468 research outputs found
An Alternative Construction of the Quantum Action for Supergravity
We develop a method to derive the on-shell invariant quantum action of the
supergravity in such a way that the quartic ghost interaction term is explicity
determined. First, we reinvestigate the simple supergravity in terms of a
principal superfibre bundle. This gives rise to the closed geometrical BRST
algebra. Therefore we determine the open BRST algebra, which realizes the
invariance of the classical action. Then, given a prescription to build the
full quantum action, we obtain the quantum BRST algebra. Together with the
constructed quantum action this allows us to recover the auxiliary fields and
the invariant extension of the classical action.Comment: 17 pages, No figure
On Auxiliary Fields in BF Theories
We discuss the structure of auxiliary fields for non-Abelian BF theories in
arbitrary dimensions. By modifying the classical BRST operator, we build the
on-shell invariant complete quantum action. Therefore, we introduce the
auxiliary fields which close the BRST algebra and lead to the invariant
extension of the classical action.Comment: 7 pages, minor changes, typos in equations corrected and
acknowledgements adde
Off-shell BRST-VSUSY superalgebra for D=4 BF theories in the superconnection formalism
We propose the superconnection formalism to construct the off-shell
BRST-VSUSY superalgebra for D=4 BF theories. The method is based on the natural
introduction of physical fields as well as auxiliary fields via
superconnections and their associated supercurvatures defined on a superspace.
We also give a prescription to build the off-shell BRST-VSUSY exact quantum
action.Comment: Latex, 13 pages, no figures, comments and references adde
Monte Carlo simulation of a hard-sphere gas in the planar Fourier flow with a gravity field
By means of the Direct Simulation Monte Carlo method, the Boltzmann equation
is numerically solved for a gas of hard spheres enclosed between two parallel
plates kept at different temperatures and subject to the action of a gravity
field normal to the plates. The profiles of pressure, density, temperature and
heat flux are seen to be quite sensitive to the value of the gravity
acceleration . If the gravity field and the heat flux are parallel (),
the magnitudes of both the temperature gradient and the heat flux are smaller
than in the opposite case (). When considering the actual heat flux
relative to the value predicted by the Fourier law, it is seen that, if ,
the ratio increases as the reduced local field strength increases, while the
opposite happens if . The simulation results are compared with theoretical
predictions for Maxwell moleculesComment: 18 pages (LaTex), 7 figures (eps
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