the results obtained in these simulations comparing experimental with numerical results and the grid influence on it. Finally, it is observed that with limited resources, reasonable good results could be obtained
Canonical sectors of five-dimensional Chern-Simons theories
The dynamics of five-dimensional Chern-Simons theories is analyzed. These
theories are characterized by intricate self couplings which give rise to
dynamical features not present in standard theories. As a consequence, Dirac's
canonical formalism cannot be directly applied due to the presence of
degeneracies of the symplectic form and irregularities of the constraints on
some surfaces of phase space, obscuring the dynamical content of these
theories. Here we identify conditions that define sectors where the canonical
formalism can be applied for a class of non-Abelian Chern-Simons theories,
including supergravity. A family of solutions satisfying the canonical
requirements is explicitly found. The splitting between first and second class
constraints is performed around these backgrounds, allowing the construction of
the charge algebra, including its central extension.Comment: 12 pages, no figure
Dynamical content of Chern-Simons Supergravity
The dynamical content of local AdS supergravity in five dimensions is
discussed. The bosonic sector of the theory contains the vielbein (),
the spin connection () and internal SU(N) and U(1) gauge fields.
The fermionic fields are complex Dirac spinors () in a vector
representation of SU(N). All fields together form a connection 1-form in the
superalgebra SU(2,2|N). For N=4, the symplectic matrix has maximal rank in a
locally AdS background in which the dynamical degrees of freedom can be
identified. The resulting efective theory have different numbers of bosonic and
fermionic degrees of freedom.Comment: 15pages, RevTeX, no figures, one column. Talk given at the Second
Meeting on Trends in Theoretical Physics, Buenos Aires, November 30-December
4, 199
Higher dimensional Chern-Simons supergravity
A Chern-Simons action for supergravity in odd-dimensional spacetimes is
proposed. For all odd dimensions, the local symmetry group is a non trivial
supersymmetric extension of the Poincar\'e group. In dimensions the gauge
group reduces to super-Poincar\'e, while for it is super-Poincar\'e with
a central charge. In general, the extension is obtained by the addition of a
1-form field which transforms as an antisymmetric fifth-rank tensor under
Lorentz rotations. Since the Lagrangian is a Chern-Simons density for the
supergroup, the supersymmetry algebra closes off shell without the need of
auxiliary fields.Comment: Revtex, 8 pages (two column format
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