CAPOZZIELLO S.

The propagation of a boson particle in the Janis-Newman-Winicour-Wyman (JNWW) gravitational field is analyzed. We derive the wave function of the scalar particle, and the effective potential experienced by quantum particles. Besides, we show that the probability to find the scalar particle near the region where the naked singularity is finite....

A detailed analysis of dynamics of cosmological models based on R n gravity is presented. We show that the cosmological equations can be written as a first-order autonomous system and analysed using the standard techniques of dynamical system theory. In the absence of perfect fluid matter, we find exact solutions whose behaviour and stability...

Higher order curvature gravity has recently received a lot of attention due to the fact that it gives rise to cosmological models which seem capable of solving dark energy and quintessence issues without using "ad hoc" scalar fields. In this Letter, a gravitational potential is obtained which differs from the Newtonian one because of a...

Higher order curvature gravity has recently received a lot of attention since it gives rise to cosmological models which seem capable of solving dark energy and quintessence issues without using "ad hoc" scalar fields. Such an approach is naturally related to fundamental theories of quantum gravity which predict higher order terms for loop...

Quintessence issues can be achieved by taking into account higher order curvature invariants into the effective action of gravitational field. Such an approach is naturally related to fundamental theories of quantum gravity which predict higher order terms in loop expansion of quantum fields in curved space-times. In this framework, we obtain a...

We study the phase space of Friedmann-Lemaître-Robertson-Walker (FLRW) models derived from scalar-tensor gravity where the non-minimal coupling is F() = ξ2 and the effective potential is V() = λn. Our analysis allows one to unfold many features of the cosmology of this class of theories. For example, the evolution mechanism towards states...

We report on recent results showing that neutrino mixing may lead to a non-zero contribution to the cosmological constant. This contribution is of a completely different nature with respect to the usual one by a massive spinor field. We also study the problem of field mixing in Quantum Field Theory in curved space-time, for the case of a scalar...

We show that the non-perturbative vacuum structure associated with neutrino mixing leads to a non-zero contribution to the value of the cosmological constant. Such a contribution comes from the specific nature of the mixing phenomenon. Its origin is completely different from the one of the ordinary contribution of a massive spinor field. We...

We report on the recent result according to which the non-perturbative vacuum structure associated with neutrino mixing leads to a non-vanishing contribution to the value of the cosmological constant. Its value is estimated by using the natural cut-off appearing in the quantum field theory formalism for neutrino mixing. © 2005 American...

We discuss an alternative approach to quintessence, modifying the usual equation of state of the cosmological fluid in order to see whether going further than the approximation of perfect fluid allows one to better reproduce the available data. We consider a cosmological model comprising only two fluids, namely baryons (modelled as dust) and...

A precise measurement of the curvature of the Universe is of prime importance for cosmology since it could not only confirm the paradigm of primordial inflation but also help in discriminating between different early-Universe scenarios. Recent observations, while broadly consistent with a spatially flat standard Λ Cold Dark Matter (ΛCDM) model,...

The standard Λ Cold Dark Matter cosmological model provides a wonderful fit to current cosmological data, but a few statistically significant tensions and anomalies were found in the latest data analyses. While these anomalies could be due to the presence of systematic errors in the experiments, they could also indicate the need for new physics...

The current cosmological probes have provided a fantastic confirmation of the standard Λ Cold Dark Matter cosmological model, which has been constrained with unprecedented accuracy. However, with the increase of the experimental sensitivity, a few statistically significant tensions between different independent cosmological datasets emerged....

The standard Λ Cold Dark Matter cosmological model provides an amazing description of a wide range of astrophysical and astronomical data. However, there are a few big open questions, that make the standard model look like a first-order approximation to a more realistic scenario that still needs to be fully understood. In this Letter of...