Time-dependent cosmological constant in the Jackiw-Teitelboim cosmology

We study the obtainment of a time-dependent cosmological constant at D=2 in a model based on the Jackiw-Teitelboim cosmology. We show that the cosmological term goes to zero asymptotically and can induce a nonsingular behavior at the origin.Comment: 4 pages, Revtex4, twocolum

On the trace anomaly and the energy-momentum conservation of quantum fields at D=2 in classical curved backgrounds

We study the conformal symmetry and the energy-momentum conservation of scalar field interacting with a curved background at D=2. We avoid to incorporate the metric determinant into the measure of the scalar field to explain the conformal anomaly and the consequent energy-momentum conservation. Contrarily, we split the scalar field in two other fields, in such a way that just one of them can be quantized. We show that the same usual geometric quantities of the anomaly are obtained, which are accompanied by terms containing the new field of the theory.Comment: 5 pages, no figure

Differential dispersion relations and elementary amplitudes in a multiple diffraction model

We discuss the evaluation of the real part of the elementary amplitudes in the context of a multiple diffraction model for $pp$ elastic scattering earlier developed. The framework is based on the concepts of analyticity and polynomial boundedness, and the techniques of dispersion relations. Novel results concern the use of derivative dispersion relations at the elementary level (constituent-constituent interactions) and an optimization of these relations in terms of one free parameter. In addition to a theoretical improvement, we achieved a satisfactory description of the physical quantities.Comment: 10 pages, aps-revtex, 5 ps figures, one reference and one Comment added, 2 references updated, minor changes. Final version to be published in Phys. Rev.

Non-Linear Supersymmetric σ\sigma -Models and their Gauging in the Atiyah-Ward Space-Time

We present a supersymmetric non-linear \s-model built up in the $N=1$ superspace of Atiyah-Ward space-time. A manifold of the K\"ahler type comes out that is restricted by a particular decomposition of the K\"ahler potential. The gauging of the \s-model isometries is also accomplished in superspace.Comment: 15 pages, Latex, no figure

Minimally Extended Left-Right Symmetric Model for Dark Matter with U(1) Portal

A minimal extension of the left-right symmetric model for neutrino masses that includes a vector-like singlet fermion dark matter (DM) is presented with the DM connected to the visible sector via a gauged U(1) portal. We discuss the symmetry breaking in this model and calculate the mass and mixings of the extra heavy neutral gauge boson at the TeV scale. The extra gauge boson can decay to both standard model particles as well to dark matter. We calculate the relic density of the singlet fermion dark matter and its direct detection cross section and use these constraints to obtain the allowed parameter range for the new gauge coupling and the dark matter mass.Comment: 19 pages, 8 figure