Noncommutative Field Theories and Gravity

We show that after the Seiberg-Witten map is performed the action for noncommutative field theories can be regarded as a coupling to a field dependent gravitational background. This gravitational background depends only on the gauge field. Charged and uncharged fields couple to different backgrounds and we find that uncharged fields couple more strongly than the charged ones. We also show that the background is that of a gravitational plane wave. A massless particle in this background has a velocity which differs from the velocity of light and we find that the deviation is larger in the uncharged case. This shows that noncommutative field theories can be seen as ordinary theories in a gravitational background produced by the gauge field with a charge dependent gravitational coupling.Comment: 8 pages. v2 and v3: minor corrections, added reference

Ontology of multi-agents processes of spatial decision

In the paper of Cavezzali, Girotti and Rabino presented at ERSA 2003 conference, features of multi-agent models and their potentiality for the study of territorial phenomena are discussed. Starting from this study, the present paper digs deeper mechanisms of multi-agent systems working, describing their ontology in a more complete and articulated way as possible, and investigating: the properties of the actors, the mechanisms of interaction among actors and between actors and environment. About the environment, particular attention has been paid to the consideration about the various modalities of treatment of territory (from pure physical support to active reactive/cognitive agent in relationship with the other agents). For these modalities, finally, two typical case-studies of multi-agent model are shown: simulation of pedestrian paths choice, the software “Turisti”, and a competitive dynamic of service centres location, “Wilson”.

Comment on "Attractive Forces between Electrons in 2 + 1 Dimensional QED"

It is shown that a model recently proposed for numerical calculations of bound states in QED$_3$ is in fact an improper truncation of the Aharonov-Bohm potential.Comment: 4 page

On the quantum dynamics of non-commutative systems

This is a review paper concerned with the global consistency of the quantum dynamics of non-commutative systems. Our point of departure is the theory of constrained systems, since it provides a unified description of the classical and quantum dynamics for the models under investigation. We then elaborate on recently reported results concerned with the sufficient conditions for the existence of the Born series and unitarity and turn, afterwards, into analyzing the functional quantization of non-commutative systems. The compatibility between the operator and the functional approaches is established in full generality. The intricacies arising in connection with the explicit computation of path integrals, for the systems under scrutiny, is illustrated by presenting the detailed calculation of the Feynman kernel for the non-commutative two dimensional harmonic oscillator.Comment: 19 pages, title changed, version to be published in Brazilian Journal of Physic

Nonperturbative solution of the Nonconfining Schwinger Model with a generalized regularization

Nonconfining Schwinger Model [AR] is studied with a one parameter class of kinetic energy like regularization. It may be thought of as a generalization over the regularization considered in [AR]. Phasespace structure has been determined in this new situation. The mass of the gauge boson acquires a generalized expression with the bare coupling constant and the parameters involved in the regularization. Deconfinement scenario has become transparent at the quark-antiquark potential level.Comment: 13 pages latex fil