Physics

In this paper a quantum { N} = 4 super-Yang Mills theory perturbed by dilaton-coupled scalars, is considered. The induced effective action for such a theory is calculated on a dilaton-gravitational background using the conformal anomaly found via AdS/CFT correspondence. Considering such an effective action (using the large N method) as a quantum correction to the classical gravity action with cosmological constant we study the effect from dilaton to the scale factor (which corresponds to the inflationary universe without dilaton). It is shown that, depending on the initial conditions for the dilaton, the dilaton may slow down, or accelerate, the inflation process. At late times, the dilaton is decaying exponentially. At the end of this work, we consider the question how the perturbation of the solution for the scale factor affects the stability of the solution for the equations of motion and therefore the stability of the Inflationary Universe, which could be eternal.

In this paper a quantum { N} = 4 super-Yang Mills theory perturbed by dilaton-coupled scalars, is considered. The induced effective action for such a theory is calculated on a dilaton-gravitational background using the conformal anomaly found via AdS/CFT correspondence. Considering such an effective action (using the large N method) as a quantum correction to the classical gravity action with cosmological constant we study the effect from dilaton to the scale factor (which corresponds to the inflationary universe without dilaton). It is shown that, depending on the initial conditions for the dilaton, the dilaton may slow down, or accelerate, the inflation process. At late times, the dilaton is decaying exponentially. At the end of this work, we consider the question how the perturbation of the solution for the scale factor affects the stability of the solution for the equations of motion and therefore the stability of the Inflationary Universe, which could be eternal.

In this paper a quantum N = 4 super Yang-Mills theory perturbed by dilaton-coupled scalars, is considered. The induced effective action for such a theory is calculated on a dilaton-gravitational background using the conformal anomaly found via AdS/CFT correspondence. Considering such an effective action (using the large N method) as a quantum correction to the classical gravity action with cosmological constant we study the effect from dilaton to the scale factor (which corresponds to the inflationary universe without dilaton). It is shown that, depending on the initial conditions for the dilaton, the dilaton may slow down, or accelerate, the inflation process. At late times, the dilaton is decaying exponentially. At the end of this work, we consider the question how the perturbation of the solution for the scale factor affects the stability of the solution for the equations of motion and therefore the stability of the Inflationary Universe, which could be eternal.

We consider an Anti-de Sitter Universe filled by quantum CFT with classical phantom matter and perfect fluid. The model represents the combination of a trace-anomaly annihilated and a phantom driven Anti-de Sitter Universes. The influence exerted by the quantum effects and phantom matter on the AdS space is discussed. Different energy conditions in this type of Universe are investigated and compared with those for the corresponding model in a de Sitter Universe.

We consider an Anti-de Sitter universe filled by quantum conformal matter with the contribution from the usual tachyon and a perfect fluid. The model represents the combination of a trace-anomaly annihilated and a tachyon driven Anti-de Sitter universe. The influence exerted by the quantum effects and by the tachyon on the AdS space is studied. The radius corresponding to this universe is calculated and the effect of the tachyon potential is discussed, in particular, concerning to the possibility to get an accelerated scale factor for the proposed model (implying an accelerated expansion of the AdS type of universe). Fulfillment of the cosmological energy conditions in the model is also investigated

A Gauss-Bonnet dark energy model is considered, which is inspired in string/M-theory and takes also into account quantum contributions. Those are introduced from a conformal quantum anomaly. The corresponding solutions for the Hubble rate, $H$, are studied starting from the Friedmann-Robertson-Walker equation. It is seen that, as a pure effect of the quantum contributions, a new solution for $H$ exists in some region, which does not appear in the classical case. The behavior of all encountered solutions is studied with care, in particular, the role played by the quantum correction term--which depends on the number of matter fields--on the stability of the solutions around its asymptotic value. It is argued that, contrary to what happens in the classical case, quantum effects remarkably lead to the realization of a de Sitter stage which corresponds to the inflation/dark energy stages, even for positive values of the f_0 constant (coupling of the field with the Gauss-Bonnet invariant).

A Gauss-Bonnet dark energy model is considered, which is inspired in string/M-theory and takes also into account quantum contributions. Those are introduced from a conformal quantum anomaly. The corresponding solutions for the Hubble rate, $H$, are studied starting from the Friedmann-Robertson-Walker equation. It is seen that, as a pure effect of the quantum contributions, a new solution for $H$ exists in some region, which does not appear in the classical case. The behavior of all encountered solutions is studied with care, in particular, the role played by the quantum correction term--which depends on the number of matter fields--on the stability of the solutions around its asymptotic value. It is argued that, contrary to what happens in the classical case, quantum effects remarkably lead to the realization of a de Sitter stage which corresponds to the inflation/dark energy stages, even for positive values of the f_0 constant (coupling of the field with the Gauss-Bonnet invariant).

In this paper a quantum N = 4 super Yang-Mills theory perturbed by dilaton-coupled scalars and spinor fields is considered. The induced effective action for such a theory is calculated on a dilaton-gravitational background using the conformal anomaly found via the AdS/CFT correspondence. Considering such an effective action (using the large N method) as a quantum correction to the classical gravity action with cosmological constant, we study the effect from the dilaton on the scale factor (this corresponds to an inflationary universe without dilaton). It is shown that, depending on the initial conditions for the dilaton, the dilaton may slow down or accelerate the inflation process. At late times the dilaton is decaying exponentially. Different possible cases corresponding to a dilatonic dS Universe are analyzed with respect to the equations of motion.

We consider an anti de Sitter universe filled by quantum CFT with classical phantom matter and perfect fluid. The model represents the combination of a trace-anomaly annihilated and a phantom driven anti de Sitter universes. The influence exerted by the quantum effects and phantom matter on the AdS space is discussed. Different energy conditions in this type of universe are investigated and compared with those for the corresponding model in a de Sitter universe.

Quantum effects lead to the annihilation of AdS Universe when dilaton is absent. We consider here the role of the form for the dilatonic potential in the quantum creation of a dilatonic AdS Universe and its stabilization. Using the conformal anomaly for dilaton coupled scalar, the anomaly induced action and the equations of motion are obtained. Using numerical methods the

The possibility of quantum creation of a dilatonic AdS Universe is discussed.Without dilaton it is known that quantum effects lead to the annihilation of AdS Universe. We consider the role of the form for the dilatonic potential in the quantum creation of a dilatonic AdS Universe. Using the conformal anomaly for dilaton coupled scalar, the anomaly induced action and the

We consider dark energy cosmology in a de Sitter universe filled with quantum conformal matter. Our model represents a Gauss–Bonnet model of gravity with contributions from quantum effects. To the General Relativity action an arbitrary function of the GB invariant, f(G), is added, and taking into account quantum effects from matter the cosmological constant is studied. For the considered model, the conditions for a vanishing cosmological constant are considered. Creation of a de Sitter universe by quantum effects in a GB modified gravity is discussed.

In this paper a quantum N = 4 super Yang-Mills theory perturbed by dilaton-coupled scalars, is considered. The induced effective action for such a theory is calculated on a dilaton-gravitational background using the conformal anomaly found via AdS/CFT correspondence. Considering such an effective action (using the large N method) as a quantum correction to the classical gravity action with cosmological constant we study the effect from dilaton to the scale factor (which corresponds to the inflationary universe without dilaton). It is shown that, depending on the initial conditions for the dilaton, the dilaton may slow down, or accelerate, the inflation process. At late times, the dilaton is decaying exponentially. At the end of this work, we consider the question how the perturbation of the solution for the scale factor affects the stability of the solution for the equations of motion and therefore the stability of the Inflationary Universe, which could be eternal.

In this paper a quantum N = 4 super Yang-Mills theory perturbed by dilatoncoupled scalars, is considered. It is shown that, depending on the initial conditions for the dilaton, the dilaton may slow down, or accelerate, the inflation process. At late times, the dilaton is decaying exponentially. At the end of this work, the question how the perturbation of the solution for the scale factor a ects the stability of the solution for the equations of motion and therefore the stability of the Inflationary Universe, which could be eternal, is considered. From another hand a dark energy cosmology model in a de Sitter universe filled with quantum conformal matter is considered. Our model represents a Gauss-Bonnet model of gravity with contributions from quantum e ects. To the General Relativity action an arbitrary function of the GB invariant, f (G), is added, and taking into account quantum e ects from matter the cosmological constant is studied. For the considered model the conditions for ...