Navegando por Autor "Nemes, Maria Carolina"
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Item A coordinate independent formulation of the Weyl–Wigner transform theory.(2002) Lobo, Augusto César; Nemes, Maria CarolinaWe present the Weyl–Wigner (WW) transform theory in a much more compact way than usual, by introducing the _ basis in an intrinsic form. This permits the derivation of new identities and also leads to generalizations, like the inclusion of /nite-dimensional systems in the WW theory, which is also discussed. We show, in this case, some striking di1erences in the structure of /nite phase space depending on the underlying dimension of quantum space being an even or odd integer.Item Implicit regularization beyond one-loop order : scalar field theories.(2007) Pontes, Carlos Renato; Scarpelli, Antônio Paulo Baêta; Sampaio, Marcos Donizeti Rodrigues; Nemes, Maria CarolinaImplicit regularization (IR) has been shown as a useful momentum space tool for perturbative calculations in dimension-specific theories, such as chiral gauge, topological and supersymmetric quantum field theoretical models at one-loop level. In this paper, we aim at generalizing systematically IR to be applicable beyond one-loop order. We use a scalar field theory as an example and pave the way for the extension to quantum field theories which are richer from the symmetry content viewpoint. Particularly, we show that a natural (minimal) renormalization scheme emerges, in which the infinities displayed in terms of integrals in one internal momentum are subtracted, whereas infrared and ultraviolet modes do not mix and therefore leave no room for ambiguities. A systematic cancellation of the infrared divergences at any loop order takes place between the ultraviolet finite and divergent parts of the amplitude for non-exceptional momenta leaving, as a by-product, a renormalization group scale.Item On the equivalence between implicit regularization and constrained differential renormalization.(2008) Pontes, Carlos Renato; Scarpelli, Antônio Paulo Baêta; Sampaio, Marcos Donizeti Rodrigues; Fernandes, José Luiz Acebal; Nemes, Maria CarolinaConstrained differential renormalization (CDR) and the constrained version of implicit regularization are two regularization independent techniques that do not rely on dimensional continuation of the space-time. These two methods, which have rather distinct bases, have been successfully applied to several calculations, which show that they can be trusted as practical, symmetry invariant frameworks (gauge and supersymmetry included) in perturbative computations even beyond one-loop order. In this paper, we show the equivalence between these two methods at one-loop order. We show that the configuration space rules of CDR can be mapped into the momentum-space procedures of implicit regularization, the major principle behind this equivalence being the extension of the properties of regular distributions to regularized ones.Item On the number of degrees of freedom in Schwinger's quantum kinematics.(1995) Lobo, Augusto César; Nemes, Maria CarolinaSome algebraic properties of Schwinger's quantum kinematical phase space theory are presented. These properties lead to a definition of the maximum number of degrees of freedom of an arbitrary finite dimensional quantum system which is different from the one originally proposed by Schwinger.Item The reference state for finite coherent states.(1997) Lobo, Augusto César; Nemes, Maria CarolinaWe propose a reference state for finite-dimensional coherent states, which is easy to deal with in comparison to former suggestions which we briefly review. We also advance explicit calculations which shows that the phase of the overlap of finite coherent state has a structure analogous to the usual infinite-dimensional continuous coherent states.