Accelerated expansion in bosonic and fermionic 2D cosmologies with quantum effects

In this work we analyze the effects produced by bosonic and fermionic constituents, including quantum corrections, in two-dimensional (2D) cosmological models. We focus on a gravitational theory related to the Callan-Giddings-Harvey-Strominger model, to simulate the dynamics of a young, spatially-lineal, universe. The cosmic substratum is formed by an {\it inflaton} field plus a matter component, sources of the 2D gravitational field; the degrees of freedom also include the presence of a dilaton field. We show that this combination permits, among other scenarios, the simulation of a period of inflation, that would be followed by a (bosonic/fermionic) matter dominated era. We also analyse how quantum effects contribute to the destiny of the expansion, given the fact that in 2D we have a consistent (renormalizable) quantum theory of gravity. The dynamical behavior of the system follows from the solution of the gravitational field equations, the (Klein-Gordon and Dirac) equations for the sources and the dilaton field equation. Consistent (accelerated) regimes are present among the solutions of the 2D equations; the results depend strongly on the initial conditions used for the dilaton field. In the particular case where fermions are included as matter fields a transition to a decelerated expansion is possible, something that does not happen in the exclusively bosonic case.Comment: 6 pages, 5 figures, to appear in EP

Canonical Quantization of the Maxwell-Chern-Simons Theory in the Coulomb Gauge

The Maxwell-Chern-Simons theory is canonically quantized in the Coulomb gauge by using the Dirac bracket quantization procedure. The determination of the Coulomb gauge polarization vector turns out to be intrincate. A set of quantum Poincar\'e densities obeying the Dirac-Schwinger algebra, and, therefore, free of anomalies, is constructed. The peculiar analytical structure of the polarization vector is shown to be at the root for the existence of spin of the massive gauge quanta.The Coulomb gauge Feynman rules are used to compute the M\"oller scattering amplitude in the lowest order of perturbation theory. The result coincides with that obtained by using covariant Feynman rules. This proof of equivalence is, afterwards, extended to all orders of perturbation theory. The so called infrared safe photon propagator emerges as an effective propagator which allows for replacing all the terms in the interaction Hamiltonian of the Coulomb gauge by the standard field-current minimal interaction Hamiltonian.Comment: 21 pages, typeset in REVTEX, figures not include

Coevolution between Terraced Landscapes and Rural Communities: An Integrated Approach Using Expert-Based Assessment and Evaluation of Winegrowers' Perceptions (Northwest Piedmont, Italy)

Terraced landscapes are characterized by many features but are also threatened by abandonment, with the loss of the historical landscape and increased hydrogeological risk. In this research, we developed an innovative integrated approach using expert-based assessment and evaluation of winegrowers’ perceptions to investigate the coevolution between terraced landscapes and rural communities. The aims were as follows: (i) to identify the historical landscape elements, (ii) to identify the landscape dynamics, and (iii) to analyze winegrowers’ perceptions about the historical landscape elements and future development prospects. The methodology was applied to a terraced vineyard landscape (545 ha) located in Piedmont (Italy). The expert-based assessment included historical analyses and field surveys. To evaluate winegrowers’ perceptions, an online questionnaire was used to understand their perceptions about the landscape’s historical elements and dynamics. The results suggest that unique historical landscape elements and traditional practices (vine pergolas supported by stone columns) are conserved in the area, but also highlight some dynamics, including new vine-breeding techniques (espaliers) and new land uses (olive groves, meadows, and woodland). Winegrowers (n = 49) recognized as identity elements the same identified as historical by experts. Regarding future prospects, almost all winegrowers preferred the conservation of vineyards and pergolas. The research methodology was able to show the mutual link between terraced landscapes and rural communities in coevolutionary terms and could be replicated in similar contexts. According to the winegrowers’ awareness, future planning strategies will have to support dynamic conservation of the landscape