Equivalence between the Lovelock-Cartan action and a constrained gauge theory

We show that the four-dimensional Lovelock-Cartan action can be derived from a massless gauge theory for the $SO(1,3)$ group with an additional BRST trivial part. The model is originally composed by a topological sector and a BRST exact piece and has no explicit dependence on the metric, the vierbein or a mass parameter. The vierbein is introduced together with a mass parameter through some BRST trivial constraints. The effect of the constraints is to identify the vierbein with some of the additional fields, transforming the original action into the Lovelock-Cartan one. In this scenario, the mass parameter is identified with Newton's constant while the gauge field is identified with the spin-connection. The symmetries of the model are also explored. Moreover, the extension of the model to a quantum version is qualitatively discussed.Comment: 17 pages. No figures. Final version accepted for publication at the EPJ

Quintais agroflorestais como estratégia de sustentabilidade ecológica e econômica.

Resumo: Um estudo preliminar no contexto sócio-histórico do Assentamento Fazenda Pirituba, na região de Itapeva-SP, evidenciou que os quintais agroflorestais (QAs), são alternativas criadas autonomamente pelos agricultores familiares assentados na busca da reprodução social das famílias (alimentação e acesso ao mercado através do PAA). O estudo dos QAs, na medida em que os resgata da invisibilidade, poderá qualificar seu desenho e manejo, além de subsidiar políticas públicas para assentamentos rurais