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Papers by Marcelo Alves

International Journal of Modern Physics D, 2001

The metric for the two-dimensional dilaton gravity can be writen in an alternative form, similar ... more The metric for the two-dimensional dilaton gravity can be writen in an alternative form, similar to the two-dimensional Schwarzschild metric, and allow us the identification of some quantitiies with those equivalent in the Schwarzschild solution. This new form, however, presents a nonphysical singularity at the horizon in the same way that in the realistic four dimensional case. We show a procedure to eliminate this horizon singularity and, as an application, the resulting metric is used to obtain the associated Hawking temperature. We discuss also some differents between this metric and the Schwarzschild one.

Classical and Quantum Gravity, 1996

We i n troduce an external eld to calculate the quantum corrections to the solutions of the 2d gr... more We i n troduce an external eld to calculate the quantum corrections to the solutions of the 2d gravity, via trace anomaly. W e show that there are black hole type solutions even in the absence of matter eld and cosmological constant. We also see that these solutions are similar to the ones obtained from dilaton two dimensional gravity.

Europhysics Letters (EPL), 2003

We study the obtainment of a time-dependent cosmological constant at D = 2 in a model based on th... more 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.

Classical and Quantum Gravity, 1992

ABSTRACT

International Journal of Modern Physics D, 2000

We discuss the two-dimensional dilaton gravity with a scalar field as the source matter. The coup... more We discuss the two-dimensional dilaton gravity with a scalar field as the source matter. The coupling between the gravity and the scalar, massless, field is presented in an unusual form. We work out two examples of these couplings, and solutions with black-hole behaviour are discussed and compared with those found in the literature.

International Journal of Modern Physics D

We discuss the two-dimensional dilaton gravity with a scalar field as the source matter where the... more We discuss the two-dimensional dilaton gravity with a scalar field as the source matter where the coupling with gravity is given, besides the minimal one, trough an external field. This coupling generalizes the conformal anomaly in the same way as those found in recent literature, but with a different motivation. The modification to the Hawking radiation is calculated explicitly and show an additional term that introduces a dependence on the (effective) mass of the black-hole.

International Journal of Modern Physics D, 2001

The metric for the two-dimensional dilaton gravity can be writen in an alternative form, similar ... more The metric for the two-dimensional dilaton gravity can be writen in an alternative form, similar to the two-dimensional Schwarzschild metric, and allow us the identification of some quantitiies with those equivalent in the Schwarzschild solution. This new form, however, presents a nonphysical singularity at the horizon in the same way that in the realistic four dimensional case. We show a procedure to eliminate this horizon singularity and, as an application, the resulting metric is used to obtain the associated Hawking temperature. We discuss also some differents between this metric and the Schwarzschild one.

Classical and Quantum Gravity, 1996

We i n troduce an external eld to calculate the quantum corrections to the solutions of the 2d gr... more We i n troduce an external eld to calculate the quantum corrections to the solutions of the 2d gravity, via trace anomaly. W e show that there are black hole type solutions even in the absence of matter eld and cosmological constant. We also see that these solutions are similar to the ones obtained from dilaton two dimensional gravity.

Europhysics Letters (EPL), 2003

We study the obtainment of a time-dependent cosmological constant at D = 2 in a model based on th... more 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.

Classical and Quantum Gravity, 1992

ABSTRACT

International Journal of Modern Physics D, 2000

We discuss the two-dimensional dilaton gravity with a scalar field as the source matter. The coup... more We discuss the two-dimensional dilaton gravity with a scalar field as the source matter. The coupling between the gravity and the scalar, massless, field is presented in an unusual form. We work out two examples of these couplings, and solutions with black-hole behaviour are discussed and compared with those found in the literature.

International Journal of Modern Physics D

We discuss the two-dimensional dilaton gravity with a scalar field as the source matter where the... more We discuss the two-dimensional dilaton gravity with a scalar field as the source matter where the coupling with gravity is given, besides the minimal one, trough an external field. This coupling generalizes the conformal anomaly in the same way as those found in recent literature, but with a different motivation. The modification to the Hawking radiation is calculated explicitly and show an additional term that introduces a dependence on the (effective) mass of the black-hole.

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